A G protein alpha subunit from Cochliobolus heterostrophus involved in mating and appressorium formation

A G alpha subunit-encoding gene (CGA1) was cloned from Cochliobolus heteros trophus, a heterothallic foliar pathogen of corn. The deduced amino acid se quence showed similarity to G alpha proteins from other filamentous fungi a nd suggested that CGA1 is a member of the G alpha(i) class. cga1 mutants ha d reduced ability to form appressoria on glass surfaces and on corn leaves; mutants nevertheless caused lesions on corn plants like those of wild type . cga1 mutants were female sterile; sexual development was completely aboli shed when the mutant allele was homozygous in a cross. Ascospores produced in crosses heterozygous at Cga1 were all wild type. The signal transduction pathway represented by CGA1 appears to be involved in developmental pathwa ys leading to either appressorium formation or mating; in sexual developmen t CGA1 is required for both fertility and ascospore viability. (C) 1999 Aca demic Press.