Identification, Introgression and Fine Mapping of a“QTL-Hotspot” for Drought Tolerance in Chickpea

With an aim of enhancing drought tolerance in chickpea (Cicer arietinum L.) a key genomic region (~7 Mb) designated as a “QTL-hotspot” harbouring QTLs for several drought tolerance related traits has been identified. This genomic region has been successfully introgressed into 3 leading varieties (JG 11, Chefe, KAK2) by using marker-assisted backcrossing (MABC) approach. As a result several MABC-derived lines, as compared to recurrent parental lines, have shown up to 12% (rainfed) to 24% (irrigated) higher yield have been developed. In parallel, Skim sequencing approach was adopted to increase the marker density and refine the “QTL-hotspot” region. With the help of reference genome, 82,127 single nucleotide polymorphisms (SNPs) were identified. By using high quality SNP data (53,175 SNPs) a bin map with 1,610 recombination bins was constructed. QTL analysis using bin map and the precise phenotyping data split the ~7 Mb region into four regions: (i) 13.16-13.23 Mb region harbouring 8 candidate genes; (ii) 13.39-13.54Mb region harbouring 11 candidate genes; (iii) 14.15-14.27 Mb region harbouring 11 candidate genes; (iv) 14.99-15.08 Mb region harbouring 9 candidate genes. Efforts are underway to clone the above mentioned drought responsive candidate genes in chickpea.