Xing Li-Bo, Zhang Dong, Li You-Mei, Shen Ya-Wen, Zhao Cai-Ping, Ma Juan-Juan, An Na, Han Ming-Yu
College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China.
College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
Plant Cell Physiol. 2015 Oct;56(10):2052-68. doi: 10.1093/pcp/pcv124. Epub 2015 Sep 26.
Flower induction in apple (Malus domestica Borkh.) is regulated by complex gene networks that involve multiple signal pathways to ensure flower bud formation in the next year, but the molecular determinants of apple flower induction are still unknown. In this research, transcriptomic profiles from differentiating buds allowed us to identify genes potentially involved in signaling pathways that mediate the regulatory mechanisms of flower induction. A hypothetical model for this regulatory mechanism was obtained by analysis of the available transcriptomic data, suggesting that sugar-, hormone- and flowering-related genes, as well as those involved in cell-cycle induction, participated in the apple flower induction process. Sugar levels and metabolism-related gene expression profiles revealed that sucrose is the initiation signal in flower induction. Complex hormone regulatory networks involved in cytokinin (CK), abscisic acid (ABA) and gibberellic acid pathways also induce apple flower formation. CK plays a key role in the regulation of cell formation and differentiation, and in affecting flowering-related gene expression levels during these processes. Meanwhile, ABA levels and ABA-related gene expression levels gradually increased, as did those of sugar metabolism-related genes, in developing buds, indicating that ABA signals regulate apple flower induction by participating in the sugar-mediated flowering pathway. Furthermore, changes in sugar and starch deposition levels in buds can be affected by ABA content and the expression of the genes involved in the ABA signaling pathway. Thus, multiple pathways, which are mainly mediated by crosstalk between sugar and hormone signals, regulate the molecular network involved in bud growth and flower induction in apple trees.
苹果（Malus domestica Borkh.）的成花诱导受复杂基因网络调控，该网络涉及多个信号通路以确保来年花芽形成，但苹果成花诱导的分子决定因素仍不清楚。在本研究中，通过对分化芽的转录组分析，我们鉴定出了可能参与介导成花诱导调控机制的信号通路的基因。通过分析现有转录组数据获得了该调控机制的假设模型，表明糖、激素和开花相关基因以及参与细胞周期诱导的基因参与了苹果的成花诱导过程。糖水平和代谢相关基因表达谱显示，蔗糖是成花诱导的起始信号。涉及细胞分裂素（CK）、脱落酸（ABA）和赤霉素途径的复杂激素调控网络也诱导苹果花的形成。CK在细胞形成和分化的调控以及这些过程中影响开花相关基因表达水平方面起关键作用。同时，在发育中的芽中，ABA水平和ABA相关基因表达水平逐渐升高，糖代谢相关基因表达水平也是如此，这表明ABA信号通过参与糖介导的开花途径来调控苹果的成花诱导。此外，芽中糖和淀粉沉积水平的变化会受到ABA含量和ABA信号通路相关基因表达的影响。因此，主要由糖和激素信号之间的相互作用介导的多条途径调控了苹果树芽生长和成花诱导所涉及的分子网络。
