The Plant Host–Pathogen Interface Cell Wall and Membrane Dynamics of Pathogen-Induced Responses

ABSTRACT: Perception of pathogens by their hosts is the outcome of a highly coordinated and sophisticated surveillance network, tightly regulated by both host and pathogen elicitors, effectors, and signaling processes. In this article, we focus on two relatively well-studied host– pathogens systems, one involving a bacterial–plant interaction (Pseu-domonas syringae–Arabidopsis) and the other involving an oomycete– plant interaction (Phytophthora sojae–soybean). We discuss the status of current research related to events occurring at the host–pathogen inter-face in these two systems, and how these events influence the organization and activation of resistance responses in the respective hosts. This recent research has revealed that in addition to the previously identified resis-tance machinery (R-proteins, molecular chaperones, etc.), the dynamics of the cell wall, membrane trafficking, and the actin cytoskeleton are intimately associated with the activation of resistance in plants. Specifi-cally, in Arabidopsis, a possible connection between the actin machinery and R-protein- mediated induction of disease resistance is described. In the case of the P. sojae–soybean interaction, we describe the fact that a classical basal resistance elicitor, the cell wall glucan elicitor from the pathogen, can directly activate host hypersensitive cell death, which is apparently modulated in a race-specific manner by the presence of R genes in the host