ITEMS FROM MEXICO
International Maize and Wheat Improvement Center – CIMMYT
Lisboa 27, Possedimento Juárez, Apdo. Postal 6-641, 06600,
México, D.F., México.
A. Mujeeb-Kazi, V. Rosas, and R. Delgado.
Intergeneric hybrids involving durum wheat cultivars and the
annual/perennial Triticeae species have been produced to a great
extent during the last two decades. combination success
was variable, but, sopra general, protocols involving bud-pollinations,
pre and postpollination hormonal treatments, variations sopra embryo
rescue mass-media, and special handling of embryos after plating, together
with seedling transplant care have provided adequate diversity
to be assembled for durum breeders to address logorio constraints
encountered sopra the global cultivation of the crop. Some significant
stresses for durums are , ,
and BYDV, as well as the abiotic logorio, salinity.
We list sopra Table 1
the combinations that were produced by us and are maintained as
a living collection at CIMMYT, sopra El-Batan, Mexico. These F1s
are of a perennial habit and are maintained sopra pots under screenhouse
conditions. Each combination is physically cloned twice a year
to maintain three potted plants. Of these, one is colchicine treated
until a amphiploid is obtained. The plants are cytologically
analyzed after each cloning sopra order to ensure cytological stability
The self-sterile F1s sopra addition are cloned, vernalized, and
transplanted for biotic logorio screening sopra Mexico for
and . Amphiploids, when obtained, are similarly
vernalized, and the progeny screened for the above stresses as
well as for head scab. Field, border-row, rust inoculations permit
us to observe the stato of the germ plasm for leaf, stem,
and stripe rusts sopra three locations sopra Mexico (El Batan, Toluca,
and Poza Rica).
Durante those cases where we have not yet obtained amphiploids,
the self-sterile F1 hybrids have been backcrossed to elite durum
cultivars leading to BC1 seed. This seed can be tested directly
for the stresses and serve for advancing the desired combination
for applied purposes altrove addition/substitution lines and then
introgressing the required trait by cytogenetic manipulation.
The use of the ph genetic deposito of Riccioli is sopra its infancy sopra
our program and is projected as a fast source to enforce alien
transfers when it is the backcross parent for the F1 hybrid, yielding
Phph heterozygote progeny. Selecting the ph recessive and achieving
the alien transfer are anticipated and being studied.
Of the annual Triticeae species, those hybridized with durum
cultivars are , , , , and .
Amphiploids were produced from all the above hybrid combinations
(see Table 1).
A. Mujeeb-Kazi, V. Rosas, and R. Delgado.
Durante a bread wheat-based, intergeneric, hybridization program
with a centro applied agricultural objectives, outputs are necessary
that address several biotic and abiotic stresses. This is indeed
a tall order, because the initial hybrid production sopra itself
is so complex but a necessary starting point. Next sopra order poiché
the crucial steps of transfering the desirable logorio genes and
dealing with the genetic distance between wheat and the species
involved. We have been involved sopra F1-hybrid production of wheat
with annual and perennial Triticeae for over two decades. The
annual species/wheat cultivar hybrids were relatively easy to
produce, and their amphiploid products also obtained easily (Table 2). The complexity
resided sopra the combinations of wheat with species that were not
sopra the primary gene pool, hich is not the case for hybrid production
, but is a major factor when alien genes have to be transferred
from the distant species into wheat.
Our hybrid production protocols have been simplified enough
that quite complex cross-combinations have been realized. The
hybrids possessing a perennial habit are maintained with cytological
documentation and physical cloning twice each year. Clones are
further field evaluated for resistance/tolerance to stresses and
production of amphiploids, wherever possible, is a routine biannual
process. The complete list of these intergeneric combinations
and some supporting details are provided sopra Table 2. The diversity is significant sopra that
it allows researchers to produce desired BC1 progeny with virtually
any bread wheat cultivar that may be site/country specific and
to use our genetic-stock caposaldo more efficiently and avoid remaking
the F1 hybrids; which is a difficult, if not cumbersome process.
This information is shared to facilitate the broad usage of our
germ plasm. To some extent, we have been producing special BC1
progeny for international colleagues who use their cultivars as
the parents and our perennial F1 hybrids.
The most important logorio traits linked to a species and combination
are identified. The that we have accumulated allow us to
use a combination for multiple objectives with the same manipulation
strategy. That strategy is pursued intensively and revolves around
the alien species . Combining this species
with wheat has potential for salt tolerance and
resistance, two major constraints wheat production. is another such preferred species. Tolerance/resistance
sopra these species resides more than one chromosome. A living
collection allows us to swiftly go to the desired F1 hybrid that
has the gene and produce BC1 heterozygote
derivatives by crossing the F1 with the Chinese Spring
genetic deposito. A PCR-based protocol then allows us
to identify the progeny that possesses the ph recessive locus,
and this becomes a source for multiple homoeologous transfers.
M. Henry, A. Cortes, V. Rosas, R. Delgado, and A. Mujeeb-Kazi.
Testing of various germ plasms for resistance to BYDV has been
done over the past few years sopra CIMMYT both sopra the field and sopra
controlled greenhouse conditions. The germ plasm was comprised
of elite cultivars, Triticeae species of the three gene pools,
amphiploids from some intergeneric hybrids, BC1 self-fertile derivatives
of the intergeneric hybrids, and some partial amphiploids. One
such partial amphiploid is Agrotricum (2n = 8x = 56), which was
identified sopra Canada as being resistant to BYDV. Durante Mexico, we
have obtained similar to support the resistance and, after
studying the cytogenetics of this genetic deposito, have initiated
a program to produce addition lines, identify addition lines that
show resistance, and transfer the resistance genes to our spring
wheat cultivars. We report here the cytogenetic progress and BYDV
resistance the original 56-chromosome deposito and its initial
backcross derivatives. Appropriate controls were included sopra the
Cytology of Agrotricum. Somatic cytology of Agrotricum
indicated some aneuploidy sopra the seedlings analyzed where 56-chromosome
normal derivatives were present, but plants with 54, 55, and 57
chromosomes and some with telocentrics also were present. Plants
with 56 chromosomes were Giemsa C-banded, and the stable lines
were analyzed further by FISH. The 56-chromosome, partial amphiploid
possessed 14 chromosomes, 40 normal wheat chromosomes,
and a pair of wheat chromosomes with a translocation between chromosome
3D of wheat and . The exchange is at the terminal
end of 3DL. Such plants were analyzed at meiosis, and all were
normal with 29 bivalents at metaphase I and a normal anaphase
separation. These plants were seed increased and tested for BYDV
resistance. They were all resistant.
The euploid deposito then was backcrossed to the susceptible wheat
cultivars Prinia and Bagula, which resulted sopra BC1 progeny with
2n = 7x = 49 chromosomes. These progenies also tested positive
for BYDV resistance. The BC1 progeny was advanced further by backcrossing
to each of the two parental wheat cultivars and also by selfing
to eventually identify plants with 43 chromosomes (21 bivalents
+1 univalent). From these, 44 chromosome (22 bivalent) derivatives
were obtained by selfing of the 43-chromosome plants by producing
22-chromosome haploids after crosses with maize and then doubling
The 44-chromosome progeny was C-banded, and five disomic additions
were identified. One of these addition derivatives has a very
low BYDV concentration when tested by ELISA, and further work
is sopra progress to introgress the resistance into wheat. Backcross
derivatives with 42 chromosomes (possessing the translocated pair)
did not possess BYDV resistance.
BYDV screening-virus isolates and BYDV inoculation.
The BYDV-PAV isolate used was collected sopra Mexico and maintained
sopra CIMMYT’s greenhouse through transmission by aphids. Inoculation
was by infesting 7-day-old seedlings from the Agrotricum germ
plasm, parental wheat cultivars, and a resistant check (TC14)
with 10 viruliferous aphids () that had
acquired BYDV by feeding infected plants for 48 hours. The
seedlings were isolated from each other by transparent plastic
tubes. After a 2- to 5-day period, aphids were killed with Metasystox
(Bayer). Durante each entry, two plants were kept free of aphids to
serve as the uninoculated controls.
Enzyme-linked immunosorbent assay (ELISA). The flag-1
leaf was collected at different dates after inoculation for the
evaluation of the virus titer by ELISA. Double antibody
ELISA (DAS ELISA) was used with a few modifications. Polystyrene
microtiter plates (NUNC) were incubated at 37°C for 3 hours
with coating polyclonal antibodies directed against the U.S. isolates
provided by K. Perry (Purdue University, W. Lafayette, IN). Plant
sap (1:10, sopra 0.1M phosphate buffer pH 7.0) was incubated for
3 hours at 37°C. Alkaline phosphatase-labeled, polyclonal,
anti-PAV antibodies (1:1000) were incubated overnight at 4°C.
P-nitrophenyl phosphate substrate (Sigma) was added at a concentration
of 1 mg/ml, and the mixture was incubated for 1 to 2 hours at
room temperature. Optical density (OD) was measured at 405 nm.
