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Author: search.filters.author.Prasad, ManojSubject: search.filters.subject.Bread wheat

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    Genetic dissection of grain weight in bread wheat through quantitative trait locus interval and association mapping
    (Springer, 2012) Mir, RR; Kumar, N; Girdharwal, N; Prasad, Manoj; Balyan, HS; Gupta, PK
    Genetic dissection of grain weight in bread wheat was undertaken through both genome-wide quantitative trait locus (QTL) interval mapping and association mapping. QTL interval mapping involved preparation of a framework linkage map consisting of 294 loci {194 simple sequence repeats (SSRs), 86 amplified fragment length polymorphisms (AFLPs) and 14 selective amplifications of microsatellite polymor- phic loci (SAMPL)} using a bi-parental recombinant inbred line (RIL) mapping population derived from Rye Selection111 9 Chinese Spring. Using the genotypic data and phenotypic data on grain weight (GW) of RILs collected over six environments, genome-wide single locus QTL analysis was conducted to identify main effect QTL. This led to identification of as many as ten QTL including four major QTL (three QTL were stable), each contributing [20% phenotypic variation (PV) for GW. The above study was supplemented with association mapping, which allowed identification of 11 new markers in the genomic regions that were not reported earlier to harbour any QTL for GW. It also allowed identification of closely linked markers for six known QTL, and validation of eight QTL reported earlier. The QTL identified through QTL interval mapping and association mapping may prove useful in marker-assisted selection (MAS) for the development of cultivars with high GW in bread wheat.
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    Variability in Indian bread wheat (Triticum aestivum L.) varieties differing in nitrogen efficiency as assessed by microsatellite markers
    (Springer, 2010) Chandna, Ruby; Gupta, Sarika; Ahmad, Altaf; Iqbal, Muhammad; Prasad, Manoj
    Wheat (Triticum aestivum L.) is a staple food for half of the world. Its productivity and agronomical practices, especially for nitrogen supplementation, is governed by the nitrogen efficiency (NE) of the genotypes. We analyzed 16 popular cultivated Indian varieties of wheat for their NE and variability estimates using a set of 21 simple sequence repeat (SSR) markers, derived from each wheat chromosome. These genotypes were categorized into three groups, viz., low, moderate, and high nitrogen efficient. Of these 16 genotypes, we have reported six, eight, and two genotypes in high, moderate, and low NE categories, respectively. The differential NE in these genotypes was supported by nitrogen uptake and assimilation parameters. The values of average polymorphic information content and marker index for these SSR markers were estimated to be 0.32 and 0.59, respectively. The genetic similarity coefficient for all possible pairs of varieties ranged from 0.41 to 0.76, indicating the presence of considerable range of genetic diversity at molecular level. The dendrogram prepared on the basis of unweighted pair-group method of arithmetic average algorithm grouped the 16 wheat varieties into three major clusters. The clustering was strongly supported by high bootstrap values. The distribution of the varieties in different clusters and subclusters appeared to be related to their variability in NE parameter that was scored. Genetically diverse parents were identified that could potentially be used for their desirable characteristics in breeding programs for improvement of NE in wheat.
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    Genome-wide QTL analysis for pre-harvest sprouting tolerance in bread wheat
    (Springer, 2009) Mohan, Amita; Kulwal, Pawan; Singh, Ravinder; Kumar, Vinay; Mir, Reyazul Rouf; Kumar, Jitendra; Prasad, Manoj; Balyan, H. S.; Gupta, P. K.
    A framework linkage map comprising 214 molecular marker (SSR, AFLP, SAMPL) loci was prepared using an intervarietal recombinant inbred line (RIL) mapping population of bread wheat. The RIL population that was developed from the cross SPR8198 (red-grained and PHS tolerant geno- type) 9 HD2329 (white-grained and PHS susceptible genotype) following single seed descent segregated for pre-harvest sprouting (PHS). The RIL population and parental genotypes were evaluated in six differ- ent environments and the data on PHS were collected. Using the linkage map and PHS data, genome-wide single-locus and two-locus QTL analyses were con- ducted for PHS tolerance (PHST). Single-locus analysis following composite interval mapping (CIM) detected a total of seven QTL, located on specific arms of five different chromosome (1AS,2AL, 2DL, 3AL and 3BL). These seven QTL included two major QTL one each on 2AL and 3AL. Two of these seven QTL were also detected following two-locus analysis, which resolved a total of four main-effect QTL (M-QTL), and 12 epistatic QTL (E-QTL), the latter involved in 7 QTL 9 QTL interactions. Interestingly, none of these M-QTL and E-QTL detected by two-locus analysis was involved in Q 9 E and Q 9 Q 9 E interactions, supporting the results of ANOVA, where genotype 9 environ- ment interaction were non-significant. The QTL for PHS detected in the present study may be efficiently utilized for marker-aided selection for enhancing PHST in bread wheat.