Regulation of root growth under osmotic stress conditions: a systems study

为不断增长的全球人口增加粮食安全是人类面临的一项重大挑战。根系构型的调节是植物对干旱反应的一个关键特征，可能导致产量效益。因此，了解干旱条件下根系发育的调控机制是植物生物学和世界农业的重要问题。（我们的实验数据和文献中的数据）与系统生物学（网络构建和时空建模），我们已经构建了一个网络，描述生长素，乙烯，细胞分裂素和POLARIS肽（拟南芥中正确的生长素，乙烯和细胞分裂素信号传导所需），揭示了调节根生长的激素串扰回路。该模型已扩展到包括生长素运输通过PIN形成（PIN）外排转运蛋白，并已实施到时空模型，它可以重现各种激素和响应基因的图案。此外，我们研究了渗透胁迫对阿坝，细胞分裂素和乙烯反应的影响，以及它们如何通过对PIN蛋白的影响来介导生长素的运输，分配和根生长。我们发现，在渗透胁迫下，拟南芥植物显示增加阿坝的反应，并证明了生长素运输的影响，通过改变PIN 1水平的主根分生组织。然后，我们利用这些信息构建了一个新的网络整合渗透胁迫和阿坝与生长素，乙烯和细胞分裂素的影响。这一网络揭示了ABA、生长素、乙烯和细胞分裂素是如何通过抑制乙烯效应阿坝限制生长素在分生组织中的积累，从而形成一个完整的ABA、生长素、乙烯和细胞分裂素系统，并为渗透胁迫下根系发育的调控提供了新的认识。本项目是在我们成功应用分子生物学和系统生物学相结合的基础上，进一步探索渗透胁迫条件下根系发育的调控，重点研究“渗透胁迫如何调控根分生组织的大小”。它将在广泛的分子和系统生物学领域提供严格的培训。它将培养分子生物学和系统生物学方面的技能。这包括以下所有或部分技能：RNA提取和cDNA合成;定量实时聚合酶链反应（qPCR）;复合光学显微镜;共聚焦激光扫描显微镜;活体成像系统;图像分析;网络构建;计算机软件;以及各种建模技术。本项目的一个重要特点是采用分子生物学和系统生物学相结合的研究方法来探索渗透胁迫下根系生长调控的复杂性。

Increasing food security for a growing global population is a major challenge facing humanity. Modulation of root system architecture is a key feature of plant responses to drought, potentially leading to yield benefits. Understanding the mechanisms regulating root development under drought conditions is therefore an important question for plant biology and world agriculture.Previously, by combining molecular biology (our experimental data and the data in the literature) with systems biology (network construction and spatiotemporal modelling), we have constructed a network describing the interactions between auxin, ethylene, cytokinin and the POLARIS peptide (required for correct auxin, ethylene and cytokinin signalling in Arabidopsis), revealing a hormonal crosstalk circuit that regulates root growth. This model has been expanded to include auxin transport via the PIN-FORMED (PIN) efflux transporters and has been implemented into a spatiotemporal model, which can reproduce the patterning of various hormones and response genes. In addition, we examined the effect of osmotic stress on ABA, cytokinin and ethylene responses and how they mediate auxin transport, distribution and root growth through effects on PIN proteins. We showed that under osmotic stress, Arabidopsis plants display increased ABA responses, and demonstrated the effects on auxin transport to the primary root meristem through altered PIN1 levels. We then used this information to construct a new network to integrate the effects of osmotic stress and ABA with auxin, ethylene and cytokinin. This network developed novel insights into how an integrated system of ABA, auxin, ethylene and cytokinin is formed due to the repression of ethylene effects by ABA to limit auxin accumulation in the meristem, and brought new understanding to the control of root development under osmotic stress. The current project builds on our success in applying combined molecular and systems biology study and further explores the regulation of root development under osmotic stress conditions.The project focuses on the question "How does osmotic stress regulate the size of the root meristem". It will deliver rigorous training across a broad range of molecular and systems biology areas. It will develop skills in both molecular biology and systems biology. This includes all or some following skills: RNA extraction and cDNA synthesis; quantitative real-time polymerase chain reaction (qPCR); compound light microscopy; confocal laser scanning microscopy; living imaging system; image analysis; network construction; computer software; and various modelling techniques. An important feature of this project is to employ a combined molecular and systems biology study to explore the complexity in the regulation of root growth under osmotic stress.