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Research Project: Sustainable Production and Pest Management Practices for Nursery, Greenhouse, and Protected Culture Crops

Location: Application Technology Research

Title: Double-stranded RNA targeting white mold Sclerotinia sclerotiorum argonaute 2 for disease control via spray-induced gene silencing

Author
item MUKHERJEE, SOUMYA - University Of Toledo
item BELIGALA, GAYATHRI - University Of Toledo
item FENG, CHENCHEN - University Of Toledo
item Marzano, Shin-Yi

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2023
Publication Date: 1/3/2024
Citation: Mukherjee, S., Beligala, G., Feng, C., Marzano, S.L. 2024. Double-stranded RNA targeting white mold Sclerotinia sclerotiorum argonaute 2 for disease control via spray-induced gene silencing. Phytopathology. https://doi.org/10.1094/PHYTO-11-23-0431-R.
DOI: https://doi.org/10.1094/PHYTO-11-23-0431-R

Interpretive Summary: Growers lack effective genetic tools to manage losses caused by Sclerotinia sclerotiorum because of a lack of resistance to the pathogen in germplasms. This necessitates the identification of alternative sources of resistance for the disease. We have identified strong candidate genes in the Sclerotinia sclerotiorum RNA silencing pathway as the targets for the development of an RNAi-based pesticide. This study developed methods for spray-induced gene silencing (SIGS) delivery of small RNAs or dsRNA to reduce the impact of Sclerotinia sclerotiorum on plants.

Technical Abstract: Sclerotinia sclerotiorum is a cosmopolitan fungal pathogen that causes significant yield losses in economically important crops. Growers lack practical genetic tools to manage losses caused by S. sclerotiorum because no complete disease resistance exists in crop germplasms. This necessitates the identification of alternative sources of resistance for the disease. RNA interference has been a promising alternative to chemical methods for controlling plant diseases. Here we selected argonaute 2, a key component of the fungal RNAi pathway, as a potential target for spray-induced gene silencing to control white mold. External application of double-stranded (ds) RNA targeting S. sclerotiorum argonaute 2 (Ago2) suppressed white mold infection both using in vitro and in vivo transcripts at 800 ng. A downregulation of Ago2 was confirmed by RT-qPCR. We compared the effectiveness of targeting different regions of Ago2, and our results indicate that targeting the PIWI/ RNaseH domain of S. sclerotiorum Ago2 is most effective in suppressing S. sclerotiorum infection. Furthermore, Mg-Fe LDH nanosheets were loaded by in vitro and in vivo transcribed dsRNA segments and significantly reduced the rate of lesion expansion at 1:20 ratio, respectively. The combination of in vivo produced dsRNA and nanosheet is promising to be further developed as environmentally friendly and pathogen-specific fungicide of white mold disease.