Filiault Daniele L, Wessinger Carolyn A, Dinneny Jose R, Lutes Jason, Borevitz Justin O, Weigel Detlef, Chory Joanne, Maloof Julin N
Section of Plant Biology, College of Biological Sciences, University of California, One Shields Avenue, Davis, CA 95616, USA.
Proc Natl Acad Sci U S A. 2008 Feb 26;105(8):3157-62. doi: 10.1073/pnas.0712174105. Epub 2008 Feb 14.
Plants have a sophisticated system for sensing and responding to their light environment. The light responses of populations and species native to different habitats show adaptive variation; understanding the mechanisms underlying photomorphogenic variation is therefore of significant interest. In Arabidopsis thaliana, phytochrome B (PHYB) is the dominant photoreceptor for red light and plays a major role in white light. Because PHYB has been proposed as a candidate gene for several quantitative trait loci (QTLs) affecting light response, we have investigated sequence and functional variation in Arabidopsis PHYB. We examined PHYB sequences in 33 A. thaliana individuals and in the close relative Arabidopsis lyrata. From 14 nonsynonymous polymorphisms, we chose 5 for further study based on previous QTL studies. In a larger collection of A. thaliana accessions, one of these five polymorphisms, I143L, was associated with variation in red light response. We used transgenic analysis to test this association and confirmed experimentally that natural PHYB polymorphisms cause differential plant responses to light. Furthermore, our results show that allelic variation of PHYB activity is due to amino acid rather than regulatory changes. Together with earlier studies linking variation in light sensitivity to photoreceptor genes, our work suggests that photoreceptors may be a common target of natural selection.
植物拥有一套复杂的系统来感知和响应其光照环境。不同栖息地的植物种群和物种的光反应表现出适应性变化；因此，了解光形态建成变异背后的机制具有重要意义。在拟南芥中，phytochrome B（PHYB）是红光的主要光感受器，在白光中起主要作用。由于PHYB已被提议作为影响光反应的几个数量性状基因座（QTL）的候选基因，我们研究了拟南芥PHYB的序列和功能变异。我们检查了33个拟南芥个体以及其近缘物种琴叶拟南芥的PHYB序列。从14个非同义多态性中，基于先前的QTL研究，我们选择了5个进行进一步研究。在更大的拟南芥种质集合中，这五个多态性之一，I143L，与红光反应的变异相关。我们使用转基因分析来测试这种关联，并通过实验证实了天然PHYB多态性导致植物对光的不同反应。此外，我们的结果表明，PHYB活性的等位基因变异是由于氨基酸而非调控变化。与早期将光敏感性变异与光感受器基因联系起来的研究一起，我们的工作表明光感受器可能是自然选择的常见目标。
