Cytokinin Regulation of Auxin Synthesis in Arabidopsis Involves a Homeostatic Feedback Loop Regulated via Auxin and Cytokinin Signal Transduction
Cytokinin Regulation of Auxin Synthesis in Arabidopsis Involves a Homeostatic Feedback Loop Regulated via Auxin and Cytokinin Signal Transduction
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DOI：
10.1105/tpc.110.074856
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发表时间：
2010-09-01
期刊：
影响因子：
11.6
通讯作者：
Ljung, Karin
中科院分区：
文献类型：
--
作者：
Jones, Brian;Gunneras, Sara Andersson;Ljung, Karin
生长素和细胞分裂素共同调节许多对植物生长、发育和环境响应至关重要的过程。我们以前已经表明，外源生长素调节拟南芥细胞分裂素的生物合成。在这项工作中，我们表明，相反，应用或诱导异位生物合成的细胞分裂素导致生长素的生物合成在年轻的，发展中的根和芽组织的快速增加。我们还表明，通过诱导细胞分裂素氧化酶的表达或一个或多个细胞分裂素生物合成异戊烯基转移酶基因的突变，降低内源性细胞分裂素水平，导致生长素生物合成减少。细胞分裂素改变了几个假定的生长素生物合成基因的转录本的丰度，表明细胞分裂素直接诱导生长素的生物合成。我们的数据表明，细胞分裂素是必不可少的，不仅要保持基础水平的生长素生物合成在发展中的根和芽组织，但生长素生物合成的动态调节响应不断变化的发展或环境条件。结合我们以前的工作，数据表明，一个稳态反馈调节回路，涉及生长素和细胞分裂素信号的行为，以保持适当的生长素和细胞分裂素浓度在发展中的根和芽组织。
Together, auxin and cytokinin regulate many of the processes that are critical to plant growth, development, and environmental responsiveness. We have previously shown that exogenous auxin regulates cytokinin biosynthesis in Arabidopsis thaliana. In this work, we show that, conversely, the application or induced ectopic biosynthesis of cytokinin leads to a rapid increase in auxin biosynthesis in young, developing root and shoot tissues. We also show that reducing endogenous cytokinin levels, either through the induction of CYTOKININ OXIDASE expression or the mutation of one or more of the cytokinin biosynthetic ISOPENTENYLTRANSFERASE genes leads to a reduction in auxin biosynthesis. Cytokinin modifies the abundance of transcripts for several putative auxin biosynthetic genes, suggesting a direct induction of auxin biosynthesis by cytokinin. Our data indicate that cytokinin is essential, not only to maintain basal levels of auxin biosynthesis in developing root and shoot tissues but also for the dynamic regulation of auxin biosynthesis in response to changing developmental or environmental conditions. In combination with our previous work, the data suggest that a homeostatic feedback regulatory loop involving both auxin and cytokinin signaling acts to maintain appropriate auxin and cytokinin concentrations in developing root and shoot tissues.