Abstract
Plant growth is tightly linked to development of vacuole. Because vacuole occupies most (>95%) of cell space. Two H + pumps, vacuolar H + -ATPase and vacuolar H +-pyrophosphatase (V-PPase) contribute to acidification of vacuolar space. They support development of vacuole energetically. V-PPase is a plant specific H + pump of which substrate is inorganic pyrophosphate.
To investigate physiological function of V-PPase, we isolated two mutants of Arabidopsis thaliana of which V-PPase gene (VHP1) was inserted by T-DNA from mutant library. Both mutants grew as well as wild type when they were cultivated in medium containing carbon source. The mutants, however, shows defect in growth in autotrophic condition. Size of mutant plants was about half of that of wild type. Severe growth-defect was observed when light limiting condition. These results indicate that V-PPase is not essential for survival of plant cell but extremely important for natural growth of plant.
