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Journal of Experimental Botany Aug 2023Plasmodesmata (PD) are plasma membrane-lined cytoplasmic nanochannels that mediate cell-to-cell communication across the cell wall. A range of proteins are embedded in...
Plasmodesmata (PD) are plasma membrane-lined cytoplasmic nanochannels that mediate cell-to-cell communication across the cell wall. A range of proteins are embedded in the PD plasma membrane and endoplasmic reticulum (ER), and function in regulating PD-mediated symplasmic trafficking. However, knowledge of the nature and function of the ER-embedded proteins in the intercellular movement of non-cell-autonomous proteins is limited. Here, we report the functional characterization of two ER luminal proteins, AtBiP1/2, and two ER integral membrane proteins, AtERdj2A/B, which are located within the PD. These PD proteins were identified as interacting proteins with cucumber mosaic virus (CMV) movement protein (MP) in co-immunoprecipitation studies using an Arabidopsis-derived plasmodesmal-enriched cell wall protein preparation (PECP). The AtBiP1/2 PD location was confirmed by TEM-based immunolocalization, and their AtBiP1/2 signal peptides (SPs) function in PD targeting. In vitro/in vivo pull-down assays revealed the association between AtBiP1/2 and CMV MP, mediated by AtERdj2A, through the formation of an AtBiP1/2-AtERdj2-CMV MP complex within PD. The role of this complex in CMV infection was established, as systemic infection was retarded in bip1/bip2w and erdj2b mutants. Our findings provide a model for a mechanism by which the CMV MP mediates cell-to-cell trafficking of its viral ribonucleoprotein complex.
Topics: Arabidopsis; Plasmodesmata; Cucumovirus; Endoplasmic Reticulum; Cytomegalovirus Infections; Plant Viral Movement Proteins; Nicotiana
PubMed: 37210666
DOI: 10.1093/jxb/erad190 -
International Journal of Molecular... Apr 2023This review focuses on the regulation of root water uptake in plants which are exposed to salt stress. Root water uptake is not considered in isolation but is viewed in... (Review)
Review
This review focuses on the regulation of root water uptake in plants which are exposed to salt stress. Root water uptake is not considered in isolation but is viewed in the context of other potential tolerance mechanisms of plants-tolerance mechanisms which relate to water relations and gas exchange. Plants spend between one third and half of their lives in the dark, and salt stress does not stop with sunset, nor does it start with sunrise. Surprisingly, how plants deal with salt stress during the dark has received hardly any attention, yet any growth response to salt stress over days, weeks, months and years is the integrative result of how plants perform during numerous, consecutive day/night cycles. As we will show, dealing with salt stress during the night is a prerequisite to coping with salt stress during the day. We hope to highlight with this review not so much what we know, but what we do not know; and this relates often to some rather basic questions.
Topics: Plant Leaves; Water; Salt Stress; Plants; Plant Roots
PubMed: 37175779
DOI: 10.3390/ijms24098070 -
International Journal of Molecular... Apr 2023Grafting is widely used to improve the stress tolerance and the fruit yield of horticultural crops. Ribonucleoprotein complexes formed by mRNAs and proteins play...
Grafting is widely used to improve the stress tolerance and the fruit yield of horticultural crops. Ribonucleoprotein complexes formed by mRNAs and proteins play critical roles in the communication between scions and stocks of grafted plants. In Pyrus betulaefolia, ankyrin was identified previously to promote the long-distance movement of the ribonucleoprotein complex(PbPTB3) by facilitating callose degradation at plasmodesmata. However, the mechanism of the ankyrin-mediated callose degradation remains elusive. In this study, we discovered a β-1,3-glucanase (EC 3.2.1.39, PbPDBG) using ankyrin as a bait from plasmodesmata by co-immunoprecipitation and mass spectrometry. Ankyrin was required for the plasmodesmata-localization of PbPDBG. The grafting and bombardment experiments indicated that overexpressing PbPDBG resulted in decreased callose content at plasmodesmata, and thereby promoting the long-distance transport of the ribonucleoprotein complex. Altogether, our findings revealed that PbPDBG was the key factor in ankyrin-mediated callose degradation at plasmodesmata.
