A viral resistance gene from common bean functions across plant families and is up-regulated in a non-virus-specific manner

Abstract

Genes involved in a viral resistance response in common bean (Phaseolus vulgaris cv. Othello) were identified by inoculating a geminivirus reporter (Bean dwarf mosaic virus expressing the green fluorescent protein), extracting RNA from tissue undergoing the defense response, and amplifying sequences with degenerate R gene primers. One such gene (a TIR-NBS-LRR gene, RT4-4) was selected for functional analysis in which transgenic Nicotiana benthamiana were generated and screened for resistance to a range of viruses. This analysis revealed that RT4-4 did not confer resistance to the reporter geminivirus; however, it did activate a resistance-related response (systemic necrosis) to seven strains of Cucumber mosaic virus (CMV) from pepper or tomato, but not to a CMV strain from common bean. Of these eight CMV strains, only the strain from common bean systemically infected common bean cv. Othello. Additional evidence that RT4-4 is a CMV R gene came from the detection of resistance response markers in CMV-challenged leaves of RT4-4 transgenic plants, and the identification of the CMV 2a gene product as the elicitor of the necrosis response. These findings indicate that RT4-4 functions across two plant families and is up-regulated in a non-virus-specific manner. This experimental approach holds promise for providing insights into the mechanisms by which plants activate resistance responses against pathogens.avirulence gene ͉ Cucumber mosaic virus ͉ geminivirus ͉ host defense response ͉ systemic necrosis

The P25 Protein of Potato Virus X (PVX) Is the Main Pathogenicity Determinant Responsible for Systemic Necrosis in PVX-Associated Synergisms

“…Several studies have postulated that systemic necrosis (SN) shares HR attributes, as a consequence of the delayed occurrence of biochemical and physiological events that are associated with programmed cell death (PCD) (8)(9)(10). Moreover, R proteins have been involved in some cases of SN responses associated with compatible virus interactions (6,11). In addition, Komatsu et al (8) determined that SGT1 and RAR1, which are both required for the function of many R proteins in incompatible interactions (12,13), also mediate SN in compatible virus infections.…”

Stability of Transgenic Resistance Against Plant Viruses

“…Besides the PDR strategy, alternative biotechnological approaches for the manufacturing of plants resistant to viruses include the expression of plant virus-resistance genes in other plants than those from which they were isolated (Farnham, 2006;Seo et al, 2006;Spassova et al, 2001) and the expression of peptides (Lopez-Ochoa et al, 2006;Rudolph et al, 2003;Uhrig, 2003) or antibodies. After the first successful application of the later strategy in 1993 by Tavladoraki and co-workers, with antibodies that reduced the susceptibility to Artichoke mottle crinkle virus using a single-chain variable fragment (scFv) directed against the CP of the virus, technical difficulties hampered a wider application of this methodology.…”

Histone H3 Interacts and Colocalizes with the Nuclear Shuttle Protein and the Movement Protein of a Geminivirus

“…Full-length histone H3 cDNAs were generated from mRNAs extracted from tomato (Solanum lycopersicum) and Nicotiana benthamiana leaf tissue by reverse transcription-PCR (RT-PCR) as previously described (48). For the tomato histone H3 gene, two degenerate primers (P7F/P8R and P9F/P10R) were used, whereas for that of N. benthamiana, one primer pair (P11F/P12R) was used.…”