CHARACTERIZATION OF MEXICAN ISOLATES OF COLLETOTRICHUM-LINDEMUTHIANUMBY USING DIFFERENTIAL CULTIVARS AND MOLECULAR MARKERS

Differential cultivars and molecular markers were used to analyze 59 i solates of the bean anthracnose pathogen, Colletotrichum lindemuthianu m, from different regions of Mexico. Ten distinct races were determine d, three of which had not been reported previously in Mexico. Isolates were found to infect only a narrow range of the differential cultivar s used and were restricted to cultivars of Middle American origin. A c omparison of random amplified polymorphic DNA and amplified fragment l ength polymorphism (AFLP) analyses was carried out on a subset of the fungal isolates. Determination of generic distances based on RFLP data and production of a dendrogram demonstrated two levels of association : i) isolates classified into two major groups according to the type o f cultivar or system of cultivation from which they originated, and ii ) isolates could be classified into smaller subgroups generally associ ated with the geographic location from which they were obtained. Boots trap analysis and determination of confidence intervals showed these g eographic groupings to be extremely robust.