ITEMS FROM INDIA

BHARATHIAR UNIVERSITY

Cytogenetics Laboratory, Department of Botany, Coimbatore­641 046, India.

Transfer and characterization of rust-resistance genes in Indian hexaploid wheat cultivars.

V.R.K. Reddy, S. Arumugam, A. Subhashini, and P. Viswanathan.

We currently are breeding for rust resistance in hexaploid wheats in our laboratory. Nineteen leaf rust-resistance genes (Lr9, 19, 24, 25, 26, 28, 29, 32, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, and 45); eight stem rust-resistance genes (Sr24, 25, 26, 27, 28, 31, 38, and 39); and eight stripe rust-resistance genes (Yr9, 11, 12, 13, 14, 15, 16, and 17) were transferred into 13 popular Indian hexaploid wheat cultivars (HD 2009, HD 2380, HD 2402, HS 240, HP 1102, HUW 318, PBW 226, HI 1077, WH 542, Lok 1, HUW 234, J 28, and K 68). These genes are present either singly or in linked combinations (e.g., Sr24 + Lr24, Sr31 + Lr26 + Yr9) from either hexaploid wheat stocks or alien addition lines such as rye and Agropyron.

A simple backcross method was used to transfer genes from hexaploid wheat stocks. Manipulation of the 5B system of wheat using homozygous recessive Chinese Spring ph mutant was used to transfer genes from alien addition lines. All the rust-resistance genes except Yr15 and Yr17 were found to be dominant. These genes were transferred by backcrossing followed by selection. The genes Yr15 and Yr17 were transferred by selfing the backcrossed progeny, followed by selection. Rust-resistant lines were constituted either at BC2F5, BC3F5, or BC5F5. Although early generation selected lines were agronomically superior, they are phenotypically different from their parents. On the other hand, BC5 lines were more similar to their respective wheat parents.

All the rust resistance genes except Lr24, Lr26, Sr24, Sr31, and Yr17 provided high degree of resistance. These five genes provided resistance only when interactive genes were present in the recipient wheat genotypes. A particular rust resistance gene obtained from two different sources had different effects on agronomic performance of the constituted lines. In general, rust resistance obtained from hexaploid wheat stocks provided good genetic background in Indian wheats.

Yield comparisons of the lines were made under rust-free conditions using the chemical control Tilt. Constituted lines were significantly higher yielding when than the untreated control. Yield levels of the constituted lines also were comparable to or slightly higher than those of the chemical-treated control. Although many lines yielded higher than the respective controls, only those lines with good agronomic performance coupled with good seed quality (color, shape, and plumpness) were selected.

The presence of rust resistance genes in Indian wheat background was successfully confirmed by various morphological (spike shape, awns, awn color, spike color, plant color, seed color, and flour color) and genetic (inheritance of rust resistance in F1, F2, and BC1) markers in hybrids derived from 'NILs / Agra Local wheat' and through monosomic analysis (NIL crossed with wheat monosomics) and biochemical (peroxidase, catalase, polyphenoloxidase, lipid, soluble proteins, secalins, endopeptidase, lipoxigenase, ribonuclease, nuclear DNA, total phenols and tannins, chlorophyll content, respiration rate, and free proline and free amino acids), and molecular markers (using OPJ 9 and OPR 11 for Lr24 and OPJ 13 for Lr9).

Publications.

Dhamodaran S and Reddy VRK. 1998. Incorporation of specific genes for rust resistance and their confirmation through genetical, biochemical and molecular studies in Triticum aestivum. In: Proc Natl Conf, Recent Trends in Spices & Medicinal Plant Research. 2-4 April, 1998, Calcutta. India. p. A-2.

Reddy VRK. 1998. Chromosome banding techniques with special reference to C-banding. In: Cellular and Chromosomal Manipulations for Crop Breeding. Centre for Plant Breeding, TNAU, Coimbatore, India. pp. 19.1 19.7.

Reddy VRK. 1998. Biochemical and nuclear DNA studies in Indian wheats and their rust resistance constituted lines. J Cytol Genet 33(1):17-19.

Reddy VRK. 1998. Differential rust reactions in Indian hexaploid wheats. In: Proc 85th Indian Sci Congr, 3-7 January, 1998, Hyderabad, India. p. 60.

Reddy VRK and Arumugam S. 1998. Incorporation of leaf and stem rust resistance genes into Indian wheat cultivars. In: Proc XXI Indian Bot Conf, 24-26 October, 1998. Ujjain, India.

Reddy VRK, Arumugam S, Subhashini A, Viswanathan P, Gothandam KM, and Murugesan GS. 1998. Chromosome banding techniques and their application in biological systems. J Nature Conserv 10(2):In press.

Reddy VRK, Subhashini A, Arumugam S, Viswanathan P, Gothandam KM, and Murugesan GS. 1998. Improvement of Indian hexaploid wheat varieties. In: Proc Natl Conf Cytogenetic Studies in Higher Plants. 21-22 August, 1998. Annamalai University, Annamalainagar, India. p. 14.

Reddy VRK, Arumugam S, Subhashini A, Viswanathan P, and Zereena V. 1998. Triticale. APSI, Muzaffarnagar. 44 pp.

Subhashini A and Reddy VRK. 1998. Transfer of specific rust resistance genes into Indian hexaploid cultivars. In: Proc Natl Sem Current Trends in Biological Sciences, 5 December, 1998. Avinashilingam University, Coimbatore, India. p. 4.

Viswanathan P, Reddy VRK, and Asir R. 1997. Disease rust reaction in hybrids involving Indian wheats and HW 1042. Indian J Cytogenet 3(1):9-12.

INDIAN AGRICULTURE RESEARCH INSTITUTE

Regional Station, Wellington ­ 643 231, Tamil Nadu, India.

Current activity and wheat stocks developed.

M. Sivasamy and R.N. Brahms.

Unique weather conditions prevailing at the IARI Regional Station in Wellington (2,000 m above sea level, mean maximum temperature = 20°C, mean minimum temperature =10°C, and mean annual rainfall = 1,500 mm) facilitate the growing of three crops per year. The occurrence of all three wheat rusts throughout the year allows us to breed and select rapidly for rust-resistant wheat lines. Through judicious and meticulous planning, a breeding strategy of selecting wheat lines across the wheat-cultivation zones in India, crossing to wheat stocks with better agronomic traits, and employing a pedigree method with limited backcrosses, we have incorporated known alien genes for resistance to the different rusts into lines with better agronomic backgrounds. Presently these varieties are being evalutated across the zones through the All-India Coordinated Wheat Improvement Program. Varietal performance is reported in Shoran et al. (1998).

Wheat stocks with the Lr9, Lr26, Sr31, and Yr9 gene complex: HW 3040, HW 3045, HW 3072, and HW 3076.

Wheat stocks with the Lr19, Lr26, Sr25, Sr31, and Yr9 gene complex: HW 3024, EIW 3030, HW 3084, and HW 3086.

Wheat stocks with the Lr24, Lr26, Sr24, Sr31, and Yr9 gene complex: HW 3006, HW 3007, EW 3014, HW 3016, HW 3018, HW 30231, HW 3025, HW 3026, HW 3027, HW 3029, HW 3032, HW 3033, HW 3034, HW 3056, HW 3060, HW 3063, HW 3065, HW 3078, HW 3079, HW 3080, HW 3081, and HW 3092.

Wheat stocks with the Lr13, Lr24, Sr24, and Sr27 gene complex: HW 3064.

Wheat stocks with the Lr13, Lr24, and Sr24 gene complex: HW 3067 and HW 3068.

Wheat stocks with the Lr26, Lr28, Sr31, and Yr9 gene complex: HW 2062- 1, HW 2062-2, HW 3069, HW 3070, HW 3085, and HW 3089.

