Pathogenic Bacteria Target Plant Plasmodesmata to Colonize and Invade Surrounding Tissues

Abstract

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. Upon immune stimulation, plants close PD as part of their immune responses. Here, we show that the bacterial pathogen Pseudomonas syringae deploys an effector protein, HopO1-1, that modulates PD function. HopO1-1 is required for P. syringae to spread locally to neighboring tissues during infection. Expression of HopO1-1 in Arabidopsis (Arabidopsis thaliana) increases the distance of PD-dependent molecular flux between neighboring plant cells. Being a putative ribosyltransferase, the catalytic activity of HopO1-1 is required for regulation of PD. HopO1-1 physically interacts with and destabilizes the plant PD-located protein PDLP7 and possibly PDLP5. Both PDLPs are involved in bacterial immunity. Our findings reveal that a pathogenic bacterium utilizes an effector to manipulate PD-mediated host intercellular communication for maximizing the spread of bacterial infection.

The Role of Plasmodesmata-Associated Receptor in Plant Development and Environmental Response

“…PLASMODESMATA-LOCATED PROTEIN 5 (PDLP5) RLP Arabidopsis thaliana AT1G70690 Biotic stress [15,21,77,78].…”

Plasmodesmata-dependent intercellular movement of bacterial effectors

“…The largest molecules can traffic through the cytoplasmic sleeve is known as the size exclusion limit (Kim and Zambryski, 2005). Soluble green fluorescent proteins (1×sGFP; 27 kDa) can freely move between plant cells through PD, whereas the movement of 2×sGFP (54 kDa) and 3×sGFP (71 kDa) are largely inhibited between Arabidopsis cells (Kim et al, 2005;Aung et al, 2020). Among different regulators, callose plays the most prominent role in regulating the PD function.…”

Open Sesame! Uncovering a Hidden Key Used by Pathogenic Bacteria to Open the Doors Connecting Plant Cells

“…But, apparently, pathogenic viruses and fungi are not the only ones who know how to modulate PD for spreading virulence signals between cells. Aung et al (2020) demonstrate, in a groundbreaking study, that pathogenic bacteria have also found a way.…”

“…Scale bars 5 50 mm. (Reprinted from Aung et al [2020], Figure 4A.) [OPEN] Articles can be viewed without a subscription.…”

“…www.plantcell.org/cgi/doi/10.1105/tpc.20.00055 contact sites, endoplasmic reticulumderived desmotubules, and their associated actin proteins, all found within the PD channel (Nicolas et al, 2018), are regulated by HopO1-1. But what is clear is that just as pathogenic bacteria are opening the doors between plant cells, this study by Aung et al (2020) is likewise opening its own doors to a whole new field of research into bacterial effector-mediated plasmodesmatal modulation.…”