Figure 9. Regulation model central to ROS.

The catalysis by Prx, SOD and NADPH oxidase (also called Rboh) lead to ROS accumulation (1, 2A,), and Rboh activity is controlled by the small GTPase (2B) that were positively regulated with PLD-derived PA (2C) and GAP proteins (2D), and negatively regulated by GDI2 (2E). PLD is a component of ABA signaling pathway to activate SAPK (3) and is the key point at which ethylene and ABA showed negative interplay (4). ABA can be diffused through ABC transporters (5). In ethylene signaling pathway, EIN3 activates ERF genes (6), and was degraded by the UPS (7). The UPS reglated plant growth and stress tolerance (8). ROS could be abolished by PrxR, AOX (9), CAT, APX (10) and P450 (11). The CAT and APX genes were trans-activated by ERF (12) and HSF (13). ROS activate calcium influx channel (14A), and stimulates Ca²⁺ release from internal Ca²⁺ stores (14B). Ca²⁺ stimulates CaM (14C), which activates HSF activity (14D). ROS stimulate HSF (15) and NAC (16). ROS exert negative regulation on auxin signaling pathway that is suppressed by SAUR and stimulated by nitrilase, respectively (17). Furthermore, ROS could be diffused through aquaporin (18). The HR genes in the present study were mapped on this model. The color bar represents the log2 transformed relative expression level on the time course of heat treatment (from left to right: 20 min, 60 min, 2 h, 4 h, and 8 h in sequence). The color scale is shown at the right. Blue: down-regulation, red: up-regulation.