The Aspergillus nidulans nsdD gene encodes a GATA-type transcription factor that is required for sexual development. To further understand the NsdD-mediated regulatory cascade, we isolated various suppressors of nsdD (SND). The silG gene presented in here was identified as a multi-copy suppressor of one of the snd mutations. Multi-copy of silG blocked cleistothecia development in an SND mutant. The silG gene is predicted to encode a 703 aa polypeptide with three C2H2 zinc finger DNA-binding domains at the C-terminus. The silG null mutant produced a high number of cleistothecia even under the visible light, which normally inhibits sexual development. However, high osmolarlity or poor carbon sources blocked sexual development of the silG deletion mutant, suggesting that SilG may play a specific role in negative regulation of sexual development in response to light. Further supporting this hypothesis, over-expression of silG resulted in a great reduction of sexual development in dark, which preferentially enhance sexual development in wild type. Accumulation of silG mRNA undulated throughout the lifecycle in a certain recurring pattern. Interestingly, silG mRNA levels elevated upon exposure to light, and this response requires the functional A. nidulans wcA(lreA) gene. Moreover, mRNA level of silG in veA1 mutant was increased in dark, implying that silG functions downstream of veA and VeA may repress silG expression in dark, which leads to sexual development.
Full conference title:
23rd Fungal Genetics Conference
- Fungal Genetics Conference 23rd (2002)