A pair of floral regulators sets critical day length for Hd3a florigen expression in rice

36.377
Hironori Itoh, Yasunori Nonoue, Masahiro Yano, Takeshi Izawa
Nature Genetics, 2010, 42(7): 635-638  DOI: 10.1038/ng.606;      追溯原文......本站官方QQ群:62473826

The critical day length triggering photoperiodic flowering is set as an acute, accurate threshold in many short-day plants, including rice. Here, we show that, unlike the Arabidopsis florigen gene FT, the rice florigen gene Hd3a (Heading date 3a) is toggled by only a 30-min day-length reduction. Hd3a expression is induced by Ehd1 (Early heading date 1) expression when blue light coincides with the morning phase set by OsGIGANTEA(OsGI)-dependent circadian clocks. Ehd1 expression is repressed by both night breaks under short-day conditions and morning light signals under long-day conditions. Ghd7 (Grain number, plant height and heading date 7) was acutely induced when phytochrome signals coincided with a photosensitive phase set differently by distinct photoperiods and this induction repressed Ehd1 the next morning. Thus, two distinct gating mechanisms—of the floral promoter Ehd1 and the floral repressor Ghd7—could enable manipulation of slight differences in day length to control Hd3a transcription with a critical day-length threshold.

一对开花调控因子设置了水稻成花素基因Hd3a表达的临界日长

引发光周期开花的临界日长十分灵敏,包括水稻在内的许多短日照植物有精确阈值。我们发现,与拟南芥成花素基因FT不同,水稻成花素基因Hd3a的表达能够被日长仅30分钟的减少切换。当蓝光与OsGI介导的生物钟设置的早晨阶段一致时,Hd3a表达被Ehd1表达诱导。短日照条件下夜晚打断与长日照条件下早晨光信号均会抑制Ehd1的表达。当光敏色素信号与不同光周期设置的不同的光敏感阶段一致时,Ghd7会受到显著诱导,这种诱导会在第二天早晨抑制Ehd1。因而,开花促进因子Ehd1和开花抑制因子Ghd7这两种不同的闸门机理能够操纵日长的细微变化,进而通过临界日长阈值调控Hd3a的转录。


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
  每穗粒数、株高和抽穗期多效性控制基因 Ghd7