蒙古沙冬青气孔及保卫细胞内向钾离子通道特性研究

Characteristics Analysis of Ammopiptanthus mongolicus Stomata and Inward Potassium Channels in Guard Cell of Ammopiptanthus mongolicus

蒙古沙冬青是一种豆科,常绿灌木,主要分布在我国西北地区。蒙古沙冬青作为沙生植物的一种,有很强抗旱能力。蒙古沙冬青具有很低的蒸腾强度,其蒸腾作用与气孔的活动密切相关。气孔开放过程,保卫细胞质膜上的内向钾离子通道介导钾离子进入保卫细胞。本研究通过观测蒙古沙冬青和拟南芥气孔及保卫细胞原生质体,结果显示,蒙古沙冬青气孔密度明显比拟南芥气孔密度要低;蒙古沙冬青气孔保卫细胞周长是拟南芥的1.7倍;而蒙古沙冬青保卫细胞的体积约是拟南芥的3倍。通过膜片钳技术,记录蒙古沙冬青和拟南芥保卫细胞原生质体内向钾离子通道电流,膜电位为-180 m V时,蒙古沙冬青电流密度明显小于拟南芥。蒙古沙冬青保卫细胞内向钾离子通道转运钾离子的能力比较弱,可推测蒙古沙冬青气孔不易开放。通过比较发现,旱生植物蒙古沙冬青低的气孔密度和保卫细胞弱的转运钾离子能力,是其具有低的蒸腾强度关键。

Ammopiptanthus mongolicus(Maxim.) Cheng f. is an evergreen and leguminous shrub mainly distributed in the northwest of China. Ammopiptanthus mongolicus as a psammophyte shows high levels of tolerance to drought.Ammopiptanthus mongolicus has very low transpiration intensity. Its transpiration is closely related to the stomatal regulation. Inward potassium channels in the guard cell plasma membrane play an important role in stomatal opening. In this study, Ammopiptanthus mongolicus and Arabidopsis stomata and guard cell protoplast was observed. Results showed that Ammopiptanthus mongolicus stomatal density significantly lower than that of Arabidopsis thaliana stomatal density. The circumference of Ammopiptanthus mongolicus guard cells is 1.7 times as length as Arabidopsis, while the volume of Ammopiptanthus mongolicus guard cells is about three times as large as Arabidopsis thaliana. Through the patch-clamp technique, Ammopiptanthus mongolicus and Arabidopsis guard cells protoplasts were used to record potassium channel currents. When membrane potential was-180 m V, Ammopiptanthus mongolicus current density was significantly less than Arabidopsis thaliana. Ammopiptanthus mongolicus guard cell inward potassium channels ability to transport potassium ions is relatively weak. That speculate Ammopiptanthus mongolicus stomata is not easy to open. By comparison, xerophyte Ammopiptanthus mongolicus low stomatal density and guard cell weak potassium ion transport ability is the key to low transpiration intensity.