Eriksson Sven, Böhlenius Henrik, Moritz Thomas, Nilsson Ove
Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-90183 Umeå, Sweden.
Plant Cell. 2006 Sep;18(9):2172-81. doi: 10.1105/tpc.106.042317. Epub 2006 Aug 18.
Flower initiation in Arabidopsis thaliana under noninductive short-day conditions is dependent on the biosynthesis of the plant hormone gibberellin (GA). This dependency can be explained, at least partly, by GA regulation of the flower meristem identity gene LEAFY (LFY) and the flowering time gene SUPPRESSOR OF CONSTANS1. Although it is well established that GA(4) is the active GA in the regulation of Arabidopsis shoot elongation, the identity of the GA responsible for the regulation of Arabidopsis flowering has not been established. Through a combination of GA quantifications and sensitivity assays, we show that GA(4) is the active GA in the regulation of LFY transcription and Arabidopsis flowering time under short-day conditions. The levels of GA(4) and sucrose increase dramatically in the shoot apex shortly before floral initiation, and the regulation of genes involved in GA metabolism suggests that this increase is possibly due to transport of GAs and sucrose from outside sources to the shoot apex. Our results demonstrate that in the dicot Arabidopsis, in contrast with the monocot Lolium temulentum, GA(4) is the active GA in the regulation of both shoot elongation and flower initiation.
在非诱导性短日条件下，拟南芥的成花取决于植物激素赤霉素（GA）的生物合成。这种依赖性至少部分可以通过GA对花分生组织特征基因LEAFY（LFY）和开花时间基因CONSTANS1抑制因子的调控来解释。虽然GA(4)是调控拟南芥茎伸长的活性GA，这一点已得到充分证实，但负责调控拟南芥开花的GA的身份尚未确定。通过GA定量分析和敏感性测定相结合的方法，我们发现GA(4)是短日条件下调控LFY转录和拟南芥开花时间的活性GA。在花起始前不久，茎尖中GA(4)和蔗糖的水平急剧增加，参与GA代谢的基因调控表明，这种增加可能是由于GA和蔗糖从外部来源运输到茎尖所致。我们的结果表明，在双子叶植物拟南芥中，与单子叶植物毒麦不同，GA(4)是调控茎伸长和花起始的活性GA。
