Oh Eunkyoo, Kim Jonghyun, Park Eunae, Kim Jeong-Il, Kang Changwon, Choi Giltsu
Department of Biological Sciences, KAIST, Daejeon 305-701, Korea.
Plant Cell. 2004 Nov;16(11):3045-58. doi: 10.1105/tpc.104.025163. Epub 2004 Oct 14.
The first decision made by an angiosperm seed, whether to germinate or not, is based on integration of various environmental signals such as water and light. The phytochromes (Phys) act as red and far-red light (Pfr) photoreceptors to mediate light signaling through yet uncharacterized pathways. We report here that the PIF3-like 5 (PIL5) protein, a basic helix-loop-helix transcription factor, is a key negative regulator of phytochrome-mediated seed germination. PIL5 preferentially interacts with the Pfr forms of Phytochrome A (PhyA) and Phytochrome B (PhyB). Analyses of a pil5 mutant in conjunction with phyA and phyB mutants, a pif3 pil5 double mutant, and PIL5 overexpression lines indicate that PIL5 is a negative factor in Phy-mediated promotion of seed germination, inhibition of hypocotyl negative gravitropism, and inhibition of hypocotyl elongation. Our data identify PIL5 as the first Phy-interacting protein that regulates seed germination.
被子植物种子做出的第一个决定，即是否萌发，是基于对各种环境信号（如水和光）的整合。光敏色素（Phys）作为红光和远红光（Pfr）光感受器，通过尚未明确的途径介导光信号传导。我们在此报告，类PIF3 5（PIL5）蛋白，一种碱性螺旋-环-螺旋转录因子，是光敏色素介导的种子萌发的关键负调节因子。PIL5优先与光敏色素A（PhyA）和光敏色素B（PhyB）的Pfr形式相互作用。对pil5突变体与phyA和phyB突变体、pif3 pil5双突变体以及PIL5过表达系的分析表明，PIL5是Phy介导的促进种子萌发、抑制下胚轴负向重力性以及抑制下胚轴伸长的负因子。我们的数据确定PIL5是第一个调节种子萌发的与Phy相互作用的蛋白。
