title: The dormancy-breaking stimuli "chilling, hypoxia and cyanamide exposure" up-regulate the expression of α-amylase genes in grapevine buds.
abstract: It has been suggested that respiratory stress is involved in the mechanism underlying the dormancy-breaking effect of hydrogen cyanamide (H2CN2) and sodium azide in grapevine buds; indeed, reductions in oxygen levels (hypoxia) and inhibitors of respiration promote bud-break in grapevines. In this study, we showed that, hypoxia increased starch hydrolysis soluble sugar consumption and up-regulated the expression of α-amylase genes (Vvα-AMYs) in grapevine buds, suggesting that these biochemical changes induced by hypoxia, may play a relevant role in the release of buds from endodormancy (ED). Three of the four Vvα-AMY genes that are expressed in grapevine buds were up-regulated by hypoxia and a correlation between changes in sugar content and level of Vvα-AMY gene expression during the hypoxia treatment was found, suggesting that soluble sugars mediate the effect of hypoxia on Vvα-AMY gene expression. Exogenous applications of soluble sugars and sugar analogs confirmed this finding and revealed that osmotic stress induces the expression of Vvα-AMY1 and Vvα-AMY3 and that soluble sugars induces Vvα-AMY2 and Vvα-AMY4 gene expression. Interestingly, the plant hormone gibberellic acid (GA3) induced the expression of Vvα-AMY3 and Vvα-AMY4 genes, while dormancy breaking stimuli, chilling and cyanamide exposure, mainly induced the expression of Vvα-AMY1 and Vvα-AMY2 genes, suggesting that these two α-amylase genes might be involved in the release of grapevine buds from the ED.
authors.affiliation: Universidad de Chile, Facultad de Ciencias, Laboratorio de Bioquímica Vegetal, Casilla 653, Santiago, Chile.
authors.forename: Sebastián
authors.initials: S
authors.lastname: Rubio
authors.affiliation: Universidad de Chile, Facultad de Ciencias, Laboratorio de Bioquímica Vegetal, Casilla 653, Santiago, Chile.
authors.forename: Amanda
authors.initials: A
authors.lastname: Donoso
authors.affiliation: Universidad de Chile, Facultad de Ciencias, Laboratorio de Bioquímica Vegetal, Casilla 653, Santiago, Chile. Electronic address: frperez@uchile.cl.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Pérez
mesh_terms: D002241:Carbohydrates / Q000032:analysis; D003080:Cold Temperature; D003484:Cyanamide / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D010802:Phylogeny; D057445:Plant Dormancy; D010937:Plant Growth Regulators / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D017422:Sequence Analysis, DNA; D015398:Signal Transduction; D013213:Starch / Q000032:analysis; D015854:Up-Regulation; D027843:Vitis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D000516:alpha-Amylases / Q000235:genetics* / Q000378:metabolism
chemical_list: D002241:Carbohydrates; D005875:Gibberellins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D018749:RNA, Plant; D003484:Cyanamide; D013213:Starch; C007842:gibberellic acid; D000516:alpha-Amylases; D010100:Oxygen
keywords: Grapevine buds; Hydrogen cyanamide; Hypoxia; Sugar signaling; α-Amylase