scholarly journals Chloroplast Hsp70 Isoform Is Required for Age-Dependent Tissue Preference of Bamboo mosaic virus in Mature Nicotiana benthamiana Leaves

2017 ◽  
Vol 30 (8) ◽  
pp. 631-645 ◽  
Author(s):  
Ying Wen Huang ◽  
Chung Chi Hu ◽  
Ching Hsiu Tsai ◽  
Na Sheng Lin ◽  
Yau Heiu Hsu

Plant viruses may exhibit age-dependent tissue preference in their hosts but the underlying mechanisms are not well understood. In this study, we provide several lines of evidence to reveal the determining role of a protein of the Nicotiana benthamiana chloroplast Hsp70 (NbcpHsp70) family, NbcpHsp70-2, involved in the preference of Bamboo mosaic virus (BaMV) to infect older tissues. NbcpHsp70 family proteins were identified in complexes pulled down with BaMV replicase as the bait. Among the isoforms of NbcpHsp70, only the specific silencing of NbcpHsp70-2 resulted in the significant decrease of BaMV RNA in N. benthamiana protopalsts, indicating that NbcpHsp70-2 is involved in the efficient replication of BaMV RNA. We further identified the age-dependent import regulation signal contained in the transit peptide of NbcpHsp70-2. Deletion, overexpression, and substitution experiments revealed that the signal in the transit peptide of NbcpHsp70-2 is crucial for both the import of NbcpHsp70-2 into older chloroplasts and the preference of BaMV for infecting older leaves of N. benthamiana. Together, these data demonstrated that BaMV may exploit a cellular age-dependent transportation mechanism to target a suitable environment for viral replication.

Biology ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 232
Author(s):  
Weiran Zheng ◽  
Haichao Hu ◽  
Qisen Lu ◽  
Peng Jin ◽  
Linna Cai ◽  
...  

Recent studies have shown that a large number of long noncoding RNAs (lncRNAs) can regulate various biological processes in animals and plants. Although lncRNAs have been identified in many plants, they have not been reported in the model plant Nicotiana benthamiana. Particularly, the role of lncRNAs in plant virus infection remains unknown. In this study, we identified lncRNAs in N. benthamiana response to Chinese wheat mosaic virus (CWMV) infection by RNA sequencing. A total of 1175 lncRNAs, including 65 differentially expressed lncRNAs, were identified during CWMV infection. We then analyzed the functions of some of these differentially expressed lncRNAs. Interestingly, one differentially expressed lncRNA, XLOC_006393, was found to participate in CWMV infection as a precursor to microRNAs in N. benthamiana. These results suggest that lncRNAs play an important role in the regulatory network of N. benthamiana in response to CWMV infection.


Plant Disease ◽  
2020 ◽  
Vol 104 (3) ◽  
pp. 853-859
Author(s):  
Happyness G. Mollel ◽  
Joseph Ndunguru ◽  
Peter Sseruwagi ◽  
Titus Alicai ◽  
John Colvin ◽  
...  

Begomoviruses are plant viruses that cause major losses to many economically important crops. Although they are poorly understood, begomoviruses infecting wild plants may have an important role as reservoirs in the epidemiology of viral diseases. This study reports the discovery and genomic characterization of three novel bipartite begomoviruses from wild and cultivated African basil (Ocimum gratissimum) plants collected in Uganda, East Africa. Based on the symptoms shown by the infected plants, the names proposed for these viruses are Ocimum yellow vein virus (OcYVV), Ocimum mosaic virus (OcMV), and Ocimum golden mosaic virus (OcGMV). Genome and phylogenetic analyses suggest that DNA-A of OcGMV is mostly related to begomoviruses infecting tomato in Africa, whereas those of OcYVV and OcMV are closely related to one another and highly divergent within the Old World begomoviruses. The DNA-A of all characterized begomovirus isolates are of a recombinant nature, revealing the role of recombination in the evolution of these begomoviruses. The viruses characterized here are the first identified in O. gratissimum and the first in Ocimum spp. in the African continent and could have important epidemiological consequences for cultivated basils and other important crops. [Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .


