title: Role of the Alternaria alternata blue-light receptor LreA (white-collar 1) in spore formation and secondary metabolism.
abstract: Alternaria alternata is a filamentous fungus that causes considerable loss of crops of economically important feed and food worldwide. It produces more than 60 different secondary metabolites, among which alternariol (AOH) and altertoxin (ATX) are the most important mycotoxins. We found that mycotoxin production and spore formation are regulated by light in opposite ways. Whereas spore formation was largely decreased under light conditions, the production of AOH was stimulated 2- to 3-fold. ATX production was even strictly dependent on light. All light effects observed could be triggered by blue light, whereas red light had only a minor effect. Inhibition of spore formation by light was reversible after 1 day of incubation in the dark. We identified orthologues of genes encoding the Neurospora crassa blue-light-perceiving white-collar proteins, a cryptochrome, a phytochrome, and an opsin-related protein in the genome of A. alternata. Deletion of the white-collar 1 (WC-1) gene (lreA) resulted in derepression of spore formation in dark and in light. ATX formation was strongly induced in the dark in the lreA mutant, suggesting a repressing function of LreA, which appears to be released in the wild type after blue-light exposure. In addition, light induction of AOH formation was partially dependent on LreA, suggesting also an activating function. A. alternata ΔlreA was still able to partially respond to blue light, indicating the action of another blue-light receptor system.
authors: Karlsruhe Institute of Technology (KIT), Institute for Applied Biosciences, Department of Microbiology, Karlsruhe, Germany.
authors: Sonja
authors: S
authors: Pruss
authors: Ramona
authors: R
authors: Fetzner
authors: Kristin
authors: K
authors: Seither
authors: Andreas
authors: A
authors: Herr
authors: Erika
authors: E
authors: Pfeiffer
authors: Manfred
authors: M
authors: Metzler
authors: Christopher B
authors: CB
authors: Lawrence
authors: Reinhard
authors: R
authors: Fischer
mesh_terms: D000528:Alternaria / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism* / Q000528:radiation effects; D003624:Darkness; D017353:Gene Deletion; D008027:Light; D009183:Mycotoxins / Q000378:metabolism*; D020283:Photoreceptors, Microbial / Q000235:genetics / Q000378:metabolism*; D064210:Secondary Metabolism; D013172:Spores, Fungal / Q000254:growth & development* / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D009183:Mycotoxins; D020283:Photoreceptors, Microbial