title: Synchrony between flower opening and petal-color change from red to blue in morning glory, Ipomoea tricolor cv. Heavenly Blue.
abstract: Petal color change in morning glory Ipomoea tricolor cv. Heavenly Blue, from red to blue, during the flower-opening period is due to an unusual increase in vacuolar pH (pHv) from 6.6 to 7.7 in colored epidermal cells. We clarified that this pHv increase is involved in tonoplast-localized Na+/H+ exchanger (NHX). However, the mechanism of pHv increase and the physiological role of NHX1 in petal cells have remained obscure. In this study, synchrony of petal-color change from red to blue, pHv increase, K+ accumulation, and cell expansion growth during flower-opening period were examined with special reference to ItNHX1. 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. This function may lead to full opening of petals with a characteristic blue color.
authors.affiliation: Graduate School of Information Science, Nagoya University, Aichi, Japan. yoshidak@is.nagoya-u.ac.jp
authors.forename: Kumi
authors.initials: K
authors.lastname: Yoshida
authors.forename: Naoko
authors.initials: N
authors.lastname: Miki
authors.forename: Kazumi
authors.initials: K
authors.lastname: Momonoi
authors.forename: Miki
authors.initials: M
authors.lastname: Kawachi
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Katou
authors.forename: Yoshiji
authors.initials: Y
authors.lastname: Okazaki
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Uozumi
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Maeshima
authors.forename: Tadao
authors.initials: T
authors.lastname: Kondo
mesh_terms: D048429:Cell Size; D003116:Color; D035264:Flowers / Q000166:cytology / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant; D006863:Hydrogen-Ion Concentration; D007477:Ions; D027741:Ipomoea / Q000166:cytology / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D008954:Models, Biological; D008969:Molecular Sequence Data; D010858:Pigmentation / Q000502:physiology*; D019441:Plant Epidermis / Q000166:cytology / Q000378:metabolism; D011523:Protoplasts / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: D007477:Ions; D017923:Sodium-Hydrogen Exchangers; D012965:Sodium Chloride