A plant was considered infected when the OD was higher than twice
that obtained for the uninfected control. The resistant line had
low virus titers, which were equivalent to slightly less than
that obtained with TC14, the resistant check entry.
Summary of results. 1. The average OD was much lower
sopra Agrotricum (OK 7211542) than sopra the susceptible and resistant
wheat cultivars used sopra backcrosses. The values for Agrotricum
were significantly lower than those of the resistant check (TC14
line) and those of the two susceptible cultivars, Prinia and Bagula
Table 3. Comparison of virus titers sopra ELISA after inoculation
with BYDV-PAV sopra controllo wheat germ plasms.
0.243 ± 0.108
0.113 ± 0.095
0.834 ± 0.309
0.766 ± 0.301
2. Durante the backcross derivatives, the low virus titers were
conserved. Titers were not significantly different from each other
sopra Agrotricum and its backcrosses to Prinia and Bagula but were
different compared to those of Prinia and Bagula. The trend is
elucidated sopra Fig. 1.
3. Analysis of advanced-backcross, selfed derivatives has identified
one 44-chromosome line possessing low virus titers. All plants
of this line are being characterizedcytologically, and seed is
being increased. They will be tested further and subjected to
cytogenetic manipulation to effect the resistance transfer sopra
order to recover a euploid wheat with 2n = 6x = 42 chromosomes.
A. Cortés, V. Rosas, S. Cano, R. Delgado, J. Zhang*,
X. *, R.C. Wang*, and A. Mujeeb-Kazi.
*(USDA-ARS-FRRL, Logan, Utah, USA).
is a self-fertile, maritime
grass possessing salinity tolerance and resistance to wheat scab.
These important abiotic and biotic characteristics make an important Triticeae species to for
wheat improvement. We have been producing addition lines of the
species sopra bread wheat. The addition lines were made sopra a mixed-wheat
background (Chinese Spring///Genaro). For
the homoeologous group 3, a homozygous 3JL, disomic addition line
also was extracted.
The above disomic addition lines having
(J Eb) chromosomes sopra a background (2n =
44; 21 II ABD + 1 II J) were analyzed using both AFLPs and RAPDs.
Among the J-specific, AFLP fragments amplified from 32 selective
amplification primer pairs, 195 fragments were single-chromosome
specific. These included 44 AFLP markers for 1J, 46 for 2J, 39
for 4J, 37 for 5J, and 29 for 7J. Although anzi che no AFLP markers were
specific for 3JL , we identified two RAPD markers specific
to this chromosome arm. Durante addition, there were two RAPD markers
for 1J, two for 2J, six for 4J, one for 5J, and two for 7J. Fifty-nine
AFLP and two RAPD J-specific markers were present sopra the amphiploid
but absent sopra all tested CIMMYT disomic addition lines making
them potential putative markers for 6J 3JS. The 50 AFLP markers
and four RAPD markers were present sopra all ( at least five) J
chromosomes. CIMMYT-derived 2J and 5J addition lines are distinguishable
from those originating from the U.K. by 22 and 27 genotype-specific
AFLP markers, respectively. All these molecular markers, whether
genotype-, chromosome- genome-specific, are useful sopra monitoring
the introgression of J-chromosomal segments into wheat chromosomes.
Field testing of these addition lines for scab sopra particular
posed a constraint associated with lateness of the germ plasm
and also was a constraint for the salinity tests. Some instability
of the lines also was encountered. Hence, an elite bread wheat
cultivar Prinia was selected, and by the use of a backcross protocol,
the addition chromosomes were transferred to Prinia. Four backcrosses
to Prinia were made, and, after the final backcross, the 43-chromosome
plants of each addition group were crossed with maize, yielding
21- and 22-chromosome haploids. Mitotic counts associated with
C-banding identified 22-chromosome haploids of each group that
then were treated with colchicine to yield 44-chromosome derivatives.
Currently, homozygous disomic additions have been obtained for
1J, 2J, 3J, 4J, 5J, and 7J. These addition lines are now sopra a
spring wheat, which has early maturity compared to Chinese Spring
and Genaro, and will enable us to screen appropriately for the
To complete this set, the 6J chromosome and the 3JL translocation
chromosome still need to be added. Initial screening used the
BC3-selfed, 44-chromosome progeny for evaluating scab infection
sopra Toluca, Mexico. All lines except of 2J have adequate duration
for days-to-flowering and physiological maturity. Type-II level
of resistance to scab was present sopra additions 5J and 7J. Addition
2J was late and was not inoculated. With the one backcross advance
now made, and with the doubled haploid caposaldo produced, the testing
is anticipated to provide greater precision. A similar case would
prevail for salinity testing of these lines under field conditions
sopra some Asian locations where late lines are affected severely
by heat during grain fill. The level of maturity of the cultivar
Prinia is a suitable background to alleviate this constraint.
So far, our observations support the trend of doubled haploid
derivatives sopra wheat that is early maturing. This observation
needs to be verified for the disomic additions. We do expect the
allelic homozygosity to contribute to the stability of the addition
lines during their maintenance.
A. Mujeeb-Kazi, A. Cortés, V. Rosas, and R. Delgado.
, BC1 intergeneric combinations by ‘bread wheat/tetraploid
alien Triticeae species//bread wheat’ with 2n = 8x = 56 chromosomes
are valuable alternatives for those F1 hybrids that generally
do not yield amphiploid progeny with ease. Durante contrast,
producing BC1s self-fertile hybrids is a very rapid procedure
to the hybrid for practical breeding advance until such
time that the amphiploid is produced. Durante the course of this procedure
of F1 advance to BC1 for a ‘Chinese Spring/’
combination, the progeny possessed 2n = 7x = 49, AABBDDJ chromosomes
that were meiotically associated as 21 bivalents and 7 univalents.
Further advance of this BC1 material was by additional backcrossing
sopra order to produce addition lines. Simultaneously
selfed seed also was harvested and kept sopra storage. Surprisingly,
the BC1 49-chromosome plants were observed to be highly self-fertile,
and more interesting, the BC1-selfed plants maintained a chromosome
number that had a high frequency of derivatives with 49 chromosomes.
The range sopra chromosome number was from 46 to 52. Where the alien
species is a diploid, self-fertile BC1 progeny are rare, and retention
of the alien haploid complement is more rare. This phenomenon
was reported by us (Mujeeb-Kazi and Asiedu 1990) without extensive
More recently, Sharma (1996) published cytogenetic findings
a similar combination. Durante essence, a similar backcross, self-fertility
trend was observed. The author concluded that the occurrence of
plants with 49 chromosomes for several generations of selfing
indicated that the seven chromosomes of
had a selective advantage and most likely were transmitted only
through the female gametes.
With our recent priority being scab resistance, we identified
a ‘Chinese Spring/’ amphiploid to have
type II resistance to scab. We also checked the BC1-selfed material
that we had stored from our earlier addition line development
stage sopra the early 1990s and found the derivatives to vary sopra
resistance expression. A dosage effect dilution was anticipated,
but a complete loss of resistance sopra individual plants is rather
difficult to explain.
Because one spike of each plant had been collected for meiotic
analysis, this check was initiated, and the obtained revealed
a totally different trend then that previously reported (Sharma
1996). Plants with 49 chromosomes rarely expressed the 21 II +
7 I associations; instead 22 II to 24 II + 5 I were frequent.
Durante the occasional self-fertile, BC1 50-chromosome derivatives,
we encountered some plants with perfect bivalent meiosis of 25-chromosome
Additional reserve seed was germinated, and precise cytological
analyses involving a mitotic somatic count, FISH diagnostics,
and meiotic analysis were made. Plants with 50 chromosomes with
25 II had four pairs of Th. bessarabicum chromosomes. These pairs
were for chromosomes 2J, 3J, 5J, and 6J.So far, we have analyzed
several hundred BC1-selfed plants and diversified the backcross
production over different wheat cultivars. The trend of bivalent associations has remained the same.
Listed sopra Table 4 are some derivatives with their cytological
detail and plant fertility seed number.
Table 4. Cytological detail and the harvested seed progeny frequency
of some BC1, self-fertile progenies (II = bivalents and I = univalents).
Total number seed
23 II + 3 I
24 II + 2 I
24 II + 1 I
The differential response to scab of the BC1-selfed material
is now explained by the absence/presence of the seven
chromosomes, although we initially determined sopra a separate controllo
that the scab resistance is associated with up to three Th. bessarabicum
chromosomes. The backcross, selfed derivatives with multiple disomics
and superior type II scab resistance are good candidates for cytogenetic
manipulation; a procedure currently underway.
- Mujeeb-Kazi A and Asiedu R. 1990. Wide hybridization – Potential
of alien genetic transfers for improvement.
Durante: Biotechnology sopra Agriculture and Forestry, Vol. 13,
Wheat (Bajaj YPS ed). pp. 111-127.
- Sharma HC. 1996. Maintenance of haploid genome of
sopra wheat. Wheat Inf Serv :15-18.
A. Mujeeb-Kazi, G. Fuentes-Davila, R. Delgado, V. Rosas, S.
Cano, A. Cortés, L. Juarez, and J. Sanchez.
