Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow, UK.
Physiological Laboratory, University of Cambridge, Cambridge, UK.
Plant Cell Environ. 2019 Aug;42(8):2399-2410. doi: 10.1111/pce.13568. Epub 2019 May 26.
Models of guard cell dynamics, built on the OnGuard platform, have provided quantitative insights into stomatal function, demonstrating substantial predictive power. However, the kinetics of stomatal opening predicted by OnGuard models were threefold to fivefold slower than observed in vivo. No manipulations of parameters within physiological ranges yielded model kinetics substantially closer to these data, thus highlighting a missing component in model construction. One well-documented process influencing stomata is the constraining effect of the surrounding epidermal cells on guard cell volume and stomatal aperture. Here, we introduce a mechanism to describe this effect in OnGuard2 constructed around solute release and a decline in turgor of the surrounding cells and its subsequent recovery during stomatal opening. The results show that this constraint-relaxation-recovery mechanism in OnGuard2 yields dynamics that are consistent with experimental observations in wild-type Arabidopsis, and it predicts the altered opening kinetics of ost2 H -ATPase and slac1 Cl channel mutants. Thus, incorporating solute flux of the surrounding cells implicitly through their constraint on guard cell expansion provides a satisfactory representation of stomatal kinetics, and it predicts a substantial and dynamic role for solute flux across the apoplastic space between the guard cells and surrounding cells in accelerating stomatal kinetics.
基于 OnGuard 平台构建的保卫细胞动力学模型为气孔功能提供了定量见解，展示了强大的预测能力。然而，OnGuard 模型预测的气孔开度动力学比体内观察到的速度慢三倍到五倍。在生理范围内对参数进行任何操作都不能使模型动力学更接近这些数据，因此突出了模型构建中缺失的一个环节。一个有充分文献记录的影响气孔的过程是周围表皮细胞对保卫细胞体积和气孔开度的约束作用。在这里，我们引入了一种机制来描述 OnGuard2 中围绕溶质释放以及周围细胞膨压下降及其随后在气孔开放过程中恢复的这种影响。结果表明，OnGuard2 中的这种约束-松弛-恢复机制产生的动力学与野生型拟南芥的实验观察结果一致，并且它预测了 ost2 H+-ATPase 和 slac1 Cl 通道突变体的开度动力学改变。因此，通过周围细胞对保卫细胞扩张的约束来隐含地包含周围细胞的溶质通量，为气孔动力学提供了令人满意的表示，并且它预测了溶质通量在保卫细胞和周围细胞之间的质外体空间中对加速气孔动力学具有实质性和动态作用。
