Essential role of the V‐ATPase in male gametophyte development

Summary Intracellular pH homeostasis is a prerequisite for biological processes and requires the action of proton pumps. The vacuolar H + ‐ATPase (V‐ATPase) is involved in regulating pH in endomembrane compartments of all eukaryotic cells. In plants, there is an additional endomembrane proton pump, H + ‐pyrophosphatase (H + ‐PPase). However, the relative roles of the two types of pumps in endomembrane acidification and energization of secondary active transport are unclear. Here, we show that a strong T‐DNA insertion allele of VHA‐A , the single copy gene encoding the catalytic subunit of the Arabidopsis V‐ATPase, causes complete male and partial female gametophytic lethality. Severe changes in the morphology of Golgi stacks and Golgi‐derived vesicles in male gametophytes are the first visible symptoms of cell degeneration leading to a failure to develop mature pollen. Similar effects on Golgi morphology were observed in pollen tubes when growth was blocked by Concanamycin A, a specific V‐ATPase inhibitor. Taken together, our results suggests that V‐ATPase function is essential for Golgi organization and development of the male gametophyte.