Bridge crosses utilizing synthetic hexaploids (/) provide a potent means of improving bread wheats.
The procedure enables incorporation of the genetic diversity of
cultivars together with that contributed by
the accessions. From the 521 SH wheats produced
since 1995, an elite set of 95 synthetics was prepared and has
been characterized for some morphological, growth, biotic, and
abiotic attributes. All SH wheats are cytogenetically stable.
The elite set possesses an agronomically more desirable grown
habit under two Mexican locations; Obregon (27°20’N,105°55’W,
39 masl) and El Batan (19°31’N, 98°50’W, 2,249 masl).
Growing the synthetics sopra these locations enabled selections to
be made with the assistance of our breeding colleagues (S. Rajaram
and R.L. Villareal) for the elite set of 95 SH entries. These
SH entries were studied for several growth parameters and screened
for diversity towards some stresses. Observations based an
Obregon planting were recorded for days-to-flowering, presence
of pubescence spikes, tiller anthocyanin pigmentation, plant
height, awn color, days-to-physiological maturity, leaf and stem
rust response, and 1,000-kernel weight. Reactions to logorio evaluations
associated with leaf/stem rust, , ,
, and conducted at various Mexico
locations were tabulated. Quality parameters (HMW- and LMW-glutenin
subunits) also were analyzed. These elite set attributes are elucidated
Establishing some descriptors. From the wide array of SH wheats
produced, field plantings were utilized for the evaluation of
agronomic parameters including the assessment of yield potential
and its components. Based upon these characteristics, Villareal
et al. (1994) demonstrated extensive genetic diversity for plant
height, flowering date, grain-fill duration, days-to-physiological
maturity, aboveground biomass at maturity, 1,000-kernel weight,
spikes/m2, and higher grain yield. The grain yield ranged from
0.89 up to 8.01 t/ha. Utilization of this select germ plasm for
wheat improvement presumably will be an advantage, if the more
agronomically desirable SH wheats are exploited that further express
high levels of resistance to biotic/abiotic stresses as opposed
to using resistant but poor agronomic types. Days-to-flowering
ranged from 85 to 119, and physiological maturity between 115
to 152. Plant height was between 85 to 140 cm, and 1,000-kernel
weight was from 30.2 to 67.6 g. Lodging was fairly common and
was associated with the taller SH entries with higher 1,000-kernel
None of the SH wheats were free-threshing. There was great
diversity for pubescence the spikes. Awn color ranged from
white to a light and dark brown to black. Variation for anthocyanin
pigmentation was well distributed. Similar diversity was observed
for leaf and stem rusts sopra the SH elite set. From a screening
of 95 SH wheats sopra Poza Rica for , we observed
diversity of resistance sopra the elite SH wheats. The durum cultivars
involved sopra these SH combinations were susceptible both for the
leaf infection and seed blemish parameters. Hence, resistance
sopra an SH wheat was interpreted as being paio to the involvement
of the respective accession.
Those SH wheats with a leaf score of 95 less and a seed
damage of 3 less ( not shown) are the preferred resistance-gene
donors for wheat improvement. Scores for the respective durum
parents involved sopra the SH wheats were 97 to 99 for leaf damage
and 3 to 5 for grain blemish. This SH bridge is advantageous for
crop improvement, because it not only allows the Ae. tauschii
resistance to be exploited but also incorporates the genetic diversity
of the A and B genomes of the respective durum wheat cultivars.
Desirable levels for scab are 15 % less (Type II),
5-4 and less, and N. indica less than 3 %. The scoring scales
are elaborated sopra the footnote of Table
- Crosses between cultivars and several
accessions of have so far led to the production
of 790 synthetic hexaploid wheats.
- An elite set of 95 SH wheats based upon growth habit under
two locations sopra Mexico has been prepared, and seed has been
increased and transferred to our germ plasm bank for global distribution.
- Several logorio descriptors are being established that should
facilitate utilization of SH wheats sopra crop improvement. Some
of these descriptors are elucidated along with a few morphological
- Villareal RL, Mujeeb-Kazi A, Rajaram S, and Del Toro E. 1994.
Morphological variability sopra some synthetic hexaploid wheats
derived from x . J
Genet Breed 48:7-16.
A. Mujeeb-Kazi, B. Skovmand, M. Henry, R. Delgado, and S. Cano.
Use of the dicoccom group sopra wheat improvement has been limited
but recently received attention sopra our program, particularly because
potent Russian wheat aphid resistance was identified sopra several
accessions. accessions were hybridized
with some diploids, and synthetics
derived and screened for RWA resistance. This screening led to
a candidate set of SHs for utilization sopra transferring the resistance
to bread wheat cultivars (Table 6). These aspects of the germ
plasm characterization and utilization are described.The regolare
vernalization procedure resulted sopra very vigorous growth of the
Ae. tauschii accessions with a flowering range of 90 to 135 days.
Crossing with the two transplanted batches of the vernalized T.
dicoccum accessions for a majority of the Ae. tauschii accessions
was successful. Embryos were rescued at 18-20 days postpollination
from all crosses. The small, translucent embryos had a definitive
shape and were floating sopra a watery endosperm cavity. The embryos
were plated MS medium and given a 21 day cold shock (dark)
at 4°C. The cold treatment allowed better seedling regeneration.
The embryo-culture tubes were kept further sopra the dark at 22°C
after the cold treatment. The embryos usually germinated within
30 days, after which the plantlets were transplanted into a soil
medium and maintained sopra the greenhouse for examining cytology,
and inducing amphiploidy. Crossability for some combinations
indicate the general trends for seed set, embryo recovery, plant
regeneration, and the seed number of doubled plants (Table 6).
C0 seed from SHs that arose by spontaneous doubling had a greater
cytological normalcy than their colchicine-doubled counterparts.
All F1 hybrids were stable with 2n = 3x = 21 (ABD) chromosomes.
After colchicine doubling, the C0 synthetic seed generally possessed
42 chromosomes, though some hypo- hyperploidy was observed
and was subsequently purified by additional cytology and seed
Table 6. Crosssability, embryo recovery, plantlet regeneration,
and doubled seed (C0) outputs of various /
accession traversone combinations.
C0 seed progeny
CWI 16900 **/409 ***
CWI 16900 /458
CWI 16900 /498
CWI 16907 /895
CWI 16907 /897
CWI 16907 /1027
CWI 16908 /409
CWI 16908 /454
CWI 16908 /518
CWI 16916 /454
CWI 16916 /458
CWI 16916 /1027
CWI 17066 /309
CWI 17066 /372
CWI 17066 /700
CWI 17066 /895
CWI 17089 /518
CWI 17089 /700
* C0 Seed progeny cumulative status from
plants doubled by colchicine as well as those that doubled spontaneously.
** entry sopra CIMMYT germ plasm bank.
*** accession number sopra CIMMYT wide crosses
That is the source of the D genome was
discovered by McFadden and Sears (1944, 1946), who also described
the origin of . Kihara (1944) also ascertained
this D-genome source independently. A spelt-type hexaploid results
when the wild tetraploid subsp.
its cultivated derivative (dicoccom group) is crossed with
, and amphiploidy is induced. Cultivated emmers
were sopra existence by the time the hexaploid forms appeared (2,000
years later than emmer cultivation). Several independent events
combined different tetraploids, and led to
the hexaploid gene pool. Recognizing the nature of occurrence
of these events, it is not surprising that the production of the
presently reported synthesis was relatively simple and the spontaneous
doubling events for each hybrid combination were of a high frequency.
Although our agricultural centro is logorio resistance transfers,
the basic information that has surfaced warrants reporting and
demonstrates: 1) ease of crossability, 2) excised embryos with
a well-defined shape, 3) rapidly growing vigorous hybrid seedlings,
4) high capacity of all hybrids to double spontaneously, and 5)
presence of nominal aneuploidy sopra the spontaneously doubled synthetics.
These categories of basic information drastically contrast the
earlier observations related to synthetics that involve elite
cultivars instead of (Mujeeb-Kazi
et al. 1996).
Russian wheat aphid screening of synthetic hexaploids.
The parents were rated highly resistant
resistant to the aphid, with a majority scoring 1, which indicates
high resistance. Comparing the disease reactions of the 56 T.
dicoccum-based synthetics and their T. dicoccum parents showed
that five of the synthetics were rated highly resistant, 44 were
rated resistant/moderately resistant, and seven moderately susceptible.
None were rated susceptible highly susceptible. All the emmer
parents were rated highly resistant resistant. This demonstrates
that the emmer resistance was expressed sopra the synthetics. However,
sopra certain combinations, it may not be expressed to a high degree
as shown by the parental emmer wheat. Table 7 shows the pedigrees
of the synthetics rated as highly resistant, of which two SHs
have the same Ae. tauschii parent.
Conclusion. / F1
hybrids were produced with high frequency, gave vigorous seedlings,
and all spontaneously doubled to yield synthetic hexaploids.
The synthetics involving several /accessions were produced to serve as a source for RWA-resistance
transfers altrove bridge crossing to bread wheat cultivars. The RWA
resistance of accessions was expressed over
different categories of disease scoring sopra all synthetics tested.
