scholarly journals Satellite Panicum Mosaic Virus Capsid Protein Elicits Symptoms on a Nonhost Plant and Interferes with a Suppressor of Virus-Induced Gene Silencing

2004 ◽  
Vol 17 (3) ◽  
pp. 263-271 ◽  
Author(s):  
Wenping Qiu ◽  
Karen-Beth G. Scholthof

The capsid protein (CP) of satellite panicum mosaic virus (SPMV) has been implicated as a pathogenicity factor, inducing severe chlorosis on millet plants co-infected with SPMV and its helper virus, Panicum mosaic virus (PMV). In this study, we tested the effects of SPMV CP on Nicotiana benthamiana, a plant that does not support PMV+SPMV infections. SPMV CP expressed from a Potato virus X (PVX) gene vector elicited necrotic lesions on N. benthamiana. Pathogenicity factors often have the additional feature of acting as suppressors of gene silencing; therefore, several assays were developed to test if SPMV CP could act in such a capacity. The results showed that SPMV CP failed to act as a suppressor of posttranscriptional gene silencing when such tests were performed with transgenic N. benthamiana plants silenced for green fluorescent protein (GFP) expression by agroinfiltration or plant virus vectors. However SPMV CP expressed from the PVX gene vector did interfere with suppressor activity associated with PVX p25. This included a rebounded level of GFP silencing along the vascular tissues, including the veins on upper noninoculated leaves. Therefore, the roles of the SPMV CP now include encapsidation of the SPMV RNA, activity as a pathogenicity factor in both host and nonhost plants, and the enigmatic feature of interfering with suppression of gene silencing.

2008 ◽  
Vol 21 (12) ◽  
pp. 1539-1548 ◽  
Author(s):  
Phillip A. Harries ◽  
Karuppaiah Palanichelvam ◽  
Sumana Bhat ◽  
Richard S. Nelson

The Tobacco mosaic virus (TMV) 126-kDa protein is a suppressor of RNA silencing previously shown to delay the silencing of transgenes in Nicotiana tabacum and N. benthamiana. Here, we demonstrate that expression of a 126-kDa protein–green fluorescent protein (GFP) fusion (126-GFP) in N. tabacum increases susceptibility to a broad assortment of viruses, including Alfalfa mosaic virus, Brome mosaic virus, Tobacco rattle virus (TRV), and Potato virus X. Given its ability to enhance TRV infection in tobacco, we tested the effect of 126-GFP expression on TRV-mediated virus-induced gene silencing (VIGS) and demonstrate that this protein can enhance silencing phenotypes. To explain these results, we examined the poorly understood effect of suppressor dosage on the VIGS response and demonstrated that enhanced VIGS corresponds to the presence of low levels of suppressor protein. A mutant version of the 126-kDa protein, inhibited in its ability to suppress silencing, had a minimal effect on VIGS, suggesting that the suppressor activity of the 126-kDa protein is indeed responsible for the observed dosage effects. These findings illustrate the sensitivity of host plants to relatively small changes in suppressor dosage and have implications for those interested in enhancing silencing phenotypes in tobacco and other species through VIGS.


2002 ◽  
Vol 15 (3) ◽  
pp. 269-280 ◽  
Author(s):  
Wenping Qiu ◽  
Jong-Won Park ◽  
Herman B. Scholthof

The p19 protein (P19) of Tomato bushy stunt virus (TBSV) is a pathogenicity determinant with host-dependent effects on virus spread and symptom induction. In addition, results in this study confirm that Potato virus X-mediated delivery of P19 suppresses posttranscriptional gene silencing (PTGS). To study the relevance of this activity for TBSV biology, we evaluated whether TBSV activates virus-induced gene silencing (VIGS) and if this process is suppressed by P19. TBSV vectors with the green fluorescent protein (GFP) gene, either active or inactive for P19 expression, were inoculated onto GFP-transgenic Nicotiana bentha-miana plants. In the absence of P19 expression, VIGS was activated, as evidenced by the disappearance of GFP mRNA and green fluorescence. Coexpression of GFP and P19 from the TBSV vector suppressed VIGS, except in the newly emerging leaves. The suppressor activity required a central P19 region that is also known to be essential for host-dependent virus spread and symptom induction. Defective interfering RNAs (DIs) that contained the 3′ end of the GFP gene induced silencing very effectively. The concomitant DI-instigated reduction in P19 accumulation failed to suppress this process, analogous to the known P19 dosage effects for other biological activities. In conclusion, (i) TBSV and its DIs are very effective inducers of VIGS, (ii) P19 is a strong suppressor of PTGS, (iii) P19 is a moderate suppressor of VIGS, and (iv) the suppressor activity is influenced by genetic and dosage features that are also important for P19-associated pathogenesis.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yuh Tzean ◽  
Ming-Chi Lee ◽  
Hsiao-Hsuan Jan ◽  
Yi-Shu Chiu ◽  
Tsui-Chin Tu ◽  
...  

