ABSTRACT
The complete nucleotide sequence of the ssRNA genome of a Chinese GPV isolate of barley yellow dwarf virus (BYDV) was determined. It comprised 5673 nucleotides, and the deduced genome organization resembled that of members of the genus Polerovirus. It was most closely related to cereal yellow dwarf virus-RPV (77% nt identity over the entire genome; coat protein amino acid identity 79%). The GPV isolate also differs in vector specificity from other BYDV strains. Biological properties, phylogenetic analyses and detailed sequence comparisons suggest that GPV should be considered a member of a new species within the genus, and the name Wheat yellow dwarf virus-GPV is proposed.
Subject(s)
Genome, Viral , Luteoviridae/genetics , Luteovirus/genetics , RNA, Viral/genetics , Base Sequence , Edible Grain/virology , Luteovirus/classification , Luteovirus/isolation & purification , Molecular Sequence Data , Open Reading Frames , Phylogeny , RNA, Viral/chemistryABSTRACT
Australian grapevine viroid (AGVd) is found in only three countries in the world. Here, the genetic diversity and phylogenetic relationships of AGVd isolates from three different grape varieties (Thomson Seedless, Jingchuan and Zaoyu) in China were studied. A hundred of independent cDNA clones from each of the three isolates, in total of 300, were sequenced. We identified 29 sequence variants including two predominant ones in Thomson Seedless, and 48 each including a unique predominant one in Jingchuan and Zaoyu. In silico structure analysis revealed that base changes were clustered in the left terminal domain of the predicted secondary structure in all three isolates. Further, these changes were shown to affect their secondary structures to varying degrees. Genetic diversity and phylogenetic analysis of four predominant sequence variants from this study, plus four others from Australia and Tunisia, revealed obvious regional disparity and variety-specificity in AGVd.
Subject(s)
Genetic Variation , Viroids/genetics , Vitis/virology , Base Sequence , China , Models, Molecular , Molecular Sequence Data , Nucleic Acid Conformation , Phylogeny , Sequence Analysis, DNA , Sequence Homology , Viroids/isolation & purificationABSTRACT
For this study, 68 plum samples were collected from 12 provinces of China. Low molecular weight RNAs were extracted and used for dot-blot, reverse transcription-polymerase chain reaction (RT-PCR), return-polyacrylamide gel electrophoresis, and biological indexing using cucumber. Results showed that 15 out of the 68 plum samples were positive for Hop stunt viroid (HSVd). Four positive samples were selected for cloning and sequence analysis. Results indicated that most HSVd sequences from the plum in China had 1-3 nucleotide changes from the closest HSVd in GenBank. In addition, the sample PB21 (cv. 'Friar') collected from Hebei province had one sequence with a 15-nt duplication (named HSVd D-15) at the 244/245 position in the lower central region. By biological indexing, cucumber seedlings, an indicator plant for HSVd, were inoculated with RNAs directly extracted from the original plum source (PB21, cv. 'Friar'). Nucleotide sequencing analysis of the progeny showed that HSVd, but not HSVd-D15, was recovered from inoculated cucumbers. Although very unlikely, the possibility that this extra sequence was the result of a PCR artifact cannot be completely ruled out.
Subject(s)
Genetic Variation/genetics , Minisatellite Repeats/genetics , Prunus/virology , Viroids/genetics , Base Sequence , Cloning, Molecular , Cucumis sativus/genetics , Electrophoresis, Polyacrylamide Gel , Molecular Sequence Data , Nucleic Acid Conformation , Nucleic Acid Hybridization , RNA, Viral/chemistry , RNA, Viral/genetics , Sequence Alignment , Sequence Analysis, DNAABSTRACT
An expression vector expected to induce RNA interference against Barley yellow dwarf virus (BYDV), which expressed a composite hpRNA with the dsRNA stem homologous of BYDV GPV replicase gene and the antisense RNA loop homologous of coat protein gene, was designed without marker gene. The vector was transferred into callus cells from wheat (Triticum aestivum L.) immature embryos by particle bombardment. To select the positive transformants as early as possible, a rapid PCR, which does not need extract wheat DNA instead of few leaves, was used at regeneration stage of plantlets. Totally 21 plants proved to contain alien sequence. Antivirus test with high dose infected virus revealed that, 9 plants showed low level of resistance to BVDV, 6 plants showed moderate resistance and 6 plants showed high level of resistance. Interestingly, both low and moderate levels of resistance plants were no symptoms when infected by viruses at low dose. It suggests the dose- dependent effect of the resistance mediated by hpRNA to BYDV-GPV.
Subject(s)
Luteovirus/growth & development , Plant Diseases/genetics , Plants, Genetically Modified/genetics , RNA, Viral/genetics , Triticum/genetics , Immunity, Innate/genetics , Models, Genetic , Nucleic Acid Conformation , Plant Diseases/virology , Plants, Genetically Modified/virology , Polymerase Chain Reaction , RNA, Viral/chemistry , Triticum/virologyABSTRACT
RNA interference (RNAi) is a phenomenon that the double-stranded RNA (dsRNA) intermediates the degradation of complementary mRNA found in many organisms. This is a specifically mechanism involved in kinds of proteins to complete the interference function. Structure of siRNA affects which strand will be assembled into RISC. Another role of siRNA is directing RITS complex to bind with homologue chromosome, and then induces heterochromatinization. Although systemic silence induced by dsRNA is observed in Caenorhabditis elegans and plants, this progress is probably transmembrane protein-dependent, and mostly, the systemic silencing is controlled by multi-factors.
