RESUMO
Gene silencing is a kind of epigenetic phenomenon discovered in transgenic plants in recent years. Gene silencing can be divided into two types: position effect and homology dependent gene silencing (HdGS). Homology-dependent gene silencing (HdGS), which is the generic term for transcriptional gene silencing (TGS), post-transcriptional gene silencing (PTGS) and RNA-mediated virus-resistance (RmVR) have been shown to frequently occur in transgenic plants. Post-transcriptional gene silencing (PTGS) is an antiviral defense system of plants, which has led to a new understanding of the relationship between viruses and plants. And it's a co-evolution result between plants and viruses. A few hypothesis models have been proposed to elucidate the mechanism of gene silencing, but they could not explain all the phenomena in gene silencing. In this paper, we reviewed the relationship between PTGS and the plants defense mechanism to virus, and proposed a model of gene silencing based on our experiments results.
Assuntos
Inativação Gênica , Vírus de Plantas/crescimento & desenvolvimento , Plantas/genética , Processamento Pós-Transcricional do RNA , Vírus de Plantas/genética , Plantas/virologia , RNA Viral/genética , RNA Viral/metabolismoRESUMO
2600 Anthers from T0 modified cry1 Ac-transgenic rice lines of Minghui 81, an elite restoring line of commercial CMS indica hybrid rice, were cultured on SK3 media. 83 green plantlets were recovered, 43 double haploid (DH) and 40 haploid among them. Results of PCR analyzes indicated that 55 plants of 83 were harbored the cry1Ac gene, and the ratio of cry1Ac-positive against cry1Ac-negative was 2:1 (55/28). 36 putative transgenic DH plants were further confirmed by Southern blot. ELISA detection showed that Cry1Ac level in different transgenic rice plants of the same cry1Ac-DH clone was almost equal and the highest one amount to 0.25% of the total soluble protein. Pest insect-resistant bioassay at field trials demonstrated that some of the homozygous cry1Ac-transgenic rice plants not only showed high-level resistance against striped stem borer (Chilo suppressalis) but also retained elite agronomy characters. These results demonstrated that rice anther culture has a great value in rice molecular breeding.
Assuntos
Proteínas de Bactérias/genética , Toxinas Bacterianas , Endotoxinas/genética , Mariposas/crescimento & desenvolvimento , Oryza/genética , Estruturas Vegetais/crescimento & desenvolvimento , Animais , Bacillus thuringiensis/genética , Toxinas de Bacillus thuringiensis , Proteínas de Bactérias/metabolismo , Southern Blotting , Técnicas de Cultura , DNA de Plantas/genética , Endotoxinas/metabolismo , Ensaio de Imunoadsorção Enzimática , Expressão Gênica , Proteínas Hemolisinas , Imunidade Inata/genética , Oryza/crescimento & desenvolvimento , Oryza/parasitologia , Estruturas Vegetais/genética , Estruturas Vegetais/parasitologia , Plantas Geneticamente ModificadasRESUMO
A modified cry1Ac gene was generated by fusing with Lys-Asp-Glu-Lue (KDEL), an endoplasmic reticulum retention signal at the 3'-ends, with signal peptide coding sequence of Soybean kunitz trypsin inhibitor (SKTI) at the 5'-ends. Vector containing the modified cry1Ac gene coding region flanked by the corn ubiquitin 1 promoter and the nopaline synthase gene (nos) terminator with Hygromycin Phosphotransferase (hpt) gene as a plant selection marker was constructed. The modified cry1Ac gene in which toxic protein targeted to endoplasmic retention was successfully transferred into Minghui 81 (Oryza sativa L. subsp. indica), an elite restoring line of commercial CMS indica hybrid rice, through particle bombardment and obtained fertile transformants. Homozygous transgenic rice lines were obtained in the third generation exploiting self-seed set reproduction and HygromycinB selection. These transgenic lines were confirmed with polymerase chain reaction (PCR) amplification, Southern blotting and ELISA detection. Pest insect-resistant bioassay indicated that some of the homozygous cry1Ac-transgenic rice plants of T2 progeny showed high-level resistance against striped stem borer (Chilo suppressalis) at field trials.