systemic movement
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2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Alassane Ouattara ◽  
Fidèle Tiendrébéogo ◽  
Nathalie Becker ◽  
Cica Urbino ◽  
Gaël Thébaud ◽  
...  

AbstractIn recent decades, a legion of monopartite begomoviruses transmitted by the whitefly Bemisia tabaci has emerged as serious threats to vegetable crops in Africa. Recent studies in Burkina Faso (West Africa) reported the predominance of pepper yellow vein Mali virus (PepYVMLV) and its frequent association with a previously unknown DNA-B component. To understand the role of this DNA-B component in the emergence of PepYVMLV, we assessed biological traits related to virulence, virus accumulation, location in the tissue and transmission. We demonstrate that the DNA-B component is not required for systemic movement and symptom development of PepYVMLV (non-strict association), but that its association produces more severe symptoms including growth arrest and plant death. The increased virulence is associated with a higher viral DNA accumulation in plant tissues, an increase in the number of contaminated nuclei of the phloem parenchyma and in the transmission rate by B. tabaci. Our results suggest that the association of a DNA-B component with the otherwise monopartite PepYVMLV is a key factor of its emergence.


Plants ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 93
Author(s):  
So-Yon Park ◽  
Kohki Shimizu ◽  
Jocelyn Brown ◽  
Koh Aoki ◽  
James H. Westwood

Cuscuta spp. are obligate parasites that connect to host vascular tissue using a haustorium. In addition to water, nutrients, and metabolites, a large number of mRNAs are bidirectionally exchanged between Cuscuta spp. and their hosts. This trans-specific movement of mRNAs raises questions about whether these molecules function in the recipient species. To address the possibility that mobile mRNAs are ultimately translated, we built upon recent studies that demonstrate a role for transfer RNA (tRNA)-like structures (TLSs) in enhancing mRNA systemic movement. C. campestris was grown on Arabidopsis that expressed a β-glucuronidase (GUS) reporter transgene either alone or in GUS-tRNA fusions. Histochemical staining revealed localization in tissue of C. campestris grown on Arabidopsis with GUS-tRNA fusions, but not in C. campestris grown on Arabidopsis with GUS alone. This corresponded with detection of GUS transcripts in Cuscuta on Arabidopsis with GUS-tRNA, but not in C. campestris on Arabidopsis with GUS alone. Similar results were obtained with Arabidopsis host plants expressing the same constructs containing an endoplasmic reticulum localization signal. In C. campestris, GUS activity was localized in the companion cells or phloem parenchyma cells adjacent to sieve tubes. We conclude that host-derived GUS mRNAs are translated in C. campestris and that the TLS fusion enhances RNA mobility in the host-parasite interactions.


Viruses ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2189
Author(s):  
Erbo Niu ◽  
Huan Liu ◽  
Hongsheng Zhou ◽  
Lian Luo ◽  
Yunfeng Wu ◽  
...  

Autophagy is an evolutionarily conserved cellular-degradation mechanism implicated in antiviral defense in plants. Studies have shown that autophagy suppresses virus accumulation in cells; however, it has not been reported to specifically inhibit viral spread in plants. This study demonstrated that infection with citrus leaf blotch virus (CLBV; genus Citrivirus, family Betaflexiviridae) activated autophagy in Nicotiana benthamiana plants as indicated by the increase of autophagosome formation. Impairment of autophagy through silencing of N. benthamiana autophagy-related gene 5 (NbATG5) and NbATG7 enhanced cell-to-cell and systemic movement of CLBV; however, it did not affect CLBV accumulation when the systemic infection had been fully established. Treatment using an autophagy inhibitor or silencing of NbATG5 and NbATG7 revealed that transiently expressed movement protein (MP), but not coat protein, of CLBV was targeted by selective autophagy for degradation. Moreover, we identified that CLBV MP directly interacted with NbATG8C1 and NbATG8i, the isoforms of autophagy-related protein 8 (ATG8), which are key factors that usually bind cargo receptors for selective autophagy. Our results present a novel example in which autophagy specifically targets a viral MP to limit the intercellular spread of the virus in plants.