Topics: Plasmodesmata; Pyrus; Ankyrins; Crops, Agricultural; Ribonucleoproteins
PubMed: 37175758
DOI: 10.3390/ijms24098051 -
Molecular Plant Pathology Aug 2023The tomato Tm-2 gene was considered to be one of the most durable resistance genes in agriculture, protecting against viruses of the Tobamovirus genus, such as tomato...
The tomato Tm-2 gene was considered to be one of the most durable resistance genes in agriculture, protecting against viruses of the Tobamovirus genus, such as tomato mosaic virus (ToMV) and tobacco mosaic virus (TMV). However, an emerging tobamovirus, tomato brown rugose fruit virus (ToBRFV), has overcome Tm-2 , damaging tomato production worldwide. Tm-2 encodes a nucleotide-binding leucine-rich repeat (NLR) class immune receptor that recognizes its effector, the tobamovirus movement protein (MP). Previously, we found that ToBRFV MP (MP ) enabled the virus to overcome Tm-2 -mediated resistance. Yet, it was unknown how Tm-2 remained durable against other tobamoviruses, such as TMV and ToMV, for over 60 years. Here, we show that a conserved cysteine (C68) in the MP of TMV (MP ) plays a dual role in Tm-2 activation and viral movement. Substitution of MP amino acid H67 with the corresponding amino acid in MP (C68) activated Tm-2 -mediated resistance. However, replacement of C68 in TMV and ToMV disabled the infectivity of both viruses. Phylogenetic and structural prediction analysis revealed that C68 is conserved among all Solanaceae-infecting tobamoviruses except ToBRFV and localizes to a predicted jelly-roll fold common to various MPs. Cell-to-cell and subcellular movement analysis showed that C68 is required for the movement of TMV by regulating the MP interaction with the endoplasmic reticulum and targeting it to plasmodesmata. The dual role of C68 in viral movement and Tm-2 immune activation could explain how TMV was unable to overcome this resistance for such a long period.
Topics: Tobacco Mosaic Virus; Cysteine; Phylogeny; Tobamovirus; Nicotiana; Plant Viral Movement Proteins
PubMed: 37086003
DOI: 10.1111/mpp.13318 -
Proceedings of the National Academy of... Apr 2023The plant immune system relies on the perception of molecules that signal the presence of a microbe threat. This triggers signal transduction that mediates a range of...
The plant immune system relies on the perception of molecules that signal the presence of a microbe threat. This triggers signal transduction that mediates a range of cellular responses via a collection of molecular machinery including receptors, small molecules, and enzymes. One response to pathogen perception is the restriction of cell-to-cell communication by plasmodesmal closure. We previously found that while chitin and flg22 trigger specialized immune signaling cascades in the plasmodesmal plasma membrane, both execute plasmodesmal closure via callose synthesis at the plasmodesmata. Therefore, the signaling pathways ultimately converge at or upstream of callose synthesis. To establish the hierarchy of signaling at plasmodesmata and characterize points of convergence in microbe elicitor-triggered signaling, we profiled the dependence of plasmodesmal responses triggered by different elicitors on a range of plasmodesmal signaling machinery. We identified that, like chitin, flg22 signals via RESPIRATORY BURST OXIDASE HOMOLOGUE D (RBOHD) to induce plasmodesmal closure. Further, we found that PLASMODESMATA-LOCATED PROTEIN 1 (PDLP1), PDLP5, and CALLOSE SYNTHASE 1 (CALS1) are common to microbe- and salicylic acid (SA)-triggered responses, identifying PDLPs as a candidate signaling nexus. To understand how PDLPs relay a signal to CALS1, we screened for PDLP5 interactors and found NON-RACE SPECIFIC DISEASE RESISTANCE/HIN1 HAIRPIN-INDUCED-LIKE protein 3 (NHL3), which is also required for chitin-, flg22- and SA-triggered plasmodesmal responses and PDLP-mediated activation of callose synthesis. We conclude that a PDLP-NHL3 complex acts as an integrating node of plasmodesmal signaling cascades, transmitting multiple immune signals to activate CALS1 and plasmodesmata closure.
