How Does pH Fit in with Oscillating Polar Growth?

The document reviewed the role of pH in oscillating polar growth in root hairs and pollen tubes, focusing on the acid growth theory and the unclear mechanisms regulating apoplastic pH (apopH). It proposed that oscillatory polar growth, occurring every 20-40 seconds, was regulated by calcium (Ca²+), reactive oxygen species (ROS), and pH gradients. NADPH oxidases (NOXs) and type-III peroxidases (PERs) were identified as key players in ROS homeostasis, influencing cell wall dynamics. The study emphasized the role of plasma membrane H+-ATPases (AHAs) in apoplastic pH regulation, modulated by auxin, affecting cell wall loosening and growth. It highlighted the need for further understanding of these oscillations and their role in plant cell expansion, suggesting future research directions to enhance crop growth under stress conditions.