Drought Tolerance in Chickpea: Is It Still Complex?

Terminal drought is one of major constraints to crop production of chickpea (Cicer arietinum L.). Therefore, inter-disciplinary and integrated genomics and breeding approaches are being employed at ICRISAT to develop drought tolerant chickpea cultivars. In this direction, by using linkage mapping approach, one genomic region (“QTL-hotspot”) harbouring QTLs for several drought tolerance traits has been identified and genotyping-by-sequencing (GBS) approach is being used to fine-map this region. In parallel, linkage disequilibrium (LD)-based genome-wide and candidate gene(s) based association mapping approaches using genotyping data for 1882 markers and sequence data for 10 genes together with phenotyping data for 24 drought tolerance traits on the reference set comprising 300 genotypes provided 335 significant marker-trait associations (MTAs). In addition, 5X- 10X coverage whole genome re-sequencing data have been generated on the reference set that is being used for GWAS analysis. Furthermore, several transcriptomics and functional genomics approaches such as RNA-seq, Massive Analysis of cDNA Ends (MACE) with parental genotypes of mapping populations as well NILs have provided some candidate genes for drought tolerance that are being validated through genetical genomics and/or TILLING approaches. In context of translational genomics, the “QTL-hotspot” has been successfully introgressed in 3 leading varieties (e.g. JG 11, Chefe, KAK2) by using marker-assisted backcrossing (MABC) approach. Several MABC-derived lines, as compared to recurrent parental lines, have shown upto 12% higher yield under rainfed conditions and upto 24% higher yield in irrigated conditions. Some of these lines, after multi-location field trials, may be released as improved varieties in chickpea grown countries.