A KINASE-ENCODING GENE FROM COLLETOTRICHUM-TRIFOLII COMPLEMENTS A COLONIAL GROWTH MUTANT OF NEUROSPORA-CRASSA

Colletotrichum trifolii is a fungal pathogen which is responsible for anthracnose disease of alfalfa. To initiate research on molecular comm unication in this fungus, a kinase-encoding gene (TB3) and the corresp onding cDNA were cloned and sequenced. The deduced amino acid sequence of TB3 closely resembles that of a Neurospora crassa serine/threonine protein kinase, COT1, required for hyphal elongation and branching. T he C-terminal catalytic domains of TB3 and COT1 are highly conserved b ut the N-terminal regions are divergent, particularly in the homopolym eric glutamine repeats of TB3. Northern analysis indicated that TB3 ex pression was highest 1 h after inducing conidial germination and Ih be fore germ tubes were first observed. Expression of TB3 transcripts ret urned to constitutive levels by 4 h after induction of germination. TB 3 complemented the cot-1 mutant of Neurospora crassa, demonstrating th e functional conservation of this kinase between a pathogenic and a sa prophytic fungus.