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

Author:
Rubio, Sebastián, Donoso, Amanda, Pérez, Francisco J.
Source:
Journal of plant physiology 2014 v.171 no.6 pp. 373-381
ISSN:
0176-1617
Subject:
Vitis, alpha-amylase, buds, cold treatment, dormancy breaking, gene expression, gene expression regulation, genes, gibberellic acid, hydrogen cyanamide, hydrolysis, hypoxia, osmotic stress, oxygen, sodium azide, starch, sugar content, sugars
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.
Agid:
5414034