EXAMINATION OF MITOCHONDRIAL-DNA RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISMS, DNA FINGERPRINTS, AND RANDOMLY AMPLIFIED POLYMORPHIC DNA OF COLLETOTRICHUM-ORBICULARE

Twenty-four isolates of Colletotrichum orbiculare, three isolates of C. magna, and two putative isolates of Glomerella cingulata var. orbiculare, representing diverse geographical and cucurbit host origins, vegetative compatibility groups, and races were examined for mitochondrial and nuclear DNA restriction fragment length polymorphisms (RFLPs) and randomly amplified polymorphic DNA (RAPD), Six isolates of C orbiculare from cocklebur, a noncucurbit host, also were examined. Four mitochondrial DNA (mtDNA) haplotypes, designated A, Al, B, and C, were observed among the isolates examined. Twenty-two isolates, representing three vegetative compatibility groups and two races pathogenic to cucurbits, had an identical mtDNA RFLP haplotype (haplotype A) with each of seven restriction enzymes. Six cocklebur isolates (nonpathogenic on cucurbits) had an mtDNA RFLP haplotype identical to the pathogenic isolates with six of the seven restriction enzymes examined; however, restriction enzyme PvuII detected a single additional restriction site in the mtDNA of the cocklebur isolates (haplotype Al). Three nonpathogenic isolates of C magna had a third mtDNA RFLP haplotype (haplotype B). Two nonpathogenic isolates of C orbiculare from honeydew melon and two nonpathogenic isolates of Glomerella cingulata var. orbiculare from cucuzzi gourd had a fourth mtDNA RFLP haplotype (haplotype C). DNA fingerprinting, which was conducted with the synthetic oligonucleotide probe (CAT)5 or a human minisatellite DNA probe, identified these same four haplotypes. Five RAPD primers also resolved the four RFLP groups. One RAPD primer resolved two groups among isolates within mtDNA RFLP haplotype A that correlated with host origin, vegetative compatibility group, and race. Thus, one RAPD primer differentiated the two races of C orbiculare. Overall, there was a strict correspondence between mtDNA RFLP haplotype, DNA fingerprint group, and RAPD group among the isolates examined.