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Cross-kingdom small RNA trafficking and environmental RNAi for plant protection against Fungal pathogens

Hailing Jin: Department of Microbiology and Plant Pathology, University of California

<div><strong>Spray-Induced Gene Silencing: a Powerful Innovative Strategy for Crop Protection</strong><strong></strong><strong> </strong></p> <p><strong>Qiang Cai, Lulu Qiao, Ming Wang, Baoye He, Arne Weiberg, Hailing Jin<sup>*</sup></strong></p> <p>Small RNAs (sRNAs) play a critical role in both host innate immunity and pathogen virulence. We have demonstrated that some sRNAs from eukaryotic pathogens, such as <em>Botrytis cinerea</em>, the fungal pathogen that causes grey mold disease on more than 1000 plant species, are translocated into host plant cells and suppress host immunity genes for successful infection. These sRNAs act as a novel class of pathogen effectors that translocate into host cells to suppress host immunity.</p> <p>Conversely, we also found that some plant-derived sRNAs, including both exogenous and endogenous sRNAs, are transferred into interacting fungal cells. Transgenic plants expressing hairpin RNAs that targeting <em>Botrytis</em> Dicer 1 and Dicer 2 genes could effectively silence fungal DCL genes, and inhibit the generation of fungal sRNA effectors to suppress grey mold disease. This strategy can be easily designed to control multiple fungal diseases simultaneously. We also identified a set of host endogenous sRNAs that are delivered into fungal cells, mainly through extracellular vesicles, to suppress fungal genes that are involved in pathogenicity. Strikingly, we discovered that some fungal pathogens, such as <em>Botrytis</em> <em>cinerea</em> and <em>Sclerotinia sclerotiorum</em>. could take up double-stranded RNAs and sRNAs from the environment. Applying sRNAs or dsRNAs that target fungal <em>Dicers</em> and pathogenicity-related genes on the surface of fruits, vegetables and flowers significantly inhibits fungal diseases. Such pathogen gene-targeting RNAs represent a new generation of effective and eco-friendly fungicides.</div>