Uncovering plant-pathogen crosstalk through apoplastic proteomic studies

Abstract

Plant pathogens have evolved by developing different strategies to infect their host, which in turn have elaborated immune responses to counter the pathogen invasion. The apoplast, including the cell wall and extracellular space outside the plasma membrane, is one of the first compartments where pathogen-host interaction occurs. The plant cell wall is composed of a complex network of polysaccharides polymers and glycoproteins and serves as a natural physical barrier against pathogen invasion. The apoplastic fluid, circulating through the cell wall and intercellular spaces, provides a means for delivering molecules and facilitating intercellular communications. Some plant-pathogen interactions lead to plant cell wall degradation allowing pathogens to penetrate into the cells. In turn, the plant immune system recognizes microbial- or damage-associated molecular patterns (MAMPs or DAMPs) and initiates a set of basal immune responses, including the strengthening of the plant cell wall. The establishment of defense requires the regulation of a wide variety of proteins that are involved at different levels, from receptor perception of the pathogen via signaling mechanisms to the strengthening of the cell wall or degradation of the pathogen itself. A fine regulation of apoplastic proteins is therefore essential for rapid and effective pathogen perception and for maintaining cell wall integrity. This review aims to provide insight into analyses using proteomic approaches of the apoplast to highlight the modulation of the apoplastic protein patterns during pathogen infection and to unravel the key players involved in plant-pathogen interaction.

Advances in proteomic technologies and their scope of application in understanding plant–pathogen interactions

“…These limitations can be overhauled by subjecting the protein mixture to specific LAP enrichment procedures and subsequent analysis by advanced proteomic approaches like isotope-based or MSbased targeted analysis, deep proteome analysis and peptide ligand-based approaches (Delaunois et al 2014;Righetti and Boschetti 2016).…”

“…Generally, apoplastic spaces are filled with a circulating fluid which contains a myriad of host defense proteins that act against the cell wall of colonizing pathogen and their secreted proteins especially, apoplastic effectors. Since, the intercellular apoplastic space is one of the major battle zones, wherein the molecular warriors of both host and pathogen dynamically interact, it is regarded as one of the potential areas for probing with proteomic approaches (Delaunois et al 2014). When cytoplasmic effectors are recognized by plants that express direct ligand-receptor or corresponding resistance (R) protein, it triggers hypersensitive response (HR) or systemic acquired resistance (SAR) as a consequence of ETI (Giraldo and Valent 2013).…”

MicroRNA Networks in Plant-Microorganism Interactions

“…When an interaction between plant and a pathogen occurs, the first response of the plant immune system is the perception of elicitors, the microbe-associated molecular patterns (MAMPs), by pattern recognition receptors (PRR) (Delaunois et al 2014). Following, a cascade of signal transduction is triggered, leading to the activation of plant defense pathways, which include the production of reactive oxygen species (ROS), synthesis of phytohormones and pathogenesisrelated (PR) proteins, and the strengthening of the plant cell wall (van Loon et al 2006;Robert-Seilaniantz et al 2011;Underwood 2012;Scheler et al 2013).…”

Plant cell wall in pathogenesis, parasitism and symbiosis

“…Xia and co-authors summarize experimental approaches based on cell imaging, spectroscopic analyses and metabolic profiling techniques (Xia et al, 2014). The review by Delaunois and co-worker provides an insight into the modulation of the apoplastic protein patterns during pathogen infection (Delaunois et al, 2014). Super-resolution microscopy using microscopy combined with specific and efficient labeling techniques yield information on three-dimensional modifications of cell wall polymers (i.e., callose-cellulose network) at the site of attempted microbial penetration (Voigt, 2014).…”