abstract
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Selecting the genotype for drought tolerance is a challenging task for wheat breeders worldwide. Low heritability, polygenic inheritance, high Genotype x Environment interaction and difficulties in phenotyping complicates the breeding process to obtain desired genetic gains for drought tolerance. The approaches involving the package of component traits of drought tolerance with respect to particular environment apart from the grain yield under stress along with marker score has proved useful for enhancing the genetic gains The research work was carried out at Indian Agricultural Research Institute, New Delhi, with the aim to validate, map and mobilize QTLs for drought tolerance using a MARS breeding strategy, A population from the cross DBW43/HI1500 was developed using parents diverse for drought tolerance traits. The base population was evaluated under three different environmental conditions representing the diverse agro-climatic zones of the India. A total of 29 markers linked to the different component traits of the drought tolerance were validated in the present population. A genetic linkage map was constructed using the 1100 polymorphic co-dominant SNPs from 35k wheat Breeder array , a total of 51 QTLs were detected on 17 chromosomes for physiological and traits of agronomical importance. Three cycles of recombination were done, favourable allelic frequency at 20 marker loci were increased in MARS derived lines (C1,C2 and C3) as compared to the base population (C0). A total of 37 individuals were found to have higher marker score than the parental lines. The positive trend of the higher marker score and overall grain yield (q/ha) based on multilocation testing was observed which is indicative of the usefulness of the marker score for drought tolerance. The line HD3296 a product of first recombination cycle (C1) tested was found to be 9.87% superior to the check, HD3043 with overall mean yield of 48.33 q/ha under restricted irrigation conditions. The products of the second (C2) and third (C3) intercrossed progenies from GCP 2 (G50, G29, G2 and G65) and GCP3 trials (G17, G74, G20, G69 and G70 ) respectively, were superior to the check variety HD3043 by 8-16.58% in multilocational evaluation. This study is the first report of successful implementation of the MARS strategies for obtaining the genetic gains under drought stress in wheat.