Institut National de la Recherche Agronomique, Laboratoire d'agronomie, F 78850, Thiverval, Grignon, France.
Plant Physiol. 1992 Feb;98(2):540-5. doi: 10.1104/pp.98.2.540.
We investigated, under laboratory and field conditions, the possibility that increasing abscisic acid (ABA) concentrations and decreasing water potentials can interact in their effects on stomata. One experiment was carried out with epidermal pieces of Commelina communis incubated in media with a variety of ABA and polyethylene glycol concentrations. In the media without ABA, incubation in solutions with water potentials between -0.3 and -1.5 megapascals had no significant effect on stomatal aperture. Conversely, the sensitivity of stomatal aperture to ABA was trebled in solutions at -1.5 megapascals compared with sensitivity at -0.3 megapascals. The effect of the change in sensitivity was more important than the absolute effect of ABA at the highest water potential. In a field experiment, sensitivity of maize stomatal conductance to the concentration of ABA in the xylem sap varied strongly with the time of the day. We consider that the most likely explanation for this is the influence of a change in leaf or epidermal water potential that accompanies an increase in irradiance and saturation deficit as the day progresses. These observations suggest that epidermal water relations may act as a modulator of the responses of stomata to ABA. We argue that such changes must be taken into account in studies or modeling of plant responses to drought stress.
我们在实验室和田间条件下研究了增加脱落酸（ABA）浓度和降低水势对气孔影响的相互作用的可能性。一项实验是用 Commelina communis 的表皮片在含有各种 ABA 和聚乙二醇浓度的培养基中进行的。在没有 ABA 的培养基中，在水势为-0.3 至-1.5 兆帕斯卡的溶液中孵育对气孔孔径没有显著影响。相反，与-0.3 兆帕斯卡相比，-1.5 兆帕斯卡溶液中气孔孔径对 ABA 的敏感性增加了两倍。在最高水势下，这种敏感性变化的影响比 ABA 的绝对影响更重要。在田间实验中，玉米气孔导度对木质部汁液中 ABA 浓度的敏感性随一天中的时间变化而强烈变化。我们认为，最有可能的解释是随着一天的进展，光照和饱和亏缺的增加伴随叶片或表皮水势的变化对气孔的影响。这些观察结果表明，表皮水关系可能是气孔对 ABA 响应的调节剂。我们认为，在研究或模拟植物对干旱胁迫的响应时，必须考虑到这些变化。
