OBJECTIVETo study viruses infecting Pinellia ternata in China.

METHODSymptom observation, DAS-ELISA and RT-PCR detection were applied.

RESULT AND CONCLUSIONDuring a survey in early spring, SMV and CMV were both commonly distributed as main viruses infecting P. ternata collected from different areas in China. But DsMV was the virus which infected P. ternate in natural condition. The infection ratio of cultivated P. ternate by SMV and CMV were 71.4% and 14.3% respectively for 21 samples collected from Ningbo, Zhejiang province; 100% and 44.4% for 18 samples from Xiaoshan, Zhejiang province; 61.9% and 33.3% for 21 samples from Hebei province; 50.0% and 41.7% for 12 samples from Anhui province; 16.7% and 16.7% for 12 samples from Sichuan province; 31.3% and none for 16 samples from Beijing. And the infection ratio of 25 wild samples from different areas of China infected by SMV and CMV were both 20.0%.

China ; Cluster Analysis ; Cucumovirus ; genetics ; isolation & purification ; DNA, Complementary ; chemistry ; genetics ; Mosaic Viruses ; classification ; genetics ; isolation & purification ; Pinellia ; virology ; Plant Diseases ; virology ; Plants, Medicinal ; virology ; Sequence Analysis, DNA

The MDMV (Maize Dwarf Mosaic Virus, MDMV) CP (Coat Protein, CP) gene was cloned by RT-PCR method and introduced into the embryonic calli derived from immature embryos of elite inbred 18-599hong and 18-599bai via particle bombardment. Bombarded calli were selected on selection medium containing 5-10 mg/L (PPT) Bialaphos. From resistant calli, 79 plantlets were regenerated. 18 of 79 were grown and harvested. The results of Southern blotting and PCR analysis demonstrated that MDMV CP have been integrated into the genome of the transgenic plants. PCR-positive progeny plants were artificially inoculated with MDMV strain B, and the average chlorosis of the functional leaves of each plant was investigated. The typical symptoms were observed from the leaves of the control inbreds. while, the presence of the MDMV CP gene provided resistance to inoculation with MDMV strain B.
Capsid Proteins ; genetics ; Cloning, Molecular ; Mosaic Viruses ; genetics ; Plant Diseases ; genetics ; virology ; Plants, Genetically Modified ; Transfection ; Zea mays ; genetics ; virology

Turnip yellow mosaic virus (TYMV) is a spherical plant virus that has a single 6.3 kb positive strand RNA genome. Information for TYMV replication is limited, except that the 3'-terminal sequence and 5'-untranslated region are required for genome replication. When a foreign sequence was inserted at the position upstream of the coat protein (CP) open reading frame (ORF), replication of the recombinant TYMV was comparable to wild type, as long as an RNAi suppressor was provided. In contrast, when the foreign sequence was inserted between the CP ORF and the 3'-terminal tRNA-like structure, replication of the recombinant virus was not detected. This result suggests that the CP ORF contains an essential replication element which should be appropriately spaced with respect to the 3'-end. Analysis of TYMV constructs containing a part or a full additional CP ORF indicates that the 3' quarter of the CP ORF is required for TYMV replication.
Animals ; Brassica napus ; Ecthyma, Contagious ; Genome ; Open Reading Frames ; Plant Viruses ; RNA ; Tymovirus ; Viruses