Plant Methods ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Decai Tuo ◽  
Peng Zhou ◽  
Pu Yan ◽  
Hongguang Cui ◽  
Yang Liu ◽  
...  

Abstract Background Cassava is an important crop for food security and industry in the least-developed and developing countries. The completion of the cassava genome sequence and identification of large numbers of candidate genes by next-generation sequencing provide extensive resources for cassava molecular breeding and increase the need for rapid and efficient gene function analysis systems in cassava. Several plant virus-induced gene silencing (VIGS) systems have been developed as reverse genetic tools for rapid gene function analysis in cassava. However, these VIGS vectors could cause severe viral symptoms or inefficient gene silencing. Results In this study, we constructed agroinfection-compatible infectious cDNA clones of cassava common mosaic virus isolate CM (CsCMV-CM, genus Potexvirus, family Alphaflexiviridae) that causes systemic infection with mild symptoms in cassava. CsCMV-CM was then modified to a viral vector carrying the Nimble cloning frame, which facilitates the rapid and high-throughput cloning of silencing fragments into the viral genome. The CsCMV-based vector successfully silenced phytoene desaturase (PDS) and magnesium chelatase subunit I (ChlI) in different cassava varieties and Nicotiana benthamiana. The silencing of the ChlI gene could persist for more than two months. Conclusions This CsCMV-based VIGS system provides a new tool for rapid and efficient gene function studies in cassava.


2007 ◽  
Vol 88 (6) ◽  
pp. 1643-1655 ◽  
Author(s):  
Jeanmarie Verchot-Lubicz ◽  
Chang-Ming Ye ◽  
Devinka Bamunusinghe

Recent advances in potexvirus research have produced new models describing virus replication, cell-to-cell movement, encapsidation, R gene-mediated resistance and gene silencing. Interactions between distant RNA elements are a central theme in potexvirus replication. The 5′ non-translated region (NTR) regulates genomic and subgenomic RNA synthesis and encapsidation, as well as virus plasmodesmal transport. The 3′ NTR regulates both plus- and minus-strand RNA synthesis. How the triple gene-block proteins interact for virus movement is still elusive. As the potato virus X (PVX) TGBp1 protein gates plasmodesmata, regulates virus translation and is a suppressor of RNA silencing, further research is needed to determine how these properties contribute to propelling virus through the plasmodesmata. Specifically, TGBp1 suppressor activity is required for virus movement, but how the silencing machinery relates to plasmodesmata is not known. The TGBp2 and TGBp3 proteins are endoplasmic reticulum (ER)-associated proteins required for virus movement. TGBp2 associates with ER-derived vesicles that traffic along the actin network. Future research will determine whether the virus-induced vesicles are cytopathic structures regulating events along the ER or are vehicles carrying virus to the plasmodesmata for transfer into neighbouring cells. Efforts to assemble virions in vitro identified a single-tailed particle (STP) comprising RNA, coat protein (CP) and TGBp1. It has been proposed that TGBp1 aids in transport of virions or STP between cells and ensures translation of RNA in the receiving cells. PVX is also a tool for studying Avr–R gene interactions and gene silencing in plants. The PVX CP is the elicitor for the Rx gene. Recent reports of the PVX CP reveal how CP interacts with the Rx gene product.


2020 ◽  
Author(s):  
Xuetong Yang ◽  
Jiali Ye ◽  
Fuqiang Niu ◽  
Yi Feng ◽  
Xiyue Song

