Construction of a Constitutively Activated Gα Mutant in the Maize Pathogen <i>Cochliobolus heterostrophus</i>
- 1 Tel-Hai College, Upper Galilee, Israel; 2Migal—Galilee Research Institute, Kiryat Shmona, Israel
Abstract
Conserved eukaryotic signaling proteins participate in development and disease in plant pathogenic fungi. Mutants in CGA 1, a heterotrimeric G protein G a subunit gene of the maize pathogen Cochliobolus heterostrophus , are defective in several developmental pathways. Conidia from CGA 1 mutants germinate as abnormal, straight-growing germ tubes that form few appressoria, and the mutants are female-sterile. The CGA 1, G α subunit, is also thought to act as a down regulator of hydrophobin expression and secretion in this fungus and in related Ascomycete species. Although cga 1 mutants can cause normal lesions on plants there are host physiology conditions under which full virulence requires signal transduction through CGA 1-mediated pathways. A G α activated mutant, cga 1 Q204L was created to help establish the role of CGA 1 in growth and development, and in mediating hydrophobin secretion and expression. The activated G α allele was transformed into a cga 1 mutant strain. The transgenic lines showed phenotypes resembling the null mutant in development, sporulation and hydrophobicity, indicating a possible role for CGA 1 as a stabilizer of these traits.
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