OsMADS51 Is a Short-Day Flowering Promoter That Functions Upstream of Ehd1, OsMADS14, and Hd3a

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Song Lim Kim, Shinyoung Lee, Hyo Jung Kim, Hong Gil Nam, Gynheung An
Plant Physiology, 2007, 145(4): 1484-1494  DOI: 10.1104/pp.107.103291;      追溯原文......本站官方QQ群:62473826

Although flowering regulatory mechanisms have been extensively studied in Arabidopsis (Arabidopsis thaliana), those in other species have not been well elucidated. Here, we investigated the role of OsMADS51, a type I MADS-box gene in the short-day (SD) promotion pathway in rice (Oryza sativa). In SDs OsMADS51 null mutants flowered 2 weeks later than normal, whereas in long days loss of OsMADS51 had little effect on flowering. Transcript levels of three flowering regulators—Ehd1, OsMADS14, and Hd3a—were decreased in these mutants, whereas those of OsGI and Hd1 were unchanged. Ectopic expression of OsMADS51 caused flowering to occur about 7 d earlier only in SDs. In ectopic expression lines, transcript levels of Ehd1, OsMADS14, and Hd3a were increased, but those of OsGI and Hd1 remained the same. These results indicate that OsMADS51 is a flowering promoter, particularly in SDs, and that this gene functions upstream of Ehd1, OsMADS14, and Hd3a. To further investigate the relationship with other flowering promoters, we generated transgenic plants in which expression of Ehd1 or OsGI was suppressed. In Ehd1 RNA interference plants, OsMADS51 expression was not affected, supporting our conclusion that the MADS-box gene functions upstream of Ehd1. However, in OsGI antisense plants, the OsMADS51 transcript level was reduced. In addition, the circadian expression pattern for this MADS-box gene was similar to that for OsGI. These results demonstrate that OsMADS51 functions downstream of OsGI. In summary, OsMADS51 is a novel flowering promoter that transmits a SD promotion signal from OsGI to Ehd1.

OsMADS51是一个作用于Ehd1,OsMADS14Hd3a上游的短日照开花促进子

目前对拟南芥的开花调控机理已经有了非常广泛的研究,但是对其他物种而言,开花调控的机制还没有被详尽阐述。本文我们对水稻短日照(SD)促进开花途径中的一个I类MADS盒基因OsMADS51 进行了功能分析。在SDs 条件下OsMADS51 无义突变体开花较正常植株晚2 周,而长日照条件下OsMADS51 的缺失对开花只有很小的影响。突变体中三个开花调节子基因Ehd1OsMADS14Hd3a 的表达降低,而OsGI1Hd1 的表达则没有变化。异位表达OsMADS51 导致在SDs 下开花提前7d。在异位表达的株系中Ehd1OsMADS14Hd3a 表达上调,OsGIHd1 的表达没有发生改变。这些结果表明OsMADS51 是一个开花促进因子,尤其在SDs下,其作用于Ehd1OsMADS14Hd3a 的上游。为了研究与其他开花促进因子的关系,我们构建了Ehd1OsGI1 的表达抑制转基因植株。在Ehd1 RNAi 植株中,OsMADS51 的表达不受影响,这支持了OsMADS51 作用于Ehd1 上游的结论。在反义表达OsGI 的植株中,OsMADS51 的转录水平降低。另外OsMADS51 基因的表达节律模式与OsGI 相类似。这表明OsMADS51 作用于OsGI 下游。因此OsMADS51 是一个新的开花促进因子基因,在SD 下参与将OsGI 的信号传递至Ehd1


基因列表
  早穗基因 Ehd1
  生物钟相关 OsGI
  成花素基因;抽穗期基因;生育期基因;光周期敏感基因;感光基因 Hd3a; FT
  MADS盒基因 OsMADS51; OsMADS65
  MADS盒基因 OsMADS14