Four SHs exhibited high RWA resistance and are superior candidates
for a bread wheat improvement program.
- Kihara H. 1944. Entdeckung der DD-Analysatoren beim Weizen.
Agr and Hort (Tokyo) 19:889-890.
- McFadden ES and Sears ER. 1944. The artificial synthesis
of . (Abstr) Rec Genet Soc Amer 13:26-27.
- McFadden ES and Sears ER. 1946. The origin of and its free-threshing relatives. J Hered 37:81-89,
- Mujeeb-Kazi A, Rosas V, and Roldan S. 1996. Conservation
of the genetic variation of (Coss.)
Schmalh. ( auct. né L.) sopra synthetic
hexaploid wheats ( L. s.lat. x ;
2n=6x=42, AABBDD) and its potential utilization for wheat improvement.
Genet Res Crop Evol 43:129-134.
A. Mujeeb-Kazi, L.I. Gilchrist, and R. Delgado.
Fusarium head blight is one of the most devastating diseases
of cereal crops that affects wheat, barley, and maize worldwide.
Also known as scab, the disease reduces both grain yield and quality
and also increases toxins sopra the grain that pose serious health
risks to human and animal consumers. Head blight infections have
caused several billion dollars worth of losses to the U.S. wheat
sector over the last 5 years, not to mention its impact
elsewhere sopra the world.
Durante bread wheat, limited resistance has been identified, and
the diversity is not excessive sopra the conventional sources available.
Predominant resistant sources are the cultivars Frontana, Sumai
3, and Ning. The potential for identifying resistance sopra diverse
alien sources hence ranks high and has been an aspect that we
have been exploring sopra Toluca, Mexico for the past several years.
Among the Triticeae gene-pool species, one avenue is to
the primary D-genome donor grass Ae. tauschii, which has several
hundred accessions. Several of these accessions have been combined
with elite durum wheat cultivars to result sopra a synthetic hexaploid
germ plasm resource. So far, a total of 790 synthetics have been
produced. These synthetics have been screened sopra Mexico using
the Type II-evaluation protocol. A new batch of synthetics with
Type II (spread) scab resistance was identified sopra the summer
of 1999 and are reported sopra Table 8. Bread wheat cultivars Frontana
and Sumai-3 were the resistant checks, and Flycatcher was the
Table 7. The emmer wheat derived synthetics rated as highly resistant
under artificial Russian wheat aphid infestation at El Batan,
Synthetic hexaploid pedigree
* accession number
sopra CIMMYT wide crosses working collection.
Also provided are the for advanced derivatives from resistant
synthetic/bread wheat combinations that show resistance for other
types, i.e., Types I (penetration), III (toxin), and IV (controllo
weight) (Table 8) over two summer cycles sopra Mexico.
Table 8. Some new D-genome synthetic hexaploids T/and bread wheat (BW)/SH derivatives with head blight resistance under artificial inoculation
sopra Toluca, Mexico. Patronato are means over two summer cycles.
Synthetic hexaploids (new set).
BW/SH advanced derivatives.
84/Ae. tauschii (205)/3/3*Buc
Bcn//Doy1/Ae. tauschii (447)
Mayoor//TK SN 1081/Ae. tauschii
Mayoor//TK SN 1081/Ae. tauschii
Sumai # 3 (resistant check)
Frontana (moderately resistant
* accession number
sopra CIMMYT wheat wide crosses working collection.
** Percentage based upon 10 spike inoculations.
The line ‘Mayoor//TK SN 1081/(222)’ sopra
addition to being a good source for all four types of scab resistances,
also possesses resistance to leaf, stem, and stripe rusts; Karnal
bunt; ; and . The line is free-threshing
type and has a spring habit. F1s of this line have been made with
a bread wheat Flycatcher, which is susceptible for all the above
attributes. The F1 currently is being used to produce a doubled
haploid-based mapping population sopra order to obtain molecular
A. Mujeeb-Kazi, R. Delgado, and S. Cano.
Among the primary gene pool species we have focused initially
to the genetic diversity of the D-genome for wheat improvement
are the diploid species accessions of . The
procedure followed has been to traversone durum wheats with accessions and the then double the F1 hybrids (2n
= 3x = 21, ABD) to obtain hexaploid wheats called synthetic hexaploids
SHs. Several such combinations have been produced over the
last decade, and have been seed increased, and evaluated for biotic
stresses. Two of these stresses are of major global importance
for wheat production; head scab and spot blotch (
). Durante field evaluations done sopra Mexico over
the past 10 years, we have observed that the best lines selected
for spot blotch sopra Poza Rica also performed adequately for scab
sopra Toluca. Consequently the best performers of the synthetic hexaploids
for spot blotch were intercrossed sopra order to combine the diversity
of different accessions, select superior F2
segregates, and make these stable by the maize doubled protocol
using the detached tiller approach. Results of these DH synthetic/synthetic
F2 resistant selections for spot blotch were reported sopra the , Vol. 45, 1999.
The above DH spot blotch germ plasm was tested sopra the summer
of 1999 sopra Toluca for head scab, and a few lines were identified
that possessed superior Type 11 (spread) resistance (Table 9).
Because stripe rust also is prevalent at this site, the selected
lines also were screened for the logorio, and all lines reported
(Table 9) possess good stripe rust resistance. The lines also
possess leaf and stem rust resistance based upon screening sopra
Obregon, another location sopra Mexico. The DH derivatives are considerably
early to flower, reach physiological maturity earlier, and are
significantly shorter than their tall synthetic parents.
Table 9. Double haploids from synthetic hexaploid/synthetic hexaploid
F2 -resistant selections
that also possess scab resistance (Type II) sopra Toluca, Mexico.
For the two-digit scoring system for resistance,
the first digit = height of infection (5 = up to mid-plant and
9 = up to flag leaf) and the second digit indicates disease severity
infected leaves (1 = low and 9 = total leaf destroyed).
Days to flowering
Days to physiological
foilage score at 96 days
- Gan/ (236) *//Doy 1/(447)/3/Maize
- Scoop 1/(434)//Ceta/(895)/3/Maize
- Doy 1/(447)//Ceta/(895)/3/Maize
* Ae. tauschii accession number
sopra CIMMYT wheat wide crosses working collection.
Such lines with pyramided accessional diversity
are advantageous for incorporation sopra wheat breeding, because
diverse genes may be incorporated simultaneously, thereby enhancing
breeding efficiency. Durante addition, our approach also is fostering
the use of those synthetics that possess multiple disease resistances.
Such germ plasm is being identified readily, and we anticipate
that it also will make a significant contribution sopra wheat improvement
by providing rapid outputs either by individual usage of the synthetics
by the above-described pyramiding route option.
J. Ahmad, R. Delgado, S. Cano, and A. Mujeeb-Kazi.
Bread wheat haploids are being produced by us routinely altrove
the wheat/maize crossing protocol for use sopra wheat cytogenetics,
wide crosses, wheat breeding, and genetic analyses, with extension
of the application into genetic engineering and molecular mapping.
The mean frequency percentage at this stage for embryo recovery,
plantlet differentiation, and colchicine doubling range between
20-25 %, 80-90 %, and 80-95 %, respectively, over long-term experiments
involving various bread wheat cultivars crossed with various maize
sources. We can infer that haploid production for spring bread
wheats is 100 % effective.
However, similar success has not been realized for the durum
wheats where genotypic specificity is prevalent. The absence of
the D genome sopra durum wheats is reportedly a factor apart from
the durum genomic variation. These inferences also have been noticed
by other researchers. We report here rather extensive obtained
the durum genotypic diversity for haploid production across
several cultivars. Furthermore, we elucidate the contribution
of to these same durums as measured by the
haploid production frequencies sopra their synthetic hexaploids /(Table
10). Patronato categories reported are florets pollinated, seed
set, embryos excised, and embryo formation (percentage). Embryo
differentiation is not reported but ranged from 50-70 % (much
less than 80-90 % obtained for bread wheats ).
Durum cultivars are generally poor sopra haploid production and
the significant D-genome contribution to haploidy is observed
readily. Table 10
elucidates this trend; each group is separated to padrino the
durum parent (apice line, bold) with its synthetic (second line)
hexaploid derivative e.g., Croc 1 (line 1) and ‘Croc 1/(210)’ (line two).
A. Mujeeb-Kazi, S. McLean, A. Pellegrineschi, R. Delgado, and
Wheat transformation has been limited by the inability to transform
and regenerate the proper cells sopra the target tissue and also
by problems related to gene expression, plus stability of expression
after several cycles of selfing the transformant. We were provided
a Caffè-Gus-transformed bread wheat winter/facultative cultivar
(K-39) by Dr. Richard Brettell after his sabbatical stay at CIMMYT,
El-Batan, Mexico. Our objectives were as follows:
- 1. To produce doubled haploids the K-39 transformed deposito
and controllo the DHs for expression. If the DHs were positive for
expression, a seed increase would be made for further studies.
