Dynamic regulation of plasmodesmatal permeability and its application to horticultural research

Abstract

Effective cell-to-cell communication allows plants to fine-tune their developmental processes in accordance with the prevailing environmental stimuli. Plasmodesmata (PD) are intercellular channels that span the plant cell wall and serve as cytoplasmic bridges to facilitate efficient exchange of signaling molecules between neighboring cells. The identification of PD-associated proteins and the subsequent elucidation of the regulation of PD structure have provided vital insights into the role of PD architecture in enforcing crucial cellular processes, including callose deposition, ER-Golgi-based secretion, cytoskeleton dynamics, membrane lipid raft organization, chloroplast metabolism, and cell wall formation. In this review, we summarize the emerging discoveries from recent studies that elucidated the regulatory mechanisms involved in PD biogenesis and the dynamics of PD opening-closure. Retrospectively, PDmediated cell-to-cell communication has been implicated in diverse cellular and physiological processes that are fundamental for the development of horticultural plants. The potential application of PD biotechnological engineering represents a powerful approach for improving agronomic traits in horticultural crops in the future.

Communications Between the Endoplasmic Reticulum and Other Organelles During Abiotic Stress Response in Plants

“…The space between the PD-PM and the desmotubule constitutes the actual channel (the cytoplasmic sleeve) that transports a wide range of molecular cargos across cell walls of neighboring cells (Tilsner et al, 2016). Given the key role of PD in generating cytosolic and membrane continuity that are essential for growth and development, stress tolerance, and plant defense, the permeability of PD (also known as size exclusion limit), governed by the size of the cytoplasmic sleeve and distribution of spokes that creates nanochannels, is constantly regulated by various of developmental and environmental signals (Sun et al, 2019). Although PD exhibits the essential features of MCS (Scorrano et al, 2019), it remains to be investigated if the ER-PM contacts in PD play any role in inter-organelle exchanges of lipids, Ca 2+ , and/or other signaling molecules.…”

Plasmodesmata Conductivity Regulation: A Mechanistic Model

“…Although a relatively large number of potential Pd components have been identified [31][32][33]38], the current understanding of the mechanisms for regulating the Pd conductivity is based on the participation of callose, which was revealed by electron microscopy studies near and within the Pd channel [131]. Our analysis of PdAPs (Table 1) shows that features of secreted proteins also play an important role in the functioning of Pd.…”

“…Sucrose, as a primary carbohydrate transported long distances in many plant species, is loaded into the phloem and unloaded into distal sink tissues. The productivity of agricultural plants largely depends on the efficiency of sucrose and other carbohydrates export from the mesophyll to the phloem through Pd, and further to the ripening fruits and grains [17,[27][28][29][30][31][32][33][34].…”

Plasmodesmata-Related Structural and Functional Proteins: The Long Sought-After Secrets of a Cytoplasmic Channel in Plant Cell Walls

“…Indeed, our knowledge on PD is much dependent on technological progress. Despite their structural complexity, PD are important for plants and require further studies [21].…”

“…They regulate the permeability of PD and control intercellular substance transport and signal communication. PD-mediated symplasmic transport is involved in a variety of plant physiological processes that are pivotal for the development of plants of economic interest, such as shoot apex dormancy, flowering, fruit ripening, fiber elongation, and plant–microbe symbiosis [21]. Understanding PD function through characterization of PD-related proteins may have the potential for improving agronomic traits in the future.…”