Agronomic characteristics of durum wheat stocks possessing
the chromosome substitution T1BL-1RS.
R.L. Villareal, O. Banuelos,
A. Miranda, and A. Mujeeb-Kazi.
Translocations involving the short arm of rye chromosome
1R have been of particular interest and are widely used in winter
and spring wheat breeding programs worldwide. Cultivar comparisons
have suggested that the T1BL-1RS
chromosomal translocation enhances agronomic performance and environmental
stability of wheat. However, there are concerns that the T1BL-1RS
translocation has an adverse effect on end-use quality of
bread wheat and genetic and disease vulnerability that is associated
with the 1RS segment. Stable cytological transfer of the T1BL-1RS
translocation from bread wheat to durum wheat has been demonstrated.
No studies are known of the effect of this translocations in
durum wheat. The objective of this study was to measure the effect
of the T1BL-1RS
chromosome on grain yield and other agronomic traits using 22
related durum lines (11 homozygous for chromosome 1B and 11 homozygous
The test lines were produced by substituting the T1BL-1RS
chromosome in durum wheat cultivar Altar 84 (homozygous for 1B)
All field trials were evaluated at the Mexican National
Institute of Forestry, Agriculture and Livestock, Campo Agricola
Experimental Valle del Yaqui (CAEVY) Research Center, Sonora,
Mexico, during the 1993-94
crop production cycles. Analysis of variance showed significant
differences between translocation group on all traits except harvest
index and plant height (Table 23). The T1BL-1RS
genotypes had 3.5 % increased grain yield, 3.3 % higher aerial
biomass at maturity, 11.7 % heavier kernels, more grain volume
weight, longer spikes, delayed heading, and an extended grainfilling
period and took longer to reach physiological maturity than the
1B genotypes. However, the 1B lines produced more kernels/m2
than the T1BL-1RS
lines in all tests. The expression of the 1RS may vary in other
durum backgrounds, primarily because of recombination events that
occur when chromosome 1BL wheat arms associate during meiosis.
These results require wider validation and T1BL-1RS
substitutions in other durum genetic backgrounds are in progress.
Table 23. Means for the 1B and T1BL-1RS substitution lines of durum wheat cultivar Altar 84 during the 1993-94 and 1994-95 crop cycles at CAEVY, Sonora, Mexico.
|Grain yield, kg/ha||5,306||5,493||*|
|Aboveground biomass, T/ha||12.0||12.4||**|
|Harvest index, %||44.1||44.1||NS|
|1000-kernel weight, g||41.9||46.8||**|
|Test weight, kg/hl||81.7||83.7||**|
|Plant height, cm||80.4||79.8||NS|
|Spike length, cm||7.6||8.6||**|
|Days to heading||81.8||85.0||**|
|Physiological maturity, day||122.4||127.2||**|
|Grain-fill duration, day||40.6||42.2||**
* and ** denote F-test significant at P = 0.05
and 0.01, respectively; NS= not significant.
Utilization of alien Triticeae germplasm resistant to barley
yellow dwarf virus for wheat improvement.
M. Henry, V. Rosas, and A. Mujeeb-Kazi.
Seven bread wheat-based, tissue culture-derived lines
developed in Australia with Th. intermedium chromatin (TC
5, 6, 7, 8, 9, 10, and 14) were analyzed for BYDV resistance.
Susceptible families of these lines also were included. The
BYDV-resistance status of these lines was established by ELISA
and immuno-dot blot analyses. Additional germplasm similarly
evaluated was comprised of Th. bessarabicum-
and Th. elongatum-wheat
amphiploids, their disomic chromosome addition lines (2n = 6x
= 42 + 2), Zhong 1 to 7 germplasm from China, a BC1
fertile amphiploid of the cross `T.
turgidum/P. juncea//T. turgidum'
(2n = 6x = 42; AABBNN), and an Agrotricum 56-chromosome line (OK
7211542). Use of the above alien germplasm in wheat improvement
is projected based upon data obtained through the above diagnostic
In the TC families, the Thinopyrum exchanges
for three families (TC6, 7, and 9) had a Robertsonian translocation,
whereas the TC families 5, 8, and 10 had one alien chromosome
arm that extended partially to the other chromosome arm. Of these
two exchange types, those entries with Robertsonian translocations
are preferred for wheat improvement, because of their lower amount
of alien chromatin.
