CLONING OF A GENE EXPRESSED DURING APPRESSORIUM FORMATION BY COLLETOTRICHUM-GLOEOSPORIOIDES AND A MARKED DECREASE IN VIRULENCE BY DISRUPTION OF THIS GENE

Appressorium formation in germinating Colletotrichum gloeosporioides i s induced by the surface wax of its host. One of the genes expressed u niquely in C. gloeosporioides during appressorium formation induced by the host signal has been designated cap20, and this gene and its cDNA were cloned and sequenced. Nucleotide sequences of both revealed an o pen reading frame that could encode a 183-amino acid polypeptide that did not have significant homology with any known proteins. Reverse tra nscriptase-polymerase chain reaction detected cap20 gene transcripts a t the infection front on the surface and within tomato fruits infected by C. gloeosporioides. Gene-disrupted mutants incapable of expressing cap20 showed a drastically decreased virulence on avocado and tomato fruits. These results suggest that cap20 plays a significant role in t he infection of the host.