Abstract
We have been studied the mechanism of petal color change of Ipomoea tricolor cv. Heavenly Blue during flower-opening period. We have already reported the involvement of ItNHX1 in the pHv increase and found synchrony of petal-color change from red to blue, pHv increase, K<+>+</+> accumulation, and cell expansion growth during flower-opening period. We concluded that ItNHX1 exchanges K<+>+</+>, but not Na<+>+</+>, with H+ to accumulate an ionic osmoticum in the vacuole, which is then followed by cell expansion growth. To clarify whether this system involving NHX was comporehensive in other morning glories during flower opening period, we studied with morning glory petals of Ipomoea tricolor cv. Pearly Gate and red flowers of Ipomoea nil cv. Scarlet O'Hara. We analyzed their vacuolar pH change and ion contents of epidermal cells from -24 h to 0 h and found that in both case vacuolar pH increased and K<+>+</+> content became higher at 0 h compared with those at -24 h. We will discuss the role of NHXs in cell growth during flower opening of morning glory petals with special reference with NHXs.
K. Yoshida et al. Proc. Jpn. Acad. Ser. B, 85, 187 (2009).