SMV is one of main diseases of soybean, which could affect yields and quality of soybean seriously. It was effective to soybean breeding by studying the expression of resistant gene to SMV with molecular technology. In this study, a soybean resistance line, DongNong 8143, was used to construct a subtractive cDNA library by SSH from soybean leaves inoculated by SMV No.1 at primary stage. cDNA dominantly or specifically expressed in infected leaves was purified using PCR Purification Kit and cloned into pGEM-T easy vector. Colonies were grown on LB-agar plates containing ampicillin, X-gal and IPTG. A subtractive plasmid library was constructed by SSH. Then the library was transformed to host bacteria E. coli DH5alpha, and the titer of the library was measured as 2 x 10(3) . 64 clones were picked up randomly and sequenced. Of them there is 50 clones which result of sequenced were good. The length of EST fragment varied from 136bp to 691bp, and the average length is 456bp. Among them, 41 sequences has poly(A). Through ESTs were compared with sequences in unigene database of GeneBank with BLASTn and BLASTx algorithm, 38 ESTs of them had comparatively clear results and the percent of them in acquired ESTs is 74%. The EST expression profile showed that the resistance-related genes include cell protection, signal transduction, restrict pathogen growth, system acquired resistance, and house-keeping gene. There are 12 ESTs, which have not comparatively clear results, that maybe new genes.
Expressed Sequence Tags ; Gene Library ; Mosaic Viruses ; Nucleic Acid Hybridization ; methods ; Plant Diseases ; genetics ; virology ; Polymerase Chain Reaction ; Soybeans ; genetics ; virology

Turnip yellow mosaic virus (TYMV) is a spherical plant virus that has a single 6.3 kb positive strand RNA as a genome. Previously, we have made the recombinant TYMV construct containing a 0.7 kb eGFP gene or a 1.8 kb GUS gene. The genomic RNAs from these constructs were efficiently encapsidated. To examine in more detail whether size constraint exists for replication and packaging of TYMV, we have inserted into the TY-GUS an extra sequence derived from either eGFP or GUS. We also made a recombinant containing RNA1 sequence of Flock house virus. These TYMV recombinants were introduced into Nicotiana benthamiana leaves by agroinfiltration. Northern blot analysis of the viral RNAs in the agroinfiltrated leaves showed that the genomic RNA band from the recombinant TYMV became weaker as longer sequence was inserted. The result also showed that the efficiency of genomic RNA encapsidation decreased sharply when an extra sequence of 2.2 kb or more was inserted. In contrast, the recombinant subgenomic RNA containing an extra sequence of up to 3.2 kb was efficiently encapsidated. Overall, these results show that size constraint exists for replication and encapsidation of TYMV RNA.
Blotting, Northern ; Genome ; Genome Size* ; Plant Viruses ; Product Packaging* ; RNA ; RNA, Viral ; Tobacco ; Tymovirus*

OBJECTIVETo test the effects of 7 virus-encoded RNA silencing suppressors (RSSs) for enhancement of a plant virus-based vector system-mediated heterologous expression of green fluorescence protein (GFP) in Nicotiana benthamiana.

METHODSSeven transient expression vectors for the 7 RSSs were constructed and co-inoculated on the leaves of Nicotiana benthamiana with PVXdt-GFP vector, a novel Potato virus X-based plant expression vector, through agroinfiltration. The protein and mRNA expression levels of the reporter gene GFP in the co-inoculated Nicotiana leaves were examined by Western blotting, ELISA and RT-qPCR to assess the effect of the RSSs for GFP expression enhancement.

RESULTSThe 7 RSSs differed in the degree and duration of enhancement of heterologous GFP expression, and the p19 protein of Tomato bushy stunt virus (TBSV) induced the highest expression of GFP. African cassava mosaic virus AC2 protein and Rice yellow mettle virus P1 protein produced no obvious enhancement GFP expression.

CONCLUSIONTransient co-expression of RSSs suppresses host silencing response to allow high-level and long-term expression of heterologous genes in plant, but the optimal RSS has to be identified for each plant virus-based expression vector system.

Genetic Vectors ; Green Fluorescent Proteins ; genetics ; Plant Viruses ; genetics ; Plants, Genetically Modified ; genetics ; metabolism ; Potexvirus ; genetics ; RNA Interference ; Tobacco ; genetics ; metabolism

