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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Sunflower Improvement Research » Research » Publications at this Location » Publication #397447
Research Project: Improvement of Sclerotinia Disease Resistance and Management

Location: Sunflower Improvement Research

Title: Host-induced gene silencing of a Sclerotinia sclerotiorum oxaloacetate acetylhydrolase using bean pod mottle virus as a vehicle reduces disease on soybean

Author
item MCCAGHEY, MEGAN - University Of Wisconsin
item SHAO, DANDAN - University Of Wisconsin
item KURCEZEWSKI, JAKE - University Of Wisconsin
item LINDSTROM, ALLY - University Of Wisconsin
item RANJAN, ASHISH - University Of Minnesota
item WHITHAM, STEVEN - Iowa State University
item CONLEY, SHAWN - University Of Wisconsin
item WILLIAMS, BRETT - Queensland University Of Technology
item SMITH, DAMON - University Of Wisconsin
item KABBAGE, MEHDI - University Of Wisconsin

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2021
Publication Date: 7/20/2021
Citation: Mccaghey, M., Shao, D., Kurcezewski, J., Lindstrom, A., Ranjan, A., Whitham, S.A., Conley, S.P., Williams, B., Smith, D.L., Kabbage, M. 2021. Host-induced gene silencing of a Sclerotinia sclerotiorum oxaloacetate acetylhydrolase using bean pod mottle virus as a vehicle reduces disease on soybean. Frontiers in Plant Science. 12:677631. https://doi.org/10.3389/fpls.2021.677631.
DOI: https://doi.org/10.3389/fpls.2021.677631

Interpretive Summary: Sclerotinia stem rot (SSR) is a fungal disease of soybean that can significantly decrease crop yield. Conventional breeding for SSR resistance has shown limited success; thus, we undertook a transgenic approach to reduce the pathogen's ability to cause disease. Soybean plants were altered in a way to make a specific ribosomal nucleic acid (RNA) molecule that would get into the Sclerotinia fungus and alter its ability to make oxalic acid. The amount of oxalic acid produced by the fungus is related to disease severity. When the transgenic soybean plants were inoculated with the fungus, the pathogen's oxalic acid production was reduced and the plants showed resistance to SSR disease. These results will help breeders develop a new strategy for the control of SSR in soybean and may lead to viable options for other crops impacted by Sclerotinia.

Technical Abstract: A lack of complete resistance in the current germplasm complicates the management of Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum in soybean. In this study, we used bean pod mottle virus (BPMV) as a vehicle to down-regulate expression of a key enzyme in the production of an important virulence factor in S. sclerotiorum, oxalic acid (OA). Specifically, we targeted a gene encoding oxaloacetate acetylhydrolase (Ssoah1), because Ssoah1 deletion mutants are OA deficient and non-pathogenic on soybean. We first established that S. sclerotiorum can uptake environmental RNAs by monitoring the translocation of Cy3-labeled double-stranded and small interfering RNA (ds/siRNAs) into fungal hyphae using fluorescent confocal microscopy. This translocation led to a significant decrease in Ssoah1 transcript levels in vitro. Inoculation of soybean plants with BPMV vectors targeting Ssoah1 (pBPMV-OA) also led to decreased expression of Ssoah1. Importantly, pBPMV-OA inoculated plants showed enhanced resistance to S. sclerotiorum compared to empty-vector control plants. Our combined results provide evidence supporting the use of HIGS and exogenous applications of ds/siRNAs targeting virulence factors such as OA as viable strategies for the control of SSR in soybean and as discovery tools that can be used to identify previously unknown virulence factors.