Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan.
J Plant Res. 2009 Mar;122(2):235-43. doi: 10.1007/s10265-008-0201-9. Epub 2008 Dec 16.
It is well known that endogenous abscisic acid (ABA) levels increase rapidly in response to drought stress and that this induces stomatal closure. In Arabidopsis thaliana, ABA levels increased rapidly in the leaves and roots when intact wild-type whole plants were exposed to drought stress. However, if the leaves and roots were separated and exposed to drought independently, the ABA level increased only in the leaves. These results suggest that, under our experimental conditions, ABA is synthesized mainly in the leaves in response to drought stress and that some of the ABA accumulated in the leaves is transported to the roots. Tracer experiments using isotope-labeled ABA indicate that the movement of ABA from leaves to roots is activated by water deficit in the roots. We also demonstrate that the endogenous ABA level in the leaves increased only when the leaves themselves were exposed to drought stress, suggesting that leaves play a major role in the production of ABA in response to acute water shortage.
众所周知，内源脱落酸（ABA）水平会因干旱胁迫而迅速增加，从而导致气孔关闭。在拟南芥中，当完整的野生型整株植物暴露于干旱胁迫时，叶片和根部的 ABA 水平会迅速增加。然而，如果将叶片和根部分开并分别暴露于干旱胁迫下，ABA 水平仅在叶片中增加。这些结果表明，在我们的实验条件下，ABA 主要是在叶片中合成以响应干旱胁迫，并且在叶片中积累的一些 ABA 被运输到根部。使用同位素标记的 ABA 的示踪实验表明，ABA 从叶片到根部的运动是由根部的水分亏缺激活的。我们还证明，只有当叶片本身暴露于干旱胁迫下时，叶片中的内源 ABA 水平才会增加，这表明叶片在响应急性缺水时对 ABA 的产生起主要作用。
