Poster: Plant Pathogen/Symbiont Interactions

Abs # 745: Identification and functional analysis of RNA dependent RNA polymerase(s) from Capsicum annuum and Chenopodium species: hosts susceptible to normally debilitated or multiple viruses

Presenter:	Carter, Shelly A., sacarter@noble.org
Authors	Carter, Shelly A. (A)   Yang, Shujun  (A)   Nelson, Richard S. (A)
Affiliations:	(A): The Samuel Roberts Noble Foundation

It is known that eukaryotic host RNA dependent RNA polymerases (RdRPs) can aid in destroying invading viral RNA as a defense against these pathogens. Several plant species have unusually high susceptibilities to plant viruses. Our current work indicates that an RdRP from Nicotiana benthamiana contains an insert of 72 nucleotides with in-frame stop codons that would produce a truncated, and likely, non-functional protein. Interestingly, this plant is also susceptible to systemic infection by a mutant strain of Tobacco mosaic virus (TMV) that has a debilitated suppressor of gene silencing and does not efficiently infect N. tabacum systemically. Here we have investigated whether another member of the Solanaceous family, Capsicum annuum cv. Marengo, contained a similarly debilitated RdRP. Capsicum annuum cv. Marengo was analyzed because it is susceptible to a wide variety of viruses and to the previously mentioned debilitated TMV mutant. Our initial studies determined that, unlike in N. benthamiana, no 72 nt insert was identified within the RdRP ORFs of this Capsicum annuum variety. We are further analyzing the RdRP ORFs within the Capsicum genome to determine if portions outside of the region of the 72 nt insert are altered. We analyzed for altered RdRP sequences within Chenopodium species because they are also hosts to many viruses. Again, we did not identify a 72 nt insert within these species, indicating that their susceptibility to viruses is not due to such a mutation.