RAPD markers linked to a rust resistance gene in cultivated groundnut (Arachis hypogaea L.)

Abstract

Groundnut rust (Puccinia arachidis Speg.) is an important air borne pathogen, which causes substantial losses in groundnut yield and quality. Although large numbers of accessions were identified as rust resistant in wild, interspecific derivative and cultivated groundnut species, transfer of resistance to well-adapted cultivars is limited due to linkage drag, which worsens yield potential and market acceptance. A F2 mapping population comprising 117 individuals was developed from a cross between the rust resistant parent VG 9514 and rust susceptible parent TAG 24. Rust resistance was governed by single dominant gene in this cross. We identified 11 (out of 160) RAPD primers that exhibited polymorphism between these two parents. Using a modified bulk segregant analysis, primer J7 (5′CCTCTCGACA3′) produced a single coupling phase marker (J71350) and a repulsion phase marker (J71300) linked to rust resistance. Screening of the entire F2 population using primer J7 revealed that the coupling phase marker J71350 was linked with the rust resistance gene at a distance of 18.5 cM. On the other hand, the repulsion phase marker J71300 was completely linked with rust resistance. Additionally, both J71300 (P = 0.00075) and J71350 (P < 0.00001) were significantly associated with the rust resistance. Marker J71300 identified all homozygous rust resistant genotypes in the F2 population and was present in all the eight susceptible genotypes tested for validation. Thus, J71300 should be applicable for marker-assisted selection (MAS) in the groundnut rust resistance breeding programme in India. To the best of our knowledge this is the first report on the identification of RAPD markers linked to rust resistance in groundnut.