What proteomic analysis of the apoplast tells us about plant–pathogen interactions

Abstract

Plant pathogens have developed different strategies during their evolution to infect and colonize their hosts. In the same way, plants have evolved different mechanisms acting against potential pathogens trying to infect and colonize their tissues. Regulation of a wide variety of proteins is required in order to perceive the pathogen and to activate the plant defence mechanisms. The apoplast is the first compartment where these recognition phenomena occur in most plantpathogen interactions, allowing the exchange of different molecules and facilitating inter-and intracellular communication in plant cells. Proteomic analysis of the apoplast in recent years has found the initial biochemical responses involved in pathogen recognition and early defence responses. However, this proteomic approach requires some specific experimental conditions to obtain an extract free of cytoplasmic proteins and nonprotein contaminants that affect the subsequent stages of separation and quantification. Obtaining the highest proportion of proteins from the apoplastic space in infected tissues requires different steps such as extraction of apoplastic washing fluids and preparation of total secreted proteins (protein precipitation, solubilization, separation and digestion). Protein identification using mass spectrometry techniques and bioinformatics tools identifying peptides for the extracellular exportation is required to confirm the apoplastic location. This review compiles the most commonly used techniques for proteomic studies, focusing on the early biochemical changes occurring in the apoplast of plants infected by a wide range of pathogens. The scope of this approach to discover the molecular mechanisms involved in the plant-pathogen interaction is discussed.

Subcellular Roles of Glutathione in Mediating Plant Defense during Biotic Stress

“…Thus, they have developed a sophisticated network of defense to protect themselves from developing diseases [ 1 , 2 , 3 ]. Physical adaptations, such as thickening of cell walls, keep the invaders outside [ 4 ]. For some pathogens these barriers are ineffective, and once inside, the plant activates chemical pathways to fight the dangerous invaders [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ].…”

Physiological and Proteomic Changes in the Apoplast Accompany Leaf Senescence in Arabidopsis

“…The AF represents around 4%to11%ofthetotalleaffreshweight (SattelmacherandHorst,2007). Its composition consists of molecules related to metabolism and signaling, such as amino acids, polysaccharides, secondary metabolites, ions, and secreted mRNA and proteins with several functions, particularly enzymes related to defense and proteolysis (Sattelmacher and Horst, 2007;Martínez-González et al, 2018). The apoplast plays a critical role in plant development, as it provides the environment for cell expansion and cell wall maintenance, ion and molecule trafficking, source-to-sink translocation of nutrients, intercellular and systemic signaling, stress perception, and response (Hoson, 1998;O'Leary et al, 2016;Rodríguez-Celma et al, 2016).…”

The Multiple Facets of Plant–Fungal Interactions Revealed Through Plant and Fungal Secretomics

“…The classical view of secretion of these proteins assumes that they are synthesized and delivered using the conventional ER secretory pathway. Several reviews on this topic have been published (Agrawal et al, 2010;Ghahremani et al, 2016;Martínez-González et al, 2018). A plant protein secreted via the canonical secretory pathway presents a N-terminal signal peptide typically 15-30 AAs long, which enables translocation of the protein across the ER in plants and which is cleaved upon secretion (Emanuelsson et al, 2007).…”

“…superoxide dismutases, catalases, peroxidases), as well as pathogenesis-related (PR) proteins (e.g. 2,3,4,5,8,10,16 and 17) (Tanveer et al, 2014;Ghahremani et al, 2016;Martínez-González et al, 2018). We refer the reader to these comprehensive reviews for further information on this topic.…”