BHABHA ATOMIC RESEARCH CENTRE
Nuclear Agriculture and Biotechnology Division, Mumbai-400085, India.
B.K.Das *, A. Saini **, Ruchi Rai *, S.G. Bhagwat *, and N.
Jawali **.
* Nuclear Agriculture & Biotechnology Division and ** Molecular
Biology Division.
Improving wheat quality by combining desirable HMW-glutenin subunits and durable rust-resistance genes in a high-yielding background is in progress. Single-plant selections made in the F3 generation are being evaluated for their agronomic characters.
Wheat-rye translocations have been widely used by breeders worldwide. Translocations involving the short arm of chromosome 1 (1RS) of rye significantly influence wheat cultivar performance, because 1RS has genes for resistance to pathogenic fungi and insect pests and also influences dough quality and agronomic traits. The reciprocal translocation involving wheat chromosome 1BS is designated as T1BL·1RS. In a study of genetic diversity among Indian wheat cultivars using RAPD markers, a 1.1-kb band was found only among cultivars lacking T1BL·1RS. Of 49 cultivars, 35 cultivars lacking T1BL·1RS amplified this band. A close link between this band and the region of 1BS involved in the translocation was postulated. An F2 population from a cross involving one parent with T1BL·1RS was analyzed. The 1.1-kb band segregated in 3:1 ratio. Segregation between the T1BL·1RS translocation and the 1.1-kb marker indicated that the new marker will be useful in identifying homozygous individuals for T1BL·1RS in early generations. The marker is being developed into SCAR a marker.
Crosses were made between Indian and Australian cultivars for genetics and breeding objectives. F2 populations were grown. These populations will be used to develop molecular marker(s) and transfer useful gene(s) to Indian cultivar backgrounds.
E. Nalini *, S.G. Bhagwat **, and N. Jawali *.
* Molecular Biology Division and ** Nuclear Agriculture and Biotechnology
Division.
Variation in the internal transcribed spacer (ITS) region was
detected using PCR-RFLP in the cultivars Kalyansona and Sonalika.
An F2 population of 150 plants resulting from a cross between
these two genotypes was analyzed. Segregation for the Kalyansona
variant was observed to fit a 3:1 ratio (X2, P = 0.2-0.3). The
ITS variant was mapped on chromosome 1B at a distance of 26.8
cM from the Glu-1B locus.
S.G. Bhagwat (Nuclear Agriculture and Biotechnology Division).
Radiation-induced mutants can be useful in genetic studies. A genetic stock with the sphaerococcum character was subjected to gamma-ray treatment. A mutant with a lax spike was isolated and stabilized into a true-breeding condition. The parent had a spike length of 5.22 ± 0.11 cm with 3.14 ± 0.07 spikelets/cm. In the mutant, the spike length was 6.8 ± 0.15 with 2.06 ± 0.07 spikelets/cm. The mutant showed a 30.2 % increase in spike length and a 34.4 % reduction in spikelets/cm. An F2 population from a cross between the mutant and parent showed segregation for lax intermediate and compact spikes. Initial results indicated monogenic inheritance of the lax spike mutation.
R. Vishwanathan *, S.G. Bhagwat **, S.P. Shouche ***, R, Rastogi
***, and J.K. Sainis *.
* Molecular Biology Division, ** Nuclear Agriculture and Biotechnology
Division, and *** Computer Division.
Grain morphology is important in assessing wheat grain quality
and in visual cultivar identification. Computer-based, image analysis
can measure morphometric parameters accurately and, thus, has
a potential for use in the assessment and identification. Grain
size and shape is influenced by environment. We designed experiments
to study how computer-based, image analysis can be used to deal
with environmental and genotypic variation. Three cultivars were
sown on three different dates in the field at Trombay in a replicated
experiment. Grain samples were collected at maturity and image
analysis was made on each replicate separately. Images were grabbed
using a scanner and analyzed with Comprehensive Image Analysis
Software (CIPS). About 45 size- and shape-related parameters were
used based on the variation. Euclidean distances were calculated.
Euclidean distances for samples of the same cultivar sown at different
times were smaller, indicating a greater resemblance between them
than compared to samples of different cultivars. The results indicate
that image analysis has the potential to overcome problems of
environmental variation to a certain extent.
BHARATHIAR UNIVERSITY
Cytogenetics Laboratory, Department of Botany, Coimbatore-641 046, India.
V.R.K. Reddy and G. Kalaiselvi.
Eight stem rust-resistance genes (Sr24, Sr25, Sr26, Sr27, Sr28, Sr31, Sr36, and Sr38), four leaf rust-resistance genes (Lr19, Lr24, Lr26, and Lr37), and two stripe rust-resistance genes (Yr9 and Yr17), present singly or in combination (in linked condition), were transferred from alien hexaploid wheat stocks into three Indian hexaploid wheat cultivars (HW 2034, HW 4001, and K 8962). Gene transfer was confirmed with biochemical markers. Changes in the enzymatic activity of peroxidase, polyphenol oxidase, catalase, esterase, and lipoxygenase in the leaves of 25-day-old plants of rust-susceptible wheat parents and rust-resistant NILs inoculated with the respective rust pathogen showed altered activity.
The constituted lines showed higher peroxidase activity compared to the healthy controls 2-7 days post-inoculation. Polyphenol oxidase activity increased in all NILs 3-7 days post-inoculation, whereas a decrease in activity was observed in the susceptible parents. Catalase activity was higher in susceptible wheat parents than in the resistant NILs. Lipoxygenase activity increased in both the susceptible wheat parents and their NILs 2 days after inoculation, but subsequently decreased 7 days after inoculation in resistant plants. A consistent increase was noticed in the susceptible parents. Esterse activity increased in all the NILs 3-7 days after inoculation but decreased in activity in the susceptible wheat parents. The total lipid content of the leaves increased in both susceptible and rust-resistant NILs 2 days after inoculation but subsequently decreased as the post-inoculation time increased. The percent decrease was greater in the susceptible parents than in the resistant NILs. Soluble protein content increased in resistant NILs 24 hours after inoculation but subsequently decreased towards later stages of infection. The percent decrease was greater in susceptible lines 7 days after inoculation.
SDS-PAGE analysis of the soluble proteins did not show any major qualitative difference in the protein profiles in the leaves of either healthy or inoculated susceptible parents and their resistant NILs 1 and 7 days after inoculation with rust spores, and most of the protein bands were common in all the lanes. However, quantitative changes were observed as seen from the intensity of the banding pattern. Some of the major protein bands were found to increase in intensity in the leaves 24 hours after inoculation in both susceptible and resistant plants. The increase was greater in the resistant plants. The intensity of the major protein bands decreased in the leaves of susceptible and resistant plants 7 days after inoculation. The decrease was greater in the susceptible plants.
The specific activity of ribonuclease-I and combined ribonuclease-II and nuclease-I was high at the 15-day stage compared to that at the 10th day in both susceptible and resistant lines. Resistant NILs had a relatively higher chlorophyll content than the susceptible wheat parents. Free amino-acid content increased up to the 8 days after inoculation in both susceptible and resistant wheat lines. After 8 days, a slight reduction was seem in both cases.
Respiration rate increased to a greater extent in resistant NILs compared to their susceptible wheat parents. By the 3rd day after inoculation, the reduction in respiration rate in the susceptible parents was dynamic, whereas in the resistant NILs, the level was more or less constant. A significant increase in total free phenols and tannin content was observed in the NILs over their respective recurrent wheat parents. The NILs had a significantly higher nuclear DNA content than their respective susceptible wheat parents. Resistant NILs accumulated proline at a more rapid rate and at higher level as a result of infection than did the susceptible wheat parents.
V.R.K. Reddy and G. Kalaiselvi.
