Molecular characterization of Colletotrichum strains derived from strawberry

Strains of Colletotrichum species derived from diseased strawberry plants f rom a wide geographical range were studied using mitochondrial and ribosoma l DNA RFLPs, and acetyl and propionyl esterase isoenzymes. Two major specie s aggregates were detected, centred on C. acutatum and C. gloeosporioides r espectively, with significant further subdivision. There were apparent disc repancies in the hierarchical nesting of some taxon groups based on the dif ferent molecular techniques. Strains assigned to C. acutatum fell into seve ral rDNA RFLP groups, but there was less variation in mtDNA RFLP band patte rns. There appears to be at least one probably clonal population in the U.S .A. which is also present in Europe, and a less well-defined series of grou ps which are at least sometimes sexually reproducing. Strains assigned to C . fragariae were found not to have distinct rDNA band patterns from the tel eomorph linked strains studied, which had been referred to as C. gloeospori oides. They did vary in this respect from C. gloeosporioides associated wit h Citrus, its type host, it was, therefore, concluded that all the strains studied with cylindrical conidia should be placed within C. fragariae, whic h is confirmed as separate from C. gloeosporioides and recognized as a holo morphic taxon. Nevertheless, a separate asexually reproducing infraspecific group was distinguishable using mtDNA information. An epitype is designate d for C. fragariae.