Strains of Colletotrichum species derived from diseased
strawberry plants from a wide geographical range were studied using
mitochondrial and ribosomal DNA RFLPs, and acetyl and propionyl esterase
isoenzymes. Two major species aggregates were
detected, centred on C. acutatum and C. gloeosporioides
respectively, with significant further subdivision. There were apparent
discrepancies in the hierarchical nesting of some taxon groups based on
the different molecular techniques. Strains assigned to C.
acutatum fell into several rDNA RFLP groups, but there was less variation
in mtDNA RFLP band patterns. 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 groups which are
at least sometimes sexually reproducing. Strains assigned to C. fragariae
were found not to have distinct rDNA band patterns from
the teleomorph linked strains studied, which had been referred to as C.
gloeosporioides. They did vary in this respect from C.
gloeosporioides associated with Citrus, its type host. It was, therefore,
concluded that all the strains studied with cylindrical conidia
should be placed within C. fragariae, which is confirmed as separate
from C. gloeosporioides and recognized as a holomorphic taxon.
Nevertheless, a separate asexually reproducing infraspecific group was
distinguishable using mtDNA information. An epitype is
designated for C. fragariae.