Lawson Tracy
Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK.
New Phytol. 2009;181(1):13-34. doi: 10.1111/j.1469-8137.2008.02685.x.
Chloroplasts are a key feature of most guard cells; however, the function of these organelles in stomatal responses has been a subject of debate. This review examines evidence for and against a role of guard cell chloroplasts in stimulating stomatal opening. Controversy remains over the extent to which guard cell Calvin cycle activity contributes to stomatal regulation. However, this is only one of four possible functions of guard cell chloroplasts; other roles include supply of ATP, blue-light signalling and starch storage. Evidence exists for all these mechanisms, but is highly dependent upon species and growth/measurement conditions, with inconsistencies between different laboratories reported. Significant plasticity and extreme flexibility in guard cell osmoregulatory, signalling and sensory pathways may be one explanation. The use of chlorophyll a fluorescence analysis of individual guard cells is discussed in assessing guard and mesophyll cell physiology in relation to stomatal function. Developments in transgenic and molecular techniques have recently provided interesting, albeit contrasting, data regarding the role of these highly conserved organelles in stomatal function. Recent studies examining the link between mesophyll photosynthesis and stomatal conductance are discussed. An enhanced understanding of these processes may be fundamental in generating crop plants with greater water use efficiencies, capable of combating future climatic changes.
叶绿体是大多数保卫细胞的一个关键特征；然而，这些细胞器在气孔反应中的功能一直是一个有争议的话题。这篇综述研究了支持和反对保卫细胞叶绿体在刺激气孔开放中起作用的证据。保卫细胞卡尔文循环活性对气孔调节的贡献程度仍存在争议。然而，这只是保卫细胞叶绿体四种可能功能之一；其他作用包括ATP供应、蓝光信号传导和淀粉储存。所有这些机制都有证据，但高度依赖于物种和生长/测量条件，不同实验室之间也报道了不一致的情况。保卫细胞渗透调节、信号传导和传感途径的显著可塑性和极端灵活性可能是一种解释。本文讨论了使用叶绿素a荧光分析单个保卫细胞来评估与气孔功能相关的保卫细胞和叶肉细胞生理学。转基因和分子技术的发展最近提供了关于这些高度保守的细胞器在气孔功能中作用的有趣数据，尽管存在差异。本文还讨论了最近研究叶肉光合作用与气孔导度之间联系的研究。加强对这些过程的理解可能是培育具有更高水分利用效率、能够应对未来气候变化的作物的基础。
