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ARS Home » Pacific West Area » Pullman, Washington » Grain Legume Genetics Physiology Research » Research » Publications at this Location » Publication #423411
Research Project: Enhancing Agronomic Performance and Nutritional Qualities of Pulse Crops

Location: Grain Legume Genetics Physiology Research

Title: SsMet1 is a critical gene in methionine biosynthesis in Sclerotinia sclerotiorum

Author
item Pierre-Pierre, Nickisha
item WEI, WEI - Washington State University
item MANASSEH, RICHARD - Washington State University
item MENDOZA, MICHELLE - Washington State University
item Vandemark, George
item Chen, Weidong

Submitted to: Frontiers in Fungal Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2025
Publication Date: 5/22/2025
Citation: Pierre-Pierre, N.N., Wei, W., Manasseh, R., Mendoza, M., Vandemark, G.J., Chen, W. 2025. SsMet1 is a critical gene in methionine biosynthesis in Sclerotinia sclerotiorum. Frontiers in Fungal Biology. 6. Article 1563395. https://doi.org/10.3389/ffunb.2025.1563395.
DOI: https://doi.org/10.3389/ffunb.2025.1563395

Interpretive Summary: The amino acid methionine plays important roles in fungal biology and cellular metabolism. The methionine biosynthesis gene SsMet1in was identified in the plant pathogenic fungus Sclerotinia sclerotiorum. This study characterized the SsMet1 gene in S. sclerotiorum by making mutants of the fungus that had the SsMet1 gene deleted. The SsMet1-deletion mutants could not grow on minimally nutritious media and did not produce a survival spore referred to as "sclerotia". Adding methionine to growth media restored mycelial growth, but not sclerotia formation of the SsMet1-deletion mutants. Additionally, the SsMet1-deletion mutants showed increased sensitivity to osmotic and thermal stresses and cell wall-damaging agents. The mutants were not able to infect detached bean leaves but supplementing media with methionine recovered the ability of the fungus top infect. The results of this study indicate that SsMet1 plays a critical role in the regulation of various cellular processes in S. sclerotiorum and could be a potential target of new fungicides for managing Sclerotinia.

Technical Abstract: Methionine, a key sulfur-containing amino acid, is involved in various important functions in cellular metabolism. Genes that encode enzymes to catalyze steps of the methionine biosynthesis pathway are essential for survival of fungi. The SsMet1 (SS1G_11000) gene in Sclerotinia sclerotiorum is an orthologue of BcStr2, a gene characterized in Botrytis cinerea that plays a key role in methionine biosynthesis. In this study, we characterized SsMet1 in S. sclerotiorum by creating SsMet1-deletion mutants, Met1-2 and Met1-4, using a split marker technique. The SsMet1-deletion mutants were unable to grow on minimal medium and did not produce sclerotia. Supplementation with methionine and homocysteine rescued the defects in mycelial growth, but not sclerotia development of the SsMet1-deletion mutants. These results indicate that SsMet1-deletion mutants are auxotrophic for methionine. In addition, the SsMet1-deletion mutants exhibited increased sensitivity to osmotic and oxidative stresses, cell wall-damaging agents, and thermal stress. The mutants were avirulent on detached bean leaves, but virulence was also restored with methionine supplementation in minimal media. All the defects were restored by genetic complementation of the mutant with wildtype SsMet1 allele. The results of this study indicate that SsMet1 plays a critical role in the regulation of various cellular processes in S. sclerotiorum.