Background Posttranscriptional gene silencing (PTGS) is one of the most important mechanisms for plants during viral infection. However, viruses have also developed viral suppressors to negatively control PTGS by inhibiting microRNA (miRNA) and short-interfering RNA (siRNA) regulation in plants. The first identified viral suppressor, P1/HC-Pro, is a fusion protein that was translated from potyviral RNA. Upon infecting plants, the P1 protein itself is released from HC-Pro by the self-cleaving activity of P1. P1 has an unknown function in enhancing HC-Pro-mediated PTGS suppression. We performed proteomics to identify P1-interacting proteins. We also performed transcriptomics that were generated from Col-0 and various P1/HC-Pro-related transgenic plants to identify novel genes. The results showed several novel genes were identified through the comparative network analysis that might be involved in P1/HC-Pro-mediated PTGS suppression. Results First, we demonstrated that P1 enhances HC-Pro function and that the mechanism might work through P1 binding to VERNALIZATION INDEPENDENCE 3/SUPERKILLER 8 (VIP3/SKI8), a subunit of the exosome, to interfere with the 5 ′ -fragment of the PTGS-cleaved RNA degradation product. Second, the AGO1 was specifically posttranslationally degraded in transgenic Arabidopsis expressing P1/HC - Pro of turnip mosaic virus (TuMV) ( P1/HC Tu plant). Third, the comparative network highlighted potentially critical genes in PTGS, including miRNA targets, calcium signaling, hormone (JA, ET, and ABA) signaling, and defense response. Conclusion Through these genetic and omics approaches, we revealed an overall perspective to identify many critical genes involved in PTGS. These new findings significantly impact in our understanding of P1/HC-Pro-mediated PTGS suppression.

Shallot (Allium cepa L. Aggregatum group) is usually cultivated vegetatively. As a result, viruses tend to accumulate within the host plants and spread to healthy plants every crop cycle, reducing yield and bulb quality. There are a very limited number of studies about the elimination of shallot viruses through heat treatment. The objective of this research was to eliminate shallot viruses through heat treatment to produce virus-free plantlets.The leaves of Biru Lancor with specific visual virus symptoms were detected by Reverse TranscriptionPolymerase Chain Reaction (RT-PCR). Then bulbs of Biru Lancor that were positively infected by viruses were used as materials for heat treatment. The treatments were a control (without treatment), electric treatment at 15 mA for 10 minutes, heat treatment in an incubator at 37°C for 4 weeks, heat treatment in a waterbath at 45°C for 60 minutes, and combination of heat treatment in an incubator at 37°C for 4 weeks and heat treatment in a waterbath at 45°C for 60 minutes. After being subjected to heat treatment, the pseudo stem were cultivated in the MS Medium + 1 mg/L BAP + 1 mg/L IBA.Virus detection by RT-PCR was conducted 28 days after planting using samples of leaves from each plantlet.The results of this research showed that the treatments of electric treatment at 15 mA for 10 minutes and combination of heat treatment in the incubator at 37°C for 4 weeks and heat treatment in the waterbath at 45°C for 60 minutes could suppress the incidence of Shallot latent virus (SLV) until 100%. Heat treatment might have an important role in the degradation of virus particles by boosting Virus-Induced Gene Silencing (VIGS) as plant responses to virus infection.

No abstract

Background: Posttranscriptional gene silencing (PTGS) is one of the most important mechanisms for plants during viral infection. However, viruses have also developed viral suppressors to negatively control PTGS by inhibiting microRNA (miRNA) and short-interfering RNA (siRNA) regulation in plants. The first identified viral suppressor, P1/HC-Pro, is a fusion protein. Upon infecting plants, the P1 protein itself is released from HC-Pro by the self-cleaving activity of P1. P1 has an unknown function in enhancing HC-Pro-mediated PTGS suppression. We performed proteomics to identify P1-interacting proteins. We also performed transcriptomics that were generated from Col-0 and various P1/HC-Pro-related transgenic plants to identify novel genes. The results showed several novel genes were identified through the comparative network analysis that might be involved in P1/HC-Pro-mediated PTGS suppression. Results: First, we demonstrated that P1 enhances HC-Pro function and that the mechanism might work through P1 binding to VERNALIZATION INDEPENDENCE 3/SUPERKILLER 8 (VIP3/SKI8), a subunit of the exosome, to interfere with the 5'-fragment of the PTGS-cleaved RNA degradation product. Second, specifically the AGO1 was specifically posttranslationally degraded in transgenic Arabidopsis expressing P1/HC-Pro of turnip mosaic virus (TuMV) (P1/HCTu plant). Third, the comparative network highlighted potentially critical genes in PTGS, including miRNA targets, calcium signaling, hormone (JA, ET, and ABA) signaling, and defense response. Conclusion: Through these genetic and omics approaches, we revealed an overall perspective to identify many critical genes involved in PTGS. These new findings significantly impact in our understanding of P1/HC-Pro-mediated PTGS suppression.

No abstract