Genetic diversity and silencing suppression activity of the p22 protein of Tomato chlorosis virus isolates from tomato and sweet pepper
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As for other bipartite criniviruses (genus Crinivirus, family Closteroviridae), the genome of Tomato chlorosis virus encodes an RNA silencing suppressor, the protein p22, in the 3′-proximal region of RNA1. This protein has been reported as having one of the longest lasting local suppressor activities when transiently expressed in Nicotiana benthamiana. Here, we examined the genetic diversity of the p22 gene in ToCV isolates from tomato and sweet pepper. The p22 gene sequences clearly grouped into two separated clades. However, functional analysis of both types of p22 proteins indicated no evident differences in suppressor activity. Our findings provide experimental evidence that the presence of a “strong” silencing suppressor is a conserved feature of ToCV isolates.
KeywordsCrinivirus Closteroviridae Plant viral suppressor
Y. L.-R. was the recipient of an AECID (Spain) fellowship. M.C.C. was the recipient of an I3P contract from the CSIC (Spain) co-financed by FSE. This work was supported by Grants AGL2013-48913-C2-1-R from the Ministerio de Economía y Competitividad, Spain, and P10-AGR-6516 from Consejería de Economía, Innovación y Ciencia (CEIC), Junta de Andalucía, Spain, co-financed by FEDER-FSE. J.N.C. and E.M.A. are members of the Research Group AGR-214, partially funded by the Consejería de Economía, Innovación y Ciencia, Junta de Andalucía, Spain. We thank F. Aparicio and I.M. Fortes for providing materials and M.V. Martín and R. Tovar for technical assistance.
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