Abarca Dolores
Department of Life Sciences, University of Alcalá, Alcalá de Henares, Spain.
Front Plant Sci. 2021 Mar 5;12:621032. doi: 10.3389/fpls.2021.621032. eCollection 2021.
The molecular mechanisms underlying root organogenesis have been under intense study for the last decades. As new tools and resources became available, a comprehensive model connecting the processes and factors involved was developed. Separate phases that allow for specific analyses of individual checkpoints were well defined. Physiological approaches provided information on the importance of metabolic processes and long-distance signaling to balance leaf and stem status and activation of stem cell niches to form new root meristems. The study of plant hormones revealed a series of sequential roles for cytokinin and auxin, dynamically interconnected and modulated by jasmonic acid and ethylene. The identification of genes specifying cell identity uncovered a network of sequentially acting transcriptional regulators that link hormonal control to cell fate respecification. Combined results from herbaceous model plants and the study of recalcitrant woody species underscored the need to understand the limiting factors that determine adventitious rooting competence. The relevance of epigenetic control was emphasized by the identification of microRNAs and chromatin remodeling agents involved in the process. As the different players are set in place and missing pieces become apparent, findings in related processes can be used to identify new candidates to complete the picture. Molecular knobs connecting the balance cell proliferation/differentiation to hormone signaling pathways, transcriptional control of cell fate or metabolic modulation of developmental programs can offer clues to unveil new elements in the dynamics of adventitious rooting regulatory networks. Mechanisms for cell non-autonomous signaling that are well characterized in other developmental processes requiring establishment and maintenance of meristems, control of cell proliferation and cell fate specification can be further explored. Here, we discuss possible candidates and approaches to address or elude the limitations that hinder propagation programs requiring adventitious rooting.
在过去几十年中，人们一直在深入研究根器官发生的分子机制。随着新工具和资源的出现，一个连接相关过程和因素的综合模型得以建立。明确界定了允许对各个检查点进行特定分析的不同阶段。生理学方法提供了有关代谢过程和长距离信号传导对平衡叶和茎状态以及激活干细胞龛以形成新根分生组织的重要性的信息。对植物激素的研究揭示了细胞分裂素和生长素的一系列相继作用，它们由茉莉酸和乙烯动态地相互连接和调节。确定指定细胞身份的基因揭示了一个顺序作用的转录调节因子网络，该网络将激素控制与细胞命运重编程联系起来。草本模式植物的综合结果以及对顽固木本物种的研究强调了理解决定不定根形成能力的限制因素的必要性。参与该过程的 microRNA 和染色质重塑因子的鉴定强调了表观遗传控制的相关性。随着不同的参与者各就其位，缺失的部分变得明显，相关过程的研究结果可用于识别新的候选者以完善整个图景。连接细胞增殖/分化平衡与激素信号通路、细胞命运的转录控制或发育程序的代谢调节的分子旋钮可以为揭示不定根调控网络动态中的新元素提供线索。在其他需要建立和维持分生组织、控制细胞增殖和细胞命运指定的发育过程中得到充分表征的细胞非自主信号传导机制可以进一步探索。在这里，我们讨论可能的候选者和方法，以解决或规避阻碍需要不定根的繁殖计划的限制。
