SHORT VEGETATIVE PHASE reduces gibberellin biosynthesis at the Arabidopsis shoot apex to regulate the floral transition
SHORT VEGETATIVE PHASE reduces gibberellin biosynthesis at the Arabidopsis shoot apex to regulate the floral transition
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DOI：
10.1073/pnas.1409567111
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发表时间：
2014-07-01
影响因子：
11.1
通讯作者：
Coupland, George
中科院分区：
文献类型：
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作者：
Andres, Fernando;Porri, Aimone;Coupland, George
在拟南芥中，环境和内源线索通过激活少量整合子基因的表达来促进开花。MADS盒转录因子短营养阶段(SVP)是开花的关键抑制因子，直接抑制这些基因的转录。然而，我们的遗传分析表明，SVP的作用不能通过抑制已知的花整合基因来完全解释。为了确定额外的SVP功能，我们分析了全基因组转录组数据，并表明赤霉素20氧化酶2在SVP突变体中上调，赤霉素20氧化酶2编码一种生长调节剂赤霉素(GA)生物合成所需的酶。GA可以促进开花，我们发现SVP突变体含有高水平的GA，这与GA相关的表型有关，如早花和器官伸长。Ga20ox2突变抑制了GA水平的升高，部分抑制了SVP突变体的生长和早花表型。在野生型植物中，当植物暴露在诱导开花的光周期中时，SVP在地上部顶端分生组织中的表达下降，这与GA20ox2的表达增加有关。破坏光周期开花途径的突变阻止了SVP的下调和GA20ox2表达的强劲增加。我们的结论是，SVP通过抑制GA的生物合成和整合子基因的表达来延迟开花，并且，作为对诱导光周期的响应，SVP的抑制有助于促进顶端GA的上升，促进快速开花。
In Arabidopsis thaliana environmental and endogenous cues promote flowering by activating expression of a small number of integrator genes. The MADS box transcription factor SHORT VEGETATIVE PHASE (SVP) is a critical inhibitor of flowering that directly represses transcription of these genes. However, we show by genetic analysis that the effect of SVP cannot be fully explained by repressing known floral integrator genes. To identify additional SVP functions, we analyzed genome-wide transcriptome data and show that GIBBERELLIN 20 OXIDASE 2, which encodes an enzyme required for biosynthesis of the growth regulator gibberellin (GA), is upregulated in svp mutants. GA is known to promote flowering, and we find that svp mutants contain elevated levels of GA that correlate with GA-related phenotypes such as early flowering and organ elongation. The ga20ox2 mutation suppresses the elevated GA levels and partially suppresses the growth and early flowering phenotypes of svp mutants. In wild-type plants, SVP expression in the shoot apical meristem falls when plants are exposed to photo-periods that induce flowering, and this correlates with increased expression of GA20ox2. Mutations that impair the photoperiodic flowering pathway prevent this downregulation of SVP and the strong increase in expression of GA20ox2. We conclude that SVP delays flowering by repressing GA biosynthesis as well as integrator gene expression and that, in response to inductive photoperiods, repression of SVP contributes to the rise in GA at the shoot apex, promoting rapid induction of flowering.