Location: Toxicology & Mycotoxin ResearchTitle: StuA is a key regulator of fumonisin production and virulence in Fusarium verticillioides
|RATH, MANISHA - University Of Georgia|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/8/2016
Publication Date: 3/14/2017
Citation: Rath, M., Crenshaw, N.J., Gold, S.E. 2017. StuA is a key regulator of fumonisin production and virulence in Fusarium verticillioides. Meeting Abstract. Meeting Book only.
Interpretive Summary: A gene (stuA) encoding a major transcription factor involved in normal development in the mycotoxigenic fungus, Fusarium verticillioides, was deleted. Mutants show reduced mycotoxin production, show a slightly reduced growth rate and have reduced virulence to maize. Three independent stuA deletion mutants were analyzed by RNA sequencing to identify stuA regulated genes. Of the 437 differentially expressed genes common to all three mutants about ¾ were upregulated and ¼ downregulated. The pathways for fumonisin production was down-regulated in all three mutants, consistent with the reduced production of the toxin. Therefore we have determined that the F. verticillioides stuA gene is a major determinant in the regulation of mycotoxin production and virulence against maize.
Technical Abstract: Fusarium verticillioides is one of the most important pathogens of maize, producing fumonisin mycotoxins during infection. Ingestion of fumonisin-contaminated corn causes fatal toxicity in livestock and is associated with neural tube birth defects and growth stunting in children. It is also a potential human carcinogen. It is critical to understand the underlying molecular mechanisms associated with fumonisin production in order to generate novel control approaches. StuA, an APSES class transcription factor, is a global regulator with StuA homologs regulating crucial developmental processes in various fungal species such as sporulation, virulence and toxin synthesis among others. Our objective was to investigate StuA’s role in virulence and fumonisin production in F. verticillioides via functional and transcriptomic analysis of 'stuA mutants. The mutants generated via Agrobacterium-mediated transformation of F. verticillioides with an OSCAR deletion construct, have stunted aerial hyphae and reduced macro- and micro-conidiation. Three of the 'stuA mutants were selected for transcriptome analysis and cultured in GYAM medium to induce toxin production. A total of 437 genes were differentially regulated across the 3 mutants compared to wild type with = 3-fold change. Out of these, 328 were downregulated and 109 upregulated. Five genes in the FUM (fumonisin) cluster and 8 genes in the FUS (Fusarin C) cluster were dramatically downregulated (= 4 fold for FUM and = 8 fold for FUS). Analysis of fumonisin levels in GYAM shows reduced fumonisin production by 'stuA mutants (= 100-fold). Additionally, maize seedlings inoculated with 'stuA mutants showed greater shoot height and weight as compared to seedlings inoculated with wild type, indicating reduced virulence of the mutants and thus an important role in virulence for the stuA gene.