Twenty T. aestivum cultivars were analyzed for their allelic variations of HMW-glutenin subunits by SDS-PAGE. A total of 10 alleles were identified, three (a, b, and c) at the Glu-A1 locus, four (a, b, c, and d) at the Glu-B1 locus, and three (a, b, and d) at the Glu-D1 locus. The most frequent HMW-glutenin subunits were 2* at Glu-A1, 7 at Glu-B1, and 2+12 at Glu-D1. The most frequent protein combinations are 2*, 7+8, 2+12 and 2*, 7, 5+10. The Glu-1 quality score ranged from 5-10. The Glu-1 quality score 8 is present in a large number of cultivars. We predict that those cultivars that possess a high Glu-1 score have good bread-making quality, i.e., above 8, and those with a Glu-1 score below 7 are of very poor bread-making quality.
V.R.K. Reddy and G. Kalaiselvi.
Gliadins from 10 common wheat cultivars were extracted and separated by SDS-PAGE. The cultivars were classified into two groups based on the presence or absence of two bands (designated as 40 and 43.5 according to their mobility) in their electrophoregrams. Cultivars of group 1 had prominent band 40 and lack band 43.5, whereas cultivars comprising group 2 showed the strong band 43.5 and lacked band 40. The cultivars containing band 43.5 possess stronger gluten properties than the cultivars containing band 40. Bands 40 and 43.5 could be gliadin components typical of bread wheats, coded by the locus on homologous chromosome group 1D. In view of the important effects of bands 40 and 43.5 on gluten properties, a better understanding of genetic aspects of these bands could be of considerable value in the qualitative breeding of common wheats.
V.R.K. Reddy and M. Binumol.
We introgressed five leaf rust-resistance genes (Lr19, Lr24, Lr28, Lr32, and Lr37), four stem rust-resistance genes (Sr24, Sr25, Sr34, and Sr38), and two stripe rust-resistance genes (Yr8 and Yr17) into three Indian wheat cultivars C 306, UP 2338, and HP 1205 in a backcross breeding program. Near-isogenic wheat lines were constituted either in the BC2F5 and/or the BC5F5. Gene transfers were confirmed with molecular markers. Isogenic lines with leaf rust-resistance gene Lr24 were used this purpose. The primers J09/1 and J09/2 gave a specific band for the resistant lines 1, 3, 5, and 7, whereas it was absent in the susceptible lines. The amplification product size was 4,000 bp. The presence of this band only in the donor parent and its resistant derivatives indicates that this fragment originated from the donor parent.
Eight RAPD primers, OPB-07, OPB-16, OPB-03, OPJ-09, OPB-18, OPB-11, OPB-06, and OPR-11, also were used to identify bands specifically present in only the resistant lines of C-306, HP1205, and UP 2338. They gave amplification products ranging from 400-1,200 bp, whereas several other bands generated by the RAPD primers were identical in both susceptible and resistant NILs.
B. Menaka, K.A. Nayeem *, M. Sivasamy *, A.J. Prabakaran *,
M.K.Menon *, and V.R.K. Reddy.
* Indian Agricultural Research Institute, Regional Station, Wellington-643231,
The Nilgiris, Tamil Nadu, India.
Fifteen T. aestivum and 15 T. turgidum subsp. dicoccum wheat cultivars were crossed with four tester T. aestivum cultivars C 306 (Ne1 ne2 ch1 Ch2), Sujatha (ne1 Ne2 Ch1 ch2), Klein Lucero (ne1 Ne2 ch1 Ch2), and Kharkof (ne1 Ne2 Ch1 ch2). All hexalpoid and tetraploid wheat genotypes were crossed separately with each of the testers. The genotypes of the wheat cultivars for hybrid necrosis and hybrid chlorosis were determined from the phenotype of their F1 hybrids. Observations on the degree of hybrid necrosis and hybrid chlorosis were taken periodically at different stages of plant growth. Six out of 15 hexalpoid wheats produced normal hybrids without any necrosis when crossed with testers C 306 and Sujatha, whereas the same cultivars produced necrotic hybrids with Klein Lucero and Kharkof indicating the presence of Ne2 in these wheats. The remaining nine wheats produced necrotic hybrids with C 306 and Sujatha, suggesting that they are carriers of Ne2. They produced normal hybrids with the other two testers. On the other hand, all 15 hexaploid wheats produced normal hybrids without any chlorosis with C 306 and Klein Lucero and chlorotic hybrids with Sujatha (except HI 667 and HI 687), also indicating that all of them are the carriers of Ch2. HI 667 and HI 687 produced normal hybrids without any chlorosis with the other two testers suggesting that they do not carry any dominant chlorotic genes.
In the dicoccum wheats, all 15 cultivars produced normal hybrids without any necrosis with C 306 and Sujatha. These lines carry Ne1. The fact that 10 out of 15 wheats produced necrotic hybrids with Klein Lucero and Kharkof also supports this conculsion. The remaining five tetraploid wheats produced normal hybrids without necrosis with the other two testers, indicating that they carry recessive necrotic alleles. All 15 dicoccum wheats produced normal hybrids without chlorosis with Sujatha and Kharkof indicating the presence of Ch1 alleles in all these cultivars. Five of the 15 tetraploid wheats also produced normal hybrids without any sympotoms of chlorosis with C 306 and Klein Lucero, suggesting that they carry recessive chlorotic alleles. The genotypes of the hexalpoid and tetraploid wheats with reference to necrosis and chlorosis genes present are given in Table 1.
| Hexaploid wheats | Tetraploid wheats | ||
|---|---|---|---|
| Cultivar | Genotype | Cultivar | Genotype |
| HD 2009 | ne1 Ne2^m^ ch1 Ch2^w^ | Azar | Ne1^w^ ne2 Ch1^s^ ch2 |
| HD 2021 | ne1 Ne2^m^ ch1 Ch2^w^ | Farmer K 6413 | Ne1^w^ ne2 Ch1^s^ ch2 |
| HD 2028 | ne1 Ne2^s^ ch1 Ch2^w^ | Felted Khapli | Ne1^w^ ne2 Ch1^s^ ch2 |
| HD 2068 | ne1 Ne2^s^ ch1 Ch2^w^ | Khapli | Ne1^w^ ne2 Ch1^m^ ch2 |
| HP 741 | Ne1^s^ ne2 ch1 Ch2^w^ | Khapli PI 33 | Ne1^m^ ne2 Ch1^m^ ch2 |
| HW 515 | Ne1^m^ ne2 ch1 Ch2^w^ | Khapli Pink 508 | Ne1^w^ ne2 Ch1^m^ ch2 |
| MP 113 | Ne1^s^ ne2 ch1 Ch2^w^ | Khapli 101 Yellow | Ne1^w^ ne2 Ch1^s^ ch2 |
| MP 114 | Ne1^s^ ne2 ch1 Ch2^w^ | Swan 248 | Ne1^w^ ne2 Ch1^s^ ch2 |
| HI 667 | ne1 ne2 ch1 ch2 | WDL 26 | Ne1^w^ ne2 Ch1^s^ ch2 |
| HUW 12 | ne1 Ne2^m^ ch1 Ch2^m^ | WDL 27 | Ne1^w^ ne2 Ch1^m^ ch2 |
| HUW 91 | ne1 Ne2^s^ ch1 Ch2^m^ | NP 201 | ne1 ne2 ch1 ch2 |
| HW 558 | ne1 Ne2^s^ ch1 Ch2^m^ | NP 202 | ne1 ne2 ch1 ch2 |
| HW 600 | ne1 Ne2^m^ ch1 Ch2^m^ | HW 65 | ne1 ne2 ch1 ch2 |
| HW 601 | ne1 Ne2^s^ ch1 Ch2^m^ | V 585 | ne1 ne2 ch1 ch2 |
| HI 687 | ne1 ne1 ch1 ch2 | V 604 | ne1 ne2 ch1 ch2 |
CH. CHARAN SINGH UNIVERSITY
Department of Agricultural Botany, Meerut - 250 004, India.
