Abstract
Petal color of blue morning glory (Ipomoea tricolor cv. Heavenly blue) changes from red to blue during the flower opening. During this blooming stage, vacuolar pH of epidermal colored cells increased from 6.6 to 7.7. To clarify the mechanism of vacuolar pH increase, we prepared vacuolar membrane from colored epidermal cells of buds and open flower petals, and then ion transport activities, proton transport activity and Na+/H+ antiporter activity, of the membrane were measured. The proton transport activities of open flower and half-open flower were higher than that of bud. Pyrophosphate dependent proton transport activities were much higher than that of ATP dependent one. The activities of tonoplast of summer and autumn petals were not different. Measurement of Na+/H+ antiporter activities are in progress.
