Plants, as well as humans and animals, are constantly under attack by pathogens, pests, and parasites, resulting in severe consequences on global food production and human health. Cell-to-cell communication between hosts and pathogens plays an essential role in regulating host defense and pathogen virulence and involves transport and exchange of regulatory molecules across the cellular boundaries. Recent findings from the PI's lab of fungal sRNAs that translocate into plant host cells to suppress host immunity provided the first example of sRNAs trafficking between pathogens and their hosts. This project will use the fungal pathogen B. cinerea, which causes grey mold diseases on almost all vegetables, fruits and many flowers, and its plant hosts to understand the mechanism of cross-kingdom small RNA trafficking and regulation, and to develop an effective RNA-based practical strategy for controlling B. cinerea and other aggressive pathogens. This project will provide excellent training opportunities for undergraduate, graduate students and postdoctoral researchers. Efforts are in place to recruit students from underrepresented minorities to work on this project.

Small RNA (sRNA)-mediated RNA interference (RNAi) plays an essential role in both host immunity and pathogen virulence. The PI's lab has discovered that sRNAs from some eukaryotic pathogens regulate pathogen virulence. Some sRNAs from an aggressive fungal pathogen, Botrytis cinerea, are translocated into host plant cells and hijack the host RNAi machinery to silence important host immunity genes. Recent studies from animal systems also suggest that mobile sRNAs are capable of trafficking between mammals and their interacting organisms. However, how these mobile sRNAs are transported between the interacting organisms, and whether plant endogenous sRNAs are secreted and translocated into pathogen cells are still largely unknown. It is also not clear what these mobile sRNAs regulate in the interacting organisms. This project aims to address these questions by determining pathways and components required for sRNA trafficking between fungal cells and plant cells; identifying and functionally characterizing these sRNAs; and developing sRNA-based effective means to control aggressive eukaryotic pathogens. The results of these studies will advance our knowledge of sRNA trafficking in the cross-kingdom RNAi between plant hosts and eukaryotic pathogens. Understanding how sRNAs communicate between organisms will facilitate utilization and manipulation of sRNAs for disease control and host immunity.

National Science Foundation (NSF)
Division of Integrative Organismal Systems (IOS)
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Michael L. Mishkind
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University of California Riverside
United States
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