There is an ongoing debate whether ROS bursts and NADPH oxidase induced alkalinization downstream of IAA are required for the root gravitropism. The answer is no. www.biorxiv.org/content/10.1...

New H2O2 monitoring in plants reveals how its important for the soil penetration - a situation where the root is bent and needs to resist the bending. Notice hydrogen peroxide outside of the root (magenta) and intracellular calcium signal (green).
Read our new MS www.biorxiv.org/content/10.1...