ISOLATION, CHARACTERIZATION, AND EXPRESSION OF A 2ND BETA-TUBULIN-ENCODING GENE FROM COLLETOTRICHUM-GLOEOSPORIOIDES F SP AESCHYNOMENE

Colletotrichum gloeosporioides f. sp. aeschynomene is a fungal plant p athogen of Aeschyplomene virginica. A beta-tubulin-encoding gene (TUB2 ) from this pathogen was cloned and sequenced. The deduced amino acid sequence of TUB2 had a high degree of homology to other fungal beta-tu bulins. A portion of TUB2 from a benomyl-resistant C. gloeosporioides f. sp. aeschynomene mutant was also cloned and sequenced. A point muta tion resulting in a glutamic acid-to-lysine substitution at amino acid 198 likely confers benomyl resistance. The mutation is relevant for u se as a selectable marker in developing a gene transfer system in C. g loeosporioides f. sp. aeschynomene. Northern (RNA) hybridizations with C.gloeosporioides f. sp. aeschynomene TUB2 and another C.gloeosporioi des f. sp. aeschynomene beta-tubulin-encoding gene (TUB1) as probes sh owed differential expression of these genes in different cell types.