Abstract

Genetic diversity in maize (Zea mays L.) is an important tool for progress in selection for traits of interest. The objective of this study was to screen genotypes for presence of markers linked to plant defense against fungal diseases, and to study the genetic diversity in gray leaf spot resistant maize genotypes. Forty-one genotypes comprising of collections from Kenya, International Maize and Wheat Improvement Centre, the International Institute for Tropical Agriculture and South Africa were identified to be resistant to gray leaf spot in Kenya in 2004. The genotypes were analyzed for variability by using twenty-eight microsatellite markers covering the entire maize genome. The results indicated diversity among lines for selected markers. Based on the diversity tree, ten clusters were observed. All genotypes occurred in clusters, except for genotypes EC573- (R12) C₈S₃-14-1, REGN 99/6, H623 and VHCY. The data indicated that, at least one line in each cluster showed a relationship in a locus with a corresponding parent. Occurrence of related lines also implied that there were common alleles that could have contributed to the gray leaf spot resistance.

Key words: SSRs markers, diversity, gray leaf spot, genotype resistance.