FISH analyses on the TC14 lines obtained subsequently
indicated a reduced alien exchange on chromosome 7D of wheat.
This line will be of a higher priority than the TC6, 7, and 9
Robertsonian translocation families for wheat improvement, because
of its reduced alien chromatin.
Only one Agrotricum (OK 7211542) plant had a ELISA
value higher than twice the healthy threshold level. All other
plants were not infected and, therefore, were considered immune
to BYDV under our experimental conditions. Comeau et al (1994)
also observed this immunity of the OK 7211542 line. The Agrotricum
partial amphiploid has 56 chromosomes. Occasionally aneuploidy
does occur, but can be selected against. Meiosis is regular with
bivalent formation. FISH analysis indicated the presence of 14
alien chromosomes and a translocated pair in 56-chromosome plants.
Some plants had a pair of telocentric chromosomes. The OK 7211542
line is our current preference for BYDV resistance transfers to
wheat and has been subjected to ph manipulation strategies to
facilitate DNA introgression into wheat.
Comeau A, Makkouk KM, Ahmad F, and Saint-Pierre
CA. 1994. Bread wheat x Agrotricum crosses as a source of immunity
and resistance to the PAV strain of barley yellow dwarf luteovirus.
Agronomic performance of some advanced derivatives of synthetic
hexaploids (T. turgidum x T. tauschii).
R.L. Villareal, O. Banyuelos,
J. Borja, A. Mujeeb-Kazi, and S. Rajaram.
Since 1989, CIMMYT has been concentrating on exploiting
goatgrass (T. tauschii), because of its wide range of resistance/tolerance
to biotic/abiotic stresses. This wild grass also appears to be
a potent source of new variability for important yield components
such as 1,000-kernel weight, increased photosynthetic rate,
and improved bread making quality. Introgression of genes from
diploid T. tauschii into hexaploid wheat via crosses with
durum wheat is an effective way of developing stable, hexaploid
lines with unique and useful genes for bread wheat improvement.
bridge allows not only the T. tauschii genes to be exploited,
but also incorporates the genetic diversity of the A and B genomes
of the respective improved durum cultivars.
Synthetic hexaploids have been used extensively in
our bread wheat hybridization program (e.g., synthetic x bread
wheat). For example, during the 1995-96
wheat cycle at Yaqui Valley, Cd. Obregon, 40 % of the program's
bread wheat F2 populations involved a synthetic hexaploid
in the cross. Crossing methodologies employed to incorporate
this germplasm include single crosses, top (three-way) crosses,
and backcrosses. Advanced lines from this breeding effort have
been produced and are being evaluated for yield. The main objective
of this study was to evaluate the yield potential of the `synthetic
hexaploid x bread wheat'
derivatives developed by CIMMYT's wheat breeding program.
The yield trials were conducted at the Mexican Agricultural
Research Center in the Yaqui Valley, Ciudad Obregon, Sonora, during
wheat production cycles. Grain yield, yield components, and other
agronomic characteristics of the 10 highest-yielding, advanced
bread wheat derivatives are shown in Table 24 (p. 176). None
of the entries yielded significantly better than the bread wheat
check cultivar Bacanora 88. Two lines, `Chen/T.
showed comparable yield potential over the check cultivar. Improved
1,000-kernel weight was significant on most of the synthetic
Over 600 synthetic hexaploids have been developed
by the Wide Crosses Program at CIMMYT with a majority from a unique
T. tauschii accessions. These germplasms are spring types
and, hence, offer an easier route for their practical utilization
and global distribution. As screening data on biotic/abiotic
conditions of synthetics become available, we anticipated that
the hybridization effort of elite synthetics with our current
high-yielding advanced lines will increase.
