The dormancy-breaking stimuli “chilling, hypoxia and cyanamide exposure” up-regulate the expression of α-amylase genes in grapevine buds

Published Date

15 March 2014, Vol.171(6):373–381, doi:10.1016/j.jplph.2013.11.009

Biochemistry

Title 

The dormancy-breaking stimuli “chilling, hypoxia and cyanamide exposure” up-regulate the expression of α-amylase genes in grapevine buds

• Author 

• Sebastián Rubio
• Amanda Donoso
• Francisco J. Pérez ^,

• Universidad de Chile, Facultad de Ciencias, Laboratorio de Bioquímica Vegetal, Casilla 653, Santiago, Chile

Received 29 July 2013. Revised 19 November 2013. Accepted 19 November 2013. Available online 5 February 2014.

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-AMYgene 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-AMY4gene 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.

Abbreviations

BR₅₀, time required to reach 50% bud-break under forcing conditions

2DOG, 2 deoxi-glucose

6DOG, 6 deoxi-glucose

ED, endodormancy

GA₃, gibberellic acid

Glc, glucose

Fru, fructose

3MG, 3 methyl glucose

Suc, sucrose

Vvα-AMYs, Vitis vinifera α-amylase genes

Keywords

α-Amylase

Grapevine buds

Hydrogen cyanamide

Hypoxia

Sugar signaling

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• ⁎ 
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