Rice Stripe Mosaic Virus, a Novel Cytorhabdovirus Infecting Rice via Leafhopper Transmission

Abstract

A new rice viral disease exhibiting distinct symptoms—yellow stripes, mosaic and twisted tips on leaves—was found in China. Electron microscopy of infected leaf cells revealed the presence of bacilliform virions and electron-translucent granular-fibrillar viroplasm in the cytoplasm. The enveloped viral particles were 300 to 375 nm long and 45 to 55 nm wide. The leafhopper Recilia dorsalis was able to transmit the virus to rice seedlings, which subsequently exhibited symptoms similar to those observed in fields. The complete genome of the virus was obtained by small-RNA deep sequencing and reverse transcription-PCR product sequencing. The anti-genome contains seven open reading frames (ORFs). The deduced amino acids of ORF1, ORF5, and ORF7 are, respectively, homologous to the nucleocapsid protein (N), glycoprotein (G), and large polymerase protein (L) of known rhabdoviruses. The predicted product of ORF2 is identified as a phosphoprotein (P) based on its multiple potential phosphorylation sites and 12.6 to 21.0% amino acid (aa) identities with the P proteins of plant rhabdoviruses. The product of ORF4 is presumed to be the viral matrix (M) protein for it shares 10.3 to 14.3% aa identities with those of other rhabdoviruses. The above five products were confirmed as the viral structural proteins by SDS-PAGE and aa sequencing analyses of purified virus preparation. ORF3 and ORF6 are considered to encode two nonstructural proteins with unknown functions. Phylogenetic analysis based on protein N, G, and L amino acid sequences indicated that the isolated virus, which we have tentatively named Rice stripe mosaic virus (RSMV), is a new species in the genus Cytorhabdovirus. To our knowledge, RSMV is the only cytorhabdovirus naturally infecting rice and the first reported leafhopper-transmitted cytorhabdovirus. Our surveys of rice fields indicate that RSMV occurs frequently in Guangdong Province, China. Although the disease incidence is low at present, it might become serious with the vector insect population increasing.

Molecular characterization of a novel cytorhabdovirus with a unique genomic organization infecting yerba mate (Ilex paraguariensis) in Argentina

“…A signal peptide was also predicted using SignalP 3.0 server (http://www.cbs.dtu.dk/services/SignalP-3.0/) in the ORF6 encoded protein. Similar signal peptides have been predicted in the glycoprotein sequences of several cytorhabdoviruses [14-16] lending supports to the notion that ORF6 may encode a glycoprotein. Furthermore, and again highlighting the distinctiveness of YmVA, its predicted P and L proteins are the longest so far among cyto- and nucleorhabdoviruses (Table S2).…”

Specificity of Plant Rhabdovirus Cell-to-Cell Movement

“…Since some of the rhabdovirus P3 homologs are structurally related to 30K superfamily proteins, we first set out to test whether there is a widespread complementation between P3 proteins and a ToMV MP mutant. The MP genes from three nucleorhabdoviruses, SYNV, PYDV, and RYSV, and two cytorhabdoviruses recently identified in China, rice stripe mosaic virus (RSMV) (47) and TYMaV (48), were cloned into the pGD binary vector (49) for transient expression. ToMV-GFPΔMP, an MPdefective ToMV clone carrying a green fluorescence protein (GFP) reporter gene substitution for the CP gene (50), was used to evaluate complementation by the rhabdovirus MPs.…”

“…In this study, we started with parallel analyses of five putative MPs of plant rhabdoviruses for their abilities to complement the movement of ToMV-GFPΔMP and PVX-GFPΔp25. These rhabdoviruses differ in infecting monocotyledonous (RSMV and RYSV) or dicotyledonous (SYNV, PYDV, and TYMaV) hosts, as well as in their nuclear (SYNV, PYDV, and RYSV) or cytoplasmic (RSMV and TYMaV) sites of replication (31,47,48). Despite these differences, all five rhabdovirus MPs complemented cell-to-cell movement of ToMV-GFPΔMP and PVX-GFPΔp25 when expressed in trans.…”

Defense and counter-defense in rice–virus interactions

“…Rice virus disease causes severe disease of rice in China and many other East Asia countries (Nicaise 2014). Up to now, 17 rice virus diseases have been reported in different areas (Shikata and Kitagawa 1977;Shikata et al 1979;Omura et al 1980;Shikata et al 1980;Xie et al 1982;Lin et al 1990;Hibino 1996;Abo et al 1997;Munoz et al 2004;Zhou et al 2008;Yang et al 2016;Wang et al 2018), and 6 of them, Southern rice black-streaked dwarf virus (SRBSDV), Rice ragged stunt virus (RRSV), Rice stripe virus (RSV), Rice dwarf virus (RDV), Rice grassy stunt virus (RGSV), and Rice black-streaked dwarf virus (RBSDV) are mainly harmful to rice production (Sasaya et al 2014). Almost all the rice viruses are transmitted by the insect vectors through persistent or nonpersistent manner and cause some common disease symptoms (Ling 1972).…”