Southern rice black-streaked dwarf virus: A new proposed Fijivirus species in the family Reoviridae

Abstract

For the past several years, a novel dwarf disease has been observed on rice (Oryza sativa) in some regions of Guangdong Province and Hainan Province, southern China. Infected plants showed stunting, dark leaf and small enations on stem and leaf back. Typical Fijivirus viroplasma containing crystalline arrayed spherical virons approximately 70-75 nm in diameter and tubular structures were detected in ultrathin sections by an electron microscope in parenchyma phloem cells of the infected plants. The virus was transmitted to rice seedlings by white-backed planthoppers, Sogatella furcifera (Hemiptera: Delphacidae), collected in the diseased fields. Analysis of dsRNA extracts from infected plants revealed ten linear segments, which were similar to the electrophoretic profile of Rice black-streaked dwarf virus (RBSDV). RT-PCR with a single primer which matched to a linker sequence ligated to both 3′ ends of the viral genomic dsRNAs resulted in amplification of genome segments 9 (S9) and 10 (S10) cDNA products. The complete nucleotide sequences of S9 and S10 were obtained from clones of the RT-PCR amplicon exhibited characteristic properties of Fijivirus including low GC content (34.5% and 35.6%), genus conserved 5′ and 3′ termini sequences and similar genome organization. Blast searches indicated that the sequences of S9 and S10 shared 68.8%-74.9% and 67.1%-77.4% nucleotide identities with those of viruses in the Fijivirus group 2, respectively. These values were similar to those among other viruses in the Fijivirus group 2 and considerably lower than those among RBSDV isolates. Phylogenetic trees based on S9 and S10 nucleotide sequences and their putative amino acid sequences showed that this virus represented a separate branch among other Fijiviruses. The virus was also detected by a nested RT-PCR assay in corn (Zea mays), barnyard grass (Echinochloa crusgalli), Juncellus serotinus and flaccidgrass (Pennisetum flaccidum) in and/or adjacent to the infected rice fields. It is proposed that this virus be considered as a new species, Southern rice black-streaked dwarf virus, in the group 2 of the genus Fijivirus in the family Reoviridae.southern rice black-streaked dwarf virus, rice, Fijivirus, Reoviridae, genome sequence Rice black-streaked virus (RBSDV) is a species of the genus Fijivirus in the family Reoviridae [1] . It has icosahedric particles approximately 70-75 nm in diameter that contain 10 genome segments of double-stranded RNAs (dsRNA), designated as S1-S10 in increasing order of electrophoretic mobility in polyacrylamide gels. Small brown planthopper, Laodelphax striatellus, is its main natural vector, and Unkanodes sapporonus and Chilodephax albifacia can also transmit the virus with a relative low efficiency [2][3][4] . In the genus Fijivirus, 8 species, Fiji disease virus (FDV), Oat sterile dwarf virus (OSDV), Garlic dwarf virus (GDV), Nilaparvata lugens reovirus (NLRV), Mal de Río Cuarto virus (MRCV), Pangola stunt virus (PaSV), Maize rough dwarf virus (MRDV) and RBSDV were recognized [1] . Among them,

Development of a Real-time RT-PCR Method for Rapid Detection and Quantification of Southern Rice Black-streaked Dwarf Virus in Rice

“…The nucleotide sequences of segment 9 of SRBSDV and RBSDV were downloaded for the GenBank database, and there was high homology of genome sequence between SRBSDV with RSBDV (74.2~74.9% identity of segment 9) [2]. Sequence multi-alignment was analyzed by software suite of DNAMAN (Lynnon Biosoft Inc, USA).…”

“…Southern rice black-streaked dwarf virus (SRBSDV), a latest member of the genus Fijivirus within the family Reoviridae, was simultaneously isolated and identified from the rice in southern of China in 2008 [1,2]. In the following three years (2009)(2010), SRBSDV caused the most important rice disease in South of China, there were over ten millions hectare of rice infected, and resulted in massive devastation of rice yield [3].…”

The Complete Genome Sequence of Southern rice black-streaked dwarf virus Isolated from Vietnam

“…The causal agent of the rice dwarf disease in the north of Vietnam has also been identified as SRBSDV (Cuong et al, 2009;Hoang et al, 2011). Further investigation suggested that the outbreak of SRBSDV in Vietnam was associated with rising populations of the white-backed plant hopper (Sogatella furcifera), which is the major vector of SRBSDV (Cuong et al, 2009;Zhou et al, 2008). As planthoppers are constantly displaced by wind currents, the spread of the virus diseases they carry will be inevitable.…”

“…Characteristic symptoms include dark-green and wrinkled leaves, incomplete tassel, tumorlike protrusions ending in small enations, tiller formation on the upper parts, up-growing rootlets, and in particular the presence of white to black waxy galls along the major veins of the leaves and culms (Wang et al, 2012;Zhou et al, 2008;Zhou et al, 2010).…”

“…Primers for cloning segments S1 to S10 of Vietnamese isolate were designed to obtain the full length sequence of each genome segment based on the previously reported SRBSDV sequences available in GenBank of NCBI (Wang et al, 2010 Zhou et al (2008). Briefly, an oligodeoxyribonucleotide primer, P-linker (5'-PO…”