Allen Trudie, Ingles Patricia J, Praekelt Uta, Smith Harry, Whitelam Garry C
Department of Biology, University of Leicester, University Road, Leicester LE1 7RH, UK.
Plant J. 2006 May;46(4):641-8. doi: 10.1111/j.1365-313X.2006.02727.x.
Plants use specialized photoreceptors to detect the amount, quality, periodicity and direction of light and to modulate their growth and development accordingly. These regulatory light signals often interact with other environmental cues. Exposure of etiolated Arabidopsis seedlings to red (R) or far-red (FR) light causes hypocotyls to grow in random orientations with respect to the gravitational vector, thus overcoming the signal from gravity to grow upwards. This light response, mediated by either phytochrome A or phytochrome B, represents a prime example of cross-talk between environmental signalling systems. Here, we report the isolation the mutant gil1 (for gravitropic in the light) in which hypocotyls continue to grow upwards after exposure of seedlings to R or FR light. The gil1 mutant displays no other phenotypic alterations in response to gravity or light. Cloning of GIL1 has identified a novel gene that is necessary for light-dependent randomization of hypocotyl growth orientation. Using gil1, we have demonstrated that phytochrome-mediated randomization of Arabidopsis hypocotyl orientation provides a fitness advantage to seedlings developing in patchy, low-light environments.
植物利用专门的光感受器来检测光的量、质量、周期性和方向，并据此调节其生长和发育。这些调节性光信号通常与其他环境线索相互作用。将黄化拟南芥幼苗暴露于红光（R）或远红光（FR）下，会导致下胚轴相对于重力向量以随机方向生长，从而克服重力信号向上生长。这种由光敏色素A或光敏色素B介导的光反应，是环境信号系统之间相互作用的一个主要例子。在这里，我们报告了突变体gil1（光下重力反应异常）的分离，在该突变体中，幼苗暴露于R或FR光后，下胚轴继续向上生长。gil1突变体在对重力或光的反应中没有表现出其他表型改变。GIL1的克隆鉴定出一个新基因，该基因是下胚轴生长方向光依赖性随机化所必需的。利用gil1，我们证明了光敏色素介导的拟南芥下胚轴方向随机化，为在斑驳、弱光环境中发育的幼苗提供了适应性优势。
