Plants frequently encounter multiple pathogens concurrently, yet the molecular bases of pathogen-pathogen interactions during mixed infections remain largely unresolved. Here we show that co-infection of rice by Rice orange leaf phytoplasma (ROLP) and Rice stripe mosaic virus (RSMV) markedly suppresses RSMV proliferation in both host plants and the insect vector. Electron microscopy and confocal imaging reveal that ROLP and RSMV co-inhabit individual rice phloem cells and undergo close membrane interaction, producing swollen RSMV virions with reduced infectivity. We further demonstrate that the ROLP membrane protein Imp interacts with the RSMV G envelope protein and competitively disrupts the G-M association essential for virion assembly. The Imp region encompassing residues 96-122 (Imp-α4) is necessary for this inhibition. Transgenic rice overexpressing Imp or Imp-α4 phenocopies these effects, displaying deformed virions and diminished viral load. These findings uncover a cross-kingdom antagonistic mechanism between two phylogenetically distant pathogens and offer conceptual directions for engineering durable antiviral resistance.
Jiaxin Qiu, Yu-Jiao Zheng, Yan-Mei Yi et al.· Plant, Cell and Environment· 0 citations
Pathogenesis-related protein 1 (PR1) serves as a canonical plant defense marker; however, its specific role in conferring resistance against insect herbivores has remained elusive. Here, we delineate a complete PR1-mediated defense pathway in rice. We show that the cysteine protease OsXCP2, in a catalytic residue-dependent manner, cleaves PR1a at the conserved CNYS motif to release the OsCAPE1 peptide, which subsequently activates broad-spectrum resistance against phloem-feeding insects. Insect herbivory induces the co-expression of OsXCP2 and OsPR1a specifically in the phloem. And loss-of-function osxcp2 mutants exhibit compromised resistance, underscoring the functional importance of this pathway in rice anti-herbivore defense. Strikingly, the glycoprotein (G) of the leafhopper-transmitted rhabdovirus rice stripe mosaic virus (RSMV) is secreted into the phloem during viruliferous insect feeding. Mechanistically, RSMV G employs a dual strategy to subvert this defense: it competitively binds the C-terminus of PR1a, thereby blocking OsXCP2-mediated cleavage, and simultaneously sequesters the liberated OsCAPE1 peptide. This concerted inhibition suppresses PR1-dependent resistance against insect feeding and consequently promotes viral transmission. In summary, our study identifies a novel PR1-activated anti-herbivore pathway in rice and reveals a sophisticated viral effector mechanism that antagonizes it to facilitate vector-borne viral transmission.
Jingya Zhao, Tong-Yu Liu, Yuexiao He et al.· Plant Communications· 0 citations
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