Open AccessFunctional analysis of Ras in Colletotrichum trifolii
Author(s) -
Ha Youngsil,
Memmott Stephen D.,
Dickman Martin B.
Publication year - 2003
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1016/s0378-1097(03)00589-5
Subject(s) - appressorium , biology , conidiation , hypha , gene , colletotrichum , gene expression , microbiology and biotechnology , cell growth , genetics , virulence , botany
Ras is a small monomeric GTP binding protein that transduces signals for growth and differentiation of eukaryotic organisms. Previously, a unique ras gene, designated Ct‐ras , was cloned from the alfalfa fungal phytopathogen, Colletotrichum trifolii . Expression of Ct‐Ras in mouse fibroblast cells (NIH3T3) demonstrated that Ct‐ras is functionally similar to the mammalian ras genes since activating mutations of Ct‐ras caused oncogenic phenotypes in nu/nu mice, including tumors. In C. trifolii , activated ‘oncogenic’ Ras (Val2) induced abnormal hyphal proliferation, defects in polarized growth and significantly reduced differentiation such as conidiation and appressorium formation in a nutrient dependent manner. Gene disruption of ct‐ras was lethal. To further evaluate the function of Ct‐Ras in C. trifolii , three different approaches were used: overexpression of cytosolic Ras by CAAX box deletion; expression of dominant negative Ct‐Ras T22N ; and antisense ct‐ras expression. Results showed that suppression of Ct‐Ras activity significantly decreases fungal germination frequencies and hyphal growth rates. Taken together, these data suggest involvement of Ct‐Ras in regulation of fungal cell growth and differentiation.