Transpiration rate. An important factor controlling the sucrose content of the guard cell apoplast of broad bean
Transpiration rate. An important factor controlling the sucrose content of the guard cell apoplast of broad bean
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DOI：
10.1104/pp.126.4.1716
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发表时间：
2001-08-01
期刊：
影响因子：
7.4
通讯作者：
De Vlieghere-He, X
中科院分区：
文献类型：
--
作者：
Outlaw, WH;De Vlieghere-He, X
保卫细胞壁的水分蒸发浓缩了质外体溶质。我们推测，这种现象提供了两种机制，响应高蒸腾速率。首先，质外体脱落酸集中在保卫细胞壁。第二，通过在保卫细胞壁中积累，质外体蔗糖（Suc）为保卫细胞提供直接的渗透反馈。作为测试这第二个假设机制的一种手段，在较高的蒸腾速率（60%相对湿度[RH]）与那些在较低的蒸腾速率（90%RH）在蚕豆（蚕豆），质外体韧皮部装载器的保卫细胞Suc含量进行了比较。在对照植物（恒定60%RH）中，保卫细胞质外体Suc含量在黎明和中午之间从97 +/- 81 fmol（fmol）保卫细胞对（-1）增加到701 +/- 142 fmol保卫细胞对（-1）。这一增加相当于约150毫米的外部，这是足以减少气孔孔径的大小。在植物中，转移到90%RH黎明前，保卫细胞质外体Suc含量在白天没有增加。与此相一致，在中午转移到90%RH的植物中，保卫细胞质外体Suc含量下降到黎明值。在所有条件下，保卫细胞共质体Suc含量在光周期期间增加，但在转移到90%RH的植物中保卫细胞共质体Suc含量更高（836 +/- 33 fmol保卫细胞对（-1））。这些结果表明，高蒸腾速率可能会导致高浓度的保卫细胞质外体Suc，从而减小气孔孔径的大小。
Evaporation of water from the guard cell wall concentrates apoplastic solutes. We hypothesize that this phenomenon provides two mechanisms for responding to high transpiration rates. First, apoplastic abscisic acid is concentrated in the guard cell wall. Second, by accumulating in the guard cell wall, apoplastic sucrose (Suc) provides a direct osmotic feedback to guard cells. As a means of testing this second hypothesized mechanism, the guard cell Suc contents at a higher transpiration rate (60% relative humidity [RH]) were compared with those at a lower transpiration rate (90% RH) in broad bean (Vicia faba), an apoplastic phloem loader. In control plants (constant 60% RH), the guard cell apoplast Suc content increased from 97 +/- 81 femtomol (fmol) guard cell pair(-1) to 701 +/- 142 fmol guard cell pair(-1) between daybreak and midday. This increase is equivalent to approximately 150 mm external, which is sufficient to decrease stomatal aperture size. In plants that were shifted to 90% RH before daybreak, the guard cell apoplast Suc content did not increase during the day. In accordance, in plants that were shifted to 90% RH at midday, the guard cell apoplast Suc content declined to the daybreak value. Under all conditions, the guard cell symplast Suc content increased during the photoperiod, but the guard cell symplast Suc content was higher (836 +/- 33 fmol guard cell pair(-1)) in plants that were shifted to 90% RH. These results indicate that a high transpiration rate may result in a high guard cell apoplast Suc concentration, which diminishes stomatal aperture size.