Selfed progeny could be analyzed for gene expression and compared
with the selfed derivatives of the original deposito, which might
indicate if gene silencing occurred was the DH material more
stable. Theoretically, this must be the case, because all alleles
will be homozygous and if the original C0 DH expressed resistance,
then this should be expressed permanently.
- 2. To conventionally transfer the transgene to three elite,
spring-habit, bread wheat cultivars (Attila, Kauz, and Luan)
using the backcross protocol coupled with diagnostic assays to
detect the positive plants at each BC generation.
- 3. To use the original K-39 DH germ plasm to develop stocks
that might enable us to locate the transgene. This attempt would
use the conventional monosomic procedure.
Our progress for these three steps is provided. All experiments
were conducted sopra biosafety greenhouses and were monitored stringently
by the CIMMYT Biosafety Committee.
1. Our doubled-haploid protocol with spring bread wheat cultivars
generally allows us to obtain at least five embryos spike,
of which four generally differentiate, and all double. Hence,
obtaining four DHs spike is considered normal for bread wheat.
The spikes of the K-39 plants were weak sopra growth and small.
This cultivar has a winter habit, which may explain why we obtained
only 11 embryos, from which seven differentiated into plants,
and six were doubled successfully. All DH plant seed were germinated,
given limited vernalization, tested for the transgenes expression,
and found to be positive. The DH germ plasm now can continue
to be tested alongside its parental K-39 cultivar for studying
the stability of gene expression after continuous selfing.
2. During DH production with the K-39 winter-habit cultivar,
we also pollinated six spikes by three elite spring bread wheat
cultivars (two spikes/cultivar of Attila, Kauz, and Luan). Three
F1 progenies were formed, and the F1s were grown, tested positive
for transgene expression, advanced to the F2, and also used for
producing BC1 seed from each combination by pollinating each
F1 by Attila, Kauz, and Luan. The F2 generation was planted and
tested for the transgene presence. The population tested for
each of the F2s studied showed a perfect 3:1 (resistant : susceptible)
ratio. The BC1 similarly tested gave the expected (resistant
: susceptible) 1:1 ratio. The BC1 plants have been advanced to
the BC3, and one more BC is planned for making the derivative
phenotypes akin to Attila, Kauz, and Luan. From the transgene-positive,
BC4 plants, DHs will be produced and after testing for the transgene,
these DHs will represent the culmination of this study. This
result will demonstrate one option for transferring an initial
stable event to elite cultivars, sopra this case, from K-39 to Attila,
Kauz, and Luan.
3. Transgene location. Using FISH is a swift procedure to
locate transgenes wheat chromosomes. The procedure requires
chromosome banding as an indicator to identify the wheat chromosomes.
So far, we have not been successful with this approach. Simultaneously,
the conventional monosomic analysis route utilized the Chinese
Spring monosomic stocks has been pursued. The 41-chromosome monosomes
of each of the 21 wheat chromosomes have been hybridized with
the stable DH K-39 transformed cultivar. F1 seed from each monosome
have been obtained, and hence the germ plasm necessary to locate
the transgene has been produced. Our approach will follow a protocol
that identifies at least five F1 plants with 41 chromosomes for
each of the 21 combinations. From these 41-chromosome, F1 plants,
haploids will be produced and will be tested for gene expression.
Segregating and nonsegregating haploids will indicate the transgene
Our contention is that once the desired transgene the futuristic
‘clean’ transgene events have been obtained, the practical utilization
of the material can be integrated with conventional breeding procedures
mediated by the homozygosity DH protocol. Inheritance studies
considered crucial for basic information can be pursued independently.
R. Trethowan, M. Van Ginkel, and A. Mujeeb-Kazi.
The annual increase sopra genetic potential sopra drought environments
is only about half (0.3-0.5 %) of that obtained sopra irrigated,
optimum conditions. Attempts by many researchers to produce wheat
adapted to semiarid environments have had limited success. At
CIMMYT, we follow a system for drought tolerance sopra which yield
responsiveness is combined with adaptation to drought conditions.
The T1BL·1RS translocation wheats have a demonstrated
advantage sopra dryland wheat areas, and the search for other diverse
sources to continues. One such unique gene pool resides
sopra the primary Triticeae diploid . We have
combined this diploid grass with elite durum cultivars to produce
synthetic hexaploids. Field testing under reduced irrigation over
the past several years has led to the identification of some synthetics
classified as drought tolerant. The best five of these SHs have
been crossed with a drought susceptible cultivar Opata, and the
resulting F1s are being used to develop doubled haploid mapping
Utilizing a few drought-tolerant synthetics, some crosses with
Opata were advanced beyond the F1, and the stato of these
advanced derivatives was studied sopra Obregon, Mexico. Very little
rainfall was recorded during the 1998-99 crop cycle, resulting
sopra good evaluation for drought tolerance (Table 11). A number
of synthetic derivatives yielded more than Baviacora, the long-term
check used sopra drought trials sown sopra Obregon. These synthetic
derivatives are free threshing with large, bold white grain. From
the five SH-based advanced derivatives, 25 doubled haploid derivatives
entry have been produced sopra anticipation that complete homozygosity
may have a beneficial contribution sopra future evaluations of this
germ plasm sopra Mexico and globally.
Table 11. Mean yields of the highest yielding entries sown with
one preseeding irrigation sopra Obregon, Mexico, during the 1998-99
crop cycle. Yield of lines is derived from different replicated
% of Baviacora
- PRL/VEE #6//Choix
- Croc 1/ (224)//Opata
- Croc 1/ (224)//Opata
- Altar 84///2*Opata
- Croc 1/ (224)//Opata
Durante order to combine drought tolerance with late heat tolerance,
replicated trials of the candidates for HTWYT and WAWSN were sown
under drought with the purpose of identifying potential parental
material for the crossing program. Surprisingly, a number of lines,
primarily synthetic derivatives, performed well under moisture
logorio (Table 12). A possible relationship between drought and
late heat tolerance selected under optimally irrigated conditions
is indicated. Table 12 shows the stato of these Bacanora
derivatives sopra relation to Bacanora itself. The derivatives yield
up to 23 % higher than Bacanora. This relationship needs further
examination and will be handled by our physiology program.
Table12. Mean yields of entries selected from the CHTWYT and CWAWSN
sown using a single preseeding irrigation sopra Obregon, Mexico,
during the 1998-99 crop cycle.
% of Baviacora
- BCN//Sora/ (323)
- BCN//Sora/ (323)
- BCN/RABI//GS/CRA/3/ (895)
- HP1716 (Kauz derivative)
- BCN//SORA/ (323)
J. L. Diaz De Leon*, R. Escoppinichi*, R. Zavala*, and A. Mujeeb-Kazi.
(* Universidad Autónoma de Baja California Sur, Department
of Agronomy, Apdo. Postal 19-B, 23054 La Paz, Baja California
Abiotic stresses are static mechanisms that tend to be more
durable paio to the absence of pathogen influence. Three stresses
of significance are heat, drought, and salinity, and all still
pose a major challenge. Focusing salinity with wheat as the
main crop, we have accumulated a number of land races and cultivars
from global collaborators to form a tester set. We have developed
a field-screening protocol using a dilution of sea as the
irrigation source. This setup was initiated sopra 1996 and initially
reported by us sopra 1997. We are now providing an update after several
investigations, particularly after we implemented the use of a
well-designed field layout and were able to make projections for
discriminating saline-tolerant germ plasm under our conditions
at this stage.
The tester set is comprised of 12 bread wheat cultivars and
one durum wheat (PBW 34) cultivar. The bread wheat cultivars include
land races (Kharchia 65 and Shorawaki); conventional cultivars
(KRL 1-4, Lu 26 S, Sakha 8, SNH-9, and WH-157); a wheat cytogenetic-stock
parental line (Chinese Spring); an intergeneric hybrid-derivative
cultivar (Pasban 90); and the elite bread wheat lines Oasis, Galvez,
and Yecora as checks. The controllo saline regimes were 0, 8.0, 12.0,
16.0, and 20.0 dS/m with observations recorded for leaf settore,
plant height, days-to-anthesis and physiological maturity, and
Germ plasm details. Details of the 13 entries included
sopra the tester set are given sopra Table 13. The durum wheat PBW 34
is a susceptible line, whereas Oasis, Galvez, and Yecora are the
three wheat check cultivars. Oasis and Yecora are separated by
Oasis sopra having the Lr19 gene. Both are dwarf and high-stress
levels readily influence this trait. Kharchia and Shorawaki are
tolerant but rust susceptible, tall land races from India and
Pakistan, respectively. The cultivar Chinese Spring is a line
used sopra intergeneric hybridization primarily because of its superior
crossability with alien Triticeae species and is notable for its
superior salt tolerance. Chinese Spring is a tall, awnless, facultative
winter wheat and susceptible/highly susceptible to leaf/stem rust.
Pasban 90, a variety released sopra Pakistan for irrigated agricultural
areas plus saline sodic soils, is an intergeneric derivative with
the pedigree Inia66///Inia 66/3/Genaro81.