P.K. Gupta, H.S. Balyan, R. Bandopadhyay, N. Kumar, S. Sharma, P.L. Kulwal, S. Rustgi, R. Singh, A. Goyal, and A. Kumar.
QTL analysis for different traits using the International
Triticeae Mapping Initiative population and a trait-specific population.
QTL analysis for grain-protein content (GPC) using two
populations (an intervarietal population and the International
Triticeae Mapping Initiative population (ITMI pop).
Genetic dissection of GPC followed single-locus and two-locus
QTL analyses, with the particular objective of studying QTL x
QTL (QQ), QTL x environment (QE), and the QTL x QTL x environment
interaction (QQE) for this trait. Two different mapping populations
were utilized. Population I was derived from a cross between two
Indian cultivars (WL711/PH132), and population II was the ITMIpop.
Each population was grown in 4-5 different environments. A total
of 14 QTL (spread over eight different chromosomes; 1A, 2B, 2D,
4A, 5B, 6D, 7A, and 7D) in population I and 12 QTL (spread over
following eight chromosomes; 1A, 1B, 1D, 2A, 2D, 3B, 5D, and 7A)
in the ITIMIpop were detected following two-locus analyses (QTLMapper),
as opposed to 10 and 7 QTL detected in Population I and the ITMIpop,
respectively, following a single-locus CIM (QTL Cartographer).
Ten M-QTL (main effect QTL) were detected in the two populations;
five in each population. The M-QTL accounted for 7.24 % of the
total variation in Population I and 7.22 % variation in the ITMIpop.
In both the mapping populations, major QTL were detected on chromosome
2D. In Population I, four E-QTL (epistatic QTL), and in the ITMIpop,
six E-QTL, were detected, which accounted for a mere 2.68 % and
6.04 % of the phenotypic variation, respectively. Contrary to
the small proportion of variation contributed by M-QTL and E-QTL
for GPC, QE and QQE contributed a substantial proportion of variation
in Population I (25.91 %) and in the ITMIpop (47.99 %). The importance
of using more than one diverse mapping population for detecting
many more QTL and using two-locus analysis in detecting interactions
has been documented in this study. This work has been submitted
for publication to Plant Physiology.
QTL analysis for preharvest sprouting tolerance (PHST) using
the ITMI pop.
QTL interval mapping for preharvest-sprouting tolerance (PHST)
with the ITMIpop used single-locus and two-locus analyses. For
this trait, 110 RILs of the ITMIpop were evaluated in four different
environments comprising three different locations. At physiological
maturity, data on PHST were recorded on each of the 110 RILs (in
each of the four environments) on a scale of 1-9 with a score
of 1 for genotypes with complete resistance to preharvest sprouting
and a score of 9 for the genotypes with complete sprouting. Marker
genotyping data of 521 mapped molecular markers was retrieved
from GrainGenes for QTL analysis. A wide range of variability
for PHST among the RILs as opposed to the narrow range of variability
between the parents (W7984 and Opata85) of the ITMIpop encouraged
us to conduct QTL interval mapping using single-locus analysis
followed by composite-interval mapping (CIM). We identified five
QTL on four chromosomes, 2B, 2D, 3B, and 3D. A two-locus analysis
using QTLMapper resolved a total of 14 QTL including eight M-QTL,
eight E-QTL, and five QTL involved in QE or QQE interactions.
Four of the five QTL detected following CIM were common to the
14 QTL detected following two-locus analysis. We observed that
more than three-fourths (76.68 %) of the variation for PHST is
due to M-QTL (47.95 %) and E-QTL (28.73 %) as opposed to a very
small fraction (3.24 %) that is due to QE and QQE. Two QTL detected
above the threshold LOD score and in more than one environment
were located on 3BL and 3DL, presumably in the vicinity of dormancy
gene TaVp1. Another QTL located on 3BL was in close proximity
to the R gene for red grain color. Thus, PHST differs from GPC
in its genetic control. PHST is mainly controlled by M-QTL and
E-QTL, whereas GPC is mainly controlled by QE and QQE interactions.
This study on PHST has been published in Functional & Integrated
Genomics.
QTL analysis of PHST and grain weight (GW) using trait-specific,
intervarietal mapping populations.
Two mapping populations consisting of 100 RILs each, one derived
from the cross 'SPR8198 (PHS tolerant)/HD2329 (PHS susceptible)'
and the other from the cross 'Rye selection (high GW)/Chinese
Spring (low GW)' are available. Phenotypic data on PHST and GW
were recorded at three different locations for 2 years for a total
of six environments. Genotyping of both populations of 100 RILs
was made using AFLP, SAMPL, and SSR markers. AFLP and SAMPL genotyping
used fluorescent primers and an ABI 377 sequencer and GeneScan/Genotyper
software. SSR analysis used the conventional method of silver
staining. Marker genotyping data for a total of 320 and 466 markers
(including a combination of AFLP, SAMPL, and SSR markers) for
the PHST and GW mapping populations, respectively, were available.
This data was used to prepare framework linkage maps of these
mapping populations. Using this genotyping data, and the phenotypic
data recorded in six environments (and also that averaged over
environments), single-marker regression analysis was conducted
for PHST. A total of 63 markers were found to be associated significantly
to QTL that contribute to variation for PHST, with an R2 ranging
from 4.09 % to 29.03 %. Marker gwm155, which was earlier mapped
on 3AL, exhibited the highest R2 (29.03 %). For GW, 79 markers
were found to be associated with QTL that contribute significantly
to variation for PHST, with R2 ranging from 3.96 % to 11.89 %.
Monosomic analysis for GPC. Continuing our earlier studies, an F2 monosomic analysis was used to identify chromosomes that carry genes/QTL for GPC. The crosses involved a high GPC (14.82 %) wheat genotype, PH132, which also is a parent of an intervarietal mapping population we used for QTL analysis for GPC and a monosomic series in Chinese Spring. Ten different chromosomes (2A, 1B, 2B, 3B, 4B, 5B, 6B, 7B, 1D, and 2D) were identified to carry genes/QTL for GPC.
The results of monosomic analysis were compared with those from our recent studies on QTL analyses conducted for eight different environments. We detected QTL for GPC on 16 different chromosomes of bread wheat using CIM by QTL Cartographer and by conducting two-locus analysis by QTLMapper, which detects QTL with main effect, epistatic effects, and 'QTL x environment' interaction. The 16 chromosomes with QTL included 9 out of the 10 different chromosomes identified by monosomic analysis. From these results, we concluded that the QTL analysis detected QTL for GPC on seven more chromosomes than were identified following monosomic analysis. Similarly, none of the QTL for GPC detected following QTL analysis could be assigned to 1D, which was one of the 10 chromosomes that were identified to carry genes/QTL for GPC following monosomic analysis. Failure to detect genes/QTL on 1D through QTL analysis should be due to inavailability of an adequate number of mapped markers on this chromosome. In the future when more markers are used, QTL analysis also should be able to detect QTL for GPC on 1D.
Development and use of EST-SSRs and EST-SNPs (using wEST).
Development of EST-SSRs from wheat EST databases.
We have extended our study on the development of wheat EST-SSRs
to increase the density of SSRs in the expressed region of the
wheat genome. For this purpose, we screened ~415,000 wESTs for
the presence of SSRs and discovered 10,415 nonredundant (nr) SSRs
giving a density of one SSR/20.15 kb. Trinucleotide repeats (TNRs)
were the most frequent. Primers also were designed for 380 nrEST-SSRs.
The above SSR-ESTs also were annotated and divided into 16 classes
based on their putative function predicted by a BLAST similarity
search.
Transferability of wheat EST-SSRs and genomic SSRs in 18
alien species of Triticeae.
