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

Soybean mosaic virus (SMV), one of the major viral diseases of Pinellia ternata (Thunb.) Breit., has had a serious impact on its yield and quality. The construction of viral infectious clones is a powerful tool for reverse genetics research on viral gene function and interaction between virus and host. To clarify the molecular mechanism of SMV infection in Pinellia ternata, it is particularly important to construct the SMV full-length cDNA infectious clone. Therefore, the infectious clone of Soybean mosaic virus Shanxi Pinellia ternata isolate (SMV-SXBX) was constructed in this study by Gibson in vitro recombination system, and the healthy Pinellia ternata leaves were inoculated by Agrobacterium infiltration, further through mechanical passage and RT-PCR, confirming that the 3' end of the SMV-SXBX infectious clone had a stable infectivity when it contained 56-nt of poly(A) tail. This method is not only convenient and efficient, but also avoids the instability of SMV infectious clones in Escherichia coli. The construction of SMV full-length infectious cDNA clones laid the foundation for further study on the molecular mechanism of SMV replication and pathogenesis.
DNA, Complementary ; Pinellia ; virology ; Plant Diseases ; virology ; Potyvirus ; isolation & purification ; metabolism

Six diseases have been found after disease surveys on Notopterygium incisum in Gansu province during 2004 to 2007. They were brown spot (Ascochyta levistici), powdery mildew (Erysiphe heraclei), grey spot (Alternaria sp. ; Alternaria burnsii), leaf spot (Septoria dearnessii), angular leaf spot (Pleospora sp.), leaf streak (Phoma sp.), bacterial angular leaf spot and a virus disease. Bacterial angular leaf spot and powdery mildew are the urgent problems waiting to be solved effectively. All these diseases were reported for the first time in China.
Apiaceae ; microbiology ; virology ; Ascomycota ; isolation & purification ; pathogenicity ; Bacteria ; isolation & purification ; pathogenicity ; China ; Plant Diseases ; microbiology ; virology ; Viruses ; isolation & purification ; pathogenicity

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

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

Studies have shown that transgenic plants expressing antiapoptotic genes from baculovirus and animals increase resistance to biotic and abiotic stress. However, the mechanism under these resistances is conjectural, or in some cases even controversy. In the present study, the p35 gene from baculovirus Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) was expressed in tobacco, and for the first time P35 protein was detected in transgenic plants by Western blotting. Inoculation of T1 transgenic tobacco leaves with tobacco mosaic virus (TMV) showed enhanced resistance, and DNA laddering was observed after TMV infection in control but not in transgenic plants. DAB staining showed that TMV infection did not affect peroxide induction of transgenic plants, Western blotting analysis of PR1 protein also showed no difference of control and transgenic plants. Inoculation of fungus (Sclerotinia sclerotiorum) using a detached leaf assay showed enhanced resistance of transgenic leave tissue. RT-PCR analysis demonstrated that p35 gene expression induced earlier expression of PR1 gene after S. sclerotiorum infection. Taken together, our results suggest that the mechanism under enhanced disease resistance by P35 protein is possibly related to the activation of PR-related proteins in addition to the inhibition of programmed cell death, depending on the pathogens challenged.
Gene Expression Regulation, Plant ; Immunity, Innate ; Plant Diseases ; genetics ; Plants, Genetically Modified ; genetics ; immunology ; virology ; Tobacco ; genetics ; immunology ; virology ; Tobacco Mosaic Virus ; Transformation, Genetic ; Viral Proteins ; genetics ; metabolism

Fluorescence ; Host-Pathogen Interactions ; Luminescent Measurements ; methods ; Luminescent Proteins ; chemistry ; genetics ; metabolism ; Plant Diseases ; virology ; Plant Viruses ; chemistry ; genetics ; metabolism ; Plants ; chemistry ; genetics ; metabolism ; virology

We report the recovery of a 7068-nt viral sequence from the "viral fossils" embedded in the genome of Alhagi sparsifolia, a typical desert plant. Although the full viral genome remains to be completed, the putative genome structure, the deduced amino acids and phylogenetic analysis unambiguously demonstrate that this viral sequence represents a novel species of the genus Badnavirus. The putative virus is tentatively termed Alhagi bacilliform virus (ABV). Southern blotting and inverse polymerase chain reaction (PCR) data indicate that the ABV-related sequence is integrated into the A. sparsifolia genome, and probably does not give rise to functional episomal virus. Molecular evidence that the ABV sequence exists widely in A. sparsifolia is also presented. To our knowledge, this is the first endogenous badnavirus identified from plants in the Gobi desert, and may provide new clues on the evolution, geographical distribution as well as the host range of the badnaviruses.
Badnavirus/genetics* ; Biological Evolution ; Desert Climate ; Fabaceae/virology* ; Genes, Plant ; Genetic Variation ; Genome, Viral ; Geography ; Open Reading Frames ; Phylogeny ; Plant Diseases/virology* ; Plasmids ; Sequence Analysis, RNA

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

NS2 and NS3 are two post-transcriptional gene silencing suppressors that are encoded by Rice stripe virus. Gene silencing suppressors are always related to the pathogenicity of viruses. In this study, the cDNA of NS2 and NS3 were recombined by overlapping PCR assays, ligated to the RNAi vector, and inserted into the PXQ expression vector using Pst I; the expressed vector was transferred into calluses induced from seeds of the japonica rice cultivar, 'Nipponbare', using an Agrobacterium-mediated method. Thirty-one T0 transgenic plants were selected by G418 screening. PCR and southern blot analyses confirmed that the target gene was transformed into transgenic rice successfully, and different transgenic plants contained various copies of the gene. The disease resistance assay revealed that T0 transgenic rice had a delayed onset of RSV for approximately 10-20 d, and the accumulation of virus in the transgenic plants was reduced by 30%-50%. This was related to the delayed onset of disease.
Disease Resistance ; Oryza ; genetics ; immunology ; virology ; Plant Diseases ; genetics ; immunology ; virology ; Plants, Genetically Modified ; genetics ; immunology ; virology ; RNA Interference ; Tenuivirus ; genetics ; immunology ; Viral Nonstructural Proteins ; genetics ; immunology