Genetic Diversity of Phaeoisariopsis griseola in Kenya as Revealed by AFLP and Group-specific Primers

Abstract

Genetic diversity of 50 Phaeoisariopsis griseola isolates collected from different agroecological zones in Kenya was studied using group-specific primers and amplified fragment length polymorphism (AFLP) markers. Group-specific primers differentiated the isolates into Andean and Mesoamerican groups, corresponding to the two common-bean gene pools. Significant poly¬morpbisms were observed with all the AFLP primer combinations used, reflecting a wide genetic diversity in the P. griseola population. A total of 207 finger¬prints was generated, of which 178 were polymorphic. Cluster analysis of the polymorphic bands also separ¬ated the isolates into the two groups defined by group¬specific primers. All the isolates examined were grouped into three virulence popula tions; Andean, Afro-Andean and Mesoamerican, and their genetic diversity measured. On average, greater diversity (;"1 '?l %) :vas detected within popl1latio~ls than between ~,,=,'populatlOns (9%). The genetic distance between Andean and Mesoamerican populations was higher CD = 0.0269) than between Andean and Afro-Andean (D = 0.0095). The wide genetic diversity reported here has significant implications in breeding for resistance to angular leaf spot and should be taken into consid¬eration when screening and deploying resistant bean genotypes