Molecular Signaling Laboratory, Department of Chemistry, Seoul National University, Seoul 151-742, Korea.
Plant J. 2011 Feb;65(3):418-29. doi: 10.1111/j.1365-313X.2010.04432.x. Epub 2010 Dec 13.
There has been a long-standing interest in the role played by sugars in flowering. Of particular interest is how sugar-related signals are integrated into flowering genetic pathways. Here, we demonstrate that the INDETERMINATE DOMAIN transcription factor AtIDD8 regulates photoperiodic flowering by modulating sugar transport and metabolism. We found that whereas AtIDD8-deficient idd8 mutants exhibit delayed flowering under long days, AtIDD8-overexpressing plants (35S:IDD8) show early flowering. In addition, the sucrose synthase genes SUS1 and SUS4 were upregulated in 35S:IDD8 plants but downregulated in idd8 mutants, in which endogenous sugar levels were altered. AtIDD8 activates the SUS4 gene by binding directly to its promoter, resulting in promoted flowering in SUS4-overexpressing plants. SUS4 expression also responds to photoperiodic signals. Notably, the AtIDD8 gene is suppressed by sugar deprivation. Therefore, we conclude that AtIDD8 regulation of sugar transport and metabolism is linked to photoperiodic flowering.
长期以来，人们一直关注糖在开花过程中所起的作用。特别引人关注的是，糖相关信号如何被整合到开花的遗传途径中。在这里，我们证明了不确定域转录因子 AtIDD8 通过调节糖的运输和代谢来调控光周期开花。我们发现，idd8 突变体在长日照下表现出开花延迟，而 AtIDD8 过表达植株（35S:IDD8）则表现出开花提前。此外，蔗糖合酶基因 SUS1 和 SUS4 在 35S:IDD8 植株中上调，但在 idd8 突变体中下调，而内源性糖水平在突变体中发生了改变。AtIDD8 通过直接结合其启动子来激活 SUS4 基因，导致在 SUS4 过表达植株中促进开花。SUS4 的表达也对光周期信号做出响应。值得注意的是，AtIDD8 基因受到糖剥夺的抑制。因此，我们得出结论，AtIDD8 对糖的运输和代谢的调节与光周期开花有关。