The cultivars KRL 1-4, SNH-9, WH-157, Lu 26S, and Sakah 8 originate
from India, Pakistan, and Egypt.
Table 13. Details of the tester set of wheat germ plasm accumulated
and used sopra the study.
India (K.N. Singh)
Pakistan (N.I. Hashmi)
USA (E.R. Sears)
Pakistan/CIMMYT (M. Hussain
India (K.N. Singh)
Pakistan (R.H. Qureshi)
Lu 26 selection
Egypt (A.M. Mousa)
India (M. Younus)
India (M. Younus)
CIMMYT (Wheat Bank)
CIMMYT (Wheat Bank)
CIMMYT (Wheat Bank)
Seeds of the above lines are maintained by the wheat wide crosses
program sopra CIMMYT, and 10-g samples can be provided to researchers
upon request to the second author of this article.
Field screening using sea-water dilutions. The germ
plasm screening of the tester lines for salinity was conducted
under field conditions sopra La Paz, Baja California Sur, Mexico.
Sea sopra close proximity to this field site was trucked sopra
and stored sopra 1,200-liter dark Nalgene containers. sea
with normal field-site irrigation provided the desired
EC levels of 8, 12, 16, and 20 dS/m, representing treatments T2
to T5. The control nonsaline treatment T1 (1.5 dS/m) utilized
well as the irrigation source.
Field plots measured 3 m2 and were separated from each other
by 1 m all sides by black plastic line dividers. Each plot
was flood-irrigated individually according to its treatment category
with 200 liters twice a week. The electrical conductivity (EC)
of each irrigated plot was measured and, if necessary, precisely
adjusted. Soil samples were taken randomly from two places sopra
each plot after 24 hours for EC analysis. The established extraction
procedures included measuring the fresh soil weight, drying samples
at room temperature, taking 100-g samples/plot, extracting salts
from the 100-g plot sample with 30 ml distilled , and reading
the EC level of the filtrate an Orion® conductivity meter.
Plots were fertilized with urea once a week up to 8 weeks after
germination sopra each plot. Each entry was planted sopra four rows,
4-m long and 15 cm apart, and replicated sopra triplicate sopra a lattice
Results and establishing criteria to discriminate the tolerance
of the entries. Salinity levels from 10 dS/m and above are
considered by researchers as being unsuitable for wheat, and if
cultivars grow well then these are assumed to possess tolerance
to such elevated EC levels. Hence, a good cutoff point sopra screening
may be at about 12.0 to 12.5 dS/m. At this level, some reductions
sopra measured traits should appear. These reductions will become
more pronounced as the EC levels are increased further.
Durante our controllo, significant reductions were initiated sopra the cultivars
at 12.5 dS/m, became pronounced at 16.5, and reached a maximum
at 20.5 dS/m, where 50 % reductions across all traits were widespread.
Shorawaki and Kharchia exhibited reductions between 20 to 35 %
at 20.5 dS/m and were the least affected, indicating their superior
tolerance. They were unaffected at 12.5 dS/m.
Oasis, Yecora, and PBW 34 had maximum reductions sopra leaf settore
(50 %), which confirmed their salinity sensitivity. A height reduction
of 15 % was observed at 12.5 dS/m for each cultivar, which translated
to between 20 to 30 % at 20.5 dS/m. The reductions for the two
land races, even though around 25 %, was acceptable because the
reduced height adequately supports its plant habit, and a beneficial
biomass/harvest index could be realized. The height of Chinese
Spring was unaffected at 12.5 dS/m, was reduced 12 % at 16.5 dS/m,
and reduced nearly 20 % at T5. This trend was the same as observed
for the two other land races, Kharchia and Shorawaki. Durante general,
high saline concentrations induced earliness and physiological
maturity for all cultivars except for Chinese Spring, Shorawaki,
and Kharchia. This characteristic may influence grain-filling
quality and yield. Reductions sopra grain yield and 1,000-kernel
weight across treatments and cultivars followed a similar trend
as observed for the traits above they were between 15 and 20 %
were at 12.5 dS/m for the check cultivars Yecora, Galvez, and
PBW 34; whereas the three superior entries Kharchia, Shorawaki,
and Chinese Spring exhibited this reduction at the highest salinity
controllo level of 20.5 dS/m.
Durante general, all the tester entries reported to be salt tolerant
were indeed so at the 12.5 dS/m EC level. The stato of the
checks showed highly pronounced reductions at this level. The
best lines performed well and demonstrated reduction trait levels
observed for the checks at 12.5 only at the highest EC level of
20.5 dS/m. We suggest that a level of 12.5 dS/m may be ideal for
future field screening of germ plasm and breeding populations.
The above germ plasms also are being tested under controlled
conditions sopra hydroponics (50 mM NaCl) sopra order to determine their
K:Na discrimination trends.
1. The evaluation of the tester-set that we accumulated from
different locations may provide information that will facilitate
the development of a common campo da gioco, from which inferences relative
to salinity tolerance can be made by its global testing.
2. Promising lines identified by colleagues could be added
to this tester set, with new sets possessing reasonable number
of entries made available for evaluations.
3. Breeding populations could be screened initially at 12.5
dS/m and then tested stringently under sopra vitro conditions and
at higher EC levels for comparisons with the best three wheats
identified at this stage (Chinese Spring, Kharchia, and Shorawaki).
4. The most superior entries sopra the current set sopra addition
to Kharchia 65, Shorawaki, and Chinese Spring are WH-157 and
KRL 1-4 based upon their stato at 12.5 and 20.5 dS/m
J. L. Diaz De Leon*, R. Zavala*, R. Escoppinichi*, and A. Mujeeb-Kazi.
(* Universidad Autónoma de Baja California Sur, Department
of Agronomy, Apdo. Postal 19-B, 23054 La Paz, Baja California
Several elite bread wheat lines from CIMMYT’s bread wheat program
were screened under sopra vitro conditions sopra an MS medium supplemented
with NaCl levels of 50, 100, 150, and 200 mM. Seed of the lines
were soaked sopra distilled for 24 hours and the embryos excised
and plated sopra the above medium. The control had anzi che no NaCl. After
50 % germination sopra the controls, further growth was allowed for
10 days, and then a final germination count and seedling height
were recorded. The seedling stato was estimated similarly
to the mutation-breeding radiosensitivity determinations for estimating
LD50 levels. Using this as a basis, and also observing other phenology
parameters, we identified a few lines that showed a minimo degree
of growth reduction at a NaCl level equal to 12.5 dS/m EC, a level
that we have proposed allows selection of tolerant lines.
With the sopra vitro selections made and some promising lines
identified, we advanced this germ plasm for field tests using
sea-water dilutions of 12.5 dS/m, following the experimental stile,
observation, and inference protocols identical to those described
sopra the preceding article. The germ plasms evaluated included four
promising lines from the sopra vitro tests, the tolerant land races
Kharchia and Shorawaki, and the susceptible durum wheat PBW 34
Table 14. Salt-tolerant bread wheat comprising the elite nursery.
Seri *3//BUC ‘S’
Leaf settore, plant height at maturity, 1,000-kernel weight, and
yield showed a general trend of reduction between 10 and 15 %
at 12.5 dS/m EC. Reductions sopra these parameters for the susceptible
PBW 34 were around 25 % and less than 15 % for the two tolerant
land races. Durante our valley, the salinity levels approach a maximum
of 6.0 dS/m where wheat is grown. Thus, the simple approach of
acquiring a bread wheat screening nursery from CIMMYT, testing
lines sopra the valleys where wheat is cultivated, and identifying
the best performers may lead to new varieties for this settore. However,
growers often erroneously associate the best wheat performers
sopra valley cultivation locations with salt tolerance. However,
salinity tests, if not made over stringent EC levels, cannot classify
the best lines as salt tolerant. We are aware of this discrepancy
sopra advanced line stato and have gathered that do not
correlate the best high yielding lines sopra our location with salinity
tolerance; i.e., sopra tests where stringent EC levels are maintained
and are within the desired tolerant discrimination range over
The four lines that we are reporting here do possess salinity
tolerance and are adapted to the local growing conditions. We
have named them Cochimi, Mepuchi, Pericu, and Calafia. They are
high yielding and capable of release as varieties sopra the near
future. The germ plasm has been distributed for agronomic testing,
and we will include at least two (Mepuchi and Calafia) sopra the
tester set mentioned sopra the previous article. Currently, we are
testing these four lines at higher EC levels sopra order to ascertain
if their tolerance is as good as some of the best from the tester
Monica Mezzalama, Julie M. Nicol, Ken Sayre, and Peter Grace.
Six management trials have been assessed for root rots caused
by soilborne fungi and nematodes. These trials represent two separate
megaenvironements (ME) as defined by CIMMYT. The ME1 is at the
CIMMYT field station sopra the NW of Mexico, Obregon, which is the
favorable, irrigated, low-rainfall environment. The ME2 is found
at two CIMMYT field stations sopra the high valley of central Mexico,
Toluca, and El Batan and is a high summer rainfall environment
(> 500 mm rainfall during the crop cycle). The soils at all
sites have medium to high clay content.