Sixty-four functional EST-SSR primers developed previously that
we used to study polymorphism, transferability (against oats,
maize, rice, rye, and barley), and genetic diversity among 52
elite wheat genotypes (Gupta et al. 2003) also were used to study
transferability to 18 alien species of Triticeae possessing different
genomes (A, B, D, M, N, and U) and ploidy levels (2x, 4x, and
6x). The results were summarized in Bandopadhyay et al. 2004.
In-gel hybridization and PCR-based approaches also were used earlier
to study interspecific SSR polymorphism among 14 species of Triticum-Aegilops
group (Sharma et al. 2002).
Development of EST-SNPs and estimation of LD. Massive databases of ESTs and gDNA clones derived from libraries enriched for genes already have been developed and are being further improved for bread wheat. To exploit these resources and reduce duplication of efforts between laboratories, a wheat SNP consortium was established. This consortium assembled all available wESTs into 40,000 contigs. From the above set of 40,000 contigs, 9,346 contained > 8 ESTs (exploitable for SNP mining) and were considered suitable for detecting SNPs. These contigs also were allocated to different members of the consortium. Each member partner received 48 contigs. From the set of 48 contigs, we were able to detect 462 HSVs (homoeologue-specific variations) and 231 SNPs, giving a density of one SNP/273.4 bp. Of these SNPs, 53.5 % represent transitions and 46.5% represent transversions. Primers also were designed and synthesized for 43 SNP containing contigs.
LD was also estimated electronically, using the above data. From the study of a few EST contigs/genes, we found that in wheat (like Arabidopsis and rice), relative to maize, LD persists for much longer distances. These results confirm the belief that LD persists for longer distances in wheat like other autogamous crops.
Physical mapping of SSRs on all 21 chromosomes of bread wheat. Approximately 1,500 SSRs have been genetically mapped in bread wheat (D. Sommers, personal communication; Sourdille et al. 2004). Only Sourdille et al. has physically mapped of some of the SSRs that they independently genetically mapped. Thus, a large number of genetically mapped SSRs still remain phylically unmapped. In the present study, using two nuillisomic-tetrasomic lines and two ditelocentric lines for each of the 21 wheat chromosomes and a total of 300 terminal deletion stocks, we tried to physically map as many as 590 SSRs (wmc, gwm, psp, cfa, and cfd). Of these, 413 markers were physically mapped. The remaining 177 of the above 590 genetically mapped SSRs could not be mapped physically, because the homoeoloci for these markers were monomorphic. A comparison of the physical maps of individual chromosomes with their genetic maps (D. Sommers, personal communication; Sourdille et al. 2004) revealed that the linear order of 95 % of the marker loci did not differ in genetic and physical maps, but the distances between the markers differed greatly in genetic and physical maps.
High-resolution mapping of genomic regions containing important QTLs for GPC. Two major QTL for GPC located on chromosome arms 2DL and 7AS, identified in our earlier studies (Prasad et al. 2002), were selected for high density mapping of the genomic regions containing these QTL. For this purpose, a large F2 population was derived from crosses between two RILs, one containing both the high-GPC alleles and the other containing low-GPC alleles for the selected QTL. DNA has been isolated from about 2,000 individual plants that is being genotyped to identify recombinants.
Future Plan of Work. High-density mapping. Individual F2 plants will be screened using markers flanking the genomic region containing the desired QTL for GPC and the recombinants for the markers flanking the QTL will be selected. Genotyping of recombinant F2 plants will be carried out using SAMPL, AFLP, STS, and SSR markers to saturate the regions of our interest. Wheat EST markers already mapped in the genomic region containing QTL of our interest and those mapped in the syntenous regions in other grasses also will be used for saturation mapping of the selected regions.
Study of organization of SSRs in repetitive and unique fractions of genomic DNA (using Cot fractionation and methyl filtration). In order to study the organization of SSRs separately in repetitive and unique fractions of genomic DNA of wheat, we separated repetitive and nonrepetitive fractions from total genomic DNA of Chinese Spring wheat using hydroxyapetite column chromatography. Repetitive DNA (low Cot fraction) in the range of 500-1,500 bp was selected for genomic library construction. A genomic library was constructed in the pUC18 (SmaI/dephosphorylated) vector. Blue-white screening was used to check transformed (with an insert) and nontransformed cells using IPTG and X-gal. About 2,000 white colonies were transferred to Hybond (N+) membrane and screened for clones representing highly repetitive DNA, using sheared genomic Chinese Spring DNA as a probe. After the first round of screening, we selected about 500 clones (clones that gave strong signals) assuming that these clones contain repetitive DNA. These clones will be used for secondary and tertiary screening. Nonredundant, positive repetitive DNA clones will be sequenced to identify the clones containing SSRs and study the organization of sequences containing SSRs. The sequence data of different clones will also be compared with wheat/Triticeae repetitive DNA sequences data available in the database. Nonredundant, repetitive DNA clones containing SSRs also will be used as probes in Southern hybridization to study the genomic organization of SSR containing repetitive DNA sequences in wheat. Physical distribution of the cloned repetitive DNA-SSRs in wheat also will be studied using FISH in mitotic metaphase chromosomes.
The single-stranded nonrepetitive DNA as separated above, will be converted to double-stranded form. The double-stranded fragments will then be size-selected over an agarose gel and cloned into the PCR4 TOPO vector. This library will be enriched for low-copy sequences like genes, and clones containing SSRs will be identified and sequenced. The information generated will be used for a study of the organization of SSRs in the unique DNA sequences.
We also propose to use methyl filtration for separation of repetitive and nonrepetitive fractions of wheat genomic DNA. Repetitive DNA is often more highly methylated than low-copy DNA. The methylated and unmethylated DNA will be separated using either methylation-sensitive restriction enzyme or bacterial host strains that preferentially restrict methylated DNA. The sequences of as many as 1,000 clones representing a sample of hypomethylated fraction of wheat genomic DNA also will be procured from Orion Genomics and used for a study of the organization of SSRs in this hypomethylated fraction of genomic DNA.
Marker-assisted selection (MAS) for high GPC and PHST. The
high-GPC gene already has been transferred from T. turgidum
subsp. dicoccoides into durum and hexaploid backgrounds,
which is a valuable resource for increasing GPC. We have one of
the high-GPC hexaploid lines Yecora Rojo (16-17 % GPC), which
was procured from Jorge Dubcovsky, University of California, Davis,
USA. Using Yecora Rojo and SPR8198 as donor parents for GPC and
PHST, respectively, we are conducting a backcrossing program for
the introgression of high GPC and PHST QTL into low-GPC and preharvest
sprouting susceptible elite Indian wheat genotypes.
CHAUDHARY CHARAN SINGH HARYANA AGRICULTURAL UNIVERSITY Department of Plant Pathology, Hisar-125004, India.
Rajender Singh, S.S. Karwasra, and M.S. Beniwal.
Soil is a reservoir of microflora that fluctuates with soil type, cropping system, and the prevailing environmental condition. Soilborne mycoflora were mapped and monitored in a cotton-wheat rotation in two wheat breeding research plots during the 1997-2001 crop seasons. The plots were '25 x 10 m' and 2 m apart. Randomly collected soil samples from the rhizosphere from the cotton (cultivar HS-6) and wheat (cultivar WH 147) crops were analyzed in order to map soil biology and pest dynamics in the different cropping systems and observe changes in the soil mycoflora populations and build-up of either pathogenic or nonpathogenic inoculum. Two treatments were used. An herbicide was applied to one plot. The other plot did not recieve any herbicide in the wheat or cotton. Isoproturon was used in the wheat plot, and Stomp was used to know its effect on soil mycoflora in the cropping sequence. Soil samples were taken at three stages, at sowing, at flowering, and at harvest in cotton; and five stages in wheat, before field preparation, at sowing, 30 days after sowing, at flowering, and at maturity.