2021 ◽  
Author(s):  
Pulkit Kanodia ◽  
W. Allen Miller

In recent years, a new class of viral noncoding subgenomic (ncsg)RNA has been identified. This RNA is generated as a stable degradation product via an exoribonuclease-resistant (xr) RNA structure, which blocks the progression of 5’→3’ exoribonuclease on viral RNAs in infected cells. Here, we assess the effects of the ncsgRNA of red clover necrotic mosaic virus (RCNMV), called SR1f, in infected plants. We demonstrate: (i) absence of SR1f reduces symptoms and decreases viral RNA accumulation in Nicotiana benthamiana and Arabidopsis thaliana plants; (ii) SR1f has an essential function other than suppression of RNA silencing; and (iii) the cytoplasmic exoribonuclease involved in mRNA turnover, XRN4, is not required for SR1f production or virus infection. A comparative transcriptomic analysis in N. benthamiana infected with wildtype RCNMV or an SR1f-deficient mutant RCNMV revealed that wt RCNMV infection, which produces SR1f and much higher levels of virus, has a greater and more significant impact on cellular gene expression than the SR1f-deficient mutant. Upregulated pathways include plant hormone signaling, plant-pathogen interaction, MAPK signaling, and several metabolic pathways, while photosynthesis-related genes were downregulated. We compare this to host genes known to participate in infection by other tombusvirids. Viral reads revealed a 10 to 100-fold ratio of positive to negative strand, and the abundance of reads of both strands mapping to the 3’ region of RCNMV RNA1 support the premature mechanism of synthesis for the coding sgRNA. These results provide a framework for future studies of the interactions and functions of noncoding RNAs of plant viruses. IMPORTANCE Knowledge of how RNA viruses manipulate host and viral gene expression is crucial to our understanding of infection and disease. Unlike viral protein-host interactions, little is known about the control of gene expression by viral RNA. Here we begin to address this question by investigating the noncoding subgenomic (ncsg)RNA of red clover necrotic mosaic virus (RCNMV), called SR1f. Similar exoribonuclease-resistant RNAs of flaviviruses are well-studied, but the roles of plant viral ncsgRNAs, and how they arise, are poorly understood. Surprisingly, we find the likely exonuclease candidate, XRN4, is not required to generate SR1f, and we assess the effects of SR1f on virus accumulation and symptom development. Finally, we compare the effects of infection by wildtype RCNMV vs an SR1f-deficient mutant on host gene expression in Nicotiana benthamiana , which reveals that ncsgRNAs such as SR1f are key players in virus-host interactions to facilitate productive infection.


2006 ◽  
Vol 80 (5) ◽  
pp. 2566-2574 ◽  
Author(s):  
Yau-Heiu Hsu ◽  
Hsin-Chuan Chen ◽  
Jeannie Cheng ◽  
Padmanaban Annamali ◽  
Bin-Yen Lin ◽  
...  

ABSTRACT Satellite RNA of Bamboo mosaic virus (satBaMV), a single-stranded mRNA type satellite encoding a protein of 20 kDa (P20), depends on the helper BaMV for replication and encapsidation. Two satBaMV isolates, BSF4 and BSL6, exhibit distinctly differential phenotypes in Nicotiana benthamiana plants when coinoculated with BaMV RNA. BSL6 significantly reduces BaMV RNA replication and suppresses the BaMV-induced symptoms, whereas BSF4 does not. By studies with chimeric satBaMVs generated by exchanging the components between BSF4 and BSL6, the genetic determinants responsible for the downregulation of BaMV replication and symptom expression were mapped at the 5′ untranslated region (UTR) of BSL6. The 5′ UTR of BSL6 alone is sufficient to diminish BaMV RNA replication when the 5′ UTR is inserted in cis into the BaMV expression vector or when coinoculation with mutants that block the synthesis of P20 protein takes place. Further, the 5′ UTR of natural satBaMV isolates contains one hypervariable (HV) region which folds into a conserved apical hairpin stem-loop (AHSL) structure (W. B. Yeh, Y. H. Hsu, H. C. Chen, and N. S. Lin, Virology 330:105-115, 2004). Interchanges of AHSL segment of HV regions between BSF4 and BSL6 led to the ability of chimeric satBaMV to interfere with BaMV replication and symptom expression. The conserved secondary structure within the HV region is a potent determinant of the downregulation of helper virus replication.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Rebeca Cuesta ◽  
Carmen Yuste-Calvo ◽  
David Gil-Cartón ◽  
Flora Sánchez ◽  
Fernando Ponz ◽  
...  

Abstract Turnip mosaic virus (TuMV), a potyvirus, is a flexible filamentous plant virus that displays a helical arrangement of coat protein copies (CPs) bound to the ssRNA genome. TuMV is a bona fide representative of the Potyvirus genus, one of most abundant groups of plant viruses, which displays a very wide host range. We have studied by cryoEM the structure of TuMV virions and its viral-like particles (VLPs) to explore the role of the interactions between proteins and RNA in the assembly of the virions. The results show that the CP-RNA interaction is needed for the correct orientation of the CP N-terminal arm, a region that plays as a molecular staple between CP subunits in the fully assembled virion.


