Zheng Chuanlin, Halaly Tamar, Acheampong Atiako Kwame, Takebayashi Yumiko, Jikumaru Yusuke, Kamiya Yuji, Or Etti
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.
Institute of Plant Sciences, Department of Fruit Tree Sciences, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel.
J Exp Bot. 2015 Mar;66(5):1527-42. doi: 10.1093/jxb/eru519. Epub 2015 Jan 5.
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.
在暖冬地区，对于商业化鲜食葡萄生产而言，用氰胺（HC）诱导打破休眠是必不可少的。HC诱导的呼吸胁迫通过一个未知的生化级联反应导致休眠解除，这可能揭示了这一现象的潜在机制。先前的研究表明脱落酸（ABA）在抑制芽分生组织活性中起核心作用，并提出去除ABA是HC诱导的级联反应中的关键步骤。在本研究中，我们对这些假设进行了验证。数据表明，ABA确实抑制葡萄（Vitis vinifera）芽的休眠解除，并减弱HC的促进作用。然而，检测到了依赖于HC的恢复情况，且其受休眠状态的影响。HC降低了VvXERICO和VvNCED的转录水平，并诱导了VvABA8'OH同源物的水平。这些ABA代谢核心调控因子的调节与HC处理芽中ABA水平降低和ABA分解代谢物水平升高相关。有趣的是，乙烯信号抑制剂减弱了HC对ABA代谢的这些影响。HC还以一种支持ABA水平和反应降低的方式调节ABA信号调节因子的表达。综上所述，数据支持HC通过调节ABA代谢和信号传导诱导去除ABA介导的抑制作用。自然休眠周期中的表达谱分析表明，在最大休眠期，HC调控的VvNCED1转录水平开始下降。与此同时，VvA8H-CYP707A4转录本水平和ABA分解代谢物急剧增加。这可能为ABA代谢也参与自然休眠的解除提供了初步支持。