From the cotton field, 10 fungal species were isolated; 12 fungal species were isolated from the wheat field. The data are presented in Tables 1 and 2. Aspergillus niger, Fusarium spp., and Helminthosporium spp. were found in the soil environment of both crops. These were nonpathogenic but perputating. Similiar observations were made by Pathak (2000) and Singh et al. (2000) in soybean-wheat and rice-0wheat systems at Sagar and Faizabad, respectively, which confirm our study.
| Fungi isolated | Sowing | Flowering | Harvest | |||
|---|---|---|---|---|---|---|
| T1 | T2 | T1 | T2 | T1 | T2 | |
| Alternaria alernata | 2.10 | 11.50 | 15.00 | 12.75 | 8.75 | 6.50 |
| Aspergillus flavus | 2.00 | 1.50 | 2.75 | 2.25 | 4.25 | 3.75 |
| Aspergillis niger | 2.90 | 2.25 | 2.75 | 2.50 | 6.50 | 5.25 |
| Cladosporium spp. | 4.00 | 3.75 | 4.50 | 3.75 | 5.00 | 4.75 |
| Curvularia lunata | -- | -- | 4.10 | 3.90 | 8.90 | 6.50 |
| Fusarium spp. | 6.90 | 6.10 | 9.00 | 7.90 | 7.50 | 7.00 |
| Helmithosporium spp. | 3.25 | 12.00 | 16.75 | 15.01 | 12.90 | 11.00 |
| Mucor spp. | 3.25 | 2.00 | 3.75 | 2.50 | 3.50 | 2.25 |
| Penicillum spp. | -- | -- | 3.10 | 2.25 | 2.90 | 2.75 |
| Rhizopus spp. | 10.00 | 9.40 | 19.50 | 17.90 | 15.25 | 11.75 |
| Before field preparation | At sowing | 30 days after sowing | Flowering | Harvest | ||||
|---|---|---|---|---|---|---|---|---|
| T1 | T2 | T1 | T2 | T1 | T2 | |||
| Alternaria alternata | 5.25 | 5.80 | 10.50 | 10.00 | 15.75 | 12.25 | 10.75 | 8.50 |
| Aspergillus flavus | 2.50 | 2.00 | 4.75 | 3.75 | 4.25 | 4.00 | 5.50 | 4.80 |
| Aspergillus niger | 2.75 | 3.00 | 3.00 | 2.25 | 3.50 | 3.00 | 5.75 | 4.90 |
| Aspergillus nidulans | 3.25 | 3.00 | 5.75 | 5.25 | 6.00 | 5.10 | 6.25 | 5.75 |
| Aspergillus terreus | 2.25 | 3.25 | 3.10 | 2.75 | 3.00 | 2.90 | 3.50 | 3.10 |
| Aspergillus sydowi | 2.25 | 2.75 | 3.50 | 2.75 | 3.10 | 2.50 | 3.25 | 2.80 |
| Fusarium spp. | 3.20 | 3.50 | 5.00 | 4.80 | 8.90 | 8.75 | 7.25 | 7.10 |
| Helmithosporium spp. | -- | -- | 2.00 | 1.25 | 3.25 | 2.50 | 4.10 | 3.50 |
| Penicillum spp. | 9.25 | 8.75 | 12.50 | 11.50 | 15.10 | 12.50 | 12.75 | 0.50 |
| Rhizopus nigricans | 10.00 | 9.75 | 16.25 | 15.50 | 20.75 | 18.75 | 16.75 | 10.80 |
| Trichoderma spp. | 1.50 | 2.70 | 5.10 | 4.80 | 5.20 | 4.90 | 4.20 | 4.00 |
| Trichoderma viridae | 1.50 | 2.50 | 5.00 | 4.50 | 5.00 | 4.70 | 4.20 | 4.00 |
References.
DIRECTORATE OF WHEAT RESEARCH
Karnal-132 001, India.
B.S. Tyagi, Gyanendra Singh, and Jag Shoran.
Summary. Wheat is the life line in a country like India where the population is around 100 crores. Wheat researchers will not only have to maintain the present growth rate in wheat productivity but also need to further accelerate the pace in productivity per year. In India, all efforts are being made to create and harness variability, which is a ladder for all crop-improvement programs. WIth this in mind, efforts were made to enhance the genetic diversity in wheat for economic traits, particularly yield attributes. A set of 90 synthetics obtained from CIMMYT-Mexico was evaluated in an augmented design for assessing genetic variability in yield-contributing traits. We observed that most of the synthetic lines had more tillers/m2 and better spike and grain size compared to the best T. aestivum (PBW 343) and T. durum (HI 8498) checks. The top 10 lines were selected for each character and these have been crossed with promising indigenous cultivars to pyramid genes for these traits. Although they produce material that is of low threshability and red grained, two to three backcrosses seem to improve such type of undesired traits. Many of the synthetics possess resistance to many diseases particularly leaf blight and rusts. In general, these synthetics also possess tolerance to abiotic stresses, namely heat and drought but have long duration. Our research deals with the variability for various economic traits in synthetics, their use as potential donors for specific traits, and the problems associated with their use in wheat improvement programs in the Indian subcontinent.
Introduction. Wheat has been linked with the development of both agriculture and civilization in many for countries in the world. Presently, wheat is the staple food of above 40 % human population across the globe. In India, wheat along with rice contributes over 40 % of the total food grain reserves, thus, reducing the need to import wheat even during poor monsoon years. Estimates predict that the population of India will be more than 1.3 billion by the year 2020. To make 180 g of wheat/capita/day available, India will need 109 x 10^6^ tons of wheat. Because a marginal increase in area under wheat is unlikely, to achieve this target no option exists but to increase the yield potential of new wheat cultivars to a greater extent. An increase of 1 %/year in production has been achieved through the higher-yielding ability of wheat cultivars during the last 30 years.
In order to strengthen and make the wheat-breeding program vibrant, the availability of diverse material is very important. Alien genetic resources are not routinely used in a breeding program. These wild species are the reservoir of various useful biotic and abiotic traits and have remained largely untapped for economically important traits such as high seed weight, protein content, high tiller number, long spikes, and disease resistance (Kerber and Dyck 1979; Ma et al. 1995; Villareal et al. 1994a, b). Most of the diversity derived from wild relatives has been from the secondary gene pool species, which needs some effort to incorporate them into the background of primary gene pool species. The synthetic hexaploid wheats may emerge as the potential resource to break the yield barrier.
Material and Methods. A set of 90 synthetic lines was procured from Wheat Genetic Resources Unit, CIMMYT, Mexico, during 1998-99 for evaluation and utilization in the Indian wheat program. These synthetic lines, which are hexaploid in nature, were originally developed at CIMMYT-Mexico by crossing durum (4x) wheats with Ae. tauschii (2x) and then making the F1s into dihaploids (6x). During the 2001-02 season, 90 synthetic lines, along with local cultivars as checks, were planted in an augmented design. For each genotype, a 3-m, six-row plot was planted with a 23 cm row-to-row distance. Normal agronomic practices were followed to raise a good crop. Data on various traits were recorded on five, randomly selected plants and then means were calculated. The tillers/m were counted from the middle two rows by randomly selecting one meter row distance at two places. Spike length was taken on the 10 different spikes of the main tiller and then averaged. Other data also were taken on the main tiller of each selected plant. Statistical analysis for testing the significance (t-test) of various traits was carried out following the approach suggested by Panse and Sukhatme (1967).