Color is an important indicator for evaluating the ornamental traits of horticultural plants, and plant pigments is a key factor affecting the color phenotype of plants. Plant pigments and their metabolites play important roles in color formation of ornamental organs, regulation of plant growth and development, and response to adversity stress. It has therefore became a hot topic in the field of plant research. Virus-induced gene silencing (VIGS) is a vital genomics tool that specifically reduces host endogenous gene expression utilizing plant homology-dependent defense mechanisms. In addition, VIGS enables characterization of gene function by rapidly inducing the gene-silencing phenotypes in plants. It provides an efficient and feasible alternative for verifying gene function in plant species lacking genetic transformation systems. This paper reviews the current status of the application of VIGS technology in the biosynthesis, degradation and regulatory mechanisms of plant pigments. Moreover, this review discusses the potential and future prospects of VIGS technology in exploring the regulatory mechanisms of plant pigments, with the aim to further our understandings of the metabolic processes and regulatory mechanisms of different plant pigments as well as improving plant color traits.
Plant Viruses/genetics* ; Plants/genetics* ; Gene Silencing ; Plant Development ; Gene Expression Regulation, Plant ; Genetic Vectors

Plant Dicer-like (DCL) and Argonaute (AGO) are the key enzymes involved in anti-virus post-transcriptional gene silencing (AV-PTGS). Here we show that AV-PTGS exhibited nucleotide preference by calculating a relative AV-PTGS efficiency on processing viral RNA substrates. In comparison with genome sequences of dicot-infecting Turnip mosaic virus (TuMV) and monocot-infecting Cocksfoot streak virus (CSV), viral-derived small interfering RNAs (vsiRNAs) displayed positive correlations between AV-PTGS efficiency and G+C content (GC%). Further investigations on nucleotide contents revealed that the vsiRNA populations had G-biases. This finding was further supported by our analyses of previously reported vsiRNA populations in diverse plant-virus associations, and AGO associated Arabidopsis endogenous siRNA populations, indicating that plant AGOs operated with G-preference. We further propose a hypothesis that AV-PTGS imposes selection pressure(s) on the evolution of plant viruses. This hypothesis was supported when potyvirus genomes were analysed for evidence of GC elimination, suggesting that plant virus evolution to have low GC% genomes would have a unique function, which is to reduce the host AV-PTGS attack during infections.
Arabidopsis ; enzymology ; genetics ; virology ; Base Composition ; Dactylis ; enzymology ; genetics ; virology ; Genes, Plant ; Genes, Viral ; Models, Genetic ; Mustard Plant ; enzymology ; genetics ; virology ; Plant Diseases ; genetics ; virology ; Plant Proteins ; metabolism ; Plant Viruses ; genetics ; pathogenicity ; Plants ; enzymology ; genetics ; virology ; Potyvirus ; genetics ; pathogenicity ; RNA Interference ; RNA, Plant ; genetics ; RNA, Small Interfering ; chemistry ; genetics ; metabolism ; RNA, Viral ; chemistry ; genetics ; metabolism ; RNA-Induced Silencing Complex ; metabolism ; Ribonuclease III ; metabolism ; Selection, Genetic ; Substrate Specificity

The aim was to establish an effective screening microarray at genus level for Pospiviroid. We analyzed nucleotide sequences from Pospiviroid viroid and designed 19 probes with genus identification characteristics. The standards of these probes included the characters of (i) a GC content between 40 and 60%, (ii) less than 50% of single nucleotide, (iii) less than 4 continuous mononucleotides, and (iv) less than 6 nucleotides in the inner hairpin. We synthesized microarrays by using these probes on glass slides. The validation results of microarray probes show effective signals from chrysanthemum stunt viroid and tomato planta macho viroid standard samples hybridization. The sensitivity results show that the microarray detected 200 pg/microL of total RNA. The microarray can be used to screen Pospiviroid viroid.
Base Composition ; Base Sequence ; Microarray Analysis ; Nucleic Acid Hybridization ; Plant Diseases ; virology ; Plant Viruses ; classification ; RNA ; Viroids ; classification

Plant virus is one of the most economical devastating microorganisms for global agriculture. Although several strategies are useful for controlling viral infection, such as resistant breeds cultivation, chemical bactericides treatment, blocking the infection source, tissue detoxification and field sanitation, viral disease is still a problem in agricultural production. Genetic engineering approach offers various options for introducing virus resistance into crop plants. This paper reviews the current strategies of developing virus resistant transgenic plants.
Agriculture ; Crops, Agricultural ; genetics ; virology ; Genetic Engineering ; Plant Diseases ; prevention & control ; virology ; Plant Viruses ; Plants, Genetically Modified ; virology