Specific Targeting of a Plasmodesmal Protein Affecting Cell-to-Cell Communication

Abstract

Plasmodesmata provide the cytoplasmic conduits for cell-to-cell communication throughout plant tissues and participate in a diverse set of non–cell-autonomous functions. Despite their central role in growth and development and defence, resolving their modus operandi remains a major challenge in plant biology. Features of protein sequences and/or structure that determine protein targeting to plasmodesmata were previously unknown. We identify here a novel family of plasmodesmata-located proteins (called PDLP1) whose members have the features of type I membrane receptor-like proteins. We focus our studies on the first identified type member (namely At5g43980, or PDLP1a) and show that, following its altered expression, it is effective in modulating cell-to-cell trafficking. PDLP1a is targeted to plasmodesmata via the secretory pathway in a Brefeldin A–sensitive and COPII-dependent manner, and resides at plasmodesmata with its C-terminus in the cytoplasmic domain and its N-terminus in the apoplast. Using a deletion analysis, we show that the single transmembrane domain (TMD) of PDLP1a contains all the information necessary for intracellular targeting of this type I membrane protein to plasmodesmata, such that the TMD can be used to target heterologous proteins to this location. These studies identify a new family of plasmodesmal proteins that affect cell-to-cell communication. They exhibit a mode of intracellular trafficking and targeting novel for plant biology and provide technological opportunities for targeting different proteins to plasmodesmata to aid in plasmodesmal characterisation.

A calmodulin‐like protein regulates plasmodesmal closure during bacterial immune responses

“…In leaves, CML41‐GFP localizes to punctate spots at the cell periphery (Fig. 2a–c), patterning that is reminiscent of plasmodesmata (Thomas et al ., 2008; Simpson et al ., 2009). We confirmed CML41‐GFP was localized to plasmodesmata by co‐staining plasmodesmal callose in Arabidopsis with aniline blue (Fig.…”

“…2d–f) or with Plasmodesmata‐located Protein 1 (PDLP1) in Nicotiana benthamiana (Fig. 2g–i) (Thomas et al ., 2008). Plasmodesmal‐association has not yet been observed for any other CMLs, suggesting a novel role for CML41 of decoding flg22‐induced Ca 2+ signals at plasmodesmata (Bender & Snedden, 2013).…”

LYM2-dependent chitin perception limits molecular flux via plasmodesmata

“…Therefore, we examined the effect of chitin and the flagellin-derived peptide flg22 on cell-to-cell movement of a constitutively expressed cytosolic marker by microprojectile bombardment of leaf tissue. This assay monitors the expression of fluorescent proteins such as GFP and monomeric red fluorescent protein (mRFP) in individual transformed cells, from where they can diffuse freely through PD and thus provide a measure of conductivity through the pore (20) (Fig. S1).…”

Grain setting defect1, Encoding a Remorin Protein, Affects the Grain Setting in Rice through Regulating Plasmodesmatal Conductance

“…A proposed model for GSD1 modulation of PD permeability. GSD1 encodes a PM protein, remorin, which is colocalized in PD with PD-specific proteins: GPI-anchored callose binding protein PDCB1, which is located at the neck region of PD (Simpson et al, 2009); and PD-located proteins PDLP1 and PDLP5 (Thomas et al, 2008;Lee et al, 2011). GSD1 interacts with OsACT1, which is associated with the desmotubule structure in PD.…”