The role of plasmodesmata regulation in root responses to macronutrient and water availability

Modulation of root morphology allows plants to intercept resources whilst avoiding areas of soil with suboptimal conditions. Plasmodesmata (PD) are membranous pores embedded in the cell wall that connect the cytoplasm of neighbouring cells. Regulation of this symplasmic connectivity by proteins that localise to PD, such as PD-located beta-1,3 glucanases and callose synthases control root morphology. Technical constraints hamper efforts to dissect PD proteomes and understand the regulation of PD transport. Here, the tool PIP1 (Plasmodesmata in silico Proteome 1) was developed that uses comparative proteomics to predict PD proteins in different species. PIP1 was validated by comparing in silico - and experimentally derived PD proteomes obtained from Arabidopsis thaliana and poplar. In combination with meta-transcriptomics, PIP1 was used to identify conditions that may involve regulation of PD in A. thaliana. Predictions were experimentally tested by measuring symplasmic transport of GFP using confocal microscopy and promoter reporter lines. Together, this work suggests that plants use mechanisms involving the regulation of symplasmic transport to mediate root responses to water availability, salinity and nutrient conditions.