Rice Necrosis Mosaic Virus Research Articles

Relationship between Resistance to <i>Rice necrosis mosaic virus</i> and the Expression Levels of Rice <i>RNA-dependent RNA polymerase 6</i> (<i>OsRDR6</i>) in Various Rice Cultivars

Relationship between Resistance to <i>Rice necrosis mosaic virus</i> and the Expression Levels of Rice <i>RNA-dependent RNA polymerase 6</i> (<i>OsRDR6</i>) in Various Rice Cultivars

RNA Isolation from Purified Rice Necrosis Mosaic Virus Particles

Rice, particularly grows in tropical and subtropical areas, is one of the most important crops worldwide. Rice necrosis mosaic virus (RNMV) was first reported in Japan and causes necrotic lesions on leaf and yellowing. This virus has been classified as member of the Potyviridae family's Bymovirus genus. The fungus, Polymixa graminis, transmits RNMV. In this study, the methodology first explained RNMV virus particle - purification by ultra-centrifugation along with sucrose and cesium chloride gradient is described. Further, confirmation of purified RNMV particles under the electron-microscope is discussed. In the last RNMV RNA isolation from the purified RNMV particles were explained.

Analysis of rice RNA-dependent RNA polymerase 6 (OsRDR6) gene in response to viral, bacterial and fungal pathogens

RNA-dependent RNA polymerases (RDRs) play key roles in gene silencing. The rice RDR6 gene was analyzed in response to viral, bacterial and fungal pathogens, after inoculation of a rice mutant line of OsRDR6, shl2-rol, with Cucumber mosaic virus, Rice necrosis mosaic virus, Xanthomonas oryzae pv. oryzae or Magnaporthe oryzae. Compared with the wild type, the mutant line accumulated more viral RNA after inoculation with the viruses and developed more severe symptoms after inoculation with the bacterium or fungus. Thus, the OsRDR6-mediated RNA silencing pathway seems to participate in defense against not only viruses, but also bacterial and fungal pathogens.

Rice necrosis mosaic virus, a fungal transmitted Bymovirus: complete nucleotide sequence of the genomic RNAs and subgrouping of bymoviruses

The complete nucleotide sequence of Rice necrosis mosaic virus (RNMV) RNA1 was determined to be 7178 nt long with one large open reading frame, potentially encoding a polyprotein of 258 kDa with the features of a typical bymovirus. The nucleotide sequence showed 56 % identity with that of Barley mild mosaic virus (BaMMV) and 46 % with those of Oat mosaic virus, Barley yellow mosaic virus and Wheat yellow mosaic virus. RNA2 was 3579 nt long, encoding a 110-kDa polyprotein, and showed 42 and 35/26 % identity with BaMMV and others, respectively. Phylogenetic analysis showed that bymoviruses were classified into two subgroups.

Overexpression of OsHAP2E for a CCAAT-binding factor confers resistance to Cucumber mosaic virus and Rice necrosis mosaic virus

HAP (CBF/NF-Y) transcription factors have important functions in regulating plant growth, development, and stress responses. In this study, we examined whether the endogenous gene OsHAP2E and the GUS transgene driven by the promoter of OsHAP2E respond to virus infection. RT-PCR analyses showed OsHAP2E expression was induced after inoculation with Cucumber mosaic virus (CMV) or Rice necrosis mosaic virus (RNMV). After inoculating OsHAP2E::GUS-transgenic plants with either virus, the levels of GUS expression increased significantly. The expression levels of GUS or OsHAP2E reached a plateau 5 days after inoculation of rice with CMV, which paralleled the accumulation of CMV RNA level. Furthermore, transgenically over-expressed lines of OsHAP2E (OsHAP2E-OX) had lower levels of CMV and RNMV RNAs than in in nontransgenic control plants. The OsHAP2E-OX lines developed no significant symptoms from RNMV while control plants had yellowing and stunting. These results suggested that OsHAP2E is induced by virus infection and contributes to resistance against viral pathogens.

Passage of rice necrosis mosaic virus property induced growth promotion in some plants of commercial importance and its molecular evidence

Rice necrosis mosaic virus (RNMV), upon inoculation, induced higher growth and yield in Ludwigia perennis and Corchorus olitorius. Crops of commercial importance, including arhar, rice bean, cotton and tomato, were tested for growth promotion and higher productivity upon RNMV inoculation. Plant growth characteristics and biochemical components were measured from control, inoculated and energised plants. To understand the molecular basis behind such phenomenon, tomato plants were selected for subtractive hybridisation and reverse northern analysis due to its known gene sequences. Significant changes in biological properties and biochemical components in all the inoculated test plants over control were observed along with better seed quality. Over-expression of genes falling in different functional categories like photosynthesis, plant growth and development, and membrane transport explained the virus-induced growth promotion phenomenon as well as the temporary passage of this property through seeds of inoculated plants.

Cytokinin-like active principle associated with rice necrosis mosaic virus induced growth promotion in jute (Corchorus olitorius L.)

Rice necrosis mosaic virus-inoculated jute plants looked more juvenile with enhanced leaf size than control ones. Such enlarged leaves and those from control ones were collected separately and extracted in chilled methanol. The crude tissue extract in case of inoculated ones showed three times higher activity in bioassay for cytokinin over control. Biological assay with fractions of crude extract separated by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) was ascertained, and one fraction from inoculated sample showing higher activity in terms of growth over respective control was selected. Ultraviolet/visible absorbance spectra of TLC-separated fractions revealed the presence of different quantities of similar kind of compounds in both control and inoculated samples. A major compound with same m/z value of 217.1 was found in both cases as revealed through electrospray ionisation mass spectrophotometry analysis along with some other minor compounds. Different proton–proton coupling and a molecular structure of the highly substituted aliphatic groups were found in the material from inoculated sample having higher cytokinin-like activity than the control one, which was noticed through 1H one-dimensional nuclear magnetic resonance analysis.

