PDLP

PDLP stands for plasmodesmata-located protein, a family of plant proteins localized to plasmodesmata, the microscopic channels that connect plant cells. PDLPs are involved in regulating intercellular transport by influencing the permeability of plasmodesmata, in part through modulation of callose deposition at the plasmodesmal neck region.

Most PDLPs are single-pass type I membrane proteins with an extracellular domain facing the cell wall and a short cytoplasmic tail. They accumulate at plasmodesmata in the plasma membrane and often participate in signaling networks that coordinate cell-to-cell communication. The proteins are considered to be part of a larger regulatory complex that integrates developmental cues and environmental signals.

Functionally, PDLPs contribute to the dynamic control of plasmodesmatal permeability. Several family members affect the synthesis or turnover of callose at plasmodesmata, leading to changes in the size exclusion limit and the movement of macromolecules between cells. In Arabidopsis, PDLP5 is among the best studied; its activity is associated with increased callose deposition and reduced intercellular transport, particularly during defense responses.

Regulation of PDLPs is linked to developmental stage and stress signaling. Expression of PDLP genes can be induced by defense hormones such as salicylic acid and by pathogen infection, aligning PDLP activity with the plant’s need to modulate connectivity under stress. PDLPs typically function alongside other plasmodesmal regulators, including callose synthases, to fine-tune cell-to-cell communication.

Members: In Arabidopsis, the PDLP family includes several genes (for example, PDLP1 through PDLP8), with distinct but overlapping expression patterns and roles. Research often uses PDLP fusions to study localization and transport effects, advancing understanding of plasmodesmal regulation.

See also: plasmodesmata, callose synthase.