Results and Discussion. The data recorded on various agronomic traits in 90 synthetic wheat lines showed a wide range of variation for yield-component characters (Table 1). The highest coefficient of variation (CV) was noted in tillers/meter (31.34) followed by seeds/spike (24.25), and 1,000-kernel weight (20.61 g). The smallest CV was estimated for spikelets/spike (10.67). For efficient and effective selection in any breeding program, the high standard deviation (SD) and high CV are the prerequisites and not actually the mean per se. For CV values in the high range, disruptive selection for higher values can be performed that will result in a higher mean in the selected population. In this study, we made a disruptive selection for three characters, tillers/meter, spike length, and 1,000-kernel weight. For effective utilization, we took the mean of the check as the minimum limit for selection. The top-ranking lines for each of the three traits, along with other agronomic characters are presented in Tables 2 (tillers/m), 3 (spike length), and 4 (1,00-kernel weight).
| Parameter | Character | ||||
|---|---|---|---|---|---|
| Spike length (cm) | Spikelets /spike | Seeds /spike | Tillers /meter | 1000-kernel weight (g) | |
| Range | 9.0-15.8 | 13.8-24.6 | 11.4-64.0 | 50-222 | 20-50.4 |
| Mean | 12.73 | 17.79 | 35.03 | 125.36 | 38.44 |
| Standard deviation | 1.68 | 1.89 | 8.49 | 39.28 | 7.92 |
| Coefficient of variation | 13.24 | 10.67 | 24.25 | 31.34 | 20.61 |
| Mean of best check | 11.62 | 19.12 | 45.99 | 70.00 | 41.45 |
| Minimum selection criterion used | > 14 | > 20 | > 45 | > 160 | > 46 |
| Number of elite lines selected | 14 | 9 | 7 | 13 | 14 |
Tillers/meter. The number of effective tillers/unit area directly contributes to yield potential. In the synthetic lines, 222 tillers/m were recorded in lines 88 and 93 in compassion to the PBW 343 check (Table 2). These lines, however, were late flowering and late in maturity. Some of the synthetics had good kernel size and spike length.
| Synthetic and Pedigree | Character | |||||
|---|---|---|---|---|---|---|
| Tillers /meter | Days to heading | Days to maturity | Spike length (cm) | Spikelets /spike | 1,000-kernel weight (g) | |
| 88 (CPI/GEDIZ/3/GOOJO 69/CRA/4/Ae. tauschii) | 222* | 112 | 141 | 12.9 | 15.8 | 31.1 |
| 93 (DEVERD 2/Ae. tauschii) | 222* | 118 | 150 | 13.1 | 17.2 | 42.5 |
| 57 (LCK 59.61/Ae. tauschii) | 214* | 107 | 147 | 14.8 | 21.5 | 32.7 |
| 66 (BOTNO/Ae. tauschii) | 210* | 122 | 160 | 15.8 | 17.0 | 34.4 |
| 3 (Altar 84/Ae. tauschii) | 200* | 119 | 152 | 11.6 | 18.0 | 44.7 |
| 55 (GAN/Ae. tauschii) | 200* | 107 | 147 | 13.2 | 19.8 | 46.5 |
| 98 (DOY/Ae. tauschii) | 186* | 116 | 152 | 9.8 | 17.0 | 46.0 |
| 27 (GARZA/BOY//Ae. tauschii) | 170* | 111 | 146 | 12.8 | 12.8 | 45.5 |
| HI 8498 (Check) | 72 | 96 | 132 | 9.8 | 17.0 | 46.0 |
| PBW 343 (Check) | 87 | 95 | 130 | 12.0 | 18.0 | 37.0 |
Spike length. Synthetic lines were selected with ~15-cm spikes compared to the best bread wheat check PBW 343. No apparent increase in the number of spikelets/spike was observed, which means that the spike were of the lax type. Synthetic line 66 showed high tillering with a maximum spike length of 15 cm, but it flowered late and produced smaller kernels (Table 3).
| Synthetic and Pedigree | Character | |||||
|---|---|---|---|---|---|---|
| Spike length (cm) | Days to heading | Days to maturity | Tillers /meter | Spikelets /spike | 1,000-kernel weight (g) | |
| 64 (BOTNO/Ae. tauschii) | 15.8* | 122 | 160 | 210 | 17.0 | 34.4 |
| 66 (BOTNO/Ae. tauschii) | 15.8* | 122 | 160 | 210 | 17.0 | 34.4 |
| 98 (DOY1/Ae. tauschii) | 15.7* | 116 | 152 | 186 | 21.2 | 42.5 |
| 8 (CPI/GEDIZ/3/GOOJO 69/CRA/4/Ae. tauschii) | 15.5* | 111 | 146 | 112 | 18.3 | 45.0 |
| 49 (68-111/RGB-U//WARD /3/FGO/4/RABI/5/Ae. tauschii) | 15.5* | 111 | 149 | 68 | 19.8 | 29.2 |
| 45 (68-111/RGB-U//WARD /3/FGO/4/RABI/5/Ae. tauschii) | 15.1* | 111 | 144 | 116 | 17.4 | 43.5 |
| 97 (RASCON/Ae. tauschii) | 15.1* | 119 | 156 | 134 | 16.4 | 45.1 |
| 7 (Altar 84/Ae. tauschi) | 15.0* | 114 | 148 | 50 | 20.2 | 21.0 |
| 40 (68-111/RGB-U//WARD RESEL/3/STIL/4/Ae. tauschii) | 15.0* | 114 | 147 | 52 | 18.8 | 44.3 |
| 44 (68-111/RGB-U//WARD /3/FGO/4/RABI /5/Ae. tauschii) | 15.0* | 106 | 144 | 96 | 17.4 | 50.0 |
| HI 8498 (Check) | 9.8 | 96 | 132 | 72 | 17.0 | 46.0 |
| PBW 343 (Check) | 12.0 | 95 | 130 | 87 | 18.0 | 37.0 |
1,000-kernel weight. Selections were made on the basis of higher kernel weight. About eight synthetic lines were selected based on a 1,000-kernel weight greater than 47 g (Table 4). Lines, 31, 33, and 38, are high tillering with good spike length, but flowered 12 days later then the check PBW 343.
| Synthetic and Pedigree | Character | |||||
|---|---|---|---|---|---|---|
| 1,000-kernel weight (g) | Spike length (cm) | Days to heading | Days to maturity | Tillers /meter | Spikelets /spike | |
| 38 (FGO/USA 2111//Ae. tauschii) | 48.7 | 114 | 147 | 156 | 13.0 | 18.2 |
| 31 (68112/wARD//Ae. tauschii) | 48.1 | 111 | 146 | 160 | 13.5 | 16.8 |
| 36 (DOY 1/Ae. tauschii) | 48.0 | 114 | 151 | 90 | 12.0 | 14.4 |
| 6 (CROC 1/Ae. tauschii) | 47.2 | 114 | 147 | 102 | 14.0 | 18.0 |
| 44 (68.111/RGB-U//WARD/3/FGO/4/RABI/5/Ae. tauschii) | 50.0* | 106 | 144 | 96 | 15.0 | 17.4 |
| 50 (CROC 1/Ae. tauschii) | 50.4* | 101 | 139 | 100 | 11.0 | 16.8 |
| 51 (PBW 114/Ae. tauschii) | 49.1* | 100 | 145 | 122 | 12.5 | 16.4 |
| 72 (GAN/Ae. tauschii) | 50.0* | 113 | 147 | 76 | 14.6 | 18.0 |
| HI 8498 (Check) | 45.0 | 96 | 132 | 72 | 9.8 | 17.0 |
Improving economic traits utilizing synthetic wheats. The
promising synthetics identified from the present study cannot
be released as cultivars, but they can serve as genetic stocks
for many yield-contributing characters and as such might prove
useful in a crossing program (Rasmusson 1996). In general, the
synthetics have been observed to be late flowering, hard threshing,
and red grained, traits that are not acceptable to Indian consumers.
On the other hand, these are stocks are resistant to disease and
biotic stresses. Promising released cultivars that are lacking
a few important economic traits were selected and crossed with
the elite synthetics in order to incorporate these traits (Table
5). In the segregating generations, we generally observed that
the threshability is hard and a few grains were red in color,
even with poor grain appearance. In a few cases, a backcross to
the wheat cultivar parent was tried to improve desirable traits.
