Abstract
Plant respiratory burst oxidase homolog (rboh) proteins, which are homologous to the mammalian NADPH oxidase2, have been implicated in the production of reactive oxygen species (ROS) both in stress responses and during development. Ten rboh genes (AtrbohA-J) have been identified in the genome of Arabidopsis. By applying a heterologous expression system with HEK293T cells, we recently showed that AtrbohC and AtrbohD possessed ROS-producing enzyme activities, which were synergistically activated by ionomycin, a Ca2+ ionophore, and calyculin A, a protein phosphatase inhibitor. (Takeda et al., Science, 2008; Ogasawara et al., JBC, 2008). However, functions and activities of the other rbohs are still unknown. To understand the significance and ROS production in plant physiology and its regulation, we have been characterizing all rboh genes using the heterologous expression system. We will report comparative analyses of ROS-producing activities and their regulatory mechanisms of various rboh proteins, and discuss their functional diversity in Arabidopsis.
