The coat protein of potato virus X is a strain‐specific elicitor of Rx1‐mediated virus resistance in potato

Abstract

The Rx1 gene in potato confers extreme resistance to potato virus X (PVX). To investigate the mechanism and elicitation of Rx resistance, protoplasts of potato cv. Cara (Rx1 genotype) and Maris Bard (rx1 genotype) were inoculated with PVX and tobacco mosaic virus (TMV). At 24 h post-inoculation in Maris Bard protoplasts there was at least 100-fold more PVX RNA than in protoplasts of Cara. TMV RNA accumulated to the same level in both types of protoplast. However, when the TMV was inoculated together with PVX the accumulation of TMV RNA was suppressed in the Cara (Rx1 genotype) protoplasts to the same extent as PVX. The Rx1 resistance also suppressed accumulation of a recombinant TMV in which the coat protein gene was replaced with the coat protein gene of PVX. It is therefore concluded that Rx1-mediated resistance is elicited by the PVX coat protein, independently of any other proteins encoded by PVX. The domain of the coat protein with elicitor activity was localized by deletion and mutation analysis to the structural core of a nonvirion form of the coat protein.

The Effector SPRYSEC-19 ofGlobodera rostochiensisSuppresses CC-NB-LRR-Mediated Disease Resistance in Plants

“…We therefore concluded that SPRYSEC-19 suppressed elicitor-dependent programmed cell death mediated by Gpa2. Gpa2 is highly similar to the virus resistance protein Rx1 that recognizes the coat protein of the avirulent Potato virus X (PVX) strain UK106 (Cp106; Bendahmane et al, 1995). Cp106 shares no sequence similarity with GpRBP-1 or with other SPRYSEC effectors.…”

Molecular cloning of a coiled-coil-nucleotide-binding-site-leucine-rich repeat gene from pearl millet and its expression pattern in response to the downy mildew pathogen

“…The CC domain with a coiled-coil structure is implicated in specific interactions with other proteins and also facilitates dimerization [12]. The CC-NB-LRR protein Rx of potato is found to interact with the Potato virus X (PVX) coat protein conferring resistance to PVX [13] and the Arabidopsis RPS4 gene is involved in resistance to Avr Rps4 of bacterial pathogens [14]. Based on the conserved domains of known R-genes across plant species, novel resistance gene analogues (RGAs) have been isolated from diverse plants by degenerate oligonucleotide primer based PCR approach [15].…”

Review Article: Molecular Mechanisms of Resistance to Potato virus X and Y in Potato

“…andigena and Rx2 from S. acaule (Ritter et al, 1991). The open reading frames of Rx1 and Rx2 show 95% identity at the nucleotide level (Bendahmane et al, 1995). Farnham and Baulcombe (2006) demonstrated that the wild-type potato NBS-LRR protein Rx confers resistance against a single strain of PVX.…”

“…In potato, ER to PVX is controlled by the dominant genes Rx1 and Rx2. Rx confers a race-specific resistance to PVX by recognition of the viral coat protein (Bendahmane et al, 1995). The gene Rx1 is located on chromosome XII and the gene Rx2 on chromosome V. On the basis of pedigree analysis, it was assumed that Rx1 derived from S. tuberosum subsp.…”