title: Twilight, a Novel Circadian-Regulated Gene, Integrates Phototropism with Nutrient and Redox Homeostasis during Fungal Development.
abstract: Phototropic regulation of circadian clock is important for environmental adaptation, organismal growth and differentiation. Light plays a critical role in fungal development and virulence. However, it is unclear what governs the intracellular metabolic response to such dark-light rhythms in fungi. Here, we describe a novel circadian-regulated Twilight (TWL) function essential for phototropic induction of asexual development and pathogenesis in the rice-blast fungus Magnaporthe oryzae. The TWL transcript oscillates during circadian cycles and peaks at subjective twilight. GFP-Twl remains acetylated and cytosolic in the dark, whereas light-induced phosphorylation (by the carbon sensor Snf1 kinase) drives it into the nucleus. The mRNA level of the transcription/repair factor TFB5, was significantly down regulated in the twl∆ mutant. Overexpression of TFB5 significantly suppressed the conidiation defects in the twl∆ mutant. Furthermore, Tfb5-GFP translocates to the nucleus during the phototropic response and under redox stress, while it failed to do so in the twl∆ mutant. Thus, we provide mechanistic insight into Twl-based regulation of nutrient and redox homeostasis in response to light during pathogen adaptation to the host milieu in the rice blast pathosystem.
authors.affiliation: Temasek Life Sciences Laboratory, Department of Biological Sciences, National University of Singapore, Singapore; Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Agronomy, South China Agricultural University, Guangzhou, China.
authors.forename: Yi Zhen
authors.initials: YZ
authors.lastname: Deng
authors.affiliation: Temasek Life Sciences Laboratory, Department of Biological Sciences, National University of Singapore, Singapore.
authors.forename: Ziwei
authors.initials: Z
authors.lastname: Qu
authors.affiliation: Temasek Life Sciences Laboratory, Department of Biological Sciences, National University of Singapore, Singapore; School of Biological Sciences, Nanyang Technological University, Singapore.
authors.forename: Naweed I
authors.initials: NI
authors.lastname: Naqvi
mesh_terms: D002940:Circadian Rhythm; D005502:Food; D005656:Fungal Proteins / Q000235:genetics; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D006706:Homeostasis / Q000502:physiology*; D025301:Hyphae / Q000235:genetics; D008027:Light; D020082:Magnaporthe / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D012275:Oryza / Q000382:microbiology; D010084:Oxidation-Reduction; D018524:Phototropism / Q000235:genetics* / Q000502:physiology; D010935:Plant Diseases / Q000382:microbiology*; D013172:Spores, Fungal / Q000254:growth & development
chemical_list: D005656:Fungal Proteins