BACKGROUND AND AIMS Branching is an important mechanism of plant shape establishment and the direct consequence of axillary bud outgrowth. Recently, hydrogen peroxide (H2O2) metabolism known to be involved in plant growth and development, has been proposed to contribute to axillary bud outgrowth. However, the involvement of H2O2 in this process remains unclear. METHODS We analyzed the content of H2O2 during bud outgrowth and characterized its catabolism, both at the transcriptional level and in terms of its enzymatic activities, using RT-qPCR and spectrophotometric methods, respectively. In addition, we used in-vitro culture to characterize the effects of H2O2 application and GSH synthesis inhibitor on bud outgrowth, in relation to known molecular markers involved in this process. KEY RESULTS Quiescent buds display a high content of H2O2 that declines when bud outgrowth is initiated, as the consequence of an increase in the scavenging activity that is associated with glutathione pathways (ascorbate-glutathione cycle and glutathione biosynthesis); catalase does not appear to be implicated. Modification of bud redox state after the application of H2O2 or BSO (inhibitors of glutathione synthesis) prevents axillary bud outgrowth by repressing organogenesis and newly-formed axis elongation. Hydrogen peroxide also represses bud outgrowth-associated marker gene expression. CONCLUSIONS These results state that high levels of H2O2 in a quiescent state prevents bud outgrowth. Induction of ascorbate-glutathione pathway scavenging activities result in a strong decrease of H2O2 content in buds, which finally allows bud outgrowth.

中文翻译：

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抗坏血酸谷胱甘肽依赖性 H2O2 清除是蔷薇花腋芽生长的重要过程

背景和目的分枝是植物形状建立的重要机制，也是腋芽生长的直接结果。最近，已知过氧化氢（H2O2）代谢参与植物生长和发育，被认为有助于腋芽的生长。然而，H2O2 在这一过程中的参与仍不清楚。方法我们分别使用 RT-qPCR 和分光光度法分析了芽生长过程中 H2O2 的含量，并在转录水平和酶活性方面表征了其分解代谢。此外，我们使用体外培养来表征 H2O2 施用和 GSH 合成抑制剂对芽生长的影响，并与该过程中涉及的已知分子标记相关。主要结果 静止芽显示出高含量的 H2O2，当芽开始生长时，H2O2 含量会下降，这是与谷胱甘肽途径（抗坏血酸-谷胱甘肽循环和谷胱甘肽生物合成）相关的清除活性增加的结果；过氧化氢酶似乎不受影响。使用 H2O2 或 BSO（谷胱甘肽合成抑制剂）后芽氧化还原状态的改变可通过抑制器官发生和新形成的轴伸长来防止腋芽生长。过氧化氢还抑制芽生长相关标记基因的表达。结论 这些结果表明，静止状态下高水平的 H2O2 会阻止芽的生长。抗坏血酸-谷胱甘肽途径清除活性的诱导导致芽中 H2O2 含量大幅下降，最终允许芽生长。