Ishikawa Ryo, Tamaki Shojiro, Yokoi Shuji, Inagaki Noritoshi, Shinomura Tomoko, Takano Makoto, Shimamoto Ko
Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, Takayama, Ikoma, Japan.
Plant Cell. 2005 Dec;17(12):3326-36. doi: 10.1105/tpc.105.037028. Epub 2005 Nov 4.
A short exposure to light in the middle of the night causes inhibition of flowering in short-day plants. This phenomenon is called night break (NB) and has been used extensively as a tool to study the photoperiodic control of flowering for many years. However, at the molecular level, very little is known about this phenomenon. In rice (Oryza sativa), 10 min of light exposure in the middle of a 14-h night caused a clear delay in flowering. A single NB strongly suppressed the mRNA of Hd3a, a homolog of Arabidopsis thaliana FLOWERING LOCUS T (FT), whereas the mRNAs of OsGI and Hd1 were not affected. The NB effect on Hd3a mRNA was maximal in the middle of the 14-h night. The phyB mutation abolished the NB effect on flowering and Hd3a mRNA, indicating that the NB effect was mediated by phytochrome B. Because expression of the other FT-like genes was very low and not appreciably affected by NB, our results strongly suggest that the suppression of Hd3a mRNA is the principal cause of the NB effect on flowering in rice.
在半夜短时间暴露于光照会抑制短日照植物的开花。这种现象被称为光间断(NB),多年来一直被广泛用作研究开花光周期控制的工具。然而,在分子水平上,对这一现象了解甚少。在水稻(Oryza sativa)中,在14小时夜间的中间时段进行10分钟的光照暴露会导致开花明显延迟。单次光间断强烈抑制了Hd3a的mRNA,Hd3a是拟南芥开花位点T(FT)的同源物,而OsGI和Hd1的mRNA不受影响。光间断对Hd3a mRNA的影响在14小时夜间的中间时段最大。phyB突变消除了光间断对开花和Hd3a mRNA的影响,表明光间断效应是由phytochrome B介导的。由于其他FT样基因的表达非常低且不受光间断的明显影响,我们的结果强烈表明,Hd3a mRNA的抑制是光间断对水稻开花影响的主要原因。