ANTHRACNOSE OF LUPINS CAUSED BY COLLETOTRICHUM LUPINI: A RECENT DISEASE AND A SUCCESSFUL WORLDWIDE PATHOGEN
P. Talhinhas, R. Baroncelli, G. Le Floch
Lupins are grain legume crops cultivated in several parts of the world, with important roles in the agricultural and natural ecosystems. Recently lupin breeding faced a new and important challenge, a destructive seed- and air-borne disease affecting stems and pods, named anthracnose. The current disease outbreak began in the 1980s and rapidly spread worldwide, affecting apparently all lupin species. The pathogen belongs to Colletotrichum lupini, a member of the acutatum species complex, and contrasts with other members of the latter by its host specificity and by its apparent clonality. However, in a matter of a few decades this pathogen managed to cause severe epidemics in lupin crops from diverse species (both of Mediterranean and North and South American origins) throughout the world, whether in humid or in dry climates, frequently causing high yield losses and in many cases leading farmers to replace lupin with other crops. Although several lupin crops rely on rich genetic resources, it proved very difficult to find effective resistance sources. Recent successes in this matter (backed by advances in genome sequencing of some lupin species) are still conditioned by the very narrow range of resistance genes available for breeders, risking a possible overcoming of such resistances if the pathogen finds itself means to create diversity that enables it to overcome resistance. To this end, advances in Colletotrichum genomics, with the forthcoming sequencing of the genome of C. lupini, are of great importance to understand the genetic nature of C. lupini host specificity and reproduction strategies.