Transgenic rice (Oryza sativa) plants expressing the Pns11 protein of rice gall dwarf virus (RGDV) displayed multiple abnormal phenotypes, some of which were highly reminiscent of the symptoms observed in RGDV-infected rice. Further analysis indicated that the apparent alterations in plant growth and morphology were correlated with the expression levels of microRNA160, microRNA162, microRNA167, microRNA168, and the microRNA target OsARF8. Especially, the striking dwarfing phenotype depended on the high expression level of microRNA167. By analogy to other categories of plant viruses, the RNA silencing suppressors encoded by plant dsRNA viruses function as pathogenicity determinants. These findings significantly deepen our current mechanistic understanding of the RNA silencing suppressor (VSR) encoded by a dsRNA virus and provide additional evidence that interference with microRNA expression is a VSR function utilized by a diverse range of viruses.