Abstract
Petal color of morning glory, Ipomoea tricolor cv. Heavenly Blue, changes from reddish-purple to blue during blooming. The color change is caused by an unusual vacuolar pH increase of the epidermal colored cells. During flower opening process the volume of colored cell increased two- to three-fold. To clarify the mechanism of this phenomenon we analyzed the ion concentration of the colored cells during flower opening. After measurements of the cell number and volume of the colored protoplasts cations and anions of the cell sap were analyzed using capillary electrophoresis. The major cation was K+ and its concentration was 50 mM at -24 h. The K+ concentration once decreased but turned to increase reaching 40 mM at the full opening. The major anion in the cells was Cl- and PO43-. The concentration of both ions decreased towards the full opening. The relationships between petal color development and cell enlargement are discussed.
