From Ethylene-Auxin Interactions to Auxin Biosynthesis and Signal Integration
From Ethylene-Auxin Interactions to Auxin Biosynthesis and Signal Integration
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从乙烯-生长素相互作用到生长素生物合成和信号整合
DOI：
10.1105/tpc.19.00339
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Alonso, Jose M.
中科院分区：
文献类型：
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作者：
Stepanova, Anna N.;Alonso, Jose M.
植物激素生物学领域与许多其他植物科学研究领域一样，从采用拟南芥（Arabidopsis thaliana）作为模型系统中受益匪浅。在这个物种中，一个巨大的遗传工具箱的发展导致了许多核心成分的生物合成、信号传导和所有关键植物激素的反应途径的识别。有了这些成分在手，研究重点逐渐转向了解不同的激素如何以协调的方式协调复杂的生物过程。经典的生理和遗传实验结果进一步鼓励了这一转变，这些实验清楚地表明，在许多关键的发育过程中，多种信号之间的相互作用非常重要。激素间存在串扰的最显著证据之一是反复报道的特征明确的生长素突变体在根中表现出乙烯反应降低。尽管有这些充分记录的观察结果，但直到2000年代中期，这些有趣关系背后的分子机制在很大程度上仍然未知。2007年，《植物细胞》连续发表了三篇文章，旨在揭示生长素和乙烯介导根系生长抑制的相互作用（Ruzicka et al., 2007; Stepanova et al., 2007; Swarup et al., 2007）。虽然从不同的角度探讨了这个问题，但这三篇文章都得出了相同的结论（即乙烯对根生长的影响的一个重要部分是通过刺激生长素的生物合成和运输介导的）。虽然利用现有突变体和生长素流入和流出载体的报告系详细剖析了特定生长素转运体的贡献，但当时，只有时空分辨率有限的生化方法才能用于研究生长素生物合成在这些激素间关系中的作用。因此，举例来说，利用生长素和乙烯活性报告使得这三篇文章的作者能够确定根的不同部分在这个相互作用过程中的具体作用。在根伸长区，生长素响应报告基因DR5的活性与乙烯抑制根生长的能力高度相关，而在根的其他区域，如分生组织区，情况并非如此。此外，乙烯引发的伸长区生长素报告基因DR5活性的增加也是激活这部分根的乙烯报告基因EBS所必需的。总之，这三篇文章为这两种植物激素相互作用提供了一个可行的时空机制模型。在这个模型中，乙烯刺激
The field of plant hormone biology, like many other research areas in plant sciences, has benefited tremendously from the adoption of Arabidopsis (Arabidopsis thaliana) as a model system. The development of a great genetic toolbox in this species led to the identification of many of the core components of the biosynthesis, signaling, and response pathways for all key plant hormones. With those components at hand, research emphasis progressively shifted toward understanding how the different hormones work in a coordinated fashion to orchestrate complex biological processes. This shift was further encouraged by the results of classical physiological and genetic experiments that clearly showed the importance of the interaction between multiple signals in a number of critical developmental processes. Among the most striking pieces of evidence for the existence of crosstalk between hormones were the repeated reports on well-characterized auxin mutants displaying reduced ethylene responses in roots. Despite these well-documented observations, the molecular mechanism behind these intriguing relations remained largely unknown until the mid 2000s.In 2007, three articles were published back to back in The Plant Cell aiming to shed new light on the interplay of auxin and ethylene mediating root growth inhibition (Ruzicka et al., 2007; Stepanova et al., 2007; Swarup et al., 2007). Although approaching this question from different angles, all three articles reached the same general conclusion (ie, an important part of ethylene effects on root growth is mediated by the stimulation of auxin biosynthesis and transport). While the contribution of specific auxin transporters was dissected in detail using existing mutants and reporter lines for the influx and efflux auxin carriers, at the time, only biochemical approaches with limited spatiotemporal resolution could be used to investigate the role of auxin biosynthesis in these interhormone relations. Thus, for example, the use of auxin and ethylene activity reporters allowed the authors of the three articles to establish specific roles for different parts of the root in this interaction process. The activity of an auxin-responsive reporter, DR5, in the root elongation zone was shown to be highly correlated with the ability of ethylene to inhibit root growth, whereas that was not the case in other regions of the root, such as the meristematic zone. Furthermore, the ethylene-triggered increase in the activity of the auxin reporter DR5 in the elongation zone was also required for the activation of the ethylene reporter EBS in this part of the root. Altogether, the three articles provided a working spatiotemporal mechanistic model for the interaction between the two plant hormones. In this model, ethylene stimulates the