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Plant, Cell & Environment Feb 2023Cell walls are essential for plant growth and development, providing support and protection from external environments. Callose is a glucan that accumulates in... (Review)
Review
Cell walls are essential for plant growth and development, providing support and protection from external environments. Callose is a glucan that accumulates in specialized cell wall microdomains including around intercellular pores called plasmodesmata. Despite representing a small percentage of the cell wall (~0.3% in the model plant Arabidopsis thaliana), callose accumulation regulates important biological processes such as phloem and pollen development, cell division, organ formation, responses to pathogenic invasion and to changes in nutrients and toxic metals in the soil. Callose accumulation modifies cell wall properties and restricts plasmodesmata aperture, affecting the transport of signaling proteins and RNA molecules that regulate plant developmental and environmental responses. Although the importance of callose, at and outside plasmodesmata cell walls, is widely recognized, the underlying mechanisms controlling changes in its synthesis and degradation are still unresolved. In this review, we explore the most recent literature addressing callose metabolism with a focus on the molecular factors affecting callose accumulation in response to mutualistic symbionts and pathogenic elicitors. We discuss commonalities in the signaling pathways, identify research gaps and highlight opportunities to target callose in the improvement of plant responses to beneficial versus pathogenic microbes.
Topics: Plasmodesmata; Plants; Arabidopsis; Glucans; Cell Wall
PubMed: 36478232
DOI: 10.1111/pce.14510 -
Frontiers in Plant Science 2012Cell-to-cell communication is fundamental to multicellular life. For this to occur effectively there must be pathways and dynamic networks for communication. These might...
Cell-to-cell communication is fundamental to multicellular life. For this to occur effectively there must be pathways and dynamic networks for communication. These might depend upon electrical or chemical signals or the mass transfer of molecules between adjacent cells. Molecular communication occurs either via an extra-cellular pathway or through physical structures, called plasmodesmata, that connect the cytoplasm of neighboring cells. Plasmodesmata bridge the rigid physical barrier presented by the cell wall to extend the symplasm from single cells to tissue domains that have functional importance for tissue growth, development, and defense. Although recent years have seen advances in our knowledge of the physical nature of PD, the trafficked molecules, and of the wider processes they affect, our knowledge of PD structure and function is still relatively rudimentary. This article will consider the technical/experimental difficulties hindering PD research and suggest priorities in the future research effort that might advance the field at a significantly faster rate.
PubMed: 22645579
DOI: 10.3389/fpls.2012.00030 -
International Journal of Molecular... Jan 2023Stomata are microscopic pores on the plant epidermis that serve as a major passage for the gas and water exchange between a plant and the atmosphere. The formation of... (Review)
Review
Stomata are microscopic pores on the plant epidermis that serve as a major passage for the gas and water exchange between a plant and the atmosphere. The formation of stomata requires a series of cell division and cell-fate transitions and some key regulators including transcription factors and peptides. Monocots have different stomatal patterning and a specific subsidiary cell formation process compared with dicots. Cell-to-cell symplastic trafficking mediated by plasmodesmata (PD) allows molecules including proteins, RNAs and hormones to function in neighboring cells by moving through the channels. During stomatal developmental process, the intercellular communication between stomata complex and adjacent epidermal cells are finely controlled at different stages. Thus, the stomata cells are isolated or connected with others to facilitate their formation or movement. In the review, we summarize the main regulation mechanism underlying stomata development in both dicots and monocots and especially the specific regulation of subsidiary cell formation in monocots. We aim to highlight the important role of symplastic connection modulation during stomata development, including the status of PD presence at different cell-cell interfaces and the function of relevant mobile factors in both dicots and monocots.
Topics: Plant Stomata; Cell Communication; Intercellular Junctions; Plant Epidermis; Plants
PubMed: 36768915
DOI: 10.3390/ijms24032593 -
Current Opinion in Plant Biology Dec 2021Fruit consumption is fundamental to a balanced diet. The contemporary challenge of maintaining a steady food supply to meet the demands of a growing population is... (Review)
Review
Fruit consumption is fundamental to a balanced diet. The contemporary challenge of maintaining a steady food supply to meet the demands of a growing population is driving the development of strategies to improve the production and nutritional quality of fruit. Plasmodesmata, the structures that mediate symplasmic transport between plant cells, play an important role in phloem unloading and distribution of sugars and signalling molecules into developing organs. Targeted modifications to the structures and functioning of plasmodesmata have the potential to improve fruit development; however, knowledge on the mechanisms underpinning plasmodesmata regulation in this context is scarce. In this review, we have compiled current knowledge on plasmodesmata and their structural characterisation during the development of fruit organs. We discuss key questions on phloem unloading, including the pathway shift from symplasmic to apoplastic that takes place during the onset of ripening as potential targets for improving fruit quality.
Topics: Biological Transport; Fruit; Phloem; Plasmodesmata; Sugars
PubMed: 34826657
DOI: 10.1016/j.pbi.2021.102145 -
Frontiers in Plant Science 2022Various species of small RNAs (sRNAs), notably microRNAs and small interfering RNAs (siRNAs), have been characterized as the major effectors of RNA interference in... (Review)
Review
Various species of small RNAs (sRNAs), notably microRNAs and small interfering RNAs (siRNAs), have been characterized as the major effectors of RNA interference in plants. Growing evidence supports a model in which sRNAs move, intercellularly, systemically, and between cross-species. These non-coding sRNAs can traffic cell-to-cell through plasmodesmata (PD), in a symplasmic manner, as well as from source to sink tissues, the phloem, to trigger gene silencing in their target cells. Such mobile sRNAs function in non-cell-autonomous communication pathways, to regulate various biological processes, such as plant development, reproduction, and plant defense. In this review, we summarize recent progress supporting the roles of mobile sRNA in plants, and discuss mechanisms of sRNA transport, signal amplification, and the plant's response, in terms of RNAi activity, within the recipient tissues. We also discuss potential research directions and their likely impact on engineering of crops with traits for achieving food security.
