The understanding of the dynamics of stomatal movements has increased substantially through genetic manipulation of plant metabolism either at the whole plant level or specifically in guard cells. However, the regulation of stomatal speediness remains not completely elucidated. Here we shown that reduced expression of guard cell sucrose synthase 2 (NtSUS2) of Nicotiana tabacum L. altered the topology and the connectivity of the guard cell metabolic network and the accumulation of metabolites positively correlated with stomatal speediness during dark-to-light transition. This leads to a slower light-induced stomatal opening, lower steady-state stomatal conductance and a strong reduction (up to 44 %) in daily whole plant transpiration in the transgenics, when compared to wild type plants. Furthermore, the transgenic lines transpired more or have lower reduction in whole plant transpiration under short water deficit periods, indicating a higher effective use of water under this condition. Our results collectively suggest that the regulation of stomatal movement and speediness involve a complex modulation of the guard cell metabolic network, in which NtSUS2 has an important role. The results are discussed on the role of guard cell metabolism for the regulation of both stomatal speediness and whole plant transpiration.

通过在整个植物水平或在保卫细胞中对植物新陈代谢进行基因操作，对气孔运动动态的了解已大大增加。然而，气孔速度的调节仍未完全阐明。在这里，我们显示了烟草的保卫细胞蔗糖合成酶2（NtSUS2）的表达降低，改变了保卫细胞代谢网络的拓扑结构和连通性，以及在暗到光过渡期间与气孔速度快速相关的代谢产物积累。与野生型植物相比，这会导致光诱导的气孔打开速度变慢，稳态气孔导度降低以及转基因植物的每日全植物蒸腾量大大降低（最多减少44％）。此外，在较短的水分亏缺时期，转基因品系在整个植物的蒸腾作用中表现出更多的减少或减少程度降低，表明在这种条件下水的有效利用率更高。我们的研究结果共同表明，气孔运动和速度的调节涉及保卫细胞代谢网络的复杂调节，其中NtSUS2具有重要作用。讨论了保卫细胞代谢在调节气孔速度和整个植物蒸腾中的作用的结果。