2018年1月25日，Plant Cell发表了题为“AUXIN RESPONSE FACTOR3 Regulates Floral Meristem Determinacy By Repressing Cytokinin Biosynthesis and Signaling”的文章。

文章由中科院植物细胞与染色体工程国家重点实验室刘西岗研究员课题组完成。

文章主要介绍了：

ARF3整合AG和生长素的活性，控制细胞分裂素的生物合成和信号传导，从而协调调节花分生组织维持和终止

花分生组织（FM）的决定对于随后的生殖发育和植物生命周期是至关重要的。尽管植物激素细胞分裂素和生长素相互作用协调植物发育的许多方面，但是细胞分裂素和生长素在FM决定中的功能以及如何作用的还不清楚。我们的结果显示，拟南芥中细胞分裂素稳态是FM决定的关键。在这个发育背景下，生长素促进ARF3的表达来抑制细胞分裂素的活性。ARF3直接抑制IPT家族基因的表达，并间接抑制LOG家族基因，此二者都编码细胞分裂素生物合成所需的酶。ARF3也直接抑制细胞分裂素受体基因AHK4的表达，导致细胞分裂素活性降低。因此，ARF3通过细胞分裂素调节细胞周期基因表达来控制细胞分裂。在花中，AG动态调节ARF3和IPTs的表达，通过细胞分裂协调调节FM维持和终止。此外，全基因组转录分析揭示了ARF3在花发育早期的抑制和激活作用。我们的研究结果建立了AG和生长素/细胞分裂素之间的分子联系，揭示了FM中干细胞维持和终止的机制。

Successful floral meristem (FM) determinacy is critical for subsequent reproductive development and the plant life cycle. Although the phytohormones cytokinin and auxin interact to coregulate many aspects of plant development, whether and how cytokinin and auxin function in FM determinacy remain unclear. Here we show that in Arabidopsis thaliana, cytokinin homeostasis is critical for FM determinacy. In this developmental context, auxin promotes the expression of AUXIN RESPONSE FACTOR3 (ARF3) to repress cytokinin activity. ARF3 directly represses the expression of ISOPENTENYLTRANSFERASE (IPT) family genes and indirectly represses LONELY GUY (LOG) family genes, both of which encode enzymes required for cytokinin biosynthesis. ARF3 also directly inhibits the expression of ARABIDOPSIS HISTIDINE KINASE4 (AHK4), a cytokinin receptor gene, resulting in reduced cytokinin activity. Consequently, ARF3 controls cell division by regulating cell cycle gene expression through cytokinin. In flowers, we show that AGAMOUS (AG) dynamically regulates the expression of ARF3 and IPTs, resulting in coordinated regulation of FM maintenance and termination through cell division. Moreover, genome-wide transcriptional profiling revealed both repressive and active roles for ARF3 in early flower development. Our findings establish a molecular link between AG and auxin/cytokinin and shed light on the mechanisms of stem cell maintenance and termination in the FM.

A model of how ARF3 integrates the repression of cytokinin by auxin and AG in FM determinacy.