Evans M L
Department of Botany, Ohio State University, Columbus 43210, USA.
Adv Space Res. 1986;6(12):61-5. doi: 10.1016/0273-1177(86)90067-0.
Calcium ions may play a key role in linking graviperception by the root cap to the asymmetric growth which occurs in the elongation zone of gravistimulated roots. Application of calcium-chelating agents to the root cap inhibits gravitropic curvature without affecting growth. Asymmetric application of calcium to one side of the root cap induces curvature toward the calcium source, and gravistimulation induces polar movement of applied 45Ca2+ across the root cap toward the lower side. The action of calcium may be linked to auxin movement in roots since 1) auxin transport inhibitors interfere both with gravitropic curvature and gravi-induced polar calcium movement and 2) asymmetric application of calcium enhances auxin movement across the elongation zone of gravistimulated roots. Indirect evidence indicates that the calcium-modulated regulator protein, calmodulin, may be involved in either the transport or action of calcium in the gravitropic response mechanism of roots.
钙离子可能在将根冠的重力感知与重力刺激根的伸长区中发生的不对称生长联系起来方面发挥关键作用。将钙螯合剂施用于根冠会抑制向重力性弯曲，而不影响生长。将钙不对称地施用于根冠的一侧会诱导根向钙源弯曲，重力刺激会诱导施用的45Ca2+穿过根冠向较低一侧进行极性移动。钙的作用可能与根中生长素的移动有关，因为：1）生长素运输抑制剂既干扰向重力性弯曲，也干扰重力诱导的钙极性移动；2）钙的不对称施用增强了生长素穿过重力刺激根伸长区的移动。间接证据表明，钙调节的调节蛋白钙调蛋白可能参与了根向重力性反应机制中钙的运输或作用。
