P-368 - Developing the first infectious clone of the Tomato Spotted Wilt Virus from a USA isolate.

The Tomato spotted wilt virus (TSWV) ranks 2nd among the most economically devastating plant viruses worldwide, causing over $1 billion in losses annually (Scholthof et al., 2011). There are resistance breaking TSWV strains emerging in pepper production in the Southern U.S. creating an urgent need for new sources of genetic resistance for breeding programs. This project aims to develop an infectious clone of TSWV which is the first reported full-length sequence from the USA, based on the design published by (Feng et al 2020) that can be used to study virus-host interactions in domestic pepper varieties. Our infectious clone system contains the 35S driven cDNAs of the viral genome segments, a unique set of silencing suppressor coding sequences, and the green fluorescent protein (GFP) gene. Constructs containing these components were tested in different combinations and inoculated via the syringe infiltration method into Nicotiana benthamiana plants. Results demonstrate we have successfully created an infectious clone of TSWV-GFP capable of systemic infection. We determined the addition of cucumber mosaic virus 2b silencing suppressor is sufficient to promote systemic infection. This contrasts the work by Feng et al. (2020) which included 6 additional genes to promote TSWV infection. This work has great significance to the field of phytopathology by reporting the first infectious clone of TSWV based on a USA isolate which can be used to identify host resistance guiding breeder’s decisions on planting, increasing crop yield and reducing losses for growers in the United States.