The Tomato spotted wilt virus cell-to-cell movement protein (NSM) triggers a hypersensitive response in Sw-5 containing resistant tomato lines and Nicotiana benthamiana transformed with the functional Sw-5b resistance gene copy.
Hallwass, M. ; Silva de Oliveira, A. ; Dianese, E.C. ; Lohuis, D. ; Boiteux, L.S. ; Inoue-Nagata, A.K. ; Resende, R.O. de; Kormelink, R.J.M. - \ 2014
Molecular Plant Pathology 15 (2014)9. - ISSN 1464-6722 - p. 871 - 880.
mosaic-virus - lycopersicon-esculentum - nonstructural protein - capsicum-chinense - coat protein - plant-cells - rna segment - tswv - tospovirus - tobacco
Although the Sw-5 gene cluster has been cloned, and Sw-5b has been identified as the functional gene copy that confers resistance to Tomato spotted wilt virus (TSWV), its avirulence (Avr) determinant has not been identified to date. Nicotiana tabacum SR1 plants transformed with a copy of the Sw-5b gene are immune without producing a clear visual response on challenge with TSWV, whereas it is shown here that N.benthamiana transformed with Sw-5b gives a rapid and conspicuous hypersensitive response (HR). Using these plants, from all structural and non-structural TSWV proteins tested, the TSWV cell-to-cell movement protein (NSM) was confirmed as the Avr determinant using a Potato virus X (PVX) replicon or a non-replicative pEAQ-HT expression vector system. HR was induced in Sw-5b-transgenic N.benthamiana as well as in resistant near-isogenic tomato lines after agroinfiltration with a functional cell-to-cell movement protein (NSM) from a resistance-inducing (RI) TSWV strain (BR-01), but not with NSM from a Sw-5 resistance-breaking (RB) strain (GRAU). This is the first biological demonstration that Sw-5-mediated resistance is triggered by the TSWV NSM cell-to-cell movement protein.
Tsw gene-based resistance is triggered by a functional RNA silencing suppressor protein of the Tomato spotted wilt virus
Ronde, D. de; Butterbach, P.B.E. ; Lohuis, H. ; Hedil, M. ; Lent, J.W.M. van; Kormelink, R.J.M. - \ 2013
Molecular Plant Pathology 14 (2013)4. - ISSN 1464-6722 - p. 405 - 415.
mediated plant transformation - capsicum-chinense - cell-death - disease-resistance - lycopersicon-esculentum - viral suppressors - sw-5 gene - potato - tospovirus - agrobacterium
As a result of contradictory reports, the avirulence (Avr) determinant that triggers Tsw gene-based resistance in Capsicum annuum against the Tomato spotted wilt virus (TSWV) is still unresolved. Here, the N and NSs genes of resistance-inducing (RI) and resistance-breaking (RB) isolates were cloned and transiently expressed in resistant Capsicum plants to determine the identity of the Avr protein. It was shown that the NSsRI protein triggered a hypersensitive response (HR) in Tsw-containing Capsicum plants, but not in susceptible Capsicum, whereas no HR was discerned after expression of the NRI/RB protein, or when NSsRB was expressed. Although NSsRI was able to suppress the silencing of a functional green fluorescence protein (GFP) construct during Agrobacterium tumefaciens transient assays on Nicotiana benthamiana, NSsRB had lost this capacity. The observation that RB isolates suppressed local GFP silencing during an infection indicated a recovery of RNA silencing suppressor activity for the NSs protein or the presence of another RNA interference (RNAi) suppressor. The role of NSs as RNA silencing suppressor and Avr determinant is discussed in the light of a putative interplay between RNAi and the natural Tsw resistance gene