Role of H+-ATPase and Alternative Oxidase in Regulation of Intracellular pH at Different Stages of Development of the Tobacco Male Gametophyte

In order to determine the role of the plasma membrane H⁺-ATPase and alternative oxidase (alternative pathway of respiration) in the regulation of intracellular pH during development of the tobacco male gametophyte, we studied the changes in pH due to the inhibition of these enzymes by orthovadanate and benzhydroxamic acid, respectively. The inhibition of these enzymes decreased the intracellular pH at all three studied stages of the male gametophyte development: middle and late binuclear pollen grains and activated mature pollen grain. The data obtained suggest that H⁺-ATPase and alternative oxidase are involved in the regulation of intracellular pH of the pollen grain during its differentiation and activation that precede germination. At the same time, during the recovery of intracellular pH after its acidification by propionic acid, it was found that other mechanisms, not related to the above mentioned, greatly contribute to the regulation of pH.