Validation of SSR markers linked to the rust and late leaf spot diseases resistance in diverse peanut genotypes

The low productivity of peanut (Arachis hypogaea L.) in India and several African countries is ascribed to many biotic stresses of which, two foliar fungal-diseases namely, late leaf spot (LLS) and rust are widespread and economically most important. Partial saturation of peanut linkage map and use of different mapping populations have led to the identification of various SSR markers linked to these diseases along with their linkage groups. In the present investigation, 22 SSR markers linked to rust and LLS diseases resistance were tested on 95 diverse genotypes for marker validation, of which 16 SSRs could be validated. Among rust resistant varieties and germplasm lines, nearly perfect marker validation was recorded but for 30 wild Arachis species, marker validation was very poor. Maximum numbers of rust and LLS linked-markers were found to be present on the linkage group 03 (eight SSRs) followed by linkage group 04 (three SSRs) which is an important step towards identification of more closely linked markers to the rust and LLS resistance QTLs and its cloning in future. Cluster analysis also grouped these foliar fungal disease resistant and susceptible genotypes separately except for those resistant genotypes where marker amplification was very poor. The results of principal coordinate analysis (PCoA) were comparable to the cluster analysis. This study will help in selection of suitable parents and marker combination for marker assisted breeding for foliar disease resistance in peanut.