Poster: Secondary Metabolism

Abs # 269: Vacuolar pH measurement and in vivo mechanism of flower color development

Presenter:	Yoshida, Kumi , yoshidak@info.human.nagoya-u.ac.jp
Authors	Yoshida, Kumi  (A)   Toyama-Kato, Yuki  (B)   Kameda, Kiyoshi  (B)   Osanai, Minako  (C)   Kondo, Tadao  (D)
Affiliations:	(A): Graduate School of Human Informatics, Nagoya University (B): School of Life Studies, Sugiyama Jogakuen University (C): Chemical Instrument Center, Nagoya University (D): Graduate School of Bioagricultural Sciences, Nagoya University
Web Site:	http://www.nacos.com/jspp/

Red through purple to blue flower color is caused by anthocyanins, though they have only few chromophores, anthocyanidins. The color variation of anthocyanins is affected by pH, concentration of pigments, co-pigments and metal ions. However, in vivo mechanism of color development and stability is still unclear. Anthocyanins are located in vacuoles of epidermal cells in flower tissue. To clarify the mechanism in living petal cells we measured vacuolar pH directly by using proton selective microelectrode. We found that vacuolar pH of epidermal colored cells of mourning glory petals increase one pH unit during blooming. Vacuolar pH value (pHv) of bud and open petals of Ipomoea tricolor cv. Heavenly blue was 6.6 and 7.7, and that of Ipomoea nil cv. Danjuro was 5.8 and 6.8 indicating that it might be physiologically correlated with flower blooming, water absorption and cell expansion. Using petal tissue and protoplasts prepared from petals vacuolar pH of various blue and red flowers (Hydrangea macrophylla, Delphinium hybridum, Meconopsis grandis, Gentiana triflora, Rosa hybridum and Camellia sasanqua) was measured. The pHv of red flower was rather low than that of blue petals.