Brassinosteroid Homeostasis in Arabidopsis Is Ensured by Feedback Expressions of Multiple Genes Involved in Its Metabolism
Brassinosteroid Homeostasis in Arabidopsis Is Ensured by Feedback Expressions of Multiple Genes Involved in Its Metabolism
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DOI：
10.1104/pp.104.058040
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发表时间：
2005-05
期刊：
影响因子：
7.4
通讯作者：
Kiwamu Tanaka;T. Asami;S. Yoshida;Yasushi Nakamura;T. Matsuo;S. Okamoto
中科院分区：
文献类型：
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作者：
Kiwamu Tanaka;T. Asami;S. Yoshida;Yasushi Nakamura;T. Matsuo;S. Okamoto
甘油类固醇（BR）的稳态对于高等植物的正常生长和发育至关重要。我们检查了11种BR代谢基因表达对拟南芥（拟南芥）中内源性BR含量减少或增加的反应性，以扩大我们对BR稳态下的分子机制的了解。在Brassinazole下种植的BR贫血的野生型植物中，五个BR特异性的生物合成基因（Det2，DWF4，CPD，BR6OX1和ROT3）和两个固醇生物合成基因（FK和DWF5）被上调。另一方面，在Br-渗透性的野生型植物中，用胸甲醇喂食，四个BR特异性合成基因（DWF4，CPD，BR6OX1和ROT3）和一个固醇合成基因（DWF7）被下调和BR。灭活基因（BAS1）被上调。但是，它们对BR水平波动的反应高度降低（DWF4）或BRI1突变体中的（其他八个基因）。综上所述，我们的结果表明，通过多种基因的反馈表达来维持BR稳态，每个基因不仅参与了BR特异性的生物合成和失活，还参与了固醇生物合成。我们的结果还表明，他们的反馈表达在BRI1介导的信号通路的控制之下。此外，突变体中的反应较弱表明，除了BRI1介导外，单独的DWF4可能会以其他方式受到调节。
Homeostasis of brassinosteroids (BRs) is essential for normal growth and development in higher plants. We examined responsiveness of 11 BR metabolic gene expressions to the decrease or increase of endogenous BR contents in Arabidopsis (Arabidopsis thaliana) to expand our knowledge of molecular mechanisms underlying BR homeostasis. Five BR-specific biosynthesis genes (DET2, DWF4, CPD, BR6ox1, and ROT3) and two sterol biosynthesis genes (FK and DWF5) were up-regulated in BR-depleted wild-type plants grown under brassinazole, a BR biosynthesis inhibitor. On the other hand, in BR-excessive wild-type plants that were fed with brassinolide, four BR-specific synthesis genes (DWF4, CPD, BR6ox1, and ROT3) and a sterol synthesis gene (DWF7) were down-regulated and a BR inactivation gene (BAS1) was up-regulated. However, their response to fluctuation of BR levels was highly reduced (DWF4) or nullified (the other eight genes) in a bri1 mutant. Taken together, our results imply that BR homeostasis is maintained through feedback expressions of multiple genes, each of which is involved not only in BR-specific biosynthesis and inactivation, but also in sterol biosynthesis. Our results also indicate that their feedback expressions are under the control of a BRI1-mediated signaling pathway. Moreover, a weak response in the mutant suggests that DWF4 alone is likely to be regulated in other way(s) in addition to BRI1 mediation.