Plasmodesmata are microscopic channels that connect adjacent plant cells, enabling direct symplastic transport of molecules, including photoassimilates. They play a crucial role in intercellular communication and the regulation of assimilate translocation from source to sink tissues. The structure, frequency, and permeability of plasmodesmata influence the efficiency of sucrose and other carbohydrate movement, impacting plant growth and yield. This review explores the ultrastructure of plasmodesmata, the molecular mechanisms governing their regulation, and their role in assimilate partitioning under normal and stress conditions. Emphasis is placed on recent advances in imaging techniques, molecular gating, and the integration of plasmodesmal function with phloem loading and unloading strategies. Understanding these pathways offers insights for improving crop productivity through targeted manipulation of assimilate transport mechanisms.
Plasmodesmata, symplastic transport, phloem loading, source–sink relationship
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