SSR markers associated for late leaf spot disease resistance by bulked segregant analysis in groundnut (Arachis hypogaea L.)

Abstract

Late leaf spot (LLS) caused by Phaeoisariopsis personata is the major foliar disease that reduces the pod yield and severely affects the fodder and seed quality in groundnut. Molecular markers linked with LLS can improve the process of identification of resistant genotypes. In the present study, a LLS susceptible genotype (TMV 2) and the LLS resistant genotype (COG 0437) were crossed and their F2 population was used for marker analysis. The phenotypic mean data on F2:3 progenies were used as phenotype. Parents were surveyed with 77 SSR (Simple Sequence Repeat) primers to identify polymorphic markers. Among SSR markers, nine primers were found polymorphic between the parents TMV 2 and COG 0437. These markers were utilized for bulked segregant analysis (BSA). Among the polymorphic SSR markers, three primers viz., PM 375162, pPGPseq5D5220 and PM 384100 were able to distinguish the resistant and susceptible bulks and individuals for LLS. In single marker analysis, the markers PM 375, PM 384, pPGPseq5D5, PM 137, PM 3, PMc 588 and Ah 4-26 were linked with LLS severity score. The phenotypic variation explained by these markers ranged from 32 to 59 %. The markers identified through BSA were also confirmed with single marker analysis. While validating the three primers over a set of resistant and susceptible genotypes, the primer PM 384100 allele had association with resistance. Hence PM 384 could be utilized in the marker assisted breeding programme over a wide range of genetic background.