2021 ◽  
Vol 12 ◽  
Author(s):  
Mireya Martínez-Pérez ◽  
Concepción Gómez-Mena ◽  
Luis Alvarado-Marchena ◽  
Riad Nadi ◽  
José Luis Micol ◽  
...  

The N6-methyladenosine (m6A) pathway has been widely described as a viral regulatory mechanism in animals. We previously reported that the capsid protein (CP) of alfalfa mosaic virus (AMV) interacts with the Arabidopsis m6A demethylase ALKBH9B regulating m6A abundance on viral RNAs (vRNAs) and systemic invasion of floral stems. Here, we analyze the involvement of other ALKBH9 proteins in AMV infection and we carry out a detailed evaluation of the infection restraint observed in alkbh9b mutant plants. Thus, via viral titer quantification experiments and in situ hybridization assays, we define the viral cycle steps that are altered by the absence of the m6A demethylase ALKBH9B in Arabidopsis. We found that ALKBH9A and ALKBH9C do not regulate the AMV cycle, so ALKBH9B activity seems to be highly specific. We also define that not only systemic movement is affected by the absence of the demethylase, but also early stages of viral infection. Moreover, our findings suggest that viral upload into the phloem could be blocked in alkbh9b plants. Overall, our results point to ALKBH9B as a possible new component of phloem transport, at least for AMV, and as a potential target to obtain virus resistance crops.


2021 ◽  
Vol 17 (9) ◽  
pp. e1009622
Author(s):  
Shelby L. Brown ◽  
Dana J. Garrison ◽  
Jared P. May

Both cellular and viral proteins can undergo phase separation and form membraneless compartments that concentrate biomolecules. The p26 movement protein from single-stranded, positive-sense Pea enation mosaic virus 2 (PEMV2) separates into a dense phase in nucleoli where p26 and related orthologues must interact with fibrillarin (Fib2) as a pre-requisite for systemic virus movement. Using in vitro assays, viral ribonucleoprotein complexes containing p26, Fib2, and PEMV2 genomic RNAs formed droplets that may provide the basis for self-assembly in planta. Mutating basic p26 residues (R/K-G) blocked droplet formation and partitioning into Fib2 droplets or the nucleolus and prevented systemic movement of a Tobacco mosaic virus (TMV) vector in Nicotiana benthamiana. Mutating acidic residues (D/E-G) reduced droplet formation in vitro, increased nucleolar retention 6.5-fold, and prevented systemic movement of TMV, thus demonstrating that p26 requires electrostatic interactions for droplet formation and charged residues are critical for nucleolar trafficking and virus movement. p26 readily partitioned into stress granules (SGs), which are membraneless compartments that assemble by clustering of the RNA binding protein G3BP following stress. G3BP is upregulated during PEMV2 infection and over-expression of G3BP restricted PEMV2 RNA accumulation >20-fold. Deletion of the NTF2 domain that is required for G3BP condensation restored PEMV2 RNA accumulation >4-fold, demonstrating that phase separation enhances G3BP antiviral activity. These results indicate that p26 partitions into membraneless compartments with either proviral (Fib2) or antiviral (G3BP) factors.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Amany Abdellatif Osman

Purpose This paper aims to analyze the Egyptian revolution as an anti-systemic movement. It illustrates how Egypt’s position in the world-economy has affected its political economy orientation and led to the marginalization of critical masses, who launched the revolution. Design/methodology/approach The paper follows Wallerstein’s world-system analysis focusing on the anti-systemic movement concept. The paper analyzes the Egyptian case based on Annales school’s longue durée concept, which is a perspective to study developments of social relations historically. Findings The Egyptian revolution was not only against the autocratic regime but also against the power structure resulting from the neoliberal economic policies, introduced as a response to the capitalism crisis. It represented the voice of the forgotten. The revolution was one of the anti-systemic movements resisting the manifestations of the capitalist world-economy. Originality/value This paper aims at proving that the Egyptian revolution was an anti-systemic movement; which will continue to spread as a rejection to the world-system and to aspire a more democratic and egalitarian world. The current COVID-19 pandemic is exacerbating the crisis of the world-system.


Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 677
Author(s):  
Rosalba Rodriguez-Peña ◽  
Kaoutar El Mounadi ◽  
Hernan Garcia-Ruiz

Viruses are dependent on host factors at all parts of the infection cycle, such as translation, genome replication, encapsidation, and cell-to-cell and systemic movement. RNA viruses replicate their genome in compartments associated with the endoplasmic reticulum, chloroplasts, and mitochondria or peroxisome membranes. In contrast, DNA viruses replicate in the nucleus. Viral infection causes changes in plant gene expression and in the subcellular localization of some host proteins. These changes may support or inhibit virus accumulation and spread. Here, we review host proteins that change their subcellular localization in the presence of a plant virus. The most frequent change is the movement of host cytoplasmic proteins into the sites of virus replication through interactions with viral proteins, and the protein contributes to essential viral processes. In contrast, only a small number of studies document changes in the subcellular localization of proteins with antiviral activity. Understanding the changes in the subcellular localization of host proteins during plant virus infection provides novel insights into the mechanisms of plant–virus interactions and may help the identification of targets for designing genetic resistance to plant viruses.


Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 662
Author(s):  
Naga Charan Konakalla ◽  
Sudeep Bag ◽  
Anushi Suwaneththiya Deraniyagala ◽  
Albert K. Culbreath ◽  
Hanu R. Pappu

Thrips-transmitted tomato spotted wilt orthotospovirus (TSWV) continues to be a constraint to peanut, pepper, tobacco, and tomato production in Georgia and elsewhere. TSWV is being managed by an integrated disease management strategy that includes a combination of cultural practices, vector management, and growing virus-resistant varieties where available. We used a non-transgenic strategy to induce RNA interference (RNAi)-mediated resistance in tobacco (Nicotiana tabacum) plants against TSWV. Double-stranded RNA (dsRNA) molecules for the NSs (silencing suppressor) and N (nucleoprotein) genes were produced by a two-step PCR approach followed by in vitro transcription. When topically applied to tobacco leaves, both molecules elicited a resistance response. Host response to the treatments was measured by determining the time to symptom expression, and the level of resistance by absolute quantification of the virus. We also show the systemic movement of dsRNA_N from the inoculated leaves to younger, non-inoculated leaves. Post-application, viral siRNAs were detected for up to nine days in inoculated leaves and up to six days in non-inoculated leaves. The topical application of dsRNAs to induce RNAi represents an environmentally safe and efficient way to manage TSWV in tobacco crops and could be applicable to other TSWV-susceptible crops.


Plant Disease ◽  
2021 ◽  
Author(s):  
Walid El Kayal ◽  
Zeinab Chamas ◽  
Islam El-Sharkawy ◽  
Jayasankar Subramanian

Plums are affected by a cancerous disease called “Black Knot disease” caused by the fungus Apiosporina morbosa. It affects both Japanese (Prunus salicina) and European plums (Prunus domestica) equally. In order to understand the spread of the disease, histological analysis was performed in two different European plum cultivars (susceptible and tolerant). Light and Scanning Electron Microscope (SEM) analyses confirmed the presence of the growing hyphae in the internal tissues of the susceptible trees. By using stereoscopic analysis with a fluorescence filter, we were able to detect the hyphae in the visible lesion area. At about 2 inches from above and below the knots, no spore or hypha was visible with the light microscope. However, SEM images showed strong evidence that the fungus is capable of migrating to adjacent vessels in the susceptible plum genotype. In fact, at that distance below and above the knots, conidia were detected inside xylem vessels suggesting a systemic movement of the fungus that has not been shown so far. No symptoms were observed in the resistant genotype. Starch granules, vessel occlusions and lipid droplets were the main distinguishable characteristics between susceptible and tolerant varieties.


2021 ◽  
Vol 29 (3) ◽  
pp. 58-68
Author(s):  
F.M. Dattilio

This article addresses the integration of cognitive-behavior therapy with families within the systemic movement. It reviews some of the updated empirical literature that supports its strategies as well as its attractiveness to systemic family therapists in Russia and across the globe.


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