Nick P, Schafer E
Institut fur Biologie II, Freiburg, Federal Republic of Germany.
Planta. 1988 Feb;173(2):213-20. doi: 10.1007/BF00403013.
The influence of gravitropic stimulation upon blue-light-induced first positive phototropism for stimulations in the same (light source and center of gravity opposite to each other) and in opposing directions was investigated in maize coleoptiles by measuring fluence-response patterns. As a result of gravitropic counterstimulation, phototropic bending was transient with maximum curvature occurring 100 min after stimulation. On a horizontal clinostat, however, the seedlings curved for 20 h. Gravistimulation in the opposite direction acted additively upon blue-light curvature. Gravistimulation in the same direction as phototropic stimulation produced a complex behaviour deviating from simple additivity. This pattern can be explained by a gravitropically mediated sensitization of the phototropic reaction, an optimal dependence of differential growth on the sum of photo- and gravistimulation, and blue-light-induced inhibition of gravitropic curvature at high fluences. These findings indicate that several steps of photo- and gravitransduction are separate. Preirradiation with red light desensitized the system independently of applied gravity-treatment, indicating that the site of red-light interaction is common to both transduction chains.
通过测量光通量-响应模式，研究了重力刺激对蓝光诱导的玉米胚芽鞘在相同方向（光源和重心相对）和相反方向刺激下的首次正向光性的影响。由于重力反向刺激，光性弯曲是短暂的，最大曲率出现在刺激后100分钟。然而，在水平回转器上，幼苗弯曲了20小时。相反方向的重力刺激对蓝光诱导的弯曲起累加作用。与光性刺激相同方向的重力刺激产生了一种偏离简单累加性的复杂行为。这种模式可以通过重力介导的光性反应致敏、差异生长对光和重力刺激总和的最佳依赖性以及高光通量下蓝光诱导的重力弯曲抑制来解释。这些发现表明，光转导和重力转导的几个步骤是分开的。红光预照射使系统脱敏，与施加的重力处理无关，表明红光相互作用的位点是两个转导链共有的。
