title: Abscisic acid (ABA) regulates grape bud dormancy, and dormancy release stimuli may act through modification of ABA metabolism.
abstract: In warm-winter regions, induction of dormancy release by hydrogen cyanamide (HC) is mandatory for commercial table grape production. Induction of respiratory stress by HC leads to dormancy release via an uncharacterized biochemical cascade that could reveal the mechanism underlying this phenomenon. Previous studies proposed a central role for abscisic acid (ABA) in the repression of bud meristem activity, and suggested its removal as a critical step in the HC-induced cascade. In the current study, support for these assumptions was sought. The data show that ABA indeed inhibits dormancy release in grape (Vitis vinifera) buds and attenuates the advancing effect of HC. However, HC-dependent recovery was detected, and was affected by dormancy status. HC reduced VvXERICO and VvNCED transcript levels and induced levels of VvABA8'OH homologues. Regulation of these central players in ABA metabolism correlated with decreased ABA and increased ABA catabolite levels in HC-treated buds. Interestingly, an inhibitor of ethylene signalling attenuated these effects of HC on ABA metabolism. HC also modulated the expression of ABA signalling regulators, in a manner that supports a decreased ABA level and response. Taken together, the data support HC-induced removal of ABA-mediated repression via regulation of ABA metabolism and signalling. Expression profiling during the natural dormancy cycle revealed that at maximal dormancy, the HC-regulated VvNCED1 transcript level starts to drop. In parallel, levels of VvA8H-CYP707A4 transcript and ABA catabolites increase sharply. This may provide initial support for the involvement of ABA metabolism also in the execution of natural dormancy.
authors.affiliation: Institute of Plant Sciences, Department of Fruit Tree Sciences, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel Institute of Plant Sciences and Genetics in Agriculture, The Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Chuanlin
authors.initials: C
authors.lastname: Zheng
authors.affiliation: Institute of Plant Sciences, Department of Fruit Tree Sciences, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel.
authors.forename: Tamar
authors.initials: T
authors.lastname: Halaly
authors.affiliation: Institute of Plant Sciences, Department of Fruit Tree Sciences, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel Institute of Plant Sciences and Genetics in Agriculture, The Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Atiako Kwame
authors.initials: AK
authors.lastname: Acheampong
authors.affiliation: RIKEN Plant Science Center, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Takebayashi
authors.affiliation: RIKEN Plant Science Center, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Jikumaru
authors.affiliation: RIKEN Plant Science Center, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kamiya
authors.affiliation: Institute of Plant Sciences, Department of Fruit Tree Sciences, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel vettior@agri.gov.il.
authors.forename: Etti
authors.initials: E
authors.lastname: Or
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018519:Meristem / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D057445:Plant Dormancy; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D027843:Vitis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D000040:Abscisic Acid
keywords: 9-cis-epoxycarotenoid dioxygenase; ABA 8′-hydroxylase; abscisic acid; bud; dormancy; grapevine.