A viral protein disrupts rice cell wall integrity and modulates interactions with viruses and insects.

The plant cell wall provides structural support and serves as a barrier against pathogen invasion. Rice grassy stunt virus (RGSV) infection suppresses genes involved in cell wall biosynthesis, but the underlying mechanism remains unclear. To further investigate this phenomenon, we generated transgenic rice lines overexpressing the RGSV-encoded p2 protein. These transgenic lines exhibited a brittle phenotype with reduced plant height, thinner sclerenchyma cell walls, decreased cellulose and increased lignin contents. Biochemical and microscopic analyses confirmed that mechanical strength of the cell wall was significantly weakened in p2-expressing plants. Notably, immunoblotting and in situ hybridization revealed partial localization of p2 to the cell wall, suggesting potential structural association. Transcriptome analysis revealed that p2 expression significantly altered the expression of genes involved in cell wall organization, hormone signaling, and pathogen interactions, suggesting a mechanistic basis for the observed phenotypes. Additionally, p2 transgenic lines exhibited increased susceptibility to multiple viruses, but unexpectedly showed enhanced resistance to the brown planthopper (BPH, Nilaparvata lugens), a major phloem-feeding pest. These findings reveal that a single viral protein can remodel the cell wall to influence both pathogen susceptibility and insect resistance, highlighting the broader ecological impacts of virus-induced cell wall remodeling in plants.