Projects
A hallmark of multicellular organisms is their ability to maintain physiological homeostasis by communicating among cells, tissues, and organs. In plants, intercellular communication is largely dependent on plasmodesmata (PD), which are membrane-lined channels connecting adjacent plant cells. In our laboratory, we are broadly interested in understanding how plants harness intercellular communication to maintain homeostasis in the regulation of growth and defense. Our long-term research goal is to determine the underlying mechanisms regulating cell-to-cell communication in plants to engineer climate-resilience crops for future agriculture.
Regulation of PD function at specific cell interfaces
Different cell types have evolved specialized functions to effectively support a multicellular organism to operate as a unit. Cells need to maintain their own cellular identity while effectively communicating with surrounding cells and tissues. It has been well established that the plant polysaccharide callose (ß-1,3-glucan) is deposited at PD, regulating the PD aperture; however, the regulation of PD at different cell interfaces is largely unknown. PD-located proteins (PDLPs) regulate callose accumulation at PD through unknown mechanisms. The Arabidopsis genome encodes eight members of PDLPs, sequentially named PDLP1-8. Our recent findings showed that PDLP5 and PDLP6 are expressed in non-overlapping cell types. The constitutive overexpression of PDLP5 and PDLP6 results in the overaccumulation of callose at PD at different cell interfaces, indicating their functional specificities in different cell types. Our studies begin to reveal that PDLPs play a major role in regulating PD function at specific cell interfaces. We will further investigate the cell type-specific function of other PDLPs in Arabidopsis.
PD function as signaling hubs
To determine the molecular function of PDLPs, we performed a proximity labeling (PL) approach. We showed that the PL assay is a powerful tool to map PD proteomes at nanometer resolution. We identified several putative functional partners of PDLP5. Among the candidate proteins, we are focusing on determining the molecular function of several Leucine-Rich Repeats Receptor-Like Kinases (LRR-RLKs) and Cysteine-Rich Receptor-Like Kinases (CRKs). Since LRR-RLKs and CRKs are known to involve in signal perception and transduction, PDLP5 might recruit them to form signaling hubs at PD. We will employ a combination of molecular, cellular, genetic, and biochemical approaches to determine the role of PD as major signaling hubs in regulating local and long-distance cell communication.
Dynamic regulation of PD during bacterial infection
Plants trigger PD closure upon microbial infection, activating PD immunity. To overcome PD immunity, microbial pathogens inject protein effectors into plant cells to target PD. The findings suggest that PD are dynamically regulated at different stages of microbial infections. To better understand the role of PD during plant immunity, we study the Arabidopsis thaliana-Pseudomonas syringae pathosystem. We utilized the PL assay to capture the changes in PDLP5-containing protein complexes upon bacterial infection. We identified a set of candidate proteins with potential roles in regulating PD function during bacterial infection. We are determining the molecular function of candidate proteins in regulating PD function and plant immunity. We will further utilize the PL assay to capture the dynamic changes in PDLP5-functional protein complexes at different stages of bacterial infection.