Sources of alien resistance genes: Lr9 - Ae. umbellulata, Lrl9 - Th. elongatum, Lr24 - Th. elongatum, Lr28 - Ae. speltoides, Lr26 - S. cereale var. Petkus, Sr24 - Th. elongatum, Sr25 - Th. elongatum, Sr31 and Yr9 - S. cereale var. Petkus Lrl9 and Sr25, Lr24, and Sr24, and Lr26/Sr31 and Yr9 are linked.

Reference.

Shoran J, Nagarajan S, Singh RP, Malik BS, Singh RVP, Bisht SS, Mohan D, Mahajan V, Singh G, Tyagi BS, Singh GP, Tiwari R, Kumar R, and Kundu S (eds). 1998. Results of the All-India Coordinated Wheat and Triticale Varietal Trials, Directorate of Wheat Research, PO Box 158, Karnal - 132 001, India. p. 47.7.

HW 1085 (Bhavani)-a rust-resistant wheat variety for the southern Hill Zone, a center for black and brown rusts.

R.N. Brahma, M. Sivasamy, S.M.S. Tomar, M.K. Menon, Aloka Saikia, and R. Asir.

At present, no wheat varieties are adapted for the medium-fertility conditions of the southern Hill Zone (comprising Nilgiri and Palney hills) that have a high degree of resistance to stem, leaf, and stripe rusts. The Nilgiri and Palney hills are the sources of leaf and stem rust inocula for the neighboring wheat-growing areas. Thus, saturation of these hills with rust-resistant varieties of wheat is of paramount importance to stop the dissemination of uredospores into the plains of India. The Central Variety Release and Identification Committee released HW 1085 in 1997 for the southern Hill Zone.

HW 1085, named Bhavani, originated from a cross between Unnath Kalyansona (HW 2002A with Lr24 and Sr24) and CPAN 3057 (YRG / Sparrow). HW 1085 was presumed to have other resistance genes in addition to the Lr26, Sr31, Yr9 gene complex.

Gene composition. HW1085 is postulated to have Sr2+, Sr8b+ 9b+ 11+, and Lr13+. The Sr2 gene provides durable adult-plant resistance to stem rust, and the Lr13 gene provides resistance to leaf rust.

Desirable physiological traits. HW 1085 has semi-erect to erect leaves that facilitate better penetration of sunlight to the lower leaves, improves aeration in the foliosphere, and offers better resistance to the minor foliar diseases by altering the microclimate. This trait is an added advantage, particularly in the hills where the weather conditions are more conducive for the development of foliar diseases.

HW 1085 is medium-early, matures in 117 days (seed to seed); and is highly resistance to leaf, stem, and stripe rusts in the seedling and adult-plant stages. The variety has seedling resistance to 19 pathotypes of stem rust, 22 leaf rust pathotypes, and 14 stripe rusts pathotypes. HW 1085 is resistant to the biotic stresses of rusts and yields well under medium-fertility conditions with restricted irrigation. An average yield of 57.4 Q/ha is expected under normal conditions. However, the yield potential of HW 1085 is 68 Q/ha.

The lustrous, amber grains will be liked by farmers and consumers. Data on agronomic trials conducted over 2 years indicate HW 1085 is superior (16.7 % at 90 N and 30P and 16 % at 60N and 30P) to the best check variety HUW 318. A yield gain of 4.3 % was obtained using the high level of fertilizer recommended. HW 1085 will replace the rust-susceptible varieties HW 971, HW 741, and HUW 318 and act as an effective genetic barrier against spread of rust inoculum to the plains of India.

MARATHWADA AGRICULTURAL UNIVERSITY

Wheat and Maize Research Unit, Parbhani 431 402 Maharashtra, India.

Hi-tech wheat production technology.

K.A. Nayeem, Syed Muzaffar, and S.T. Shirale.

In Maharashtra (in peninsular India), some of the progressive farmers harvested high wheat yields between 80 and 105 Q/ha in various crop competitions organized through the Commissionerate of Agriculture, Pune. One such farmer, Mr. Kautukrao Lokde, a resident of the village of Brahmapur Tq. Hingoli in the district of Parbhani, produced Front-Line Demonstrations in 1996-97. This farmer obtained yields of 90 Q/ha in his competition trial and was honored by the Governor of Mharashtra as 'Krishibhushan'. He and his team averaged 80 Q/ha wheats for 4 hectares. The team recorded the highest grain yield in Parbhani-51, which had profuse tiller production of 30­35 per plant. MACS-2496 had 25-30 tillers per plant. The number of grains ranged from 110-125 in both the cultivars.

The farmers were hesistant to give the details of their success when questioned about cultural practices, particularly the use of fertilizers and irrigation. However, the farmers finally stated that additional practices were used. For each kilogram of wheat seed, 3 kg of a 19:19:19 fertilizer mixture were used. This rate is their normal fertilizer application practice for obtaining higher yields. The Front-line Demonstrations provide 2.5 bags each of fertilizer mixture and urea. The additional bag of urea applied increased the total N per hectare to 175-180 kgs. Eight to 10 irrigations at an interval of 15 days were used instead of the normal 5-6. The crop also was sprayed twice with Diathan Z-78, once after 40 days and a second time at spike energence. Both cultivars were free from rusts.

Parbhani-51 is preferred for its chapati-making qualities as compared with MACS-2496.

Genetic variability in advanced generations of durum wheat.

K.A. Nayeem and N.S. Karad.

During1995-96, 155 advanced progenies were received from CIMMYT. Seventy-six lines selected for their grain characterstics were evaluated for various genetic parameters in the next season. A randomized-block design with four standard checks, HD 4502, Raj 1555, MACS-2486, and PBND 1625, was used in the 1997-98 growing season. Various characteristics, including the export quality traits of yellow-berry percent, hectoliter weight, sedimentation value, and protein percent, were studied for their genetic variability, heritability, and genetic advance. The results revealed that both additive and nonadditive gene actions are important in controlling different traits (Table 1). Characters with little difference in their genotypic and phenotypic variances were noted, and more emphasis should be placed on these characters for enhancing the grain yield. Characters with high heritability estimates and high genetic advance means have high additive gene effects, so selection will be more effective and convenient.

Plant height, number of tillers/meter, number grains/spike, hectoliter weight, yellow-berry percent, and yield/plot were recorded until the crop was 50 % headed. Yield/plot was positively and significantly correlated with the number of grains/spike and the test weight. The maximum direct effects were observed for the number of grains/spike and test weight on grain yield.

To the contrary, the quality characteristics of protein content and sedimentation value indicated a nonadditive gene action. High genotypic and phenotypic coefficients of variation were found for yellow-berry percent, grain yield/plot, test weight, and number of tillers. High heritability and high genetic advance were observed for the number of tiller/meter, number of grains, test weight, and hectoliter weight. Thus, these traits could be effectively used in developing high-yielding and export-quality durum wheats. PBNS 4262, 4264, 4541, 4537, 4279, 4280, 4560 and 4275 were found suitable as export-quality durum genotypes on the basis of international standards for wheat (Table 2).

Electrophoretic characterization of induced mutants in wheat.

K.A. Nayeem, P.M. Swami, and S.G. Bhagwat.

The land race 'Sharbati' was subjected to recurrent irradiation. Thirteen of the induced mutants and Sharbati were studied for their protein-banding pattern at the Bhabha Atomic Research Centre, Mumbai, in 1997-98.

Electrophorogram analysis. The electrophorogram of the seed-extracted, HMW-glutenin subunits of the 14 genotypes is depicted in Fig. l and the qualitative and quantitative differences in banding patterns are listed Table 3. The 14 genotypes have a maximum of 20 and a minimum of 15 protein bands. However, in all the 14 induced mutants of Sharbati, marked qualitative and quantitative differences were observed for their banding patterns. In total, 26 bands were recognized in this group.

