Zhang S Q, Outlaw W H, Aghoram K
Department of Biological Science, Florida State University, Tallahassee, FL, 32306-4370, USA.
J Exp Bot. 2001 Feb;52(355):301-8.
The relationships of guard cell ABA content to eight stress-related physiological parameters were determined on intact Vicia faba L. plants that were grown hydroponically with split-root systems. Continuous stress was imposed by the addition of PEG to part of the root system. The water potentials of roots sampled after the addition of PEG were 0.25 MPa lower than the water potentials of other roots of the same plant, which were similar to the roots of untreated plants. The leaflet water potentials of plants sampled within 2 h of stress imposition were similar to those of control plants. However, leaf conductance was lower in plants sampled after only 20 min of stress imposition, and the root- and leaflet apoplastic ABA concentrations of these plants were higher than those of untreated plants. As the essence of this report, there was a linear relationship between guard cell ABA content and leaf conductance. Leaflet apoplastic ABA concentrations <150 nM were also linearly related to leaf conductance, but higher leaflet apoplastic ABA concentration did not cause equally large further declines in leaf conductance. It is suggested that evaporation from guard cell walls caused ABA to accumulate in the guard cell apoplast and this pool was saturated at high leaflet apoplastic ABA concentrations.
利用具有分根系统的水培蚕豆植株，测定了保卫细胞脱落酸（ABA）含量与8个胁迫相关生理参数之间的关系。通过向部分根系添加聚乙二醇（PEG）施加持续胁迫。添加PEG后取样的根系水势比同一植株其他根系的水势低0.25 MPa，这些根系与未处理植株的根系相似。胁迫施加后2小时内取样的植株小叶水势与对照植株相似。然而，仅在胁迫施加20分钟后取样的植株叶片导度较低，且这些植株的根和小叶质外体ABA浓度高于未处理植株。作为本报告的核心内容，保卫细胞ABA含量与叶片导度之间存在线性关系。小叶质外体ABA浓度<150 nM时也与叶片导度呈线性相关，但较高的小叶质外体ABA浓度并未导致叶片导度同样大幅下降。研究表明，保卫细胞壁的蒸发导致ABA在保卫细胞质外体中积累，且在高小叶质外体ABA浓度下该库达到饱和。
