Meta-QTL analysis enabled identification of candidate genes and haplotypes for enhancing biotic stress resistance in chickpea

Abstract

Fusarium wilt, Ascochyta blight and Botrytis grey mould caused by fungal pathogens are major biotic stresses that lead to 100% yield loss in chickpea (Cicer arietinum L.). Several independent studies reported the genomic regions, using heterogeneous populations, that are of limited use in breeding programs for the development of enhanced disease resistance in climate change scenarios. In order to identify the consensus genomic regions, we developed a consensus integrated map and performed Meta-QTL analysis using 52 QTLs reported in 17 independent studies. The consensus integrated map spanned 1292.04 cM with 669 markers on all eight linkage groups. In total, we report 10 Meta-QTLs distributed on four linkage groups (CaLG02, CaLG03, CaLG04 and CaLG06) and 172 genes belonging to a wide range of gene-families that are involved in multiple disease resistance. Among these, the key genes such as Glutaredoxin, Reticuline oxidase-like protein, and RING-Finger proteins, which have been previously reported for disease resistance. The confidence interval of reported Meta-QTLs decreased 4.89 folds from the original QTL studies whose confidence interval ranged from 0.84 to 28.94 cM. Among these genes, Ca_13066 and Ca_05186 present in Meta-QTL4_6 and Meta-QTL6_8, that play major role in biotic stress resistance pathways possessed 3 and 8 haplotypes respectively. Our study provides a better understanding of the genetic mechanisms underlying these three important biotic stresses. Further, the Meta-QTLs, candidate genes and haplotypes reported in this study can be used for developing climate resilient and disease resistant chickpea cultivars.