PubMed: 35783973
DOI: 10.3389/fpls.2022.928729 -
Journal of Experimental Botany May 2020The long-distance translocation of nutrients and mobile molecules between different terminals is necessary for plant growth and development. Plasmodesmata-mediated... (Review)
Review
The long-distance translocation of nutrients and mobile molecules between different terminals is necessary for plant growth and development. Plasmodesmata-mediated symplastic trafficking plays an important role in accomplishing this task. To facilitate intercellular transport, plants have evolved diverse plasmodesmata with distinct internal architecture at different cell-cell interfaces along the trafficking route. Correspondingly, different underlying mechanisms for regulating plasmodesmal structures have been gradually revealed. In this review, we highlight recent studies on various plasmodesmal architectures, as well as relevant regulators of their de novo formation and transition, responsible for phloem loading, transport, and unloading specifically. We also discuss the interesting but unaddressed questions relating to, and potential studies on, the adaptation of functional plasmodesmal structures.
Topics: Biological Transport; Phloem; Plant Development; Plants; Plasmodesmata
PubMed: 31872215
DOI: 10.1093/jxb/erz567 -
Plant Physiology Dec 2021Sucrose, hexoses, and raffinose play key roles in the plant metabolism. Sucrose and raffinose, produced by photosynthesis, are translocated from leaves to flowers,... (Review)
Review
Sucrose, hexoses, and raffinose play key roles in the plant metabolism. Sucrose and raffinose, produced by photosynthesis, are translocated from leaves to flowers, developing seeds and roots. Translocation occurs in the sieve elements or sieve tubes of angiosperms. But how is sucrose loaded into and unloaded from the sieve elements? There seem to be two principal routes: one through plasmodesmata and one via the apoplasm. The best-studied transporters are the H+/SUCROSE TRANSPORTERs (SUTs) in the sieve element-companion cell complex. Sucrose is delivered to SUTs by SWEET sugar uniporters that release these key metabolites into the apoplasmic space. The H+/amino acid permeases and the UmamiT amino acid transporters are hypothesized to play analogous roles as the SUT-SWEET pair to transport amino acids. SWEETs and UmamiTs also act in many other important processes-for example, seed filling, nectar secretion, and pollen nutrition. We present information on cell type-specific enrichment of SWEET and UmamiT family members and propose several members to play redundant roles in the efflux of sucrose and amino acids across different cell types in the leaf. Pathogens hijack SWEETs and thus represent a major susceptibility of the plant. Here, we provide an update on the status of research on intercellular and long-distance translocation of key metabolites such as sucrose and amino acids, communication of the plants with the root microbiota via root exudates, discuss the existence of transporters for other important metabolites and provide potential perspectives that may direct future research activities.
Topics: Amino Acids; Biological Transport; Membrane Transport Proteins; Phloem; Plasmodesmata; Sugars
PubMed: 34015139
DOI: 10.1093/plphys/kiab228 -
Plasmodesmata-Mediated Cell-to-Cell Communication in the Shoot Apical Meristem: How Stem Cells Talk.Plants (Basel, Switzerland) Mar 2017Positional information is crucial for the determination of plant cell fates, and it is established based on coordinated cell-to-cell communication, which in turn is... (Review)
Review
Positional information is crucial for the determination of plant cell fates, and it is established based on coordinated cell-to-cell communication, which in turn is essential for plant growth and development. Plants have evolved a unique communication pathway, with tiny channels called plasmodesmata (PD) spanning the cell wall. PD interconnect most cells in the plant and generate a cytoplasmic continuum, to mediate short- and long-distance trafficking of various molecules. Cell-to-cell communication through PD plays a role in transmitting positional signals, however, the regulatory mechanisms of PD-mediated trafficking are still largely unknown. The induction and maintenance of stem cells in the shoot apical meristem (SAM) depends on PDmediated cell-to-cell communication, hence, it is an optimal model for dissecting the regulatory mechanisms of PD-mediated cell-to-cell communication and its function in specifying cell fates. In this review, we summarize recent knowledge of PD-mediated cell-to-cell communication in the SAM, and discuss mechanisms underlying molecular trafficking through PD and its role in plant development.
PubMed: 28257070
DOI: 10.3390/plants6010012 -
The New Phytologist Dec 2020
PubMed: 33459358
DOI: 10.1111/nph.16783 -
Current Opinion in Plant Biology Feb 2014Shoot apical meristems of deciduous woody perennials share gross structural features with other angiosperms, but are unique in the seasonal regulation of vegetative and... (Review)
Review
Shoot apical meristems of deciduous woody perennials share gross structural features with other angiosperms, but are unique in the seasonal regulation of vegetative and floral meristems. Supporting longevity, flowering is postponed to the adult phase, and restricted to some axillary meristems. In cold climates, photoperiodic timing mechanisms and chilling are recruited to schedule end-of-season growth arrest, dormancy cycling and flowering. We review recently uncovered generic meristem properties, perennial meristem fate, and the role of CENL1, FT1 and FT2 in bud formation and flowering. We also highlight novel findings, suggesting that dormancy release is mediated by mobile lipid bodies that deliver enzymes to plasmodesmata to recover symplasmic communication and meristem function.
Topics: Flowers; Magnoliopsida; Meristem; Models, Biological; Morphogenesis; Plant Proteins; Plant Shoots; Plasmodesmata; Seasons; Wood
PubMed: 24507499
DOI: 10.1016/j.pbi.2013.11.009