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

Ninety-nine isolates of Fusarium oxysporum f. sp. ciceris (Foc), representative of the two pathotypes (yellowing and wilt) and the eight races described (races 0, 1A, 1B/C, 2, 3, 4, 5, and 6), were used in this study. Sixty isolates were analyzed by the RAPD technique using DNA bulks for each race and 40 primers. Bands presumably specific for a DNA bulk were identified and this specificity was confirmed by further RAPD analysis of individual isolates in each DNA bulk. Primers OPI-09, OPI-18, OPF-06, OPF-10, and OPF-12 generated RAPD marker bands for races 0, 1B/C, 2, 3, 4, 5, and 6. The reliability and utility of this procedure was validated in 'blind trials' using 39 new Fac isolates. Ten of the 39 isolates had already been typed to race by pathogenicity tests and 29 were typed both by pathogenicity and RAPD testing 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 Fac 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 isolates 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 Fac races, to assist in the early detection of introduced race(s) and to facilitate the efficient deployment of available host resistance.