The University of Queensland, Australian Research Council Centre of Excellence for Integrative Legume Research and School of Biological Sciences, St. Lucia 4072, Australia.
Plant Cell. 2009 Nov;21(11):3459-72. doi: 10.1105/tpc.109.069013. Epub 2009 Nov 30.
Bud outgrowth is regulated by the interplay of multiple hormones, including auxin, cytokinin, strigolactones, and an unidentified long-distance feedback signal that moves from shoot to root. The model of bud outgrowth regulation in pea (Pisum sativum) includes these signals and a network of five RAMOSUS (RMS) genes that operate in a shoot-root-shoot loop to regulate the synthesis of, and response to, strigolactones. The number of components in this network renders the integration of new and existing hypotheses both complex and cumbersome. A hypothesis-driven computational model was therefore developed to help understand regulation of shoot branching. The model evolved in parallel with stepwise laboratory research, helping to define and test key hypotheses. The computational model was used to verify new mechanisms involved in the regulation of shoot branching by confirming that the new hypotheses captured all relevant biological data sets. Based on cytokinin and RMS1 expression analyses, this model is extended to include subtle but important differences in the function of RMS3 and RMS4 genes in the shoot and rootstock. Additionally, this research indicates that a branch-derived signal upregulates RMS1 expression independent of the other feedback signal. Furthermore, we propose xylem-sap cytokinin promotes sustained bud outgrowth, rather than acting at the earlier stage of bud release.
芽生长的调控是由多种激素相互作用的结果，包括生长素、细胞分裂素、独脚金内酯和一个从芽到根移动的未识别的长距离反馈信号。豌豆（Pisum sativum）芽生长调控模型包括这些信号和五个 RAMOSUS（RMS）基因的网络，该网络在芽-根-芽循环中起作用，调节独脚金内酯的合成和对其的响应。该网络中的组件数量使得整合新的和现有的假设既复杂又麻烦。因此，开发了一个假设驱动的计算模型来帮助理解芽分枝的调控。该模型与逐步的实验室研究并行发展，有助于定义和测试关键假设。该计算模型用于通过确认新假设捕获了所有相关的生物数据集来验证参与芽分枝调控的新机制。基于细胞分裂素和 RMS1 表达分析，该模型扩展到包括 RMS3 和 RMS4 基因在芽和砧木中的功能的细微但重要的差异。此外，这项研究表明，一个源自分枝的信号可以上调 RMS1 的表达，而不依赖于其他反馈信号。此外，我们提出木质部汁液细胞分裂素促进芽的持续生长，而不是在芽释放的早期阶段起作用。