Band l (Rm 0.32) was specific to PBNS-3950, PBNS-3942, and the PBNS check. Band 3 (Rm 0.36) was specific to PBNS-3950. Band 8 (Rm 0.46) was specific to PBNS-3950. Band 19 (Rm 0.76) was specific PBNS 3969 and PBNS-3964. Band 2 (Rm 0.35) was present in every line except for PBNS-3950. Band No.4 (Rm 0.40) was present in nine of the lines, PBNS-3965, PBNS-3953, PBN-3905, PBNS-3912 PBNS-3914, PBNS-3914-1, PBNS-3942, PBNS-3964, and the PBNS check, and was of medium intensity. Band 5 (Rm 0.43) was present, although staining lightly, in PBNS-3963-1, PBNS-3969, PBNS-3950, PBNS-3957-1, and PBNS-3948. The medium-intense band 6 (Rm 0.44) was found in PBN~3963-1, PBNS-3969, PBNS-3950, PBNS-3957-1, PBNS 3942, PBNS-3948, PBNS-3969, and the PBNS-check. Band 7 (Rm 0.45) was specific to PBNS-3965.

Quantitative differences were observed in band 9 (Rm 0.47), which was present in all entries except PBNS 3950. The intensity of this band was dense in all the lines except PBNS-3953, where it was of medium intensity. Band 10 (Rm 0.55) was lightly intense in all lines. Band 11 (Rm 0.57) was present in PBNS-3963-1 as a light band, of dark intensity in PBNS-3969 and PBNS-3957-1, and medium intense in PBNS-3942.

Variability index. The variability index was calculated to estimate the evolutionary relationships among the genotypes. The data in Table 4 indicate that the variability index values ranged from 5.6 in (PBNS-3914 and PBNS 3914-1) to 71.6 (PBNS-3953 and PBNS 3942). These values suggest the presence of a high degree of dissimiliarity among genotypes. Wide variation clearly can be achieved by adopting recurrent irradiation in the hexaploid wheats.

Table 3. Qualitative and quantitative differences in the HMW-glutenin subunit banding patterns of 13 induced mutant of the land race Sharbati. For location of specific bands, see Fig. 1.

Genotype	Qualitative differences		Quantitative differences
	Total no. of bands	Specific band no.	Dark	Medium	Light
PBNS-3963-1	19	5 (Rm 0.43) 6 (Rm 0.44) 11 (Rm 0.57)	6	8	5
PBNS-3965	17	7 (Rm 0.45)	6	8	3
PBNS-3969	19	5 (Rm 0.43) 6 (Rm 0,44) 11 (Rm 0.57)	9	7	3
PBNS-3950	18	1 (Rm 0.32) 3 (Rm 0.36) 5 (Rm 0.43) 6 (Rm 0.44) 8 (Rm 0.46)	4	12	2
PBNS-3953	15	---	1	11	3
PBNS-3957-1	19	5 (Rm 0.43) 6 (Rm 0.44) 11 (Rm 0.57)	6	10	3
PBNS-3905	18	---	7	9	2
PBNS-3912	18	---	9	6	3
PBNS-3914	18	---	8	8	2
PBNS-3914-1	18	---	8	8	2
PBNS-3942	20	l (Rm 0.32) 6 (Rm 0.44) 11 (Rm 0.57)	9	10	1
PBNS-3948	18	5 (Rm 0.43) 6 (Rm 0.44)	3	7	8
PBNS-3964	18	6 (Rm 0.44) 19 (Rm 0.77)	5	10	3
PBNS-check	18	1 (Rm 0.32) 6 (Rm 0.44)	5	10	3

CH. CHARAN SINGH UNIVERSITY

Department of Agricultural Botany, Meerut (U.P.), India.

Development of molecular markers for wheat breeding at Meerut, a center for the Wheat Biotechnology Network in India.

P.K. Gupta, H.S. Balyan, P.C. Sharma, B. Ramesh, Rajeev K. Varshney, Joy K. Roy, and Manoj Prasad.
Our project on wheat biotechnology is sponsored by the Department of Biotechnology (DBT), Government of India, under the Wheat Biotechnology Network. The project is entitled 'Characterizating and using the Quality Traits in Wheat Aided by Molecular Markers.' Punjab Agricultural University (PAU), Ludhiana; G.B. Pant University of Agriculture & Technology (GBPUA&T), Pantnagar; Directorate of Wheat Research (DWR), Karnal; National Chemical Laboratory (NCL), Pune; and Agharkar Research Institute (ARI), Pune are the other network partners. The major objective of our group is to develop molecular markers linked to genes for the grain quality traits of grain protein content (GPC), grain size (GS), and preharvest-sprouting tolerance (PHST).

Seed material. The parent genotypes differing for the three quality traits were supplied by PAU, Ludhiana. The following genotypes were included: PH132, PH133 (high GPC), and WL711 (low GPC); Chinese Spring (small grain); Rye Selection 111 (bold grain); HD2329 (PHS susceptible); and SPR 8198 (PHS resistant). The RILs and advanced lines for each of the above traits were developed at PAU, Ludhiana, from the crosses 'PH132 / WL711', 'Chinese Spring / rye Selection 111', and 'HD2329 / SPR8198'.

Development of molecular markers. The molecular markers currently in use may be classified as hybridization-based or PCR-based and include the following: (i) RFLPs, (ii) RAPDs, (iii) STSs, (iv) SSRs, (v) DAF, and (vi) AFLPs. In bread wheat, RFLPs and RAPDs were found to be of limited value because of their inability to detect adequate polymorphism and sometimes a lack of reproducibility. Therefore, we are focusing mainly on the remaining four classes of molecular markers. These markers (SSRs, STS, DAF, and AFLPs) are being exploited for tagging genes for the above traits to facilitate marker-assisted selection for improving grain quality of bread wheat.

In-gel hybridization. In-gel hybridization using 23 SSR probes representing different di-, tri-, and tetranucleotide repeats, in combination with 14 restriction enzymes (eight 6-base cutters and six 4-base cutters), were used for detection of DNA polymorphism in parents differing for each of the three traits. Multilocus fingerprints shown earlier to be characteristic of the majority of plant genomes were not obtained in bread wheat, and a very low level of polymorphism was detected using as many as 142 probe­enzyme combinations. In 107 probe­enzyme combinations, 1­12 bands were scored. In the remaining 35 probe­enzyme combinations, smear-like patterns were observed. Among the 107 cases, 50 had only a solitary band. This solitary band was > 23 kb in size in 40 of the 50 cases and was more often obtained with trinucleotide repeats. This characteristic > 23 kb band also was present in 21 other combinations, albeit in association with other smaller bands of < 5 kb. On the basis of the observed hybridization patterns, the different SSR probes could be grouped into three types: (i) probes with a solitary band > 23 kb with different enzymes (e.g., (CAG)s), (ii) probes with varying patterns with different restriction enzymes (e.g. (GGCA)4), and (iii) probes giving a solitary band with four enzymes and a ladder-like pattern with TaqI (e.g., (CAA)s). A detailed analysis of results suggested that SSR probes are not suitable for detecting polymorphism in bread wheat, and the microsatellites studied using in-gel hybridization are not evenly distributed over the whole genome of this species and are probably present only in the repetitive DNA sequences. However, these results do not exclude the possibility of the occurrence of microsatellites in unique sequences, because the in-gel hybridization technique is not suitable for the study of microsatellites in unique sequences.

Microsatellite-primed polymerase chain reaction (MP-PCR). The MP-PCR approach was tried to study inter-microsatellite length polymorphism using synthetic simple sequence repeat (SSR) oligonucleotide primers. A total of 14 SSR primers comprising different di-, tri-, and tetranucleotide repeats was used in a PCR assay to detect polymorphism between parent genotypes. Scorable fragments were observed using tri- and tetranucleotide SSR primers. However, a smear was obtained with primers representing dinucleotide repeats. Out of the 12 primers amplifying scorable fragments, only two primers ((GATA)4 and (GACA)4) revealed polymorphism in at least one pair of parents differing for any of the three quality traits examined. The MP-PCR approach did not give reproducible results in bread wheat. Despite positive results, this approach is not being pursued any further in our laboratory.

