A Novel Regulator Couples Sporogenesis and Trehalose Biogenesis in Aspergillus nidulans

Abstract

Trehalose is a compatible osmolyte produced by bacteria, fungi, insects and plants to protect the integrity of cells against various environmental stresses. Spores, the reproductive, survival and infection bodies of fungi require high amounts of trehalose for long-term survival. Here, via a gain-of-function genetic screen, we identify the novel regulator VosA that couples the formation of spores and focal trehalose biogenesis in the model fungus Aspergillus nidulans. The vosA gene is expressed specifically during the formation of both sexual and asexual spores (conidia). Levels of vosA mRNA and protein are high in both types of spore. The deletion of vosA results in the lack of trehalose in spores, a rapid loss of the cytoplasm, organelles and viability of spores, and a dramatic reduction in tolerance of conidia to heat and oxidative stress. Moreover, the absence of vosA causes uncontrolled activation of asexual development, whereas the enhanced expression of vosA blocks sporulation, suggesting that VosA also functions in negative-feedback regulation of sporogenesis. VosA localizes in the nucleus of mature conidia and its C-terminal region contains a potential transcription activation domain, indicating that it may function as a transcription factor primarily controlling the late process of sporulation including trehalose biogenesis. VosA is conserved in most fungi and may define a new fungus-specific transcription factor family.