Table 24. Agronomic characteristics of ten high yielding advanced bread wheats derived from 'synthetic hexaploid x T. aestivum' crosses at Yaqui valley, Sonora, Mexico, during the 1994-95 and 1995-96 wheat seasons.
|Chen/T. tauschii (205)//Kauz|
|Chen/T. tauschii (224)//Opata|
|Chen/T. tauschii (205)//Kauz|
|Chen/T. tauschii (205)//Waver|
|Chen/T. tauschii (205)//Weaver|
|Chen/T. tauschii (205)//Kauz|
|Chen/T. tauschii (205)//Kauz|
|Chen/T. tauschii (205)//Kauz|
|Chen/T. tauschii (224)//Opata|
|Chen/T. tauschii (205)//Kauz|
|Bacanora 88 (Bread wheat check)||7,911||16.2||45.9||131||87||80.5||38.6|
Table 25. The crossability data of Triticum turgidum/A-genome diploid species (T. boeoticum, T. monococcum, and T. urartu) accessions.
|T. turgidum / T. boeoticum||80||44||41|
|T. turgidum / T. monococcum||56||4||2|
|T. turgidum / T. urartu||76||14||2|
Production, cytogenetics, maintenance, and breeding implications
of A-genome amphiploids (2n = 6x = 42, AAAABB).
S. Cano, A. Cortes,
R. Delgado, and A. Mujeeb-Kazi.
The A-genome primary gene pool diploid species (T. boeoticum, T. monococcum, and T. urartu) and their accessions provide genetic diversity that can be utilized by bridge crosses where AAAABB amphiploids produced by `T. turgidum/A-genome diploid species' accession hybridizations are exploited. All F1 hybrids (2n = 3x = 21, AAB) are low- to high-frequency crosses and require embryo rescue and colchicine treatment for inducing fertility (2n = 6x = 42, AAABB). Meiotic analyses of F1 hybrids gives evidence of A-genome recombination. Derived C0 fertile products predominantly express bivalent associations. The AAAABB hexaploids express diversity that facilitates stress screening and provide a means for durum wheat improvement. One hundred seventy such AAAABB stocks are available and are described.
The vernalization procedure resulted in very vigorous
growth of all A-genome diploid accessions with a flowering range
days. Thus, a majority of the accessions were able to be crossed
with the T. turgidum cultivars. Embryos were rescued at
16 days postpollination from all crosses. Embryos were small,
translucent, generally ill-defined, and floating in a watery
endosperm cavity. Crossability data for some combinations indicating
the general trend observed for seed set, embryos recovered, and
plants regenerated are presented in Table 25 above.
All genuine F1 hybrids were stable for
2n = 3x = 21 (AAB) chromosomes. The C0 amphiploid
seed generally possessed 42 chromosomes after colchicine doubling.
Some hypo- or hyperploidy did exist, but was subsequently
purified by additional cytology and seed increase. C-banding
elucidated the AAAABB chromosomes as some amphiploids so analyzed.
