The role of reactive oxygen species in regulation of the plasma membrane H⁺-ATPase activity in Masson pine (Pinus massoniana Lamb.) roots responding to acid stress.

This article investigates the role of reactive oxygen species (ROS) in regulating plasma membrane (PM) H+- ATPase activity in Masson pine (Pinus massoniana Lamb.) roots under acid stress simulated by acid rain (SAR). The study demonstrates that acid stress and exogenous hydrogen peroxide (H2O2) increase cellular ROS levels, antioxidant enzyme activities, PM NADPH oxidase activity, and PM H+- ATPase activity, which correlate positively with seedling growth and acid tolerance. Inhibition of PM H+- ATPase or NADPH oxidase activities by specific inhibitors reduces ROS accumulation, antioxidant enzyme activities, PM H+- ATPase activity, and seedling growth, indicating a coordinated interaction among ROS signaling, PM NADPH oxidase, and PM H+- ATPase in acid stress response. The authors propose a model where acid stress induces ROS production via PM NADPH oxidase, which acts as a signaling molecule to enhance PM H+- ATPase activity, thereby maintaining cellular ion homeostasis and promoting acid tolerance in Masson pine roots.