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AUXIN RESPONSE FACTOR3 Regulates Floral Meristem Determinacy By Repressing Cytokinin Biosynthesis and Signaling
Successful floral meristem (FM) determinacy is critical for subsequent reproductive development (生殖发育) 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.
成功的花分生组织确定是随后生殖发育和植物生命循环的重要阶段。尽管植物激素细胞分裂素和生长素互作共调控植物多方面的发育阶段,然而细胞分裂素和生长素是否以及如何在花分生组织确定中起到功能性的作用还未知。本文的研究显示拟南芥中的细胞分裂素内稳态对于花分生组织的确定至关重要。在该发育进程中,生长素促进生长素响应因子ARF3基因的表达以抑制细胞分裂素的活性。ARF3会直接抑制异戊烯基转移酶IPT家族基因,间接抑制LOG家族基因,这两个家族的基因都编码细胞分裂素生物合成通路上的酶。ARF3还会直接抑制拟南芥组氨酸激酶AHK4基因的表达,该基因是一个细胞分裂素受体基因,会导致细胞分裂素活性的降低。综上,ARF3通过细胞分裂素调控细胞周期基因来控制细胞分裂。在花中,研究显示AG会调控ARF3和IPTs基因的表达,进而通过细胞分裂协调调控花分生组织的维持和终止。此外,全基因范围的转录谱显示ARF3在早期花发育中同时扮演着抑制和激活作用。本文的发现鉴定了一个AG和生长素/细胞分裂素之间的分子关联,并揭示了花分生组织中干细胞维持和终止的分子机理。
通讯:刘西岗 (http://sourcedb.genetics.cas.cn/zw/zjrck/201211/t20121102_3676523.html)
个人简介:1993-1997年,河北师范大学,生物学学士;1998-2001年,河北师范大学,分子细胞生物学硕士;2001-2004年,河北师范大学,分子细胞生物学博士;2004-2007年,北京生命科学研究所,植物细胞生物学博士后;2007-2009年,美国加州大学河滨分校,植物发育生物学博士后;2009-2011年,美国加州大学河滨分校,植物发育生物学访问学者。
doi: https://doi.org/10.1105/tpc.17.00705
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