Molecular cloning and sequence analysis of a putative ras gene of the phytopathogenic fungus Botryotinia fuckeliana.

We solated and determined the complete nucleotide sequence of a ras gene from Botryotinia fuckeliana, the causal agent of gray mold disease. Furthermore, in two other phytopathogenic fungi, Magnaporthe grisea (rice blast fungus) and Colletotrichum lagenarium (an anthracnose fungus), ras gene homologs were identified by amplifying gene fragments in polymerase chain reactions. The putative ras gene of B. fuckeliana encoded a polypeptide of 212 amino acids, and the coding sequence was interrupted by three short introns. The amino-terminal one third of the predicted Ras protein was highly homologous, and the next one third moderately homologous, to those of mammalian Ras proteins. The carboxy-terminal one third showed no homology, except in the last several amino acids that conformed to the acylation consensus.