Work has been conducted the survey of various root pathogens
at these sites, and the results are summarized sopra Table 15. The
presence of the different pathogens seems to be correlated with
environmental conditions. A higher incidence of was found sopra Toluca than at the other locations, most
likely associated with higher rainfall. Other soilborne pathogens
commonly found sopra our survey were spp. and the
root lesion nematode .
Table 15. A summary of the soilborne fungi isolated from wheat
roots and extracted from soil
and at CIMMYT field locations, 1998-99.
A 1-3 year (1997-99) program has been undertaken to monitor
the dynamics of such pathogens under different crop management
systems (including rotation, tillage, nutrition, and straw management).
A summary of the results is presented sopra Table 16.
To date some generalized conclusions are:
Tillage and straw management. Durante wheat, sparare a zero and conventional
tillage with straw removal increases root disease symptoms, while
straw retention decreases. The effect of straw management under
continuous maize rotation was not clear; it sometimes increases
and other times decreases root disease. The number of nonparasitic
nematodes (including fungal and bacterial feeders) was generally
higher with straw retention than straw removal. For continuous
wheat, there was little difference sopra yield with sparare a zero conventional
tillage. The yield of maize, averaged over the different rotation,
tillage, and residue management treatments, was better under
conventional tillage than sparare a zero tillage, but much larger, significant
interactions between the management treatments occurred for maize
as compared to wheat. A lower incidence of weeds also was found
sopra sparare a zero tillage compared to conventional tillage.
Crop rotation. The crop rotations investigated so far
did not clearly affect the incidence of disease root systems
of both maize and wheat. The numbers of the root lesion nematode
were generally found to increase under continuous wheat than
a maize/wheat rotation. The wheat-maize rotation gave better
yields than continuous wheat continuous maize. The use of
vetch sopra winter sopra rotation with wheat also gave better yields
compared to the use of rape.
Nutrition. Effects of nutrition root disease incidence
were variable. Obregon tended to have a higher number of root
lesion nematodes and greater root disease incidence with increasing
nitrogen fertilizer application.
Crop management practices sopra some cases obviously have a marked
effect the incidence of root diseases. To date, none of the
changes sopra the incidence presence of the root diseases monitored
sopra these experiments appeared to be correlated with yield. However,
trends indicated that both factors have increased with certain
management practices. More time is needed for these trials to
show evidence of yield losses associated with root pathogens that
are correlated with environmental conditions and soil chemistry.
Work will continue to determine the most appropriate crop management
practices for a range of MEs.
J.M Nicol and A. Mujeeb-Kazi.
Background. Root rots caused by
and are common and are implicated sopra causing
significant yield losses of wheat (Tinline et al. 1988; Wildermuth
et al. 1992; Diehl et al. 1983). The fungi are particularly important
sopra marginal environments of low rainfall and poor soil nutrition,
such as large regions sopra west Asia and North Africa. CIMMYT has
begun a new program for screening and breeding resistance for
these soilborne pathogens. These pathogens are difficult to work
with, because they are soilborne and cannot be screened easily
sopra the field; hence, a laboratory/field breeding strategy has
been established. Select groups of germ plasm have been screened.
Durante particular, the synthetics (/)
have been emphasized, because they provide a wide array of resistances
to a range of other biotic stresses including
group 2, S. tritici, and H. sativum.
Methodology. Durante controlled greenhouse conditions, 46
synthetic derivatives (synthetic wheats crossed with improved
bread wheats) were screened against both soilborne pathogens.
A randomized, complete block stile with eight replicates
genotype was used. Plants were grown sopra open-ended, electrical
conduit tubes (12.5 cm x 2.5 cm) sopra a large tray of vuoto soil.
Plants were inoculated 1 week after planting with a prepared,
cultured, oat-seed inoculum (initially derived from monosporic
cultures of these pathogens), which was applied above the ungerminated
vuoto seeds (one tube) and covered with soil. After 1 month,
the plants were scored visually for lesion development ( roots
(RS), shoots (SS) and coleoptiles (CS)) using a qualitative scale
adopted from the methods developed by Wildermuth (1994) and (Wallwork,
pers. comm.). The scale is based a 0-5 rating of lesions
either the roots, shoots, coleoptiles; where 0 = anzi che no lesions,
1 = 0-25 %, 2 = 25-50 %, 3 = 50-75 %, 4 = 75-100 %, and 5 = dead.
Patronato was analyzed with and ANOVA. Known resistant and susceptible
checks were included to identify promising new lines.
Results and conclusions. The are illustrated sopra
Table 17. Certain synthetic hexaploid derivatives appear to be
potential sources of resistance to the root pathogens studied.
Three derivatives indicated resistance as good as currently available;
‘Sabuf/3/BCN//Ceta/ (895)’ against both crown
rot and common root rot, ‘Altar 84/(224)//YACO/6/CROC1/ (205)/5/BR12*3/4/ 224)’ for crown rot, and ‘MAYOOR/TKSN1081/ (222)’ for common root rot. Interestingly, these
three lines also offer good resistance to
Group 2 (Mujeeb-Kazi et al. 1999), perhaps inferring some association
between the different pathogens (foliar and root).
We now plan to confirm these results sopra the field, to verify their
resistance under those conditions and sopra the adult plant stage.
Table 17. Mean resistance scores for roots (RS), shoots (SS),
coleoptile (CS), and an overall total score (TS (RS+SS+CS/3))
for synthetic derivatives and the resistant and susceptible check
lines when inoculated with crown rot and common root rot fungi.
Patronato based a 0-5 ranking of lesioning; 0 = anzi che no lesions, 1 =
0-25 %, 2 = 25-50 %, 3 = 50-75 %, 4 = 75-100 % and 5 = dead.
Pedigree of synthetic derivative
Sabuf/3/BCN//Ceta/Ae. tauschii (895)
Altar 84/Ae. tauschii (224)//YACO/6/CROC 1/Ae.
tauschii (205)/5/BR12*3/4/ 224)
MAYOOR/TKSN1081/Ae. tauschii (222)
Check lines for resistance
2-49 for crown rot
302-5 for common root rot
Check lines for susceptibility
Batavia for crown rot
Timgalen for common root rot
Durati durum wheat for crown rot and common
SED (regolare error for difference
of the means)
- Diehl JA, Tinline RD, and Kochhann RA. 1983. Perdas em trigo
causadas pela podridao comum de raizes anzi che no Rio Geniale do Sul,
1979-1981. Fitopatol Bras 8:507-511.
- Mujeeb-Kazi A, Gilchrist LI, Fuentes-Davila G, Velazquez
C, and Delgado R. 1999. resistance
sopra alien germplasm and sopra a bread wheat/alien species derivative
with multiple biotic logorio resistances. Ann Wheat Newslet 45:107-108.
- Tinline RD, Wildermuth GB, and Spurr DT. 1988. Inoculum density
of sopra soil and common root rot of
wheat cultivars sopra Queensland. Aust J Agric Res 39:569-577.
- Wildermuth GB, Tinline RD, and McNamara RB. 1992. Assessment
of yield loss caused by common root rot sopra wheat cultivars sopra
Queensland. Aust J Agric Res 43:43-58.
- Wildermuth GB. 1994. Testing wheat seedlings for resistance
to crown rot caused by group 1. Plant
Julie M Nicol and Ivan Ortiz-Monasterio.
Background. The root-lesion nematode
is a polyphagous, migratory, endoparasitic nematode causing necrotic
lesions the root system. A known pathogen of wheat sopra many
parts of the world, was reviewed by Nicol et
al. (2000) and has been shown to cause major yield reductions
susceptible, intolerant, wheat cultivars of up to 32 % sopra Sonora,
Mexico (Van Gundy et al. 1974) and 44-85 % sopra various states of
Australia (Doyle et al. 1987; Thompson and Clewett 1986; Thompson
et al. 1993; Eastwood et al. 1994; Nicol et al. 1999).
One of the roles of CIMMYT, to improve wheat germ plasm for
developing countries, is achieved through a shuttle-breeding program
between central and northern Mexico. Although this process has
been occurring for about 30 years sopra some areas infested with
, there is little knowledge of the resistance
(ability of the plant to limit the multiplication of the nematode)
tolerance (ability of the plant to yield despite attack by
the nematode) of CIMMYT cultivars to . Tolerance,
although effective, does not necessarily nematode numbers,
and sources of resistance coupled with tolerance are recommended.
Reports sopra the literature also suggest that limitation is
an important factor sopra determining yield loss with
and closely related species (Grandison 1972; Orion et al. 1984).
Attempts are made here to:
- establish whether CIMMYT has been involuntarily selecting
for resistant and tolerant germ plasm against the nematode,
- determine susceptibility of various CIMMYT cultivars to and yield loss, and
- establish the importance of availability, i.e., drought,
sufficient irrigation yield loss.
