USE OF GENETIC FINGERPRINTING AND RANDOM AMPLIFIED POLYMORPHIC DNA TO CHARACTERIZE PATHOTYPES OF FUSARIUM-OXYSPORUM F SP CICERIS INFECTING CHICKPEA

Isolates of Fusarium oxysporum f.. sp. ciceris induce either yellowing or wilt syndromes in chickpea and can be characterized into seven races by means of biological typing. DNA from 63 isolates of F. o. ciceris and from 11 isolates of other fungi was amplified by the random amplified polymorphic DNA (RAPD) technique by using the polymerase chain reaction with single primers. The primers used were based either on known ribosomal DNA sequences from Penicillium hordei or on sequencing primers. The amplification products were analyzed for polymorphisms by gel electrophoresis to determine whether pathotypes and/or races could be distinguished at the molecular level. UPGMA (unweighted paired group method with arithmetic averages) cluster analysis and principal coordinate analysis were used to divide the F. o. ciceris isolates into two distinct clusters that correlated with the pathotypes causing the yellowing or wilt disease syndrome of chickpea. These clusters were clearly distinct from other F. oxysporum formae speciales and from other chickpea pathogens such as F. eumartii, F. solani, and Ascochyta rabiei. Nineteen of the F. o. ciceris isolates, which had previously been characterized with regard to race by chickpea differential lines, were used initially to identify yellowing or wilt pathotype-associated DNA markers. One isolate that had previously been characterized as a yellowing-inducing isolate was subsequently shown to be a misclassified nonpathogenic isolate. Another 22 isolates of F. o. ciceris were subsequently correctly identified as to disease pathotype in a ''blind trial.'' In a further trial, twenty-one previously uncharacterized (by host inoculation) isolates were identified as yellowing-or wilt-inducing pathotypes by RAPD analysis, and these identifications were later confirmed in all cases by chickpea differential line tests under controlled environmental conditions.