We noticed that by making a few backcrosses, the population improved
for such traits. We concluded from the study that the use of synthetics
for improving some economic traits in wheat has potential only
if the recipient parents are selected carefully and the material
is advanced by judicious backcrossing, thereby eliminating undesirable
traits. We expect that this type of crossing program also may
break the negative linkages between important traits, thus pyramiding
the positive genes in a good agronomic background.
| Cross combination | Traits improved |
|---|---|
| HI 8498/Synthetic 44//HI 8498 | Spike length, 1,000-kernel weight, grains/spike |
| PBW 34/Synthetic 93//PDW 233 | Tillers/m, grain appearance, grain/spike |
| PBW 343/Synthetic 88//PBW 343 | Tillers/m, powdery mildew resistance |
| C 306/Synthetic 55 | Rust resistance, tillers/m, lodging resistance |
| K 9107/Synthetic 57 | Leaf blight resistance, tillers/m |
| HUW 234//Synthetic 72 | Leaf blight resistance, rust resistance, spike length |
| K 9006/Synthetic 66 | Leaf blight resistance, tillers/m |
| WH 542/Synthetic 55 | Tillers/m, grain/spike, 1,000-kernel weight |
| WH 542/ Synthetic 44 | Spike length, 1,000-kernel weight |
| A-9-30-1/ Synthetic 3 | Tillers/m, drought and heat resistance |
Acknowledgment. The authors greatly acknowledge the courtesy of CIMMYT-Mexico for providing the synthetic material and necessary passport data. We are also thankful to the Project Director, DWR, Karna,l for extending all possible help and support for the present study.
Reference.
INDIAN AGRICULTURAL RESEARCH INSTITUTE REGIONAL STATION
New Delhi, India.
B.S. Malik, A.P. Sethi, V. Tiwari, R.K. Sharma, S. Chaudhary, and V.C. Sinha.
In Eastern India, the wheat growing area of approximately 8.9 x 10^6^ ha covers the states of eastern Uttar Pradesh, Bihar, Jharkhand, W.Bengal, Orissa, the plains of Assam, and other far eastern states. Wheat is one of the major cereal crops of this cold region and comprises an important component of rice-wheat cropping sequence. The difference between the yield and production of wheat in western and eastern parts of the country is big. The western part averages productivity of 3.8 t/ha, whereas the eastern region averages 2.7 t/ha. Low productivity in eastern region is due to delayed wheat sowing caused mainly by limitations of the rice-wheat cropping system. Rice is grown mainly in rainfed areas. A short winter, heat stress in both early and late growth stages, high disease pressure particularly from leaf rust and blight, and edaphic problems are other limiting factors causing a reduction in productivity of wheat in eastern India.
One cultivar that has shown great promise for increasing productivity in hot-humid conditions of eastern India is Poorva, which was released by the Central Sub-Committee on Crop Standard, Notification and Release of Varieties in November 2003 for cultivation under irrigated, timely sown conditions. Poorva was tested under the name HD2824 in coördinated evaluation experiments conducted under the auspices of All India Coordinated Wheat Improvement Project for 3 years from 2000-01 to 2002-03.
HD2824 was developed by the pedigree method from the cross 'PTO/CNO79/PRL/GAA//HD1951', which involves Mexican and Indian wheats. In multilocational trials conducted over 3 years to evaluate yield ability, HD2824 exhibited an average increase of 5 to 14 % over the check cultivars PBW343, HUW468, HD2733, and K9107. The cultivar gave an average yield of 46 t/ha and a potential yield level of 6.5 t/ha (Figs. 1 and 2). HD2824 also has shown plasticity for delayed sowings, which meets the agronomic requirements of the predominantly adopted rice-wheat cropping system in eastern India.
HD2824 has a new gene, Lr23, for resistance against leaf rust. Lr23 will help to contain the spread of virulent and prevalent pathotypes of the group 77. The postulated resistance genes in the variety are Sr31 + Lr23 + Lr26, and Yr9, which give durable resistance to rust. For leaf blight, which is the major disease of the area, HD2824 is moderately resistant to resistant under natural and artificial conditions.
The characteristic features of HD2824 are a semispreading growth habit; a plant height of 85-90 cm; waxy, dark-green, semierect leaves; white tapering ears with nonpubescent glumes; and a maturity of 120-125 days. The grains are amber, hard, and lustrous with a 1,000-kernel weight of 41 g. HD2824 makes excellent unleavened bread that is preferred by people of the region.
INDIAN AGRICULTURAL RESEARCH INSTITUTE REGIONAL STATION
Wellington - 643 231, the Nilgiris, Tamilnadu, India.
M. Sivasamy, A.J. Prabakaran, K.A. Nayeen, and R.N. Brahma.
Introduction. Until high-yielding, paddy cultivars were introduced, the major cereal crops cultivated in the nontraditional areas (areas adjoining the Southern Hills in the states of Tamilnadu, Karnataka, and Andhra Pradesh) were sorghum followed by pearl millet; ragi; minor millets like Varagu and Pani Varagu, and foxtail millets; and dicoccum wheat. These areas are in the plains, where ever cooler weather conditions prevail in isolated packets. Over time, they slowly were replaced by cotton and vegetable crops. Today, some pockets exist where farmers cultivate dicoccum wheat. Although the climate is favorable and soil types suitable in these areas and the adjoining hills, farmers did not prefer wheat, because they were growing rice and other remunerative vegetable crops. Because of the lack of frequent monsoons and a shortage of irrigation water, farmers now are looking for a alternate, viable cereal crops.
Several reasons demand the introduction of wheat. The availability of suitable wheat strains (developed at IARI, Regional Station, Wellington) that are adaptable to these regions with high per day productivity. Recently, extensive research has lead to developing and identifying genotypes suitable for cultivation in the warmer areas that possess resistance to biotic stress (rusts and Fusarium root rot). A collaborative research program with Tamilnadu Agricultural University, Coimbatore, and the IARI Regional Station, Wellington, was initiated in the year 1997-98 Rabi to identify genotypes tolerant/resistant to biotic and abiotic stresses. Initially, cultivars for the plains area were selected. Five years of intensive research lead to the identification of the genotypes HW 3070, HW 3094, DWR 162, MACS 2496, and HD 2285, which possess resistance to Fusarium root rot and are consistent performers under the conditions at the test locations. Common to this region is a short winter of approximately 90 days from October to February with a few periods of high temperature and high humidity. Typical winter temperature variation for this area appear in Fig. 1. This climate facilitates severe incidences of Fusarium root rot. Of the selected cultivars, subsequent station trials and agricultural research trials in 12 districts revealed that HW 3070 and HW 3094 were capable of producing consistent higher yields (1.5-2.0 tons/ha) over the others and have remarkable resistance to foliar diseases and Fusarium wilt. These cultivars mature in about 90 days and per day productivity is far higher than in the conventional areas.
Findings of the expert team include
1. Bread and dicoccum wheat can be successfully cultivated with 5-6 irrigations in various districts of Tamilnadu and Karnataka in the areas adjoining hills.
2. The area is prone to water logging and not suitable for wheat.
3. Intercropping with coconut and tapioca plantations with better drainage can be used.
4. In many districts, the time of sowing was found to be crucial. Any delay in sowing beyond 15 November can result in a yield loss. The best suited planting time is 15 October to 15 November.
5. Spacing between rows should be 20 cm rather than 23 cm, which we normally recommend, with no seed-to-seed spacing. Wider spacing results in poor stands with poor tillering. From our observations, closer spacing clearly altered the microenvironment, which facilitated better tillering under the regions climatic conditions (very short winter spell with intermitant high temperature ranges).
6. Study to standardize different agrotechniques should be initiated.
To take advantage of favorable weather conditions prevalent in this part of the country, the hilly areas in southern India are highly suitable for cultivation of wheat all through the year. The main seasons, kharif and rabi, can be followed either under rainfed or restricted irrigated conditions. In the Lower Hills and areas adjoining them, the weather conditions are highly favorable for cultivation of wheat between October and February. However, planting should not be delayed past 15 November except in areas where there is a longer winter. In these areas, cultivars with a longer growth cycle can be grown if sowing is made during the last week of October. The optimal temperatures for wheat growth are day temperatures below 30 C and night temperatures below 20 C, particularly during grain filling.
