Genome wide association studies for red leaf spot (Colletotrichum sublineolum) in sorghum

Abstract

Abstract Evaluation of red leaf spot disease (Colletotrichum sublineolum) resistance in Sorghum bicolor (L.) Monech crop is recognized as a necessary objective towards anthracnose resistance in warm and humid climates. A fixed diversity set of 121 genotypes were assessed for red leaf spot disease response for two years during 2020-21(E1) and 2021-22 (E2). On the basis of differential response to red leaf spot, a panel of 86 genotypes were selected for genotyping by sequencing (GBS). The best linear unbiased predictors (BLUPs) of disease score and area under disease progress curve (AUDPC) along with identified SNPs in GBS were used for genome wide association studies (GWAS). A large number of significant marker-trait associations were identified for test traits. A total of 30 SNPs were identified for final disease score of plant at harvest and 38 SNPs were identified for AUDPC during E1 and E2. Chromosome S02 (six) and S06 (six) harboured maximum number of SNPs followed by S04 (five) for disease score. Linkage disequilibrium decay (LD) in population was estimated to be ~ 50kb. Annotations helped to predict candidate genes in the genomic regions associated SNPs for test traits. Important candidate genes involved were RLP, WRKY, F-box protein, CDP, zinc finger and putative disease resistance protein. Four lines IS 7017, IS 8015, IS 8256 and SCL 4 were free from infection, indicating resistance to red leaf spot and can also serve as donors in cultivar improvement breeding for red leaf spot.