Revision of the genus Colletotrichum

Colletotrichum is an economically important genus of plant pathogens, causing substantial losses and postharvest damage to a wide range of crops, especially in the tropics. Modern phylogenetic analysis is revealing many new species of Colletotrichum, and providing insights into speciation processes.

Image at left: Damage to cultivated yam in Vanuatu, caused by Colletotrichum gloeosporioides. © Paul Cannon
Image at right: An endophytic form of Colletotrichum gloeosporioides agg. from Guyana. © Paul Cannon

Traditional methods for species definition and diagnosis are quite inadequate to portray variation within the economically important plant pathogenic genus Colletotrichum. Multiple species infect host plants with varying impact on plant health, making control and international trade safety problematic. We are using modern phylogenetic methods based on a set of seven genes to elucidate relationships and define species, and correlate these data with morphological and cultural features. Colletotrichum species adopt many biological life strategies, some being host-specific while others show no preference. Most infect living plant tissues and then remain dormant and symptomless before changing to a destructive necrotrophic phase, while others live as endophytes and only grow actively once plant tissues have died naturally. Some of these appear to have beneficial impacts on plant growth through production of bioactive chemicals that inhibit herbivory. An important recent finding is that ITS sequences (adopted as the standard barcode gene for fungi) do not distinguish between many of the closely related Colletotrichum species.

Key papers published since 2006:

• Damm, U., Woudenberg, J.H.C., CANNON, P.F., Johnston, P.R., Weir, B., Tan, Y.P., Shivas, R.P. & Crous, P.W. (in press). The Colletotrichum boninense species complex. Studies in Mycology.
• Damm, U., Woudenberg, J.H.C., CANNON, P.F. & Crous, P.W. (2009). Colletotrichum species with curved conidia from herbaceous hosts. Fungal Diversity 39: 45-87.
• Hyde, K.D., Cai, L., CANNON, P.F., Crouch, J.A., Crous, P.W., Damm, U., Goodwin, P.H., Chen, H., Johnston, P.R., Jones, E.B.G., Liu, Z.Y., McKenzie, E.H.C., Moriwaki, J., Noireung, P., Pennycook, S.R., Pfenning, L.H., Prihastuti, H., Sato, T., Shivas, R.G., Tan, Y.P., Taylor, P.W.J., Weir, B.S., Yang, Y.L. & Zhang, J.Z. (2009). Colletotrichum – names in current use. Fungal Diversity 39: 147-182.
• Rojas, E.I., Rehner, S.A., Samuels, G.J., Van Bael, S.A., Herre, E.A., CANNON, P.F., Chen, R., Pang, J.-f., Wang, R.-w., Zhang, Y.-p. & Sha, T. (2010). Colletotrichum gloeosporioides s.l. associated with Theobroma cacao and other plants in Panama: multilocus phylogenies distinguish pathogen and endophyte clades. Mycologia 102: 1318-1338.
• CANNON, P.F., Buddie, A.G. & Bridge, P.D. (2008). The typification of Colletotrichum gloeosporioides. Mycotaxon 104: 189-204.