Plasmodesmal regulator PDLP5 connects phytohormone signaling to symplasmic transport in Arabidopsis thaliana
Date
2017
Authors
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Publisher
University of Delaware
Abstract
The characterization of Plasmodesmata Localized Protein 5 (PDLP5) has revealed that it has important connections to two hormone signaling pathways: salicylic acid (SA) basal defense, and auxin-regulated lateral root emergence. PDLP5 is expressed within the SA defense pathway under control of the genes EDS1, ICS1, and NPR1. PDLP5 both upregulates, and is upregulated by, SA. Overexpressing PDLP5 activates SA accumulation and defense signaling genes, stunting plant growth and causing spontaneous lesion formation in the leaves. In roots, PDLP5 expression is indirectly correlated with the lateral root emergence rate and root branching. PDLP5 is inducible by auxin, and is expressed in a very specific set of endodermal, cortical, and epidermal cells overlying emerging LRP in an auxin-dependent manner. The timing and location of fluorescent auxin sensors in the LRP-overlying cells increased in pdlp5-1 and was reduced in 35S:PDLP5. Using an endodermal tissue-specific promoter expressing diffusible GFP, it was shown that direct upregulation of PDLP5 by either SA treatment, or pER8:PDLP5 induction by estradiol, significantly reduced the movement of GFP into neighboring tissue layers. Overall, PDLP5 appears to be an important regulator connecting symplasmic communication to hormone signaling in Arabidopsis thaliana.