The taxonomy of Colletotrichum isolates associated with lupin anthracnose

Abstract

Forty-three Colletotrichum isolates fromLupinus species worldwide are delineated into 3 groups:vegetative compatibility group (VCG)-1 (4 isolates), VCG-2 (37 isolates), andCOL-3 (2 isolates). The 3 groups are readily distinguishable by randomamplified polymorphic DNA (RAPD) profiles. All Australian lupin isolates areVCG-2. VCG-1 and VCG-2 isolates produce predominantly cylindrical conidia, hadregular colony margins, and were grey to brown, lacking pinkish pigmentationon potato dextrose agar (PDA) consistent with the taxonomic criteria forColletotrichum gloeosporioides. COL-3 isolates producepredominantly fusiform conidia, and had an irregular colony margin and apinkish pigmentation on PDA consistent with C. acutatum.COL-3 isolates are possibly strawberry pathogens which can cross-infectlupins. An examination of reference cultures ofC. gloeosporioides and C. acutatumfound that published ‘species specific primer’ polymerase chainreaction (PCR) tests based on ITS sequence homology produced results contraryto the traditional taxonomy based on morphology. RAPD analysis appears todetect greater genetic variation in Colletotrichumisolates than previously published ITS1 sequence homology data, which does notsupport moving lupin anthracnose pathogens VCG-1 and VCG-2 fromC. gloeosporioides intoC. acutatum.

Additional key words: Colletotrichum gloeosporioides,Colletotrichum acutatum, Lupinus,vegetative compatibility, RAPD analysis.