INRA, UMR Biogeco 1202, 69 route d'Arcachon, 33612 Cestas, France.
BMC Plant Biol. 2010 Oct 6;10:217. doi: 10.1186/1471-2229-10-217.
Plants are subjected to continuous stimuli from the environment and have evolved an ability to respond through various growth and development processes. Phototropism and gravitropism responses enable the plant to reorient with regard to light and gravity.
We quantified the speed of maritime pine seedlings to reorient with regard to light and gravity over 22 days. Seedlings were inclined at 15, 30 and 45 degrees with vertical plants as controls. A lateral light source illuminated the plants and stem movement over time was recorded. Depending on the initial angle of stem lean, the apical response to the lateral light source differed. In control and 15° inclined plants, the apex turned directly towards the light source after only 2 h. In plants inclined at 30° and 45°, the apex first reoriented in the vertical plane after 2 h, then turned towards the light source after 24 h. Two-dimensional gel electrophoresis coupled with mass spectrometry was then used to describe the molecular response of stem bending involved in photo- and gravi-tropism after 22 hr and 8 days of treatment. A total of 486 spots were quantitatively analyzed using image analysis software. Significant changes were determined in the protein accumulation of 68 protein spots. Early response gravitropic associated proteins were identified, which are known to function in energy related and primary metabolism. A group of thirty eight proteins were found to be involved in primary metabolism and energy related metabolic pathways. Degradation of Rubisco was implicated in some protein shifts.
Our study demonstrates a rapid gravitropic response in apices of maritime pine seedlings inclined >30°. Little or no response was observed at the stem bases of the same plants. The primary gravitropic response is concomitant with a modification of the proteome, consisting of an over accumulation of energy and metabolism associated proteins, which may allow the stem to reorient rapidly after bending.
植物不断受到环境刺激，并通过各种生长和发育过程进化出响应能力。向光性和向重性反应使植物能够重新定向光和重力。
我们量化了在 22 天内，马尾松幼苗重新定向光和重力的速度。幼苗以 15、30 和 45 度倾斜，以垂直植物作为对照。侧向光源照亮植物，记录随时间的茎运动。根据茎倾斜的初始角度，顶端对侧向光源的反应不同。在对照和 15°倾斜的植物中，顶端在仅 2 小时后直接转向光源。在 30°和 45°倾斜的植物中，顶端首先在 2 小时后在垂直平面上重新定向，然后在 24 小时后转向光源。然后使用二维凝胶电泳结合质谱法来描述光和向重性处理 22 小时和 8 天后涉及茎弯曲的分子反应。使用图像分析软件对总共 486 个斑点进行了定量分析。确定了 68 个蛋白质斑点的蛋白质积累发生了显著变化。鉴定出早期响应的向重性相关蛋白，已知其在能量相关和初级代谢中起作用。发现 38 种蛋白质参与初级代谢和能量相关代谢途径。Rubisco 的降解与一些蛋白质移位有关。
我们的研究表明，在倾斜>30°的马尾松幼苗的顶端中存在快速向重性反应。在同一植物的茎基部观察到很少或没有反应。主要的向重性反应伴随着蛋白质组的修饰，包括与能量和代谢相关的蛋白质的过度积累，这可能使茎在弯曲后能够快速重新定向。
