Christian Mandelli,* Emanuelle Chrysilla, and Laurent Deluc
*Oregon State University, 2750 SW Campus Way, Corvallis, OR 97331 (mandellc@oregonstate.edu)

In plant-pathogen interactions, small RNAs (sRNAs) ranging from 21 to 24 nucleotides have a pivotal role in inducing epigenetic and post-transcriptional gene silencing via RNA interference mechanisms. This knowledge is the basis for new crop protection technologies that mostly rely on the production of transgenic plants expressing a double-stranded RNA molecule specific to pathogen sequence(s). This induces in the host the RNA interference mechanism, also termed host-induced gene silencing (HIGS). However, the use of genetically modified organisms (GMOs) raised scientific and public concerns. A new innovative strategy, termed spray-induced gene silencing (SIGS), allows RNAi induction without requiring plant genetic modification. Spraying dsRNAs on the leaf surface results in their cellular uptake and processing into siRNAs. Our group developed a long-term research project aiming to exploit this technology to control grapevine red-blotch disease. As a first step, we aim to characterize the responses of grapevine following grapevine red blotch virus (GRBV) infection by producing i) the landscape of small RNAs produced during the early steps of infection, ii) the methylome targeting the viral genome, and iii) the grapevine transcriptome associated with plant pathogen responses. To achieve these objectives, we will use Agro-drenching and green grafting for the plant infections and next generation sequencing for transcript characterization. Altogether, we hope to identify the “hot spots” for transcriptional and post-transcriptional gene silencing during the early phase of infection and use them to design the dsRNAs necessary for SIGS application.

Funding Support: California Department of Food and Agriculture