Topics: Arabidopsis Proteins; Arabidopsis; Plasmodesmata; Signal Transduction; Salicylic Acid; Chitin
PubMed: 37068237
DOI: 10.1073/pnas.2216397120 -
Frontiers in Plant Science 2023Chloroplasts have important roles in photosynthesis, stress sensing and retrograde signaling. However, the relationship between chloroplast peptide chain release factor...
Chloroplasts have important roles in photosynthesis, stress sensing and retrograde signaling. However, the relationship between chloroplast peptide chain release factor and ROS-mediated plant growth is still unclear. In the present study, we obtained a loss-of-function mutant by EMS mutation. The mutant has few lateral roots and a pale green leaf phenotype. By map-based cloning, the gene was located on AT3G62910, with a point mutation leading to amino acid substitution in functional release factor domain. Using yeast-two-hybrid and BiFC, we confirmed protein was characterized locating in chloroplast by co-localization with plastid marker and interacting with ribosome-related proteins. Through observing by transmission electron microscopy, quantifying ROS content and measuring the transport efficiency of plasmodesmata in dig8 mutant, we found that abnormal thylakoid stack formation and chloroplast dysfunction in the mutant caused increased ROS activity leading to callose deposition and lower PD permeability. A local sugar supplement partially alleviated the growth retardation phenotype of the mutant. These findings shed light on chloroplast peptide chain release factor-affected plant growth by ROS stress.
PubMed: 37063204
DOI: 10.3389/fpls.2023.1172275 -
Viruses Mar 2023Viruses infect all cellular life forms and cause various diseases and significant economic losses worldwide. The majority of viruses are positive-sense RNA viruses. A... (Review)
Review
Viruses infect all cellular life forms and cause various diseases and significant economic losses worldwide. The majority of viruses are positive-sense RNA viruses. A common feature of infection by diverse RNA viruses is to induce the formation of altered membrane structures in infected host cells. Indeed, upon entry into host cells, plant-infecting RNA viruses target preferred organelles of the cellular endomembrane system and remodel organellar membranes to form organelle-like structures for virus genome replication, termed as the viral replication organelle (VRO) or the viral replication complex (VRC). Different viruses may recruit different host factors for membrane modifications. These membrane-enclosed virus-induced replication factories provide an optimum, protective microenvironment to concentrate viral and host components for robust viral replication. Although different viruses prefer specific organelles to build VROs, at least some of them have the ability to exploit alternative organellar membranes for replication. Besides being responsible for viral replication, VROs of some viruses can be mobile to reach plasmodesmata (PD) via the endomembrane system, as well as the cytoskeleton machinery. Viral movement protein (MP) and/or MP-associated viral movement complexes also exploit the endomembrane-cytoskeleton network for trafficking to PD where progeny viruses pass through the cell-wall barrier to enter neighboring cells.
