Fusarium oxysporum is a soil-borne facultative parasite that causes economically important losses on a wide variety of crops. F. oxysporum produces three kinds of asexual spores, microconidia, macroconidia, and chlamydospores. Ellipsoidal microconidia and falcate macroconidia are formed from phialides; globose chlamydospores with thick walls are formed acrogenously from hyphae or by the modification of hyphal cells. We identified the F. oxysporum homologs of medA and stuA, which have been identified to encode the developmental regulators for asexual and sexual sporulation in Aspergillus nidulans. The medA homolog, named REN1, was identified by restriction enzyme-mediated integration mutagenesis. The stuA homolog, named FoSTUA, was isolated by a PCR-based cloning. Although the REN1 mutants exhibit normal growth and form chlamydospores, they lack microconidia and macroconidia and form rod-shaped, conidium-like cells. Thus, REN1 is required specifically for development of microconidia and macroconida. The FoSTUA mutants produce microconidia, macroconidia, and chlamydospores. Mutation in FoSTUA, however, quantitatively affects the development of macroconidia and chlamydospores: numbers of macroconidia and chlamydospores were significantly reduced and increased, respectively, by the mutation. We propose that REN1 is comprised in the core pathway for development of microconidia and macroconidia in F. oxysporum.
Fungal Genet. Newsl. 50 (Supl):abstract
Full conference title:
22nd Fungal Genetics Conference
- Fungal Genetics Conference 22nd (2001)