Identification of pathogenic races 0, 1B/C, 5, and 6 of Fusarium oxysporumf. sp ciceris with random amplified polymorphic DNA (RAPD)

Ninety-nine isolates of Fusarium oxysporum f. sp. ciceris (Foc), representa tive of the two pathotypes (yellowing and wilt) and the eight races describ ed (races 0, 1A, 1B/C, 2, 3, 4, 5, and 6), were used in this study. Sixty i solates were analyzed by the RAPD technique using DNA bulks for each race a nd 40 primers. Bands presumably specific for a DNA bulk were identified and this specificity was confirmed by further RAPD analysis of individual isol ates in each DNA bulk. Primers OPI-09, OPI-18, OPF-06, OPF-10, and OPF-12 g enerated RAPD marker bands for races 0, 1B/C, 2, 3, 4, 5, and 6. The reliab ility and utility of this procedure was validated in 'blind trials' using 3 9 new Foc isolates. Ten of the 39 isolates had already been typed to race b y pathogenicity tests and 29 were typed both by pathogenicity and RAPD test ing in this study. In these 'blind trials', we assigned the 39 new isolates to a race solely on the basis of their RAPD haplotype. Thus, we concluded that Foc races 0, 1B/C, 5, and 6 can be characterized by the RAPD markers. Cluster analysis of the RAPD data set resulted in three clusters of isolate s within Foc. The yellowing isolates were grouped in two distinct clusters which correspond to races 0 and 1B/C. The wilt isolates constitute a third cluster that included races 1A, 2, 3, 4, 5, and 6. These results provide a means of studying the distribution of Foc races, to assist in the early det ection of introduced race(s) and to facilitate the efficient deployment of available host resistance.