The Role of Plant Bax Inhibitor-1 in Suppressing H2O2-Induced Cell Death

Hydrogen peroxide (H2O2) is known to be a typical endogenous signaling molecule that triggers programmed cell death in plants and metazoan. In this respect, they seem to share the mechanism of cell death caused by H2O2 and other reactive oxygen species (ROS). Bax inhibitor-1 (BI-1) is a well-conserved protein in plants and animals that serves as the inhibitor of mammalian proapoptotic proteins as well as plant ROS-induced cell death. As a target of H2O2, mitochondrion is considered to be an organelle of the primary ROS generation and perception. Thus, analysis of mitochondrial behavior in relation to functional roles of regulatory proteins (e.g., BI-1) will lead us to understand the core mechanisms of cell death regulation conserved in eukaryotes. In this chapter, we first introduce techniques of analyzing H2O2- (and ROS-) mediated changes in mitochondrial behavior. Next, we describe our understanding of the functions of plant BI-1 in regulation of ROS-induced cell death, with a technical basis for assessment of tolerance to ROS-mediated cell death in model plant systems.