Abstract only

Chickpea, an important food legume is generally grown in marginal environments of semi-arid regions of Asia and Africa|where the crop production is heavily challenged by abiotic stresses such as terminal drought and biotic factors like|legume pod borer (Helicoverpa armigera), fusarium wilt and ascochyta blight. With an objective to tackle these|production constraints through molecular breeding, in collaboration with several partners around the world, significant|genomic resources have been developed recently (http://www.icrisat.org/gt-bt/ICGGC/homepage.htm). For instance,|1,655 novel SSRs have been isolated from the SSR-enriched library (311) and BAC-end sequences (1,344), a DArT|array has been developed with >16,000 features and >20,000 ESTs from drought and salinity stress challenged tissues|based on Sanger sequencing. Further, a set of 443,969 sequence tags were generated through FLX-454 sequencing|from a pool of normalized cDNA assembled from developmental stages and abiotic stresses challenged tissues of a|reference chickpea genotype (ICC 4958). Analysis of Sanger as well as FLX-454 sequence data provided 103,215|tentative unique sequences (TUSs). In parallel, transcriptomes of drought and Helicoverpa challenged tissues were|sequenced using Solexa sequencing approach. Over 37 million drought responsive tags were obtained from ICC 4958|and ICC 1882 and their alignment with the TUSs provided 26,083 nucleotide variants (SNPs) between the two|genotypes. Similarly, 81.2 million tags were generated from Helicoverpa challenged tissues of ICCC 37 and ICC 506|genotypes and a total of 65,536 nucleotide variants were identified. In collaboration with University of California-Davis, a|pilot Illumina GoldenGate assay for 768 SNPs has been developed. By using above mentioned resources, an integrated|genetic map with >1534 marker loci has been developed based on an interspecific mapping population (C. arietinum ICC|4958 �� C. reticulatum PI 489777). With an objective of identification of candidate markers associated with drought|tolerance (root traits), the most challenging production constraint, two intraspecific mapping populations (ICC 4958 �� ICC|1882 and ICC 283 �� ICC 8261) have been phenotyped for root traits in two environments and genotyped with >250 SSR|markers. Marker-trait analysis has revealed several QTLs including one major QTL in both mapping populations that|contributed up to 30% phenotypic variation for drought-tolerance component traits. This genomic region containing|several QTLs for drought tolerance is being introgressed into three elite chickpea lines (JG 11, ICC 92318 and KAK 2),|using marker-assisted backcrossing (MABC) approach, to develop superior cultivars with enhanced drought tolerance. It|is therefore anticipated that developed genomic resources at large scale should facilitate genomics-assisted breeding|that would lead to sustainable crop production of chickpea in developing countries.

English

CIMMYT Staff Publications Collection