Molecular Plant-Microbe Interactions (2007) 20, 547-558

P. Margaria, M. Ciuffo, D. Pacifico and M. Turina (2007)
Evidence that the nonstructural protein of Tomato spotted wilt virus is the avirulence determinant in the interaction with resistant pepper carrying the Tsw gene
Molecular Plant-Microbe Interactions 20 (5), 547-558
Abstract: All known pepper cultivars resistant to Tomato spotted wilt virus (TSWV) possess a single dominant resistance gene, Tsw. Recently, naturally occurring resistance-breaking (RB) TSWV strains have been identified, causing major concerns. We used a collection of such strains to identify the specific genetic determinant that allows the virus to overcome the Tsw gene in Capsicum spp. A reverse genetic approach is still not feasible for TSWV; therefore, we analyzed reassortants between wild-type (WT) and RB strains. Our results confirmed that the S RNA, which encodes both the nucleocapsid protein (N) and a nonstructural protein (NSs), carries the genetic determinant responsible for Tsw resistance breakdown. We then used full-length S RNA segments or the proteins they encode to compare the sequences of WT and related RB strains, and obtained indirect evidence that the NSs protein is the avirulence factor in question. Transient expression of NSs protein from WT and RB strains showed that they both can equally suppress post-transcriptional gene silencing (PTGS). Moreover, biological characterization of two RB strains carrying deletions in the NSs protein showed that NSs is important in maintaining TSWV infection in newly emerging leaves over time, preventing recovery. Analysis of another RB strain phenotype allowed us to conclude that local necrotic response is not sufficient for resistance in Capsicum spp. carrying the Tsw gene.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Massimo Turina, Paolo Margaria, Davide Pacifico

Research topic(s) for pests/diseases/weeds:
molecular biology - genes
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Orthotospovirus tomatomaculae	Green pepper/chilli (Capsicum)