The demand for wheat has increased because of changes in eating habits. Thanks to the promotional effort of government and nongovernmental agencies about the need for a balanced diet, changes in the eating habits of people in southern India have increased the demand for wheat. Today, families who do not use wheat in their weekly diet are hard to find. Needless to say, 80 % of the wheat processing industries are situated in southern India and, hence, the demand for wheat has grown manyfold. In the Southern Hills, because of lower tea sales and the high cost of production of commercial crops, farmers are slowly switching to a cropping system that includes wheat as one of the food crops. Evidenced by the recent upward revision of area under wheat (in Kharif and Rabi seasons), in the Southern Hills.
The wheat crop ensures food grain for the family and fodder for the cattle. Wheat is amenable for intercropping or mixed cropping During 2003-04, experimental crops of wheat as an intercrop with tapioca under rainfed (October sown) was very successful in the Kalrayan Hills. Farmers in this region are looking for a viable, alternative crop. Traditional crops like cotton, vegetables, paddy, and other cereals have failed in the recent past because of infrequent monsoons. The availability of water is scarce until and beyond the Rabi season. In this situation, wheat has provn to be a viable, alternative cereal crop.
The advantages of cultivating wheat in these regions include
1. Wheat requires less water. Wheat requires 5 to 6 irrigations during its critical growth stages, the first immediately after sowing (life irrigation), a second on the 15th day after sowing, a third during the crown root-initiation stage (30-35 days) with one weeding and top dressing, a fourth during boot stage, and a fifth during milk stage (60-65 days). One or two irrigation can be skipped if there is any precipitation during this period.
2. Wheat is a short duration crop. Research has indicated that in the Lower Hills and adjoining areas, the wheat crop matures in about 85-90 days.
3. No major pests or diseases occur. The recommended cultivars have rust-resistant genes. Except for termites towards maturity, which can be controlled effectively by application Neem cake or Lindane during top dressing (around day 35-40).
4. Domestic requirement of wheat grains is met.
5. Bread wheat is easy to thresh.
6. A successful wheat crop gives high profitability with the minimum yield of 1,000 kg/acre in about just 90 days. The per day productivity is far better than any other wheat cultivating area in the country. Wheat is amenable to intercropping and mixed cropping. Wheat can be sold locally and purchase by flour-mills ensures marketing. Wheat flour can be made at the local iron mills. Wheat seeds can be stored up to 3 years in the plains under the ambient conditions. Cultivation of the nutritionally rich, dicoccum wheat ensures high remuneration.
PUNJAB AGRICULTURAL UNIVERSITY
Department of Plant Breeding, Genetics and Biotechnology, Ludhiana-141004, India.
Livinder Kaur, Shikha Agarwal, and R.G. Saini.
The prevalence of strip rust race 46S119 having virulence on the gene Yr9 originating from S. cereale is responsible for the break down of stripe rust resistance of some high-yielding cultivars in the Indian subcontinent. Incorporating genes for resistance against this race in the development of cultivars for use in the cooler, northern states of India is, therefore, a priority. Because quantitatively inherited, nonhypersensitive genes for slow-rusting resistance provide long-lasting resistance, their use seems to be the best approach for development of cultivars. Based on multirace tests conducted at Punjab Agricultural University, 18 bread wheats were identified as putative carriers of diverse genes conferring such resistance. These wheats were crossed with the two susceptible Indian cultivars Agra Local and WL711 to examine the nature and number of genes conferring nonhypersensitive resistance in each of these wheats. Observations on seedling infection types and field reaction of the 18 parental lines and their F1s with susceptible cultivars to race 46S119 are given in Table 1. All cultivars except VL404 were susceptible to race 46S119, indicating that all these cultivars except VL404 have adult-plant resistance to this race. The F1s from all crosses, except those with the cultivar Dove, were more susceptible than the resistant parent indicating that both resistance alleles are essential for producing the parental phenotype in 17 crosses. This response of the F1s also suggests an additive effect of the resistance alleles. Kaur et al. (2002) have reported such additive resistance in some wheats earlier. Further generations are being evaluated to examine the nature of the Yr genes in these cultivars.
Acknowledgement. The authors acknowledge financial assistance from the Indian Council of Agricultural Research, New Delhi, to carry out this work at Punjab Agricultural University, Ludhiana.
| Cultivar/line | Infection type and growth stage | |||
|---|---|---|---|---|
| Seedling reaction | Adult plant | F1s with Agra Local | F1s with WL711 | |
| Ciano 79 | S | 0.2 | 2.5 | 1.5 |
| CSP44 | S | 14.0 | 19.0 | 40.0 |
| CIM5 (Roussalka/Azteca 67/Pavon 76) | S | 25.0 | 40.0 | 50.0 |
| CIM6 (Dove/Buck Buck) | S | 0.0 | 12.5 | 20.0 |
| CIM7 (Mirlo/Buck Buck) | S | 0.0 | 7.5 | 7.5 |
| CIM53 (pedigree unnown) | S | 0.6 | 15.0 | 20.0 |
| Diaz | S | 2.0 | 11.0 | 30.0 |
| Dove | S | 0.1 | 0.1 | 0.25 |
| VL404 | R | 0.6 | 20.0 | 20.0 |
| Bajio 67 | S | 20.0 | 40.0 | 30.0 |
| Cook | S | 1.5 | 11.0 | 35.0 |
| CIM33 (Patio/Alondra/PAT72300/3/Pavon 76) | S | 30.0 | 40.0 | 60.0 |
| HI977 | S | 25.0 | 35.0 | 45.0 |
| Era | S | 30.0 | 35.0 | 35.0 |
| FKN | S | 30.0 | 40.0 | 50.0 |
| Lerma Rojo | S | 25.0 | 30.0 | 35.0 |
| Pitic 60 | S | 30.0 | 45.0 | 40.0 |
| Son-Kl-Rend | S | 45.0 | 50.0 | 50.0 |
| Agra Local (susceptible parental line) | S | 60.0 | ||
| WL711 (susceptible parental line) | S | 75.0 | ||
References.
SHER-E-KASHMIR UNIVERSITY OF AGRICULTURAL SCIENCES AND TECHNOLOGY
Division of Plant Breeding and Genetics, FOA, R.S. Pura, Jammu, India.
J.S. Bijral, Bikram Singh, and Tuhina Dey.
Aegilops umbellulata, a diploid species with the U genome, is a potential source for resistance to powdery mildew, Hessian fly, and greenbug. Leaf rust-resistance gene Lr9 from Ae. umbellulata was transferred to cultivated wheat by Sears (1956). However, cytogenetic information of wheat/Ae. umbellulata hybrids is lacking and chiefly concerns hybrid production. No germ plasm is available globally for incorporating the genetic diversity for wheat improvement, thus, we are reporting on the production of T. turgidum subsp. dicoccoides/Ae. umbellulata hybrids.
Aegilops umbellulata accession 3732, received from H.S. Dhaliwal, Punjab Agricultural University, Ludhiana, India, was crossed as a male with T. turgidum subsp. dicoccoides accession 4637. No embryo rescue or culture techniques were used, and the hybrid embryos were allowed to develop on the female plants under field conditions. The average crossability rate was 2 %.
Morphologically, the F1 hybrids were intermediate between the parents and were self-sterile. The hybrid status of the F1 plants was confirmed cytologically. Somatic chromosome number of all hybrid plants was 2n = 3x = 21 (ABU genomes). Chromosome pairing in the F1 hybrids averaged 21 univalents/meiocyte, which indicated a complete lack of homology between the parental AB and U genomes.