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 ).