Pathogen-derived resistance targeted against the negative-strand RNA of tobacco mosaic virus: RNA strand-specific gene silencing?
✍ Scribed by María Rosa Marano; David Baulcombe
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 418 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0960-7412
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✦ Synopsis
Summary
Tobacco plants transformed with the open‐reading frame (ORF) of tobacco mosaic virus strain U1 (TMV‐U1) encoding a 54 kDa (54K) region of the viral replicase are resistant against TMV strain U1. These plants are not resistant against the crucifer strain of TMV or the heterologous virus, potato virus X (PVX). However, they are resistant against derivatives of PVX containing fragments of the 54K ORF inserted either in the sense or anti‐sense orientation. The smallest fragment that was a target of the resistance mechanism was a 383 nucleotide region from the central part of the 54K ORF. A transient gene expression assay revealed that this central region was also the target of a post‐transcriptional gene silencing mechanism. However, unlike other examples of gene silencing associated with virus resistance, the silencing was specific for the anti‐sense rather than the coding strand of the target RNA. Based on these data the authors propose that the TMV resistance is due, at least in part, to a type of transgene silencing.