DNA amplification fingerprinting. DNA amplification fingerprinting (DAF) has been profitably used to fingerprint several plant species and also to develop molecular markers for gene tagging in crops like soybean. In bread wheat, we used this technology for the first time to examine its suitability for detection of polymorphism leading to possible gene tagging. Ten arbitrary, 8-mer, GC-rich linear primers and 10, 11-mer, minihairpin primers, each having a 3-mer-core sequence at the 3'-end, were utilized for DNA amplification. PCR products obtained using nine linear primers resolved into 20­35 bands (< 2 kb), whereas the PCR products obtained using four mini-hairpin primers resolved into 54­60 bands of < 2 kb. The remaining seven primers produced poor DAF profiles with a high background smear. Thirteen primers producing characteristic fingerprints revealed polymorphism between pairs of genotypes differing for GPC, GS, and PHST. However, contrary to earlier claims, neither the average number nor the proportion of polymorphic products obtained with minihairpin primers suggested their superiority over the linear primers. We believe that using more primers, DAF technology may greatly supplement other PCR approaches for developing molecular markers in bread wheat. Our efforts to convert the polymorphic fragments into SCAR markers failed, so we did not use these techniques any further for tagging the genes for the three quality traits.

Development of sequence tagged microsatellite site (STMS) markers. As a partner of the Wheat Microsatellite Consortium (WMC), a collaborative project coördinated by AGROGENE, France, we developed STMS markers to be used for gene tagging in wheat. We were supplied a set of 48 genomic DNA clones from a microsatellite-rich wheat library prepared by Edwards et al. (1995) at IACR-Long Ashton Research Station, University of Bristol, Long Ashton, UK. Of the 48 clones, we were able to sequence only 42 clones, of which eight contained no microsatellites. The remaining 34 clones contained 42 different microsatellites, eight having more than one microsatellite (generally two). The microsatellites included mono-, di-, and tri-nucleotide repeats but no tetranucleotide repeats. Dinucleotide repeats were most abundant followed by tri- and monorepeats. Of the 42 microsatellites detected, there were three mono-, 25 di-, nine tri-nucleotide repeats; four compound repeats; and one unusual repeat. An unusual type of mononucleotide repeat where 13 tri-nucleotide (AAA) units were interspersed with oligonucleotides of different lengths also was detected. The compound repeats (detected in four SSRs) were present both for dinucleotide and trinucleotide repeats. Perfect repeats were present in 19 SSRs, and imperfect repeats in another 19 SSRs. Based on DNA sequence data submitted to AGROGENE, the primer pairs were designed on the basis of sequences flanking the microsatellites. Only 16 STMS primer pairs could be developed from the above sequences. These primer pairs have been designated as WMC250 to WMC265 in the primer pool of the Wheat Microsatellite Consortium (WMC). However, from the WMC, we subsequently received as many as 232 STMS primer pairs including the above 16. All these primer pairs have been used between the parent genotypes differing for the three traits. We expect to receive another set of > 250 WMC primers to make a repertoire of ~500 STMS primer pairs for our use.

Identification of an STMS marker linked with a QTL for grain protein content (GPC). A total of 232 STMS primer pairs was used for detection of polymorphism between the two parental genotypes differing for GPC. Of these, 167 primer pairs gave scorable amplification products. Fifty-seven of these primer pairs detected polymorphism between the parental genotypes. Using these 57 primers, bulked segregant analysis was conducted on two pooled DNA samples, each consisting of 5-8 RILs representing the two tails of the normal distribution. With 56 of the 57 STMS primer pairs, no apparent association between the markers and protein content was observed. The remaining primer (WMC41) exhibited amplification profiles characteristic of high and low-protein parents in the corresponding bulks following bulked segregant analysis, suggesting an association of this marker with protein content. Selective genotyping of individual RILs belonging to the two bulks was done to further confirm this association. The results revealed that out of the eight RILs belonging to high-protein pool, seven showed a profile similar to the high-protein parent, six of the RILs belonged to the low-protein pool, and four RILs had a profile similar to low-protein parent. These data confirmed an apparent association between the WMC41 marker and protein content. Subsequently, all the 100 RILs were genotyped using the above STMS primer pair, and the data on cosegregation of the marker and protein content were used for QTL analysis. The QTL analysis used the single marker linear regression approach. The regression of protein content on the WMC41 marker was highly significant, indicating a linkage between the molecular marker and a QTL for protein content (designated as QGpcl.ccsu-2DS). An R2 value of 0.1873 suggested that WMC41-linked QTL contributed to 18.73 % of the total variation in protein content of the RILs. These results suggest that the marker WMC41 may be either tightly linked to a QTL with a small effect or loosely linked to a QTL with a large effect. Following the analysis of nullisomic-tetrasomic and ditelosomic lines, the WMC41 locus was assigned to 2DS, suggesting the presence of the QTL on the short arm of chromosome 2D.

Identification of a STMS and a STS marker linked with preharvest sprouting tolerance. A total of 232 STMS and 138 STS primer pairs were used for detection of polymorphism between the two parents, one tolerant and the other susceptible to PHS. Of these primer pairs, 57 STMSs and 30 STSs revealed reproducible polymorphism. These polymorphic STMS and STS primer pairs were used in a bulked segregant analysis. One STMS primer (wmcl04) and one STS primer (MST101) showed an apparent association with PHS tolerance. These primers were used in selective genotyping of 100 RILs, and a significant association was observed for the STMS (X2 = l9.07) and STS (X2 = 17.34) markers earlier identified using bulked segregant analysis.

Genome-specific microsatellites in Triticeae. As a preliminary experiment, we studied the distribution of microsatellites in five species belonging to the genus Aegilops and three species belonging to the genus Triticum. The results indicated genome specificity of some of these SSRs. We plan to extend this study further to examine the distribution and genome specificity of the 42 SSRs available with us involving wild/cultivated species of the Triticeae. The evolutionary relationships between members of Triticeae also may be studied.

Publications.

Balyan HS, Sharma PC, Ramesh B, Kumar A, Varshney RK, Roy JK, Dhaliwal HS, Singh H, and Gupta PK. 1998. Towards development of molecular markers for tagging genes for quality traits in bread wheat. In: Proc 9th Inter Wheat Genet Symp (Slinkard AE ed). University Extension Press, University of Saskatchewan, Saskatoon, Canada. 3:84-88.

Gupta PK. 1997. Nomenclature in Triticeae with emphasis on D genome diploid species. Wheat Inf Serv 85:52 55.

Gupta PK. 1998. Mutation breeding in cereals and legumes. In: Somaclonal Variation and Induced Mutations in Crop Improvement (Jain SM, Ahloowalia BS, and Brar DS, eds). Kluwer Academic Publishers, Dordrecht, Netherlands. pp. 311-332.

Gupta PK, Balyan HS, Sharma PC, and Rarnesh B. 1998. Genetics and molecular biology of seed storage proteins in wheat. In: Genetics and Biotechnology in Crop Improvement (Gupta PK ed). Rastogi Publications, Meerut, India. pp. 126-157.

Gupta PK, Balyan HS, Prasad M, Varsheny RK, and Roy JK. 1999. Development of molecular markers for some grain quality traits in bread wheat. In: PAG VII, San Diego, CA. P454 (abstract).

Gupta PK, Balyan HS, Sharma PC, Ramesh B, Kumar A, Varshney RK, and Roy JK. 1998. Towards tagging of some grain quality traits in bread wheat. In: XVIIIth Inter Cong Genet, 10­15 August, 1998, Beijing, China. pp. 53, 3P71 (abstract).

