Cotelle Valérie, Leonhardt Nathalie
Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPS Castanet-Tolosan, France.
UMR7265, Laboratoire de Biologie du Développement des Plantes, Service de Biologie Végétale et de Microbiologie Environnementales, Institut de Biologie Environnementale et Biotechnologie, CNRS-CEA-Université Aix-Marseille Saint-Paul-lez-Durance, France.
Front Plant Sci. 2016 Jan 28;6:1210. doi: 10.3389/fpls.2015.01210. eCollection 2015.
Guard cells are specialized cells located at the leaf surface delimiting pores which control gas exchanges between the plant and the atmosphere. To optimize the CO2 uptake necessary for photosynthesis while minimizing water loss, guard cells integrate environmental signals to adjust stomatal aperture. The size of the stomatal pore is regulated by movements of the guard cells driven by variations in their volume and turgor. As guard cells perceive and transduce a wide array of environmental cues, they provide an ideal system to elucidate early events of plant signaling. Reversible protein phosphorylation events are known to play a crucial role in the regulation of stomatal movements. However, in some cases, phosphorylation alone is not sufficient to achieve complete protein regulation, but is necessary to mediate the binding of interactors that modulate protein function. Among the phosphopeptide-binding proteins, the 14-3-3 proteins are the best characterized in plants. The 14-3-3s are found as multiple isoforms in eukaryotes and have been shown to be involved in the regulation of stomatal movements. In this review, we describe the current knowledge about 14-3-3 roles in the regulation of their binding partners in guard cells: receptors, ion pumps, channels, protein kinases, and some of their substrates. Regulation of these targets by 14-3-3 proteins is discussed and related to their function in guard cells during stomatal movements in response to abiotic or biotic stresses.
保卫细胞是位于叶片表面的特化细胞，它们界定了控制植物与大气之间气体交换的气孔。为了在使水分损失最小化的同时优化光合作用所需的二氧化碳吸收，保卫细胞整合环境信号以调节气孔孔径。气孔的大小由保卫细胞的体积和膨压变化驱动的运动来调节。由于保卫细胞感知并转导多种环境信号，它们为阐明植物信号传导的早期事件提供了一个理想的系统。已知可逆的蛋白质磷酸化事件在气孔运动的调节中起关键作用。然而，在某些情况下，仅磷酸化不足以实现对蛋白质的完全调节，但它是介导调节蛋白质功能的相互作用分子结合所必需的。在磷酸肽结合蛋白中，14-3-3蛋白在植物中是研究得最清楚的。14-3-3蛋白在真核生物中以多种同工型存在，并已被证明参与气孔运动的调节。在这篇综述中，我们描述了目前关于14-3-3蛋白在保卫细胞中调节其结合伙伴（受体、离子泵、通道、蛋白激酶及其一些底物）的作用的知识。讨论了14-3-3蛋白对这些靶标的调节作用，并将其与它们在保卫细胞响应非生物或生物胁迫的气孔运动中的功能联系起来。
