Bryce W. Falk
Univ. of California - USA
Bryce Falk received his BS degree from Cal Poly in California in 1974, and PhD in Plant Pathology from UC Berkeley in 1978. He did postdoctoral work at UC Riverside and became Assistant Professor of Plant Pathology at the University of Florida, Everglades Research and Education Center in 1980. He came to UC Davis in 1985 and was advanced to Distinguished Professor in 2013. He teaches classes in Plant Pathology, Plant Virology and General Virology. His research deals with plant viruses, insect vectors of plant pathogens and biotechnological applications for plant disease control. He has over 180 publications. His research has funding from Federal, State and commercial sources. He has had over 25 graduate students and 25 postdocs from all over the world, and has collaborations worldwide. He is a Fellow of the AAAS and APS, and Adjunct Professor Henan Agricultural University, Zhengzhou, China.
Summary of lecture
RNAi-based strategies against insect vectors of plant pathogens
RNAi-based strategies against insect vectors of plant pathogens RNA interference (RNAi) is a natural gene regulation and antiviral defense in eukaryotes. RNAi functions by targeting specific RNAs, and then degrading them or inhibiting their translation ability. Because RNAi specificity is directed by Watson:Crick base pairing of interfering RNAs and the RNA target, interfering RNAs can be designed towards specific RNAs, including those of pests and pathogens. RNAi is already used in commercial agriculture for anti-viral resistance in plants, and more recently has shown great promise for insect control. We are investigating different RNAi-based strategies to specifically target insect vectors of plant pathogens, including mealybugs, psyllids and sharpshooter leafhoppers. In vitro assays, including delivery of interfering RNAs by injection and/or artificial diet feeding yield RNAi effects, but also can show off-target effects on non-target RNAs and insects often do not show the desired phenotypic response. Our best results have been obtained by performing on-plant assays allowing for insects to go through a generation, and by using recombinant plant viruses to express interfering RNAs. In order to increase target specificity, we now have attempted to use plant viruses to express artificial microRNAs (amiRNAs). The cytoplasmic replicating Tobacco mosaic virus did not yield specific amiRNAs, but the nuclear replicating Tomato mottle virus did. Recently our efforts have moved towards attempting to use insect-infecting viruses to induce systemic RNAi responses in recipient insects. We used next-generation sequencing and identified 5 viruses of the Asian citrus psyllid (Diaphorina citri). We are attempting now to use these for D. citri.