Gupta PK, Roy JK, and Prasad M. 1999. DNA chips, microarrays and genomics. Curr Sci (submitted).

Gupta PK and Varshney RK. 1999. Molecular markers for genetic fidelity during micropropogation and germplasm conservation. Curr Sci (accepted).

Gupta PK and Varshney RK. 1999. Microsatellite markers for genetics and plant breeding with emphasis on bread wheat. Euphytica (submitted).

Gupta PK, Varshney RK Sharma PC, and Ramesh B. 1999. Molecular markers and their application in wheat breeding. Plant Breed (submitted).

Kumar A, Varshney RK, Roy JK, Gupta PK, Balyan HS, Sharma PC, and Ramesh B. 1998. Microsatellites for marker assisted selection in bread wheat: Possibilities, achievements and limitations. In: Natl Symp "DNA Technologies: Forensic and Other Applications". IICT & CCMB, Hyderabad, India. 23­24 February, 1998. pp. 37 (abstract).

Prasad M, Varshney RK, Kumar A, Balyan HS, Sharma PC, Edwards KJ, Singh H, Dhaliwal HS, Roy JK, and Gupta PK. 1999. A microsatellite marker associated with a QTL for grain protein content on chromosome arm 2DL of bread wheat. Theor Appl Genet (accepted).

Prasad M, Varshney RK, Roy JK, Balyan HS, and Gupta PK. 1999. The use of microsatellites for detecting DNA polymorphism, genotype identification and diversity in wheat. Theor Appl Genet (submitted).

Prasad M, Varshney RK, Kumar A, Balyan HS, Sharma PC, Edwards KJ, Singh HS, Dhaliwal HS, Roy JK, and Gupta PK. l999. Tagging a QTL for grain protein content in bread wheat using microsatellite marker. In: Natl Symp "Emerging DNA Technologies for the Next Millennium". CCMB, Hyderabad, India. 23 February, l999. p. 13 (abstract).

Prasad M, Varshney RK, Roy JK, Balyan HS, Singh HS, Dhaliwal HS, and Edwards KJ. l999. Identification of an STMS marker linked with pre-harvest sprouting tolerance in bread wheat. In: Natl Symp "Emerging DNA Technologies for the Next Millennium". CCMB, Hyderabad, India. 23 February, l999. p. 14 (abstract).

Roy JK, Kumar A, Varshney RK, Gupta PK, Balyan HS, Sharma PC, and Ramesh B. 1998. Development of putative molecular marker(s) for protein content in bread wheat using STS-PCR. In: Natl Symp "DNA Technologies: Forensic and Other Applications". IICT & CCMB, Hyderabad, India. 23­24 February, 1998. pp. 44 (abstract).

Roy JK, Prasad M, Varshney RK, Balyan HS, Blake TK, Dhaliwal HS, Singh H, Edwards KJ, and Gupta PK. 1999. Identification of a microsatellite on chromosomes 6B and a STS on 7D of bread wheat showing association with preharvest sprouting tolerance. Theor Appl Genet (in press).

Roy JK, Varshney RK, Prasad M, Balyan HS, Singh H, Dhaliwal HS, Blake T, and Gupta PK. 1999. Identification and chromosomal localization of STS marker linked with pre-harvest sprouting tolerance in bread wheat. In: Natl Symp "Emerging DNA Technologies for the Next Millennium". CCMB, Hyderabad, India. 23 February, l999. p. 12 (abstract).

Sen A, Balyan HS, Sharma PC, Ramesh B, Kumar A, Roy JK, Varshney RK, and Gupta P.K. 1997. DNA amplification fingerprinting (DAF) as a new source of molecular markers in bread wheat. Wheat Inf Serv 85:35-42.

Sen A, Kumar A, Varshney RK, Roy JK, Balyan HS, Sharma PC, Ramesh B, and Gupta PK. 1997. Comparison of four PCR based approaches for detection of DNA polymorphism in bread wheat. In: Inter Group Meeting "Wheat Research Needs Beyond 2000 AD". DWR, Karnal, India. 12­14 August, 1997. pp. 74, P1.5-1, (abstract).

Varshney RK, Kumar A, Sen A, Balyan HS, Sharma PC, Ramesh B, and Gupta PK. 1997. Oligonucleotide fingerprinting for detection of DNA polymorphism in bread wheat. In: Inter Group Meeting "Wheat Research Needs Beyond 2000 AD". DWR, Karnal, India. 12­14 August, 1997. pp. 82, P1.5-9 (abstract).

Varshney RK, Sharma PC, Gupta PK, Balyan HS, Ramesh B, Roy JK, Kumar A, and Sen A 1998. Low level of polymorphism detected by SSR probes in bread wheat. Plant Breed 117:182-184.

Studies on ribosomal DNA (rDNA) polymorphism, genetic diversity, GA-insensitive dwarfing genes, breeding methods, character association, and gene effects in wheat.

P.K. Gupta, H.S. Balyan, P.K. Sharma, R.S. Lohia, and T. Singh.

Allelic polymorphism at rDNA loci. This work was done under the auspices of the CSIR-ES, Government of India, and encompasses studies on variation in the rDNA repeat-unit length, variation in the relative abundance of rDNA in different collections, variations in the extent of methylation at certain specific regions, and variation in nucleotide sequences in the internal transcribed spacer (ITS) region. Material for this study included 60 accessions of common wheat, which were collected from Directorate of Wheat Research, Karnal, India. Genomic DNA from all the accessions was isolated, purified, and checked for quality, and the concentration was estimated for subsequent use in the above studies. The DNAs were individually digested with the restriction endonucleases SacI, EcoRI, and BamHI. The digested DNAs were electrophoresed in 1 % agarose gel at 56 V for 18 h and transferred to Hybond N+ membrane. To detect variation in the rDNA repeat-unit length, filters were hybridized with an rDNA probe (pTa71, a 9.0 kb EcoRI fragment of wheat rDNA repeat unit) and exposed to x-ray film. Autoradiograms with SacI-digested DNA showed one common band of 3.9 kb from the coding region of the repeat unit and 2-4 other bands. Autoradiograms of BamHI-digested DNA showed one common band of ~ 3.7 kb from the coding region and 5­9 more bands in different lanes representing different accessions. However, EcoRI-digested DNA showed only one polymorphic band in all the accessions except a few where the presence of one more band also was observed. The length of the rDNA repeat unit calibrated from the above autoradiograms varied from ~ 8-11 kb. These results suggested variation in the length of the repeat unit among the T. aestivum accessions. This variation can be assigned to the allelic forms of different rDNA loci already determined by several workers.

To study the variation in the nucleotide sequence of the ITS region of the rDNA repeat unit, 50 ng of genomic DNA from each of the 60 accessions of wheat was amplified by PCR. The ITS5 and ITS4 primers were utilized. PCR-amplification products along with a 100-bp DNA molecular-weight marker were separated in 1.5 % agarose gel at 70 V in TBE buffer for 3 h. Amplification of the ITS region was successful for all the 60 accessions. Each accession showed a single band of about 750 bp, and one (E 3414) had an additional band representing a product of ~760 bp. These results suggest that variation in the length of ITS region also occurs at the different NORs in bread wheat. To our knowledge, this situation (the variation in ITS length) is uncommon within the species of Triticum. The PCR products are being used for sequencing to detect sequence variation.