Field plantings were utilized for establishing descriptive
parameters and for a seed increase from the wide array of AAAABB
wheats produced. Extensive genetic diversity for plant height,
flowering date, grain-fill duration, awn color, days to physiological
maturity, and 1,000-kernel weight was demonstrated. Utilization
of this germplasm for durum wheat improvement will presumably
be at an advantage if the more agronomically desirable amphiploids
that further express high levels of resistance to biotic/abiotic
stresses are exploited as opposed to using resistant, but poor,
F1 hybrids are generally the first step
leading to a gene introgression program and may be advanced directly
by backcrossing followed by selection. However, production of
a crucial second step, because it allows for a more reliable evaluation
of the genetic value of the alien genes (Jiang et al. 1994) in
the derived background through a permanent germplasm base. Though
amphiploid instability is a frequent occurrence, all the 170 AAAABB
C0 amphiploids produced generally were cytologically
stable. The predominance of bivalents with a high seed set/amphiploid
has enabled adequate production of seed for distribution and stress
testing. We contend that the maximum exchanges from the diploid
accessions into durum wheat occur at the F1, with the
reduced tri- and quadrivalent associations extending these
arrangements further. Anaphase separation normalcy exists in
Ma H, Singh RP, and Mujeeb-Kazi A. 1996. Resistance
to stripe rust in durum wheats, some diploid A genome accessions
and their synthetic hexaploids. Euphytica (in press).
Mujeeb-Kazi A, Sitch LA, and Fedak G. 1996.
The range of chromosomal variations in intergeneric hybrids involving
some Triticeae. Cytologia 61:125-140.
Mujeeb-Kazi A, William MDHM, and Islam-Faridi
MN. 1996. Homozygous 1B and 1BL/1RS chromosome substitutions
in Triticum aestivum and T. turgidum cultivars.
Mujeeb-Kazi A. 1996. Cytogenetics of hybrids
Thinopyrum elongatum (2n=2x=14, or 2n=4x=28) with Hordeum
vulgare, Secale cereale and Triticum turgidum. Cytologia
Mujeeb-Kazi A, Islam-Faridi MN, and Cortes
A. 1996. Genome identification in some wheat and alien Triticeae
species intergeneric hybrids by fluorescent in situ hybridization.
Mujeeb-Kazi A. 1996. Apomixis in trigeneric
hybrids of Triticum aestivum/Leymus racemosus/Thinopyrum elongatum.
Mujeeb-Kazi A and Riera-Lizarazu O. 1996.
Polyhaploid production in the Triticeae by sexual hybridization.
In: In vitro haploid production in higher plants, Vol.
1 (Jain SM, Sopory SK, and Veilleus RE eds). Kluwer Academic
Publishers. p. 275-296.
William MDHM and Mujeeb-Kazi A. 1996. Development
of genetic stocks and biochemical markers to facilitate utilization
of Aegilops variabilis in wheat improvement. Cytologia
Mujeeb-Kazi A, William MDHM, Cortes
A, Islam-Faridi MN, and Rosas V. 1996. Some disomic Thinopyrum
elongatum (2n=2x=14) chromosome additions to wheat produced
by the wheat x Zea mays polyhaploid induction methodology.
Villareal RL, Del Toro E, Mujeeb-Kazi A, and
Rajaram S. 1995. The 1BL/1RS chromosome translocation effect
on yield characteristics in a Triticum aestivum L. cross.
Plant Breed 114:497-500.
Villareal RL and Mujeeb-Kazi A. 1996. Exploitation
of synthetic hexaploids (Triticum turgidum x T. tauschii)
for some biotic resistances in wheat. In: 8th Assemb
Wheat Breed Soc Austr (Richards RA, Wrigley CW, Rawson HM, Rebetzke
GJ, Davidson JL, Brettell RIS eds). The Australian National University,
Canberra, Australia. pp. 185-188.
Villareal RL, Fuentes-Davila G, Mujeeb-Kazi
A, and Rajaram S. 1995. Inheritance of resistance to Tilletia
indica (Mitra) in synthetic hexaploid wheat x Triticum
aestivum crosses. Plant Breed 114:547-548.
Villareal RL, Del Toro E, Rajaram S, and Mujeeb-Kazi
A. 1996. The effect of chromosome 1AL/1RS translocation on agronomic
performance of 85 F2-derived F6 lines
from three Triticum aestivum L. crosses. Euphytica 89:363-369.
Villareal RL, Mujeeb-Kazi A, and Rajaram S.
1996. Inheritance of threshability in synthetic hexaploid (Triticum
turgidum x T. tauschii) by T. aestivum crosses.
