Previously we identified NsdD , a crucial activator for sexual development in Aspergillus nidulans. While increased dose of nsdD caused elevated formation of fruiting bodies (cleistothecia) even under the unfavorable environmental conditions, nsdD mRNA levels did not change, suggesting that multiple copies of the nsdD promoter might relieve repressive effects by negative regulators. To dissect complex regulatory networks of sexual development, we identified a multi-copy suppressor (nrsA ) that abolished enhanced cleistothecia formation by increased dose of nsdD. The nrsA gene is predicted to encode a novel 293 aa protein with a homeobox domain at the C terminus. Deletion of nrsA resulted in elevated cleistothecial development even in the presence of stresses, but caused lowered asexual sporulation. Conversely, forced expression of nrsA blocked formation of cleistothecia, while enhancing asexual development, indicating that nrsA act as a key negative regulator of sexual development, which may confer properly balanced progression of sexual and asexual development in response to environmental factors. Steady state mRNA levels of nrsA increased at the later phases of sexual/asexual development as well as in the presence of osmotic stresses during vegetative growth. Taken together, we propose that the homeo-domain protein NrsA administrates coordinated regulation of two distinct developmental programs in A. nidulans.
Full conference title:
23rd Fungal Genetics Conference
- Fungal Genetics Conference 23rd (2002)