Genetic diversity. Three-hundred bread (273) and durum (27) wheat genotypes including Indian and exotics were evaluated for 10 quantitative characters, including grain yield, in an augmented block design with 20 blocks. Five of these characters (grain yield, biological yield, tiller number, grain weight/ear, and grains/ear) were highly variable. Among the remaining five traits, two (flag leaf area and 100-grain weight) showed moderate variability, and the remaining three (plant height, peduncle length, and harvest index) showed relatively low variability. Following a nonhierarchical Euclidean cluster analysis, all the 300 genotypes were grouped into 16 clusters with unequal numbers of genotypes. Genotypes with different places of origin/release and different ploidy levels (bread versus durum wheats) were often grouped together in the same clusters. Genotypes from the same place of origin and those having a similar ploidy level were scattered in different clusters, suggesting that the level of genetic diversity among the cultivars released from different places and those released from the same place did not differ. Similarly, the level of genetic diversity among genotypes at the same ploidy level did not differ from that among genotypes with different ploidy levels. On the basis of the data on genetic divergence and mean performance of yield and other traits, five superior genotypes including two (MUW 109 and CPAN 3064) from cluster VI, one (CPAN 1556) from cluster I, and two (MUW 104 and CPAN 1998) from cluster IV were selected. Each of these genotypes was found to be very promising for one or more characters and was at least reasonably good for other remaining characters in comparison to the best check cultivars. Therefore, these genotypes may be involved in a multiple-crossing program in different combinations, using a specific combination of two genotypes from two different clusters to recover transgressive segregates. Furthermore, on the basis of character associations, selection of plants with high biological yield coupled with optimum harvest index (~ 50 %) should result in progenies with high grain yield potential in wheat.

Pleiotropic effects of GA-insensitive dwarfing genes in late-sown conditions. We are concerned about the suitability of cultivation of dwarf wheats under abiotic stress environments. In view of this, the pleiotropic effects of the GA-insensitive Rht-B1b, Rht-D1b, and Rht-B1c dwarfing genes on grain yield and yield contributing traits under late-sown conditions were studied. Material included 33, 14, and 68 random pairs of near isogenic, tall (containing either Rht-B1a or Rht-D1a alleles for tallness) and dwarf (containing either Rht-B1b, Rht D1b, or Rht-B1c dwarfing alleles) lines derived from the crosses 'K68 (Rht-B1a) / HD2009 (Rht-B1b)', 'K68 (Rht D1a) / WH147 (Rht-D1b)', and 'K68 (Rht-B1b) / Tom Thumb (Rht-B1c)'. Each random pair of tall and dwarf NILs was the progeny of a single heterozygous plant, which could be traced to a separate F2 plant. The random pairs of NILs for each of the three GA-insensitive dwarfing genes were evaluated under late-sown conditions in a randomized complete block experiment. The tall and dwarf NILs of each random pair were evaluated as two separate groups in each replication with similar randomization patterns. Under late-sown conditions, the Rht-B1b, Rht-D1b, and Rht B1c dwarfing genes were associated with 22.5 %, 14.2 %, and 26.7 % reductions in grain yield, respectively. The negative effect of each of the three dwarfing genes on grain yield was due to a significant reduction in biological yield. The poor biological yield of Rht-B1b- and Rht-D1b-containing dwarf lines was mainly due to a reduced number of light tillers, whereas in the Rht-B1c-containing lines, it was caused by light tillers and reduced numbers of grains/floret, grains/spike, and 100-grain weight. The mechanisms involved in grain yield reduction in lines containing different dwarfing genes were thus different. However, the poor biological and grain yields of the dwarf lines may arise because of their greater sensitivity to abiotic stress factors, particularly warm conditions, associated with late sowing. To obtain beneficial effects of the dwarfing genes on grain yield potential under stress conditions, adjustment of the genome by selection may often be needed.

Pleiotropic effects of GA-insensitive dwarfing genes in a rainfed environment. The semidwarf wheats, because of their high yield potential and lodging resistance, have been widely adopted by farmers for cultivation under irrigated and high fertility conditions. However, the suitability of such wheats for replacing the traditional drought-tolerant tall wheats is still questioned. For this reason, we attempted to understand the pleiotropic effects of two major dwarfing genes, Rht-B1b and Rht-D1b, on grain yield and its component traits under rainfed environment to assess the suitability of semidwarf wheats for cultivation under water stress. The material for this study was comprised of random F7 semidwarf (17 Rht-B1b and 7 Rht-D1b) and tall (9 Rht-B1a and 14 Rht-D1a) lines and their parent genotypes. Each of the random lines could be traced to separate F2 plant of the crosses 'K68 (Rht-B1a) / HD2009 (Rht-B1b)' and 'K68 (Rht-D1a) / WH147 (Rht-D1b)'. The genotypes of random dwarf and tall lines were confirmed by a GA-response test. The experimental field was irrigated prior to sowing, and the soil moisture was judged to be optimum at the time of planting of the experiments. The random dwarf and tall lines along with their parents were separately evaluated in RBD experiments under irrigated (nonstress) and rainfed (water stress) environments. Rainfall during the crop season of this experiment was much less than the average of the preceding 3 years, creating a water-stressed environment in the absence of irrigation. Data were recorded on 11 characters including culm length, grain yield, and component traits.

The results showed that Rht-B1b and Rht-D1b dwarfing genes have negative effects on grain yield under water stress. The decline in grain yield in the dwarf lines was due to the significant and greater reduction in biological yield caused by reduced number of lighter tillers and yield/spike resulting from reductions in number of florets and grains/spike (Rht-B1b) or grain weight (Rht-D1b) and early maturity. Poor biological and grain yields of the water-stressed dwarf lines were linked to their greater sensitivity to factors associated with diminished soil moisture. However, variability in stress susceptibility index values, a measure of stress susceptibility among the water-stressed dwarf lines, and a negative association between stress susceptibility index and grain yield were noted. We conclude from these results that it should be possible to select semidwarf lines containing the above dwarfing genes with high grain-yield potential and greater tolerance to water stress in the appropriate segregating populations.

The effect of GA-insensitive dwarfing genes on the tillering ability in spring wheat genotypes. The presence of GA-insensitive dwarfing genes provides the dwarf wheats have several advantages over traditional tall wheats. These advantages include greater numbers of smaller grains per ear or of tillers and a higher harvest index. In winter wheats, the expression of higher number of smaller grains is quite pronounced, but the expression of higher number of tillers is inconsistent. However, in dwarf spring wheats, the expression of higher number of tillers is an important feature, whereas expression of the number of grains is not. In view of this, a study was conducted on the tillering ability of GA-insensitive dwarf spring genotypes of bread wheat. For this purpose, F2 populations were derived from the following three crosses: 'K68(Rht-B1a) / HD2009(Rht-B1b)', 'K68(Rht-D1a) / WH147(Rht-D1b)', and 'K68(Rht-B1b) / Tom Thumb(Rht-B1c)'. Selection for tall and dwarf culm lengths in association with lower and higher number of tillers was carried out from F2 to F5. In the F6, the tall and dwarf progenies of various populations were classified following the GA-response test to identify the tall and dwarf (containing GA-insensitive dwarfing alleles) populations with lower and higher number of tillers. The 12 selected populations were separately evaluated in RBD experiments for culm length and number of tillers. The results showed that none of the three Rht-B1b, Rht-D1b, and Rht-B1c dwarfing genes had any clear advantage in increasing the number of tillers. Thus, the previously noted association of greater tillering ability of GA-insensitive dwarf genotypes with change in GA-IAA balance needs further examination. However, the results of this study suggested that greater tillering response might be obtained with selection for tall-dwarf rather than for dwarf genotypes.

Modulation in the pleiotropic effects of GA-insensitive dwarfing genes due to changes in tillering behavior. Four types of populations were selected in each of the above three crosses, including: (i) dwarf with a high number of tillers (DH), (ii) dwarf with a low number of tillers (DL), (iii) tall with a high number of tillers (TH), and (iv) tall with a low number of tillers (TL). The DH and TH populations had higher biological yields than the DL and TL populations. A detailed analysis indicated the significant contribution of the number of tillers (a component of grain yield) to biomass regardless of the presence or absence of dwarfing genes. Biological yield was positively and significantly associated with grain yield in all populations, suggesting the significant role of biological yield in determining grain yield. Furthermore, all the dwarf populations had a higher harvest index than the respective tall populations. Two of the DH populations (containing Rht-B1b and Rht-D1b) also were significantly higher yielding than the respective TH populations. The higher grain yield of these DH populations was mainly due to improved fertility and 100-grain weight.

