GENETIC DIVERSITY OF COLLETOTRICHUM SUBLINEOLUM ISOLATES FROM A SINGLE FIELD IN SOUTHERN ETHIOPIA AND EVIDENCE FOR THE EXISTENCE OF MAT2 GENOTYPES IN DIFFERENT PARTS OF THE COUNTRY

Abstract

An AFLP analysis was carried out to study the genetic diversity of Colletotrichum sublineolum isolates collected from a single field in southern Ethiopia. The AFLP analysis revealed the presence of genetic variation among the tested isolates. Dice similarity coefficient ranged from 0.69 to 0.96 averaging at 0.87. Cluster and principal coordinate analyses categorized the isolates into nine and six major groups, respectively. The presence of diverse isolates even in a single field should be given due consideration in future breeding programs. Such a diversity calls for a need to stack diverse resistance genes using the gene pyramiding technique to come up with durable sources of resistance against C. sublineolum. A mating type genes identification study was also conducted with the help of PCR on 23 single spore isolates of C. sublineolum collected from different parts of Ethiopia. The degenerate primers SKCM1 and NcHMG were used to amplify the mating type (MAT) genes, MAT1 and MAT2, respectively. MAT2 genes were amplified from 15 of the 23 isolates while no amplification product was obtained using SKCM1. This may suggest that Ethiopian C. sublineolum populations might be composed of only MAT2 genotypes. However, further work that includes large number of isolates from several sorghum growing regions is needed to come up with a conclusive result on the mating system of the pathogen populations in Ethiopia.