Wilkinson S., Davies W. J.
The Lancaster Environment Centre, Lancaster University, Bailrigg, Lancaster, LA1 4YQ, UK.
Plant Cell Environ. 2002 Feb;25(2):195-210. doi: 10.1046/j.0016-8025.2001.00824.x.
There is now strong evidence that the plant hormone abscisic acid (ABA) plays an important role in the regulation of stomatal behaviour and gas exchange of droughted plants. This regulation involves both long-distance transport and modulation of ABA concentration at the guard cells, as well as differential responses of the guard cells to a given dose of the hormone. We will describe how a plant can use the ABA signalling mechanism and other chemical signals to adjust the amount of water that it loses through its stomata in response to changes in both the rhizospheric and the aerial environment. The following components of the signalling process can play an important part in regulation: (a) ABA sequestration in the root; (b) ABA synthesis versus catabolism in the root; (c) the efficiency of ABA transfer across the root and into the xylem; (d) the exchange of ABA between the xylem lumen and the xylem parenchyma in the shoot; (e) the amount of ABA in the leaf symplastic reservoir and the efficiency of ABA sequestration and release from this compartment as regulated by factors such as root and leaf-sourced changes in pH; (f) cleavage of ABA from ABA conjugates in the leaf apoplast; (g) transfer of ABA from the leaf into the phloem; (h) the sensitivity of the guard cells to the [ABA] that finally reaches them; and lastly (i) the possible interaction between nitrate stress and the ABA signal.
目前有确凿证据表明，植物激素脱落酸（ABA）在干旱植物气孔行为和气体交换的调节中发挥着重要作用。这种调节涉及ABA在保卫细胞处的长距离运输和浓度调节，以及保卫细胞对给定剂量激素的不同反应。我们将描述植物如何利用ABA信号机制和其他化学信号，来响应根际环境和大气环境的变化，调节通过气孔流失的水量。信号传导过程的以下组成部分在调节中可发挥重要作用：（a）根中ABA的隔离；（b）根中ABA的合成与分解代谢；（c）ABA穿过根并进入木质部的效率；（d）茎中木质部腔与木质部薄壁组织之间ABA的交换；（e）叶共质体库中ABA的含量，以及由根和叶来源的pH变化等因素调节的ABA从该隔室中隔离和释放的效率；（f）叶质外体中ABA结合物的ABA裂解；（g）ABA从叶向韧皮部的转移；（h）保卫细胞对最终到达它们的[ABA]的敏感性；最后（i）硝酸盐胁迫与ABA信号之间可能的相互作用。
