Abstract
Plant cells are connected to their neighbors via plasmodesmata facilitating the exchange of nutrients and signaling molecules. During immune responses, plasmodesmata close, but how this contributes towards a full immune response is unknown. To investigate this, we developed two transgenic lines with which we could induce plasmodesmal closure independently of immune elicitors, using the over-active CALLOSE SYNTHASE3 allele icals3m and the C-terminus of PDLP1 to drive callose deposition at plasmodesmata. Induction of plasmodesmal closure increased the expression of stress responsive genes, salicylic acid accumulation and resistance to Pseudomonas syringae DC3000. More homogeneous plasmodesmal closure using icals3m also led to the accumulation of starch and sugars, decreased leaf growth, as well as hypersusceptibility to Botrytis cinerea. Based on the profile of responses, we conclude that plasmodesmal closure itself activates stress signaling, raising questions of what signals mediate this response and whether these responses occur in all circumstances when plasmodesmata close.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
This version of the manuscript now contains additional data: - plasmodesmal callose staining over 72h post infection with the Pseudomonas syringae mutant hrcC - a representation of the variance in GFP mobility datasets from wild-type, chitin-treated wild-type, LexA::icals3m, LexA::PLUG and PDLP1-OE plants - an examination of differential expression following plasmodesmal closure of ER-stress associated genes - an analysis of DEGs specific to LexA::icals3m and LexA::PLUG