RNA-seq analysis of the biological roles for the WcoA and CryD photoreceptors of Fusarium fujikuroi

Light plays a major role as an environmental signal for fungi. They use it to control a large diversity of biological processes, such as development and sporulation, adaptation to stress conditions, circadian rhythmicity and secondary metabolism. The outstanding chemical diversity of the secondary metabolites produced by many Fusarium species makes these fungi attractive research models. The rice pathogen Fusarium fujikuroi is well known in the study of the synthesis of some metabolites, as bikaverin, gibberellins, and carotenoids. As in Neurospora crassa, this fungus accumulates the xanthophyll neurosporaxanthin in response to light through the transcriptional induction of the structural genes of the carotenoid pathway. In contrast to N. crassa, the mutation of the gene for the only white-collar protein of F. fujikuroi, WcoA, slows down the synthesis of carotenoids under light, but does not impede its accumulation. Moreover, a wcoA mutant exhibits a more complex phenotype, that includes a reduced synthesis of carotenoids in the dark, as well as alterations in growth, mycelial hydrophobicity and production of other secondary metabolites, as bikaverin. To gain more insights on the global regulatory roles of WcoA both in the dark and as a photoreceptor, RNA-seq analysis of a wild type strain and a wcoA mutant have been performed in darkness and after different times of illumination. To test former observations that point to DASH cryptochrome CryD as an accessory photoreceptor in carotenogenesis, the data, currently under analysis, have been extended to the effect of light in a mutant of this cryptochrome gene.