Table_1_Impact of the White Collar Photoreceptor WcoA on the Fusarium fujikuroi Transcriptome.XLSX

The proteins of the White Collar 1 family (WC) constitute a major class of flavin photoreceptors, widely distributed in fungi, that work in cooperation with a WC 2 protein forming a regulatory complex. The WC complex was investigated in great detail in Neurospora crassa, a model fungus in photobiology studies, where it controls all its major photoresponses. The fungus Fusarium fujikuroi, a model system in the production of secondary metabolites, contains a single WC-1 gene called wcoA. The best-known light response in this fungus is the photoinduction of the synthesis of carotenoids, terpenoid pigments with antioxidant properties. Loss of WcoA in F. fujikuroi results in a drastic reduction in the mRNA levels of the carotenoid genes, and a diversity of morphological and metabolic changes, including alterations in the synthesis of several secondary metabolites, suggesting a complex regulatory role. To investigate the function of WcoA, the transcriptome of F. fujikuroi was analyzed in the dark and after 15-, 60- or 240-min illumination in a wild strain and in a formerly investigated wcoA insertional mutant. Using a threshold of four-fold change in transcript levels, 298 genes were activated and 160 were repressed in the wild strain under at least one of the light exposures. Different response patterns were observed among them, with genes exhibiting either fast, intermediate, and slow photoinduction, or intermediate or slow repression. All the fast and intermediate photoresponses, and most of the slow ones, were lost in the wcoA mutant. However, the wcoA mutation altered the expression of a much larger number of genes irrespective of illumination, reaching at least 16% of the annotated genes in this fungus. Such genes include many related to secondary metabolism, as well as others related to photobiology and other cellular functions, including the production of hydrophobins. As judged by the massive transcriptomic changes exhibited by the wcoA mutant in the dark, the results point to WcoA as a master regulatory protein in F. fujikuroi, in addition to a central function as the photoreceptor responsible for most of the transcriptional responses to light in this fungus.

White Collar 1（WC）家族蛋白是一类主要的黄素光受体（flavin photoreceptors），广泛分布于真菌界，可与WC2蛋白协同形成调控复合物。WC复合物在光生物学研究的模式真菌粗糙脉孢菌（Neurospora crassa）中得到了深入解析，该复合物调控其所有主要的光响应过程。作为次级代谢产物生产研究的模式系统，藤仓镰孢菌（Fusarium fujikuroi）仅携带一个WC-1基因，命名为wcoA。该真菌中最经典的光响应为类胡萝卜素（carotenoids）的光诱导合成——这类萜类色素（terpenoid pigments）具备抗氧化活性。在藤仓镰孢菌中缺失WcoA会导致类胡萝卜素合成相关基因的mRNA水平大幅下降，并引发多种形态与代谢变化，包括多种次级代谢产物合成的改变，这提示WcoA具备复杂的调控功能。为探究WcoA的功能，本研究对野生型菌株以及已报道的wcoA插入突变体（insertional mutant）分别在黑暗条件下，以及光照15分钟、60分钟或240分钟后的转录组（transcriptome）进行了分析。以转录水平变化四倍为筛选阈值，野生型菌株在至少一种光照处理条件下，共有298个基因被激活、160个基因被抑制。这些基因呈现出多样化的响应模式：部分基因表现为快速、中等或缓慢的光诱导，另有部分则表现为中等或缓慢的光抑制。所有快速与中等的光响应，以及绝大多数缓慢的光响应，在wcoA突变体中均消失。然而，无论是否处于光照条件，wcoA突变均改变了数量更多的基因的表达，该基因数量至少达到该真菌注释基因总数的16%。这类基因包括众多与次级代谢相关的序列，以及与光生物学、其他细胞功能相关的基因，例如疏水蛋白（hydrophobins）的编码基因。综合wcoA突变体在黑暗条件下展现出的大规模转录组变化，研究结果表明：除了作为介导该真菌绝大多数光响应转录调控的光受体这一核心功能外，WcoA同时也是藤仓镰孢菌中的一类主调控蛋白（master regulatory protein）。