2020 ◽  
Vol 11 ◽  
Author(s):  
Song Peng ◽  
Jun Zhang ◽  
Xintao Tan ◽  
Yiqiang Huang ◽  
Jing Xu ◽  
...  

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors originating from chromaffin cells in the adrenal medulla (PCCs) or extra-adrenal sympathetic or parasympathetic paraganglia (PGLs). About 40% of PPGLs result from germline mutations and therefore they are highly inheritable. Although dysfunction of any one of a panel of more than 20 genes can lead to PPGLs, mutations in genes involved in the VHL/HIF axis including PHD, VHL, HIF-2A (EPAS1), and SDHx are more frequently found in PPGLs. Multiple lines of evidence indicate that pseudohypoxia plays a crucial role in the tumorigenesis of PPGLs, and therefore PPGLs are also known as metabolic diseases. However, the interplay between VHL/HIF-mediated pseudohypoxia and metabolic disorder in PPGLs cells is not well-defined. In this review, we will first discuss the VHL/HIF axis and genetic alterations in this axis. Then, we will dissect the underlying mechanisms in VHL/HIF axis-driven PPGL pathogenesis, with special attention paid to the interplay between the VHL/HIF axis and cancer cell metabolism. Finally, we will summarize the currently available compounds/drugs targeting this axis which could be potentially used as PPGLs treatment, as well as their underlying pharmacological mechanisms. The overall goal of this review is to better understand the role of VHL/HIF axis in PPGLs development, to establish more accurate tools in PPGLs diagnosis, and to pave the road toward efficacious therapeutics against metastatic PPGLs.


2018 ◽  
Vol 92 (14) ◽  
Author(s):  
Craig G. Webster ◽  
Elodie Pichon ◽  
Manuella van Munster ◽  
Baptiste Monsion ◽  
Maëlle Deshoux ◽  
...  

ABSTRACTPlant viruses transmitted by insects cause tremendous losses in most important crops around the world. The identification of receptors of plant viruses within their insect vectors is a key challenge to understanding the mechanisms of transmission and offers an avenue for future alternative control strategies to limit viral spread. We here report the identification of two cuticular proteins within aphid mouthparts, and we provide experimental support for the role of one of them in the transmission of a noncirculative virus. These two proteins, named Stylin-01 and Stylin-02, belong to the RR-1 cuticular protein subfamily and are highly conserved among aphid species. Using an immunolabeling approach, they were localized in the maxillary stylets of the pea aphidAcyrthosiphon pisumand the green peach aphidMyzus persicae, in the acrostyle, an organ earlier shown to harbor receptors of a noncirculative virus. A peptide motif present at the C termini of both Stylin-01 and Stylin-02 is readily accessible all over the surface of the acrostyle. Competition forin vitrobinding to the acrostyle was observed between an antibody targeting this peptide and the helper component protein P2 ofCauliflower mosaic virus. Furthermore, silencing thestylin-01but notstylin-02gene through RNA interference decreased the efficiency ofCauliflower mosaic virustransmission byMyzus persicae. These results identify the first cuticular proteins ever reported within arthropod mouthparts and distinguish Stylin-01 as the best candidate receptor for the aphid transmission of noncirculative plant viruses.IMPORTANCEMost noncirculative plant viruses transmitted by insect vectors bind to their mouthparts. They are acquired and inoculated within seconds when insects hop from plant to plant. The receptors involved remain totally elusive due to a long-standing technical bottleneck in working with insect cuticle. Here we characterize the role of the two first cuticular proteins ever identified in arthropod mouthparts. A domain of these proteins is directly accessible at the surface of the cuticle of the acrostyle, an organ at the tip of aphid stylets. The acrostyle has been shown to bind a plant virus, and we consistently demonstrated that one of the identified proteins is involved in viral transmission. Our findings provide an approach to identify proteins in insect mouthparts and point at an unprecedented gene candidate for a plant virus receptor.