Plant Breed (in press).
UNIVERSIDAD AUTONOMA AGRARIA ANTONIO NARRO
Departamento de Fitomejoramiento, Programa de Cereales de Grano
Saltillo, Coahuila, Codigo
Postal 25315, Mexico.
Northern Mexico wheat production in 1995-96.
and M. Colin-Rico.
climatic conditions were generally good in most cereal-growing
areas under irrigation in the northern Mexico region, which includes
the states of Coahuila, Nuevo Leon,
Durango, Zacatecas, and parts of San Luis Potosi
and Chihuahua. Rainfed growing areas were severely stressed by
nearly 5 years of drought.
The wheat milling industry in Coahuila is very concerned
about stimulating both the bread and durum wheat cultivation in
Coahuila, mainly to reduce industrial costs by reducing the freightage
costs. Nevertheless, grain quality may be the most important
production trouble, mainly for durum wheat production in relation
to yellow berry.
Development of bread wheat populations.
In 1995, two bread wheat population were made by
crossing 20 Mexican varieties: Yaqui
62, Nadadores 63, Siete Cerros 66, Tanori
71M, Toluca 73, Jupateco 73, Jupateco 73M, Torim 73, Cleopatra
74, Zacatecas 74, Salamanca 75, Pavon
76, Nacozari 76, Ciano 79, Ciano 79M, Abasolo 81, Celaya 81, and
CP-1 with two male-sterile donor populations. The pollination
of 400 spikes of AZ-MSFRS-80RR population (Crop Sci
18:698, 1978), with a pollen mix of the Mexican varieties
produced the population named ARIZONA-UAAAN (AZ-UAN).
The other population, named MONTANA-UAAAN (MT-UAN),
was made by pollinating 400 male-sterile spikes of the population
MTMSSF-88 (Crop Sci 29:838, 1989). Both populations
are under enhancement by phenotypic recurrent selection. Both
bread wheat populations show high variability for plant height,
days-to-flowering, and ripening. The AZ-UAN population is
spike-awned and the MT-UAN population is awnless.
Development of a durum wheat population.
In 1995, a durum wheat population was made by hand-mating
100 pure lines selected from several CIMMYT nurseries, including
four Mexican durum varieties: Mexicali 75, Yavaros 79, Altar
84, and Aconchi 89. CIMMYT nurseries were the Durum Yield Trial,
High Protein Lines Trial, Drought Tolerant Lines Trial, and the
24th International Durum Screening Nursery (IDSN). The population
CIMMYT-UAN is unexpectedly very uniform in maturity, plant
height, grain, and plant type in spite of the number of parents
involved, which may to indicate the reduced genetic base in durum
wheat breeding at CIMMYT.
ITEMS FROM NEPAL
NEPAL AGRICULTURAL RESEARCH COUNCIL
National Wheat Research Program, Pupandehi, Bhairahawa, Nepal.
M.R. Bhatta, D.R. Pokharel, Ashok Mudwari, and B.R.
Wheat crop and production statistics.
Wheat is the third major cereal crop of Nepal, after rice and maize. A minor cereal until 1960, wheat cultivation was limited to a small area (< 1,00,000 ha) in the western hills. The introduction of Mexican semidwarf, high-yielding varieties during mid-1960s had a highly significant impact on both the area and production of wheat in Nepal. Wheat occupied an area of 653,500 ha during the 1995-96 crop season. with total production of 1,012,930 MT and productivity of 1,550 kg/ha. The total wheat area, production, and productivity have been increased by 3.0, 10.7, and 7.6 %, respectively, compared to the 1994-95 wheat season. Weather conditions during the crop season were favorable, because of frequent rains and the absence of desiccating hot winds. The low productivity of wheat was due to low fertilizer use by wheat growers, inadequate irrigation facilities, late planting due to a late harvest of the rice crop, low seed replacement, and plant diseases particularly foliar blight complex caused by B. sorokiniana and P. tritici repentis. The major wheat cultivars currently popular are Nepal 297, UP 262. BL 1022, Bhrikuti, BL 1135, and Triveni in the terai region; and Annapurna-1 and Annapurna-3 (both Vee 'S'), Annapurna-4, and RR 21 in the hills.
