Amit Deokar, Mandeep Sagi, Bunyamin Tar’an

Theoretical and Applied Genetics; June 2019, Volume 132, Issue 6, pp 1861–1872

Key message

A high-density linkage map of chickpea using 3430 SNPs was constructed and used to identify QTLs and candidate genes for ascochyta blight resistance in chickpea.

Abstract

Chickpea cultivation in temperate conditions is highly vulnerable to ascochyta blight infection. Cultivation of resistant cultivars in combination with fungicide application within an informed disease management package is the most effective method to control ascochyta blight in chickpeas. Identifying new sources of resistance is critical for continued improvement in ascochyta blight resistance in chickpea. The objective of this study was to identify genetic loci and candidate genes controlling the resistance to ascochyta blight in recombinant inbred lines derived from crossing cultivars Amit and ICCV 96029. The RILs were genotyped using the genotyping-by-sequencing procedure and Illumina^® GoldenGate array. The RILs were evaluated in the field over three site-years and in three independent greenhouse experiments. A genetic map with eight linkage groups was constructed using 3430 SNPs. Eight QTLs for resistance were identified on chromosomes 2, 3, 4, 5 and 6. The QTLs individually explained 7–40% of the phenotypic variations. The QTLs on chromosomes 2 and 6 were associated with the resistance at vegetative stage only. The QTLs on chromosomes 2 and 4 that were previously reported to be conserved across diverse genetic backgrounds and against different isolates of Ascochyta rabiei were confirmed in this study. Candidate genes were identified within the QTL regions. Their co-localization with the underlying QTLs was confirmed by genetic mapping. The candidate gene-based SNP markers would lead to more efficient marker-assisted selection for ascochyta blight resistance and would provide a framework for fine mapping and subsequent cloning of the genes associated with the resistance.

See https://link.springer.com/article/10.1007/s00122-019-03322-3

Figure 1:

Linkage map of chickpea RILs with eight linkage groups (LG1–LG8) showing the quantitative trait loci (QTLs) for resistance to ascochyta blight under field and greenhouse conditions and the candidate genes. The scale on the left side indicates the genetic distance in centimorgan (cM). Eight QTLs for ascochyta blight resistance are shown on the left side of the corresponding linkage group. Candidate genes co-localized with the QTLs are depicted in red colour on the right side of corresponding linkage group.