Abstract
The present study is the first observation of mycoparasitic behavior in the predominantly plant-associated fungal genus Diaporthe . Several isolates of the Phomopsis dieback pathogen Diaporthe eres s.l. were obtained from grapevine and identified by sequencing the internal transcribed spacer, translation elongation factor 1-α, and β-tubulin loci. The interactions of the isolates with Botrytis cinerea strains were examined by detailed microscopic analysis. All the tested isolates showed necrotrophic mycoparasitism against the target organism. Additional experiments with a D. eres s.l. isolate showed that mycoparasitism was also expressed against a Botryosphaeria dothidea target organism, a causal agent of Botryosphaeria dieback, another grapevine trunk disease syndrome. In addition to the first description of the mycoparasitism of D. eres , the study points out the complexity of microbial interactions established by trunk disease pathogens.