Topics: RNA; Virus Replication; Cytoskeleton; RNA Replication; RNA Viruses; Viral Proteins; Plant Viruses
PubMed: 36992453
DOI: 10.3390/v15030744 -
RNA Biology Jan 2023Small RNAs (sRNAs) are short non-coding regulatory RNA sequences that silence the complementary expressive transcripts through an endogenous RNA mediated interference... (Review)
Review
Small RNAs (sRNAs) are short non-coding regulatory RNA sequences that silence the complementary expressive transcripts through an endogenous RNA mediated interference mechanism (RNAi). These sRNAs typically move through plasmodesmata and phloem in plants to support disease resistance, and also through septal pores and vesicles in fungi to act as effector of pathogenicity. Notably, recent reports have shown the occurrence of a bidirectional trafficking of these sRNAs between the host plants and the attacking fungal phytopathogen which have significant implication in the nature of the infection. While the trans-species sRNAs from the pathogen can silence the host mRNAs and inhibit the host immunity genes, the sRNA modules from the host plants can silence the mRNA in the pathogen by impeding the expression of the pathogenicity-related genes. In the present review, we discuss the current state of sRNA trafficking between the plant and the pathogen with special emphasis on the mechanism of cross-kingdom communication which could contribute to the development of pathogen and pest control in future agriculture.
Topics: Agriculture; RNA Interference; RNA, Fungal; RNA, Messenger; RNA, Small Untranslated; Plants; Fungi
PubMed: 36988190
DOI: 10.1080/15476286.2023.2195731 -
International Journal of Molecular... Mar 2023Carnivorous plants in the genus obtain nutrients by secreting viscous glue drops and enzymes that trap and digest small organisms. Here, we used to test the long-held...
Carnivorous plants in the genus obtain nutrients by secreting viscous glue drops and enzymes that trap and digest small organisms. Here, we used to test the long-held theory that different trichomes play different roles in carnivorous plants. In the leaves of , we observed a 1:2.5:14 ratio of long-stalked, short-stalked, and sessile trichomes. We demonstrated that the stalked trichomes play major roles in the production of glue droplets, while the sessile trichomes secrete digestive enzymes, namely proteases and phosphatases. In addition to absorbing digested small molecules via channels/transporters, several carnivorous plants employ a more efficient system: endocytosis of large protein molecules. By feeding fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA) to monitor protein transport, we found that sessile trichomes exhibited more endocytosis than long- and short-stalked trichomes. The uptaken FITC-BSA was delivered to the neighboring short epidermal cells in the same row as the sessile trichomes, then to the underlying mesophyll cells; however, no signals were detected in the parallel rows of long epidermis cells. The FITC control could be taken up by sessile trichomes but not transported out. Our study shows that has developed a well-organized system to maximize its food supply, consisting of stalked trichomes for prey predation and sessile trichomes for prey digestion. Moreover, the finding that sessile trichomes transfer large, endocytosed protein molecules to the underlying mesophyll, and putatively to the vascular tissues, but not laterally to the terminally differentiated epidermis, indicates that the nutrient transport system has evolved to maximize efficiency.
Topics: Animals; Trichomes; Predatory Behavior; Plant Leaves; Lamiales; Digestion
PubMed: 36982381
DOI: 10.3390/ijms24065305 -
Plants (Basel, Switzerland) Feb 2023Systemic acquired resistance (SAR) occurs when primary infected leaves produce several SAR-inducing chemical or mobile signals that are transported to uninfected distal... (Review)
Review
Systemic acquired resistance (SAR) occurs when primary infected leaves produce several SAR-inducing chemical or mobile signals that are transported to uninfected distal parts via apoplastic or symplastic compartments and activate systemic immunity. The transport route of many chemicals associated with SAR is unknown. Recently, it was demonstrated that pathogen-infected cells preferentially transport salicylic acid (SA) through the apoplasts to uninfected areas. The pH gradient and deprotonation of SA may lead to apoplastic accumulation of SA before it accumulates in the cytosol following pathogen infection. Additionally, SA mobility over a long distance is essential for SAR, and transpiration controls the partitioning of SA into apoplasts and cuticles. On the other hand, glycerol-3-phosphate (G3P) and azelaic acid (AzA) travel via the plasmodesmata (PD) channel in the symplastic route. In this review, we discuss the role of SA as a mobile signal and the regulation of SA transport in SAR.
PubMed: 36903874
DOI: 10.3390/plants12051013