Amino acids in Tobamovirus coat protein controlling pepper L1a gene-mediated resistance

• Published in: Molecular plant pathology 2012-10, Vol.13 (8), p.915-922
• Main Authors: MIZUMOTO, HIROYUKI, NAKAMURA, IKUMI, SHIMOMOTO, YOSHIFUMI, SAWADA, HIROMASA, TOMITA, REIKO, SEKINE, KEN-TARO, KIBA, AKINORI, NISHIGUCHI, MASAMICHI, KOBAYASHI, KAPPEI, HIKICHI, YASUFUMI
• Format: Article
• Language: English
• Subjects: Amino acids; Biological and medical sciences; Capsicum; Coat protein; Disease resistance; Fundamental and applied biological sciences. Psychology; L gene; Leaves; Original; Paprika mild mottle virus; Phytopathology. Animal pests. Plant and forest protection; Plant viruses and viroids; Tobacco; Tobacco mild green mosaic virus; Tobamovirus; Virions
• ISSN: 1464-6722; 1364-3703
• DOI: 10.1111/j.1364-3703.2012.00801.x

SUMMARY In pepper plants (genus Capsicum), the resistance against Tobamovirus spp. is conferred by L gene alleles. The recently identified L variant L1a can recognize coat proteins (CPs) of Tobacco mild green mosaic virus Japanese strain (TMGMV‐J) and Paprika mild mottle virus Japanese strain (PaMMV‐J), but not of Pepper mild mottle virus (PMMoV), as the elicitor to induce resistance at 24 °C. Interestingly, L1a gene‐mediated resistance against TMGMV‐J, but not PaMMV‐J, is retained at 30 °C. This observation led us to speculate that L1a can discriminate between CPs of TMGMV‐J and PaMMV‐J. In this study, we aimed to determine the region(s) in CP by which L1a distinguishes TMGMV‐J from PaMMV‐J. By using chimeric CPs consisting of TMGMV‐J and PaMMV‐J, we found that the chimeric TMGMV‐J CP, whose residues in the β‐sheet domain were replaced by those of PaMMV‐J, lost its ability to induce L1a gene‐mediated resistance at 30 °C. In contrast, the chimeric PaMMV‐J CP with the β‐sheet domain replaced by TMGMV‐J CP was able to induce L1a gene‐mediated resistance at 30 °C. Furthermore, viral particles were not detected in the leaves inoculated with either chimeric virus. These observations indicated that the amino acids within the β‐sheet domain were involved in both the induction of L1a gene‐mediated resistance and virion formation. Further analyses using chimeric CPs of TMGMV‐J and PMMoV indicated that amino acids within the β‐sheet domain alone were not sufficient for the induction of L1a gene‐mediated resistance by TMGMV‐J CP. These results suggest that multiple regions in Tobamovirus CP are implicated in the induction of L1a gene‐mediated resistance.