Significant plant virus diseases in India and a glimpse of modern disease management technology

India has a diverse agroclimate representing tropical, subtropical and temperate climates with zones ranging from average to high in temperature, humidity and rainfall; from low to scarce rainfall in deserts to cold to very cold plains and upland areas. Thus it is the home of one of the richest flora and fauna in the world. For pests and pathogens, too, tropical and subtropical climates are ideal for growth and development. A majority of the world’s fruits, vegetables, cereals, pulses, oil seed crops, fiber crops, sugarcane, spices, and ornamentals are cultivated in India. Virus diseases and their vectors are also in abundance. Since ancient times, virus-like diseases and management practices have been known in India. This knowledge has now been revived and adopted in organic farming, especially for medicinal and aromatic plants. Current trends for extensive and intensive agriculture, open international agricultural trade, and thus food security and sustained economy have brought new challenges in the fight against virus diseases. In this changing scenario, current diseases of significance are caused by begomoviruses, badnaviruses, cucomoviruses, potyviruses, ilarviruses in crops such as vegetables, fruits, ornamentals, fiber crops, and sugarcane. Variability in the viruses is also common. Briefly reviewed here is the positive effect of an isolate of Rice necrosis mosaic virus; when artificially inoculated on jute and mesta fiber crops enhanced their fiber contents. Diseases of significance, e.g., leaf fleck disease of sugarcane, citrus yellow mosaic disease, banana bunchy top, banana bract mosaic, mungbean yellow mosaic, mosaic in chrysanthemum, gladiolus and orchids are also discussed. Efficient, reliable diagnostic tools have been developed and used extensively. Some of the advanced laboratories have been accredited for virus indexing under the National Certification System for tissue-cultured plants. International standards for phytosanitary measures have been promulgated, and a mandatory nodal agency is in place for the conservation and exchange of germplasm; a Containment Level-4 facility to examine incoming transgenics and a fully equipped laboratory to intercept virus-infected plant material are functional. A National Agricultural Biosecurity System will soon be in place. All these measures are essential to protect agricultural systems and to compete in the international agriculture market. Continued vigilance, disease mapping and adopting the latest technology are required to practice sustainable agriculture.

A bymovirus PCR primer and partial nucleotide sequence provides further evidence for the recognition of rice necrosis mosaic virus as a bymovirus

Rice necrosis mosaic virus (RNMV) has physico-chemical and biological properties typical of the Bymovirus genus. However, to date no sequence data has been reported for RNMV. In this paper we report the use of a PCR primer, designed from an area of high homology between bymoviruses and related macluraviruses within the NIb gene, which generated a 1.4kb fragment from the 3' terminal region of RNA 1 of RNMV. The sequence data generated from this region confirmed the classification of RNMV as a member of the Bymovirus genus.

Growth promotion in plants by rice necrosis mosaic virus

Ludwigia perennis L. infected with rice necrosis mosaic virus (RNMV) showed an increase in both shoot growth and leaf size, along with characteristic chlorotic lesions on leaves. The promotion of growth over the controls extended over a considerable period of time (70 d). Inoculation with RNMV resulted in increased plant height, leaf size, stem diameter, and number and size of fiber bundles in Corchorus olitorius L., C. capsularis L., Hibiscus sabdariffa L. and H. cannabinus L.

Comparative electron microscopy of inclusions associated with five soil-borne filamentous viruses of cereals.

Leaf samples were collected from wheat, barley, oat and rice plants infected with wheat yellow mosaic virus (WYMV) or wheat spindle streak mosaic virus (WSSMV), barley yellow mosaic virus (BYMV), oat mosaic virus (OMV) and rice necrosis mosaic virus (RNMV), respectively, and leaf cells were examined under an electron microscope. Complex membranous bodies, and pinwheel or cylindrical inclusions were developed in the cytoplasm of leaf cells infected with each of these viruses except OMV. OMV produced pinwheel inclusions, but no membranous bodies. Pinwheel inclusions in host cells infected with each of other four viruses than OMV were composed of single-layered plates 11-13nm in thickness. Plates in the OMV infected cells showed 3 layers 9-11nm in thickness. These facts indicate a close relationship among WYMV, WSSMV, BYMV and RNMV. OMV may be rather distantly related to them.

Weed Hosts of Rice Necrosis Mosaic Virus

Weed Hosts of Rice Necrosis Mosaic Virus

Rice necrosis mosaic

Rice necrosis mosaic virus was observed in rice cultivarTaichung (Native) 1 at maximum tillering stage. The disease was transmitted by sap and soil.Nephotettix virescens, Nephotettix nigropictus andNilaparvata lugens failed to transmit the disease. Thermal inactivation point, dilution end point and ageingin vitro have been studied. Yield reduction due to this virus varied from 12·7 to 100% on different rice cultivars tested. Disease was more common in upland and directly seeded crop. The virus produced granular x-bodies in inner epidermis of leaf sheath of infected plants.

Some experiments on the vector of rice necrosis mosaic virus

Some experiments on the vector of rice necrosis mosaic virus

Occurrence of rice necrosis mosaic virus disease in Tochigi Prefecture

Occurrence of rice necrosis mosaic virus disease in Tochigi Prefecture

Occurrence of rice necrosis mosaic virus in Shizuoka Prefecture

Occurrence of rice necrosis mosaic virus in Shizuoka Prefecture