2013 ◽  
Vol 26 (10) ◽  
pp. 1165-1175 ◽  
Author(s):  
Ida Bagus Andika ◽  
Liying Sun ◽  
Rong Xiang ◽  
Junmin Li ◽  
Jianping Chen

Some viruses only infect plants at cool temperatures but the molecular mechanism underlying this low-temperature dependence remains unclear. Chinese wheat mosaic virus (CWMV, genus Furovirus) was able to infect wheat and Nicotiana benthamiana plants at 16 but not at 24°C. When CWMV-infected plants were transferred to 24°C for 2 weeks, the newly emerged leaves and roots became virus free. Co-infection with Potato virus Y rescued CWMV accumulation in N. benthamiana plants after a temperature shift to 24°C. In transgenic N. benthamiana plants silenced for the N. benthamiana RNA-dependent RNA polymerase 6 (NbRDR6), CWMV was able to accumulate in roots but not in leaves after a temperature shift to 24°C. Deep sequencing of small RNAs showed that, at 16°C, abundant CWMV small interfering (si)RNAs accumulated in infected N. benthamiana plants. Silencing of NbRDR6 increased the abundance of CWMV siRNAs and the generation of siRNAs from hotspots in the CWMV genome. In contrast, when shifted to 24°C for 1 week, CWMV siRNAs were markedly fewer in roots of NbRDR6-silenced than in roots of wild-type plants but were similar in the leaves of those plants. Our results demonstrate the root-specific role of NbRDR6 in the inhibition of CWMV accumulation and biogenesis of CWMV siRNAs at higher temperatures.


2019 ◽  
Vol 32 (11) ◽  
pp. 1475-1486 ◽  
Author(s):  
Yuki Matsuo ◽  
Fawzia Novianti ◽  
Miki Takehara ◽  
Toshiyuki Fukuhara ◽  
Tsutomu Arie ◽  
...  

Plant activators, including acibenzolar-S-methyl (ASM), are chemical compounds that stimulate plant defense responses to pathogens. ASM treatment inhibits infection by a variety of plant viruses, however, the mechanisms of this broad-spectrum and strong effect remain poorly understood. We employed green fluorescent protein (GFP)-expressing viruses and Nicotiana benthamiana plants to identify the infection stages that are restricted by ASM. ASM suppressed infection by three viral species, plantago asiatica mosaic virus (PlAMV), potato virus X (PVX), and turnip mosaic virus (TuMV), in inoculated cells. Furthermore, ASM delayed the long-distance movement of PlAMV and PVX, and the cell-to-cell (short range) movement of TuMV. The ASM-mediated delay of long-distance movement of PlAMV was not due to the suppression of viral accumulation in the inoculated leaves, indicating that ASM restricts PlAMV infection in at least two independent steps. We used Arabidopsis thaliana mutants to show that the ASM-mediated restriction of PlAMV infection requires the NPR1 gene but was independent of the dicer-like genes essential for RNA silencing. Furthermore, experiments using protoplasts showed that ASM treatment inhibited PlAMV replication without cell death. Our approach, using GFP-expressing viruses, will be useful for the analysis of mechanisms underlying plant activator–mediated virus restriction.


2017 ◽  
Vol 30 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Teresa Cordero ◽  
Lidia Cerdán ◽  
Alberto Carbonell ◽  
Konstantina Katsarou ◽  
Kriton Kalantidis ◽  
...  

Zucchini yellow mosaic virus (ZYMV) induces serious diseases in cucurbits. To create a tool to screen for resistance genes, we cloned a wild ZYMV isolate and inserted the visual marker Rosea1 to obtain recombinant clone ZYMV-Ros1. While in some plant-virus combinations Rosea1 induces accumulation of anthocyanins in infected tissues, ZYMV-Ros1 infection of cucurbits did not lead to detectable anthocyanin accumulation. However, the recombinant virus did induce dark red pigmentation in infected tissues of the model plant Nicotiana benthamiana. In this species, ZYMV-Ros1 multiplied efficiently in local inoculated tissue but only a few progeny particles established infection foci in upper leaves. We used this system to analyze the roles of Dicer-like (DCL) genes, core components of plant antiviral RNA silencing pathways, in ZYMV infection. ZYMV-Ros1 local replication was not significantly affected in single DCL knockdown lines nor in double DCL2/4 and triple DCL2/3/4 knockdown lines. ZYMV-Ros1 systemic accumulation was not affected in knockdown lines DCL1, DCL2, and DCL3. However in DCL4 and also in DCL2/4 and DCL2/3/4 knockdown lines, ZYMV-Ros1 systemic accumulation dramatically increased, which highlights the key role of DCL4 in restricting virus systemic movement. The effect of DCL4 on ZYMV systemic movement was confirmed with a wild-type version of the virus.


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