Discovery of a novel whitefly- and aphid-transmitted polerovirus on rice plants with dwarfing and fewer tillering symptoms.

Rice is the most important cereal grain worldwide and is cultivated mainly in Asian countries. Rice viral disease epidemics caused by insect-borne viruses are a major threat to rice production. However, to date, how many unknown viruses naturally infect rice plants in the field remains vague. Here, we identified a novel polerovirus tentatively named rice dwarf polerovirus (RDPV) via RNA-seq technology in rice plants showing dwarfing and fewer tillering symptoms collected from paddy fields in Hainan Province, China. The RDPV genome consists of a positive-sense, single-stranded RNA molecule that is 5832 nt in size and is deduced to encode seven viral proteins. Phylogenetic analyses based on the full-length genome sequence and RNA-dependent RNA polymerase (RdRp) amino acid sequence revealed that RDPV is in an evolutionary branch with known viruses in the Polerovirus genus. Interestingly, virus transmission experiments demonstrated that RDPV can be transmitted by two completely different vectors, i.e., whiteflies and aphids, from diseased rice plants to healthy rice seedlings. Furthermore, we constructed an infectious cDNA clone of RDPV and found that it can infect Nicotiana benthamiana plants via Agrobacterium-infiltrated inoculation. Thus, we concluded that RDPV is a novel whitefly- and aphid-transmitted rice polerovirus. These findings contribute to expanding our knowledge of rice polerovirus diversity, and developing efficient strategies to manage this rice viral disease.