Abstract Background: Environment-sensitive genic male sterility is of vital importance to hybrid vigor in crop production and breeding, therefore, it is meaningful to identify and study the function of the genes related to pollen development and male sterility, which still not fully understanding currently. In this study, Yanzhan 4110S, a new thermo-sensitive genic male sterility (TGMS) wheat line, and its near isogenic line Yanzhan 4110 were carried out cytological features observation, bioinformatics analysis to investgate the abortion state and identified the genes involved in pollen development which have fertility regulation function. Barely stripe mosaic virus-induced gene silencing was used to verify the genes function.Results: Cytological analysis showed pollen abortion event of Yanzhan 4110S occur at the later uninucleate stage (Lun) under higher temperature induction (day/night temperatures of 22 °C/20 °C), when the anthers were collected and assessed for transcriptomic profiling through high-throughput sequencing. We then in-depth analyzed the differentially expressed genes (DEGs) by Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, the results showed that the occurrence of Yanzhan 4110S male-sterility most likely related to metabolic pathway, including phenylpropanoid biosynthesis in the biosynthesis of other secondary metabolites, starch and sucrose metabolism in carbohydrate metabolism, carbon fixation in photosynthetic organisms as well as carbon metabolism in energy metabolism. The weighted gene co-expression network analysis in the transcriptome profiles further identified some hub genes, where the key genes involved in those pathways were intersection between the unique DEGs of Yanzhan 4110S in anther and hub genes, totally 228 genes, which were highly related to pollen development including TaMut11 and TaSF3. Moreover, further verification through barely stripe mosaic virus-induced gene silencing elucidated that the silencing of TaMut11 and TaSF3 caused pollen abortion, finally resulting in the declination of fertility. So, the genes TaMut11 and TaSF3 are related to fertility conversion of Yanzhan 4110S.Conclusion: Through comparative transcriptome bioinformatics analysis, the genes TaMut11 and TaSF3 associated with pollen development and male sterility induced by high temperature were identified in Yanzhan 4110S, and verificated by barely stripe mosaic virus-induced gene silencing. These findings provided researching the abortive mechanism in environment-sensitive genic male sterility wheat.


2019 ◽  
Vol 71 (6) ◽  
pp. 2142-2156 ◽  
Author(s):  
Xue Yang ◽  
Yuwen Lu ◽  
Fang Wang ◽  
Ying Chen ◽  
Yanzhen Tian ◽  
...  

Abstract The chloroplast protein ferredoxin 1 (FD1), with roles in the chloroplast electron transport chain, is known to interact with the coat proteins (CPs) of Tomato mosaic virus and Cucumber mosaic virus. However, our understanding of the roles of FD1 in virus infection remains limited. Here, we report that the Potato virus X (PVX) p25 protein interacts with FD1, whose mRNA and protein levels are reduced by PVX infection or by transient expression of p25. Silencing of FD1 by Tobacco rattle virus-based virus-induced gene silencing (VIGS) promoted the local and systemic infection of plants by PVX. Use of a drop-and-see (DANS) assay and callose staining revealed that the permeability of plasmodesmata (PDs) was increased in FD1-silenced plants together with a consistently reduced level of PD callose deposition. After FD1 silencing, quantitative reverse transcription–real-time PCR (qRT–PCR) analysis and LC-MS revealed these plants to have a low accumulation of the phytohormones abscisic acid (ABA) and salicylic acid (SA), which contributed to the decreased callose deposition at PDs. Overexpression of FD1 in transgenic plants manifested resistance to PVX infection, but the contents of ABA and SA, and the PD callose deposition were not increased in transgenic plants. Overexpression of FD1 interfered with the RNA silencing suppressor function of p25. These results demonstrate that interfering with FD1 function causes abnormal plant hormone-mediated antiviral processes and thus enhances PVX infection.


2019 ◽  
Vol 20 (16) ◽  
pp. 3976 ◽  
Author(s):  
Hongqiu Zeng ◽  
Yanwei Xie ◽  
Guoyin Liu ◽  
Yunxie Wei ◽  
Wei Hu ◽  
...  

Agrobacterium-mediated transient expression and virus-induced gene silencing (VIGS) are very useful in functional genomics in plants. However, whether these methods are effective in cassava (Manihot esculenta), one of the most important tropical crops, remains elusive. In this study, we used green fluorescent protein (GFP) and β-glucuronidase (GUS) as reporter genes in a transient expression assay. GFP or GUS could be detected in the infiltrated leaves at 2 days postinfiltration (dpi) and were evidenced by visual GFP and GUS assays, reverse-transcription PCR, and Western blot. In addition, phytoene desaturase (PDS) was used to show the silencing effect in a VIGS system. Both Agrobacterium GV3101 and AGL-1 with tobacco rattle virus (TRV)-MePDS-infiltrated distal leaves showed an albino phenotype at 20 dpi; in particular, the AGL-1-infiltrated plants showed an obvious albino area in the most distal leaves. Moreover, the silencing effect was validated by molecular identification. Notably, compared with the obvious cassava mosaic disease symptom infiltrated by African-cassava-mosaic-virus-based VIGS systems in previous studies, TRV-based VIGS-system-infiltrated cassava plants did not show obvious virus-induced disease symptoms, suggesting a significant advantage. Taken together, these methods could promote functional genomics in cassava.


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