IDENTIFICATION OF RACES OF COLLETOTRICHUM-LINDEMUTHIANUM WITH THE AIDOF PCR-BASED MOLECULAR MARKERS

Inoculation of a common bean differential series is the usual method f or identification of races of Colletotrichum lindemuthianum. This proc edure is extremely useful for phytopathological as well as breeding pu rposes, but it requires strict control of the number of spores and inc ubation conditions. Furthermore, this method may result in misclassifi cations of isolates because of the subjectivity of symptom evaluation. We propose the use of DNA-based molecular markers as an auxiliary too l to aid the classification of races of C. lindemuthianum. Specific DN A bands were identified for races 73, 65, and 64 by polymerase chain r eaction (PCR) amplification of bulked DNA samples from isolates of the se three races with random primers. The presence of these bands was ch ecked on four isolates previously classified by inoculation on a diffe rential series as belonging to races 23, 72, 79, and 585. The molecula r procedure showed that two of these isolates had been misclassified, confirming the high potential of the proposed procedure to aid the ide ntification of races of C. lindemuthianum. Amplification products obta ined with 44 different primers also allowed the determination of the g enetic distances among isolates from races 73, 65, and 64. These data were used to cluster the isolates into three groups that coincide with the ones obtained by inoculation.