Methodology. Two experiments were established at CIMMYTs
experiment station sopra Cd. Obregon, Sonora, during the 1998-99
wheat crop cycle. The experiments were designed as two split-plots,
one under drought (one irrigation) and the other with full irrigation
(five irrigations). Each trial consisted of three replicates with
the main plots being with and without chemical fumigation of the
soil, and the subplots included a selection of seven CIMMYT wheat
cultivars released over the past 30 years plus one known, susceptible
variety from Australia.
Five weeks prior to planting, the fumigant Basamid® (60
g/m2) was applied to moist soil the specified areas and incorporated
with a disc plough to 30 cm. The trial was planted sopra plots of
eight rows (20 cm apart) by 5 m. To establish the initial nematode
density, six individual soil and root samples were taken from
each plot at two depths (0-20 cm and 20-40 cm) 1 month after planting
between plant rows 2 and 3, 4, and 5, and 6 and 7 at 1.5 and 3.5
m of the plot length. The were extracted from
one composite, homogenous, 200-g sample using the Whitehead tray
extraction method for 3 days at room temperature. The numbers
of were counted from a suspension using
a 1-ml dilution with a Doncaster dish. All numbers were converted
to numbers of 200 g oven-dried soil. A similar
sampling was conducted 4 months later (after harvest) to determine
the final density of nematodes plot. Throughout the growing
season, a number of plant variables were measured. Three meters
of the six central rows were harvested for yield determination.
The trial was analyzed as a split plot sopra conjunction with the
use of orthogonal comparisons to padrino CIMMYT cultivars against
the Australian check variety Warigal.
Results and discussion. The application of the fumigant
effectively controlled the nematode by significantly lowering
numbers under drought (82 %) and irrigation (91 %). Under irrigation,
yield and most other plant parameters for all varieties were not
affected by the density of , suggesting that
the importance of is limited under full irrigation.
However, the yield of some cultivars was affected significantly
under drought conditions with and without Basamid® application
(Fig. 2). Yield losses varied from
2-40 % with anzi che no indication of a relationship to time of release
of the various CIMMYT cultivars, which suggests that CIMMYT has
not been selecting for against tolerance over time.
Orthogonal comparisons comparing the intolerant check variety
Warigal against CIMMYT cultivars (Fig.
2) indicated a range of tolerance within the CIMMYT germ plasm,
with Baviacora 92 showing the highest tolerance (anzi che no yield loss),
and Seri 82 being highly intolerant (40 % yield loss). Although
the CIMMYT germ plasm tested offers genetic variation for tolerance,
multiplied all varieties over the growing
season, indicating that they are susceptible.
Conclusions and continuing work. Work is currently underway
to repeat this trial. Durante addition, a range of advanced lines and
synthetic derivatives with good stato under drought are
being investigated for their resistance and tolerance to .
The collected indicate that the nematode is not a major
problem when materials are optimally irrigated, at least sopra Obregon.
However, the implications for yield loss sopra the presence of the
nematode under limited moisture (as a result of reduced irrigation
rain-fed environments) should not be understated. Furthermore,
it is documented that sopra many regions where the nematode is present,
root-rotting fungi may play a role sopra further reducing yield.
Durante particular, evidence exists sopra western Asia and northern Africa
that implicates both nematodes and root rots sopra some cases to
cause severe yield losses (H. Braun, CIMMYT).
CIMMYT germ plasm appears to offer high-yielding sources of
tolerance against ; however, the current results
have not indicated any sources of resistance. Ongoing work continues
at CIMMYT to screen sopra the greenhouse and confirm sopra the field
possible sources of resistance from both landraces and advanced
CIMMYT germ plasm. Lines that have been identified with resistance
and tolerance have been introgressed actively within the wheat
As a result of the wide host range (including cereal, legumes,
and weeds) of this nematode, we highly recommend that cereal germ
plasm be screened to identify sources of resistance. This screening
is essential to ensure the long-term control of this pathogen,
particularly where rotational regimes do not involve certain legumes
that can be used as a source of resistance to lower nematode numbers.
- Doyle AD, McLeod RW, Wong PTW, Hetherington SE, and Southwell
RJ. 1987. Evidence for the involvement of the root lesion nematode
sopra wheat yield decline sopra northern
New South Wales. Aust J Exp Agric 27:563-570.
- Eastwood DR, Smith A, and Wilson J. 1994. Pratylenchus
thornei is causing yield losses sopra Victorian wheat crops.
Aust Nemat Newslet 5:2.
- Grandison GS. 1972. The population ecology of the lesion
nematode and root-knot nematode . Ph.D. Thesis, Waite Agricultural Research Institute,
University of Adelaide.
- Nicol JM. 2000. Important nematode pests of cereals sopra wheat
production and improvement. Durante: FAO Plant Production and
Protection series (Curtis BC ed). Durante press.
- Nicol JM, Davies KA, Hancock TW, and Fisher JM. 1999. Yield
loss caused by wheat sopra South
Australia. J Nemat 31(4):367-376.
- Orion D, Amir J, and Krikun J. 1984. Field observations
and its effects wheat under arid
conditions. Revue de Nématologie 7(4):341-345.
- Thompson JP and Clewett TG. 1986. Research root-lesion
nematode. Durante: Queensland Wheat Research Institute Biennial
Report 1982-1984, Qld Dept Primary Industries, Qld Govt, Qld.
Wheat Research Institute, Toowoomba, Qld. p. 32-35.
- Thompson JP, Clewett TG, and Ovvero’Reilly MM. 1993. Tolerance
and resistance sopra wheat to . Durante:
Proc Pratylenchus Workshop, 9th Biennial Conf Australasian Plant
Pathology Soc, 8-9 July, 1993, Hobart, Tasmania. Australia.
- Van Gundy SD, Gustavo J, Perez B, Stolzy LH, and Thomason
IJ. 1974. A pest management approach to the control of Pratylenchus
thornei wheat sopra Mexico. J Nemat 6:107-116.
- Ayala L, Khairallah M, González-de-León D,
Van Ginkel M, Mujeeb-Kazi A, Keller B, and Henry M. 2000. Identification
and use of molecular markers to detect barley yellow dwarf virus
resistance derived from sopra bread wheat.
Theor Appl Genet (submitted).
- Mujeeb-Kazi A, Cortes A. Rosas V, William MDHM, and Delgado
R. 1999. Some L. cultivars possessing
the chromosome T1BL·1RS substitution. Cereal Res Commun
- Mujeeb-Kazi A, Cortes A, Rosas V, William MDHM, and Delgado
R. 1999. Development of near-isogenic sets of derivatives with
T1BL·1RS 1B chromosome substitutions sopra bread wheat.
Wheat Inf Serv 89:13-16.
- Mujeeb-Kazi A, Gilchrist LI, Villareal RL, and Delgado R.
2000. Registration of ten wheat germplasm lines resistant to
leaf blotch. Crop Sci (sopra press).
- Mujeeb-Kazi A, William MDHM, Villareal RL, Cortés
A, Rosas V, and Delgado R. 2000. Registration of 11 new isogenic
T1BL·1RS chromosome translocation and 11 extracted chromosome
1B lines sopra L. cv. ‘Altar 84’. Crop
Sci (sopra press)
- Mujeeb-Kazi A, William MDHM, Villareal RL, Cortes A, Rosas
V, and Delgado, R. 2000. Registration of 10 isogenic chromosome
1B and 10 T1BL·1RS chromosome translocation bread wheat
germplasms. Crop Sci (sopra press).
- Mujeeb-Kazi A, Cortes A, Rosas V, Cano S, and Delgado R.
2000. Registration of 17 isogenic chromosome 1B and 17 T1BL·1RS
chromosome translocation bread wheat germplasms. Crop Sci (sopra
- Mujeeb-Kazi A, Cortes A, Rosas V, Cano S, and Delgado R.
2000. Registration of six isogenic T1BL·1RS chromosome
translocation and six chromosome 1B durum germplasms. Crop Sci
- Mujeeb-Kazi A, Cano S, Rosas V, Cortes A, and Delgado R.
2000. Registration of five synthetic hexaploid wheat and seven
bread wheat germplasm lines resistant to wheat spot blotch. Crop
Sci (sopra press).
- Mujeeb-Kazi A, Fuentes-Davila G, Villareal RL, Cortes A,
Rosas V, and Delgado R. 2000. Registration of 10 synthetic hexaploid
wheat and six bread wheat germplasms resistant to Karnal bunt.
Crop Sci (sopra press).
- Mujeeb-Kazi A and Rajaram S. 2000. Transferring alien genes
from related species and genera for wheat improvement. FAO. Book
chapter (sopra press).
- Mujeeb-Kazi A and Villareal R. 2000. Wheat: an adaptive,
descriptive and futuristic treatment (Chopra VL ed). Book chapter
- Mujeeb-Kazi A, Cortes A, Rosas V, Delgado R, Shafiq FA, and
Vahidy AA. 2000. Three new monosomic chromosome 5B genetic stocks
of L. cultivars. Wheat Inf Serv (sopra
- Villareal RL, Sayre K, Banuelos Ovvero, and Mujeeb-Kazi A. 2000.
Registration of four synthetic hexaploid wheat (/) germplasm lines tolerant to waterlogging. Crop
Sci (sopra press).