Plant pathogens and other biological pests represent significant obstacles to crop Protection worldwide. Even though there are many effective conventional methods for controlling plant diseases, new methods that are also effective, environmentally safe, and cost-effective are required. While plant breeding has traditionally been used to manipulate the plant genome to develop resistant cultivars for controlling plant diseases, the emergence of genetic engineering has introduced a completely new approach to render plants resistant to bacteria, nematodes, fungi, and viruses. The RNA interference (RNAi) approach has recently emerged as a potentially useful tool for mitigating the inherent risks associated with the development of conventional transgenics. These risks include the use of specific transgenes, gene control sequences, or marker genes. Utilizing RNAi to silence certain genes is a promising solution to this dilemma as disease-resistant transgenic plants can be generated within a legislative structure. Recent investigations have shown that using target double stranded RNAs via an effective vector system can produce significant silencing effects. Both dsRNA-containing crop sprays and transgenic plants carrying RNAi vectors have proven effective in controlling plant diseases that threaten commercially significant crop species. This article discusses the methods and applications of the most recent RNAi technology for reducing plant diseases to ensure sustainable agricultural yields.
Nodamura virus (NoV) B2, a suppressor of RNA interference, binds double stranded RNAs (dsRNAs) and small interfering RNAs (siRNAs) corresponding to Dicer substrates and products. Here, we report that the amino terminal domain of NoV B2 (NoV B2 79) specifically binds siRNAs but not dsRNAs. NoV B2 79 oligomerizes on binding to 27 nucleotide siRNA. Mutation of the residues phenylalanine49 and alanine60 to cysteine and methionine, respectively enhances the RNA binding affinity of NoV B2 79. Circular dichroism spectra demonstrated that the wild type and mutant NoV B2 79 have similar secondary structure conformations.
Natural antisense transcripts (NATs) are involved in cellular development and regulatory processes. Multiple NATs at the Sox4 gene locus are spatiotemporally regulated throughout murine cerebral corticogenesis. In the study, we evaluated the potential functional role of Sox4 NATs at Sox4 gene locus. We demonstrated Sox4 sense and NATs formed dsRNA aggregates in the cytoplasm of brain cells. Over expression of Sox4 NATs in NIH/3T3 cells generally did not alter the level of Sox4 mRNA expression or protein translation. Upregulation of a Sox4 NAT known as Sox4ot1 led to the production of a novel small RNA, Sox4_sir3. Its biogenesis is Dicer1-dependent and has characteristics resemble piRNA. Expression of Sox4_sir3 was observed in the marginal and germinative zones of the developing and postnatal brains suggesting a potential role in regulating neurogenesis. We proposed that Sox4 sense-NATs serve as Dicer1-dependent templates to produce a novel endo-siRNA- or piRNA-like Sox4_sir3.
The R2R3-MYB genes regulate pigmentation and morphogenesis of flowers, including flower and cell shape, and therefore have importance in the development of new varieties of orchids. However, new variety development is limited by the long breeding time required in orchids. In this study, we identified a cDNA, DhMYB1, that is expressed during flower development in a hybrid orchid, Dendrobium hybrida (Dendrobium bobby messina X Dendrobium chao phraya) then used the direct application of dsRNA to observe the effect of gene silencing on flower phenotype and floral epidermal cell shape.
Stool specimens from 334 infants and young children hospitalized with diarrhea in the General Hospital, Kuala Lumpur, Malaysia between August and November, 1987 were analyzed for the presence of rotavirus double-stranded (ds) RNA by polyacrylamide gel electrophoresis. Of the 334 specimens analyzed, 32 (9.6%) were positive for rotavirus RNA. One specimen (designated G147) exhibited a ds RNA electropherotype profile characteristic of Group C rotavirus and was selected for further characterization. In Northern blot hybridization studies, the gene 5 segment of strain G147 hybridized with a cDNA probe generated from the cloned gene 5 (which encodes the VP6 inner capsid protein that is group specific) of porcine Group C rotavirus strain Cowden, confirming the classification of strain G147 in Group C. The association of Group C rotavirus with diarrheal illness in Malaysia is consistent with earlier studies that suggest a global distribution of this virus and supports the need for additional epidemiologic studies.