School of Biological Sciences, University of Ulsan, Ulsan 680-749, Korea.
Plant Cell Physiol. 2013 Jan;54(1):48-56. doi: 10.1093/pcp/pcs098. Epub 2012 Jul 10.
We recently investigated the roles of the phototropin 1 (PHOT1) LOV (light, oxygen or voltage) domains in mediating phototropic curvature in transgenic Arabidopsis seedlings expressing either wild-type PHOT1 or PHOT1 with one or both LOV domains inactivated by a single amino acid replacement. We have now investigated the role of the PHOT1 LOV domains in chloroplast movement and in leaf positioning in response to blue light. Low fluence rate blue light is known to mediate a chloroplast accumulation response and high fluence rate blue light an avoidance response in Arabidopsis leaves. As was the case for phototropism, LOV2 of PHOT1 is essential for chloroplast accumulation and LOV1 is dispensable. PHOT1 LOV2 is also essential to maintain developing primary leaves in a horizontal position under white light from above and LOV1 is again dispensable. A red light pulse given to dark-adapted light-grown plants followed by 2 h of darkness enhances both the chloroplast accumulation response under dim blue light and the chloroplast avoidance response under strong blue light. The effect is far-red reversible. This photoreversible response is normal in a phyB null mutant but does not appear in a phyA null mutant. These results suggest that phyA mediates the enhancement, induced by a red light pulse, of blue light-induced chloroplast movements.
我们最近研究了光受体 1（PHOT1） LOV（光、氧或电压）结构域在介导转基因拟南芥幼苗光形态弯曲中的作用，这些转基因幼苗表达野生型 PHOT1 或 LOV 结构域中的一个或两个被单个氨基酸替换而失活的 PHOT1。我们现在研究了 PHOT1 LOV 结构域在叶绿体运动和蓝光反应中的叶位中的作用。低光强的蓝光被认为介导叶绿体积累反应，高光强的蓝光则介导叶绿体逃避反应。与向光性一样，PHOT1 的 LOV2 对于叶绿体积累是必需的，而 LOV1 则是可有可无的。 LOV2 对于在来自上方的白光下维持发育中的初生叶处于水平位置也是必需的，而 LOV1 再次是可有可无的。黑暗适应的光生长植物给予红光脉冲，随后黑暗 2 小时，增强了弱蓝光下的叶绿体积累反应和强光下的叶绿体逃避反应。该效应可被远红光逆转。这种光可逆反应在 phyB 缺失突变体中是正常的，但在 phyA 缺失突变体中则不出现。这些结果表明 phyA 介导了红光脉冲诱导的增强，从而增强了蓝光诱导的叶绿体运动。
