The global regulator FfSge 1 is required for expression of secondary metabolite gene clusters but not for pathogenicity in F usarium fujikuroi

Abstract

Summary The plant pathogenic fungus F usarium fujikuroi is the causal agent of bakanae disease on rice due to its ability to produce gibberellins. Besides these phytohormones, F . fujikuroi is able to produce several other secondary metabolites ( SMs ). Although much progress has been made in the field of secondary metabolism, the transcriptional regulation of SM biosynthesis is complex and still incompletely understood. Environmental conditions, global as well as pathway‐specific regulators and chromatin remodelling have been shown to play major roles. Here, the role of FfSge 1, a homologue of the morphological switch regulators Wor 1 and Ryp 1 in C andida albicans and H istoplasma capsulatum , respectively, is explored with emphasis on secondary metabolism. FfSge 1 is not required for formation of conidia and pathogenicity but is involved in vegetative growth. Transcriptome analysis of the mutant Δ ffsge 1 compared with the wild type, as well as comparative chemical analysis between the wild type, Δ ffsge 1 and OE : FfSGE 1 , revealed that FfSge 1 functions as a global activator of secondary metabolism in F . fujikuroi . Double mutants of FfSGE 1 and other SM regulatory genes brought insights into the hierarchical regulation of secondary metabolism. In addition, FfSge 1 is also required for expression of a yet uncharacterized SM gene cluster containing a non‐canonical non‐ribosomal peptide synthetase.

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