The response of actin to Al3+requires the activity of a NADPH oxidase
Reactive oxygen species (ROS) generated by the membrane-associated NADPH oxidase Reactive burst oxidase Homologue (RboH) represent an important early signal in the activation of defence in grapevine (Chang & Nick, 2012; Duan et al., 2016). We asked, therefore, whether the apoplastic oxidative burst generated by RboH- would be required for aluminum-dependent actin bundling (Figure 2D ). To investigate this possibility, we used diphenylene iodonium (DPI), a specific inhibitor of NADPH oxidases, to suppress the formation of apoplastic superoxide anions. When DPI was administered alone, it did not cause any significant bundling of actin (Figure 2A, Figure 2C ). However, it was able to suppress the bundling response evoked by 200 µM Al3+ (Figure 2B, Figure 2C ) demonstrating that the ROS generated by RboH are necessary for aluminium-induced actin bundling (Figure 2D ).