Coffee flowering requires a period of water deficit followed by rainfall to break flower bud dormancy and promote anthesis. Since drought followed by re-watering can increase shoot ethylene production, we investigated changes in root, leaf and flower bud ethylene production and expression of genes within the ethylene biosynthesis and signalling pathways and their relationship to coffee flowering. Drought decreased foliar and flower bud ethylene production without changing root ethylene production, even though all tissues likely accumulated the ethylene precursor ACC (1-aminocyclopropane-1-carboxylic acid), since ACS gene expression was maintained while ACO gene expression decreased. The ethylene receptor CaETR4-like was not differentially expressed in leaves under water deficit, but it was downregulated in roots. Re-watering restored shoot ethylene production, which seems important in promoting anthesis. 1-MCP (1- Methylcyclopropene), an ethylene action inhibitor, triggered coffee anthesis without re-watering the plants, which hitherto was considered essential to allow flowering. 1-MCP positively regulated foliar and flower bud ethylene biosynthesis genes (CaACS1-like and CaACO1-like), similar to re-watering, and downregulated CaETR4-like, suggesting that changes in ethylene levels and sensitivity are required to promote coffee anthesis. Thus, drought and re-watering-induced changes in ethylene levels and sensitivity allow coffee flowering, while the growth regulator 1-MCP can potentially regulate anthesis time and intensity.

中文翻译：

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干旱和再浇水会改变乙烯的产生和敏感性，并与咖啡开花有关

咖啡开花需要一段时间的缺水，然后是降雨，以打破花蕾休眠并促进开花。由于干旱后重新浇水可以增加枝条乙烯的产生，我们研究了根、叶和花芽乙烯产生的变化以及乙烯生物合成和信号通路中基因的表达及其与咖啡开花的关系。尽管所有组织都可能积累乙烯前体 ACC（1-氨基环丙烷-1-羧酸），但干旱会降低叶和花芽乙烯的产量，而不会改变根的乙烯产量，因为 ACS 基因表达保持不变，而 ACO 基因表达降低。乙烯受体 CaETR4 样在缺水的叶子中没有差异表达，但它在根中被下调。重新浇水恢复了芽乙烯的产生，这对于促进开花似乎很重要。1-MCP（1-甲基环丙烯）是一种乙烯作用抑制剂，无需重新浇灌植物即可引发咖啡开花，迄今为止，这被认为是开花所必需的。1-MCP 正调节叶和花芽乙烯生物合成基因（CaACS1 样和 CaACO1 样），类似于再浇水，并下调 CaETR4 样，表明需要改变乙烯水平和敏感性来促进咖啡开花。因此，干旱和再浇水引起的乙烯水平和敏感性的变化允许咖啡开花，而生长调节剂 1-MCP 可以潜在地调节开花时间和强度。无需给植物重新浇水即可触发咖啡开花，这在迄今为止被认为是允许开花所必需的。1-MCP 正调节叶和花芽乙烯生物合成基因（CaACS1 样和 CaACO1 样），类似于再浇水，并下调 CaETR4 样，表明需要改变乙烯水平和敏感性来促进咖啡开花。因此，干旱和再浇水引起的乙烯水平和敏感性的变化允许咖啡开花，而生长调节剂 1-MCP 可以潜在地调节开花时间和强度。无需给植物重新浇水即可触发咖啡开花，这在迄今为止被认为是允许开花所必需的。1-MCP 正调节叶和花芽乙烯生物合成基因（CaACS1 样和 CaACO1 样），类似于再浇水，并下调 CaETR4 样，表明需要改变乙烯水平和敏感性来促进咖啡开花。因此，干旱和再浇水引起的乙烯水平和敏感性的变化允许咖啡开花，而生长调节剂 1-MCP 可以潜在地调节开花时间和强度。表明乙烯水平和敏感性的变化是促进咖啡开花所必需的。因此，干旱和再浇水引起的乙烯水平和敏感性的变化允许咖啡开花，而生长调节剂 1-MCP 可以潜在地调节开花时间和强度。表明乙烯水平和敏感性的变化是促进咖啡开花所必需的。因此，干旱和再浇水引起的乙烯水平和敏感性的变化允许咖啡开花，而生长调节剂 1-MCP 可以潜在地调节开花时间和强度。