Wheat breeding activities.
cropping system comprises more than 84 % of the total wheat area.
The major objectives of the wheat breeding and varietal improvement
program are to develop wheat cultivars that fit well into the
cropping pattern, with high yield potential; resistance to multiple
diseases (leaf and stripe rusts, major foliar blight pathogens,
and loose smut); and tolerance to postanthesis heat stress. To
create genetic variability for desirable traits, a modest hybridization
program with 150 to 200 crosses per year among selected parents
are made. F2 populations are space-planted, and individual
plant selection is made. A modified bulk system is used in the
F3 and F4 generations. Plant progenies
in segregating generations are selected based on resistance to
disease especially to the black point fungus, remaining green
at high temperature regimes during grain filling, and grain plumpness.
This year, as many as 1,779 advanced/fixed lines were evaluated
in the form of screening nurseries and yield trials at 14 different
testing sites. A total of 2,449 segregating plan-V progenies
were evaluated, and some 1,910 progenies were selected for the
next cycle. New genotypes identified for release are BL 1496
(PRL"S"/TONI//CHIL"S") and NL 713 (CPAN169/HD2204)
for the Terai, and NL 665 (LIRA/FUFAN/NEE#5"S") and
WK 685 (PGO/SERI) for the hills.
Disease situation and breeding strategy.
Leaf rust and the foliar blight complex fungi are the most serious
yield-reducing pathogens in the Terai areas, whereas stripe rust
and loose smut are the major problems in the hills. Two species
of foliar blight pathogens, B. sorokiniana and P.
tritici repentis, are the causes of blight symptoms in
wheat. The predominance of the two species changes with the environmental
conditions. Bipolaris sorokiniana predominates when the
temperatures are relatively higher.
Leaf and stripe rust incidence was less and appeared
late in the season even in susceptible cultivars in 1996. Helminthosporium
leaf blight has remained a serious problem in all wheat-growing
environments of the Terai. Yield loss to this pathogen is estimated
at 23.8 to 27 % in susceptible cultivars. Recently released wheat
cultivars BL 1135 and Bhrikuti possess a moderate degree of resistance
to the foliar blight complex pathogens. Virulence for Lr26
and Yr9 was detected at a moderate level. The importance
of adult plant resistance gene Lr34 and its combination
with other genes is greatly realized in limiting leaf rust epidemics.
Our present breeding strategy is to combine these durable resistance
genes into a high-yielding, better-adapted, and foliar blight-resistant
The CIMMYT wide cross advanced lines from T. curvifolium
(CHRlYA 1, CHRIYA 3, and CHRIYA 7) in addition to some Chinese,
Brazilian, and Zambian lines have exhibited a moderate degree
of foliar-blight resistance under Bhairahawa conditions. Some
of these lines have been widely utilized in the hybridization
program and have given adequate level of resistance in segregating
populations. Limited studies on the genetics of foliar blight
resistance involving resistant versus susceptible genotypes indicated
both qualitative and quantitative types of resistance.
Zero tillage cultivation of wheat. A new technique of zero-tillage wheat cultivation recently was developed by the National Wheat Research Program for low-land rice areas where wheat cultivation was not possible because of excessive moisture following the rice harvest. This technique involves soaking the wheat seed in fresh water for 10 to 12 hours, mixing the soaked seed with fresh cow dung, and then broadcasting the seed in standing rice 1 week before the rice is harvested, or surface-seeding just after the rice harvest. Fertilizers can be successfully applied 10 to 20 days after wheat seeding. This technique is being popularized among low-land rice farmers to bring one-third of winter rice fallow under the wheat crop.
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