The effect of a change in number of tillers in GA-insensitive dwarf wheats on the ability to tolerate water stress. The above-mentioned 12 populations were evaluated in spaced plantings under irrigated and rainfed environments. Culm lengths of the dwarf (DH and DL) and tall (TH and TL) populations were adversely affected when water stressed. The absolute average culm length of the tall populations remained greater than that of the respective dwarf populations. Because of water stress, a negative change was noted in four characters (grain yield, biological yield, tiller number, and days-to-maturity) in all the tall and dwarf populations. A similar change also was noted in a few other characters but was not observed across all the populations. The grain yield of DH (Rht B1b) and DH (Rht-D1b) populations showed greater declines than that in the respective TH populations. However, the absolute grain yield of the DH (Rht-D1b) population was significantly greater than that of its respective TH population. The lower range values of the stress-susceptibility indices, a measure of stress susceptibility, of the DH populations were relatively smaller than those of the other populations.

Selected progenies of different populations also were evaluated under solid-seeded, irrigated (nonstress) as well as rainfed (water stress) environments. Under irrigated conditions, the mean number of tillers in all the DH and TH (except one) populations were greater than in the respective DL and TL populations. This is in agreement with the results of the experiments conducted under spaced plantings in an irrigated environment. The number of tillers contributed positively towards biological yield irrespective of the culm length. The biological yield of the DH (Rht B1b) and DH (Rht-D1b) populations was not significantly different from those of the respective TH populations. The lower biological yields of the DL populations than the TL populations were due to either lighter culm weight or lower number of tillers. The harvest index in all the dwarf populations was higher in all cases, though not significantly, than that in the respective tall populations because of the positive change in one or more spike-related traits in the DH populations. The higher harvest index in DH (Rht-B1b) population was associated with higher grain yield than in the respective TH (Rht-B1a) population. A similar trend was noticed for the DH (Rht-D1b) population. However, the clear yield advantage of the above two DH populations under spaced plantings was eroded to some extent under dense planting.

Water stress caused a significant decline in the grain yield of all dwarf and tall populations. A reduction also was noticed in nearly all or some of the yield-contributing characters and the biological yield in all populations. However, the decline in grain yield in the dwarf populations was relatively lower than that in the tall populations. Furthermore, the DH (Rht-B1b) and DH (Rht-D1bI) populations were the highest yielding, although not always significantly. The lower magnitude of the lower-range values of stress susceptibility indices of DH populations suggests the possibility of recovering genotypes with better ability to cope up with the water stress. We concluded that for irrigated (nonstress) and rainfed (water stressed) environments, breeding for high-tillering, dwarf genotypes (containing either Rht-B1b or Rht-D1b gene) may be a rewarding strategy for achieving high productivity.

Breeding methods: Usefulness of biparental matings and geno-phenotypic selection for yield improvement. This study was conducted to find the usefulness of biparental matings over selfing and of a geno phenotypic (GP) selection scheme over a phenotypic (P) selection scheme for improvement of grain yield in wheat. For this purpose, in each of the two double-cross hybrids, 80 biparental (BIPF1s) and 160 selfed (F3s) families were developed from intermating in pairs and selfing of 160 randomly chosen F2 plants. The families of BIPF1 and F3 base populations along with the parents were separately evaluated in RBD experiments. Selection in these populations was exercised following a P selection scheme (selection of top 5 % and 10 % plants) and a GP selection scheme (selection of the best two plants from each of the top 25 % and 50 % families allowing 5 % and 10 % selection intensities, respectively) to generate F4 (F4P5 %, F4GP5 %, F4P10 %, and F4GP10 %) and BIPF2 (BIPF25 %, BIPF2GP5 %, BIPF2P10 %, and BIPF2GP10 %) subpopulations. These subpopulations were evaluated in RBD experiments. The results showed that following the GP and P selection schemes, the predicted and realized responses to selection for grain yield from the first cycle of selection and the predicted response to selection for grain yield from the second cycles of selection were greater under biparental matings than selfing. Similarly, the GP selection scheme resulted into greater response for yield improvement than the P selection scheme under the biparental matings as well as selfing. These results clearly suggested that the GP selection scheme following intermatings in the F2 may be exercised to obtain enhanced and continuous gains in grain yield in succeeding generations. The improvement in grain yield was linked with increases in plant height, tiller number, and biological yield. These traits also were significantly and positively associated with grain yield in all populations. An index comprising these traits may be utilized for selecting high-yielding wheat genotypes of suitable height.

Character association. Correlation and path coefficient analyses using 14 agronomic characters (days-to flowering, plant height, flag leaf area, peduncle length, flag leaf sheath length, days-to-maturity, tillers/plant, biological yield/plant, grains/ear, grain weight/ear, grain yield/plant, days from flowering to maturity, 100-grain weight, and harvest index) were made on 300 bread and durum wheat genotypes. Out of the 13 characters excluding grain yield, nine characters (biological yield, tiller number, harvest index, flag leaf sheath length, plant height, 100 grain weight, grain weight/ear, peduncle length, and flag leaf area) showed positive correlation with grain yield. However, the magnitudes of correlation coefficients were high for only three characters, e.g., biological yield (0.93), tiller number (0.69), and harvest index (0.43), suggesting the importance of these characters in improving grain yield. Despite the positive correlation of nine characters with grain yield, path coefficient analysis suggested that only biological yield (direct effect = 0.91) and harvest index (direct effect = 0.32) had high direct effects in increasing grain yield. The remaining characters exhibited their contribution to grain yield only through biological yield with which they also had a positive correlation. These other characters showed positive correlations with grain yield only because they had positive correlations with biological yield. High indirect effects towards grain yield via biological yield and positive correlations therewith suggest that these characters are directly important for increasing biological yield and, hence, indirectly the grain yield. Therefore, to bring about improvement in grain yield, a selection index should be constructed, giving due importance to the above-mentioned characters to increase biological yield together with harvest index. Because the tiller number showed high positive correlations with both grain yield and biological yield and had the highest indirect effect via biological yield in affecting the grain yield, this character may be the most important trait in increasing biological yield and eventually the grain yield.

Genetic characterization of some quantitative characters. Six generations (P1, P2, F1, F2, BC1, and BC2) of the three crosses of bread wheat, 'CPAN 1961 / MUW 27', 'CPAN 1933 / HW 517', and 'Eagle / Mendose' were studied for the genetic characterization of 13 quantitative characters, including grain yield/plant, days-to flowering, tillers/plant, plant height, days-to-maturity, spikelets/spike, biological yield/plant, grains/ear, grain weight/ear, 100-grain weight, and harvest index. None of the characters was consistent in exhibiting the same specific gene effects (additive, dominance, or interaction) in all the three crosses. Both additive and nonadditive gene effects were found to be important for different traits in the three crosses. Complementary and duplicate types of epistasis were observed for different traits. In such situations, biparental crossing followed by recurrent selection should be adopted to exploit these effects simultaneously for realizing improvement in grain yield.

Publications

Balyan HS and Singh O. 1994. Pleiotropic effects of GA-insensitive Rht genes on grain yield and its component characters in wheat. Cereal Res Commun 22:195-200.

Balyan HS and Singh T. 1997. The usefulness of biparental mating and geno-phenotypic selection for yield improvement in wheat (Triticum aestivum L.). Indian J Genet 57:401-410.

Balyan HS and Lohia RS. 1998. Pleiotropic effects of Rht dwarfing genes on grain yield and its component traits in wheat under rainfed environment. Indian J Genet 58:169-176.

