The Holomorph Apiognomonia quercina/Discula quercina as a Pathogen/Endophyte in Oak

Abstract

This chapter summarises research carried out on thè biology, ecology and thè impact of thè holomorph Apiognomonia quercina/Discuta quercina in oak forests. The major life-history traits and aspects of thè epidemiology (isolation, survival, reproduction, dispersal, host selectivity) and contro! of thè oak anthracnose agent are elucidated. The role of weather patterns in disrupting thè delicate interaction between thè host tree and thè microorganism is outlined. The evidence suggests that changes in thè climate profoundly alter thè plant-endophyte symbiosis, generating conflicts of interest between thè partners in thè interaction. When sucri competing interests arise, thè survival and reproduction of one member of thè interaction do not conform with that of thè partner. The interaction becomes thus disadvantageous and harmful to one of thè organisms and thè symbiosis from mutualistic or neutral turns antagonistic. The fungal partner, which under normal conditions survives in quiescence, with a low biomass, resumes growth but now switches from a latent, asymptomatic occupier of inner oak tissues to an aggressive coloniser that sporulates profusely over thè tree surface. The importance of investigating thè functioning and thè role of thè plant-endophyte symbiosis in perennial host trees in naturai forests is stressed.