Balyan HS and Lohia RS. 1998. On the tillering ability of GA-insensitive dwarf spring bread wheat genotypes. In: Proc 9th Inter Wheat Genet Symp (Slinkard AE ed). Univ Extension Press, Saskatoon, Canada. 2:150-152.

Lohia RS. 1998. The effects of Rht1, Rht2 and Rht3 dwarfing genes on yield and yield component characters in wheat (Triticum aestivum L.). Ph.D. Dissertation, Ch. Charan Singh University, Meerut.

Sharma PK. 1995. Genetic divergence and character association analysis in wheats, and AMMI analysis of a pearl millet yield trial. Ph.D. Dissertation, Ch. Charan Singh University, Meerut.

Sharma PK. 1998. Character association analysis in wheat. J Cytol Genet 33:11-15.

Sharma PK, Garg DK, and Sharma PC. 1996. Genetic characterization of some quantitative characters in wheat (Triticum aestivum L.). Indian J Genet 56:281-284.

Sharma PK, Gupta PK, and Balyan HS. 1998. Genetic diversity in a large collection of wheat (Triticum spp.). Indian J Genet 58:(in press).

UNIVERSITY OF AGRICULTURAL SCIENCES & TECHNOLOGY
SKUAST

Regional Agricultural Research Station, Sher-E-Kashmir, R.S. Pura­181 102, Jammu, India.

Triticum aestivum / Aegilops kotschyi hybrids and their cytology.

J.S. Bijral, Kuldip Singh, and T.R. Sharma.

Aegilops kotschyi is a wild species that grows sympatrically with Ae. bicornis, Ae. crassa, Ae. juvenalis, Ae. vavilovii, and Ae. longissima and is known to contain genes for drought, heat, and salt tolerance (Kimber and Feldman 1987) and eye spot resistance (Bang and Hulsbergen 1992). Furthermore, its cytoplasm, which is possibly similar to that of Ae. longissima, can be used interchangeably with that of T. timopheevi to induce male sterility in cultivated wheats (Tsunewaki et al. 1980). The introduction of these traits, especially drought and salt tolerance, into cultivated wheat will undoubtedly increase its range, so that wheat may be grown in conditions where it is currently impossible. A set of interspecific hybrids between T. aestivum and Ae. kotschyi was produced with the above objectives in mind. This report presents the morpho-cytogenetics of these F1 hybrids.

Materials and methods. The bread wheat cultivars UP 2338 and RSP 81, the homoeologous-pairing mutant of Chinese Spring (CS phlb phlb), and an accession of Ae. kotschyi (3502) were used in this study. Manually emasculated wheat spikes were pollinated with freshly collected Ae. kotschyi pollen under field conditions. In addition to three 'T. aestivum / Ae. kotschyi' crosses, a reciprocal cross involving Ae. kotschyi (the female parent) and CS phlb phlb also was produced.

For meiotic studies, immature Fl spikes were fixed in a 1:3 acetic acid­alcohol solution for 24 h, and meiotic preparations were made by squashing the anthers in 2.0 % acetocarmine.

Results and discussion. The Fl hybrid plants were completely self-sterile and resembled the wheat parents in gross morphology. Pollination of hybrid plants with wheat parents failed to set any BC1 seeds.

The hybrid status of the presumptive Fl plants was confirmed cytologically. All of the plants derived from different cross combinations had the expected 35 chromosomes. The mean chromosome pairing in the Fl progeny of the various cross combinations was 'UP 2338 / Ae. kotschyi' 27.25 I + 3.78 II + 0.06 III, 'RSP 81 / Ae. kotschyi' 28.95 I + 2.29 II + 0.38 III, 'CS (phlb ph1b) / Ae. kotschyi' 30.76 I + 2.04 II 0.04 VI, and 'Ae. kotschyi / CS (ph1b phlb)' 31.10 I + 1.58 1I + 0.12 IV (see Table 1). Sears (1982) reported that chromosome pairing in 'T. aestivum / Ae. kotschyi' hybrids varied from 1 to 6.92 bivalents (ring + rod) per cell. Additionally, bivalents and quadrivalents were recorded in some meiocytes.Ae. kotschyi (the female parent) and CS phlb phlb also was produced.

Table 1. Mean chromosome pairing in 'T. aestivum / Ae. kotschyi' and 'Ae. kotschyi / T. aestivum' Fl hybrids.

Cross combination	Chromosome associations at MI
	I	II			III	IV
		rod	ring	total
UP 2338 / Ae. kotschyi (3502)	25.25 (25-29)*	2 56 (2-4)	1.22 (0-3)	3.8 ---	0.06 (0-1)	--- ---
RSP81 / Ae. kotschyi (3502)	28.95 (24-31)	1.04 (0-2)	1.25 (0-2)	2.29 ---	0.38 (0-1)	--- ---
CS ph1b ph1b / Ae. kotschyi (3502)	30.76 (29-33)	0.92 (0-2)	1.12 (0-2)	2.04 ---	--- ---	0.04 (0-1)
Ae. kotschyi (3502) / CS ph1b ph1b	31.19 (29-35)	0.85 (0-3)	0.73 (0-2)	1.58 ---	--- ---	0.12 (0-1)
* Figures in parentheses indicate range.

The series of T. aestivum­Ae. kotschyi hybrids with various levels of chromosome pairing described by Sears (1982), as well as those from this report, are typical and best fit the 3:2 model of chromosome pairing developed by Kimber (1983). Alonso and Kimber (1983) have shown that the relationship between the B and the S genomes is similar to that between the A and D genomes in tetraploid hybrids of cultivated wheat with S-genome diploids. A similar relationship in the T. aestivum­Ae. kotschyi pentaploid (ABDUS) hybrids may be reasonably assumed. Two equally probable patterns of chromosome pairing can be visualized in these pentaploid hybrids, ADU:BS or BSU:AD (Kimber 1984). Obviously, the first pairing pattern will have a greater probability for the introduction of alien variation through induced homoeologous synapsis (Riley et al. 1968), because the two alien U and S genomes are in different clusters. Recently, Bang and Hulsbergen (1992) have succeeded in obtaining stable lines that are 2n = 42 and have eye spot resistance introgressed from Ae. kotschyi.

Acknowledgment. Our sincere thanks are due to Dr. H.S. Dhaliwal, Director, Biotechnology Centre, Punjab Agriculture Universily, Ludhiana, for kindly supplying seed of Ae. kotschyi (accession 3502).

References.

Alonso LC and Kimber G. 1983. A study of genomic relationships in wheat based on telocentric chromosome pairing II. Z Pflanzenzuchtg 90:273-284.

Bang R and Hulsbergen H. 1992. Triticum aestivum-Aegilops kotschyi introgression lines with eye spot resistance. EWAC Newslett 1992:50

Kimber G. 1983. Technique selection for the introduction of alien variation in wheat. Z Pflanzenzuchtg 92:15 21.

Kimber G and Feldman M. 1987. Wild wheat-an introduction. Special Report 353, University of Missouri Columbia. Pp. 62.

Riley R, Chapman V, and Johnson R. 1968. The incorporation of alien disease resistance in wheat by genetic interference with the regulation of meiotic chromosome synapsis. Genet Res 12:100-201.

Sears ER. 1982. A wheat mutation conditioning an intermediate level of homoeologous chromosome pairing. Can J Genet Cytol 24:715-719.

Tsunewaki K, Endo TR, Kobayushi M, Mukai Y, and Panayotov I. 1980. Genetic diversity of the cytoplasm in Triticum and Aegilops. Japan Soc Promot Sci, Tokyo. Pp. 290.

Kimber G. 1984. Evolutionary relationships and their influence on plant breeding. In: Gene Manipulation in Plant Improvement, Proc16th Stadler Genetics Symp (Gustafson JP ed). Plenum Press, New York. Pp. 281-294.