Expression and characterization of plasma membrane aquaporins in stomatal complexes of Zea mays
Expression and characterization of plasma membrane aquaporins in stomatal complexes of Zea mays
复制标题
DOI：
10.1007/s11103-014-0232-7
复制
发表时间：
2014-10-01
影响因子：
5.1
通讯作者：
Chaumont, Francois
中科院分区：
文献类型：
--
作者：
Heinen, Robert B.;Bienert, Gerd Patrick;Chaumont, Francois
气孔是植物地上部分表面的微孔，它的边界有两个特殊的细胞，称为保卫细胞，它们根据内源和环境信号控制气孔开度。像植物中发生的大多数运动一样，气孔的打开和关闭是基于液力的。在开放过程中，质膜和液泡膜转运蛋白的激活导致保卫细胞中的溶质积累。为了重新建立被扰动的渗透平衡，水跟随溶质进入细胞，导致细胞膨胀。大量的研究有助于了解气孔运动的机制和调控。然而，尽管跨膜水流动在这一过程中很重要，但只有少数研究提供了水通道参与的证据，称为水通道蛋白。在这里，我们显微解剖了玉米气孔复合体，发现水孔蛋白质膜内源蛋白(PIP)亚家族的成员在这些复合体中表达，并且它们的mRNA表达通常遵循昼夜模式。通过在非洲爪哇卵母细胞和酵母细胞中的异源表达，研究了其中两个ZmPIP1；5和ZmPIP1；6的底物特异性。我们的数据显示，在ZmPIP2；1亚型存在的情况下，这两种亚型都促进了水的跨膜扩散。此外，两者都表现出与二氧化碳扩散促进剂NtAQP1相当的二氧化碳渗透性。这些数据表明，ZmPIP在气孔复合体中可能具有多种生理作用。
Stomata, the microscopic pores on the surface of the aerial parts of plants, are bordered by two specialized cells, known as guard cells, which control the stomatal aperture according to endogenous and environmental signals. Like most movements occurring in plants, the opening and closing of stomata are based on hydraulic forces. During opening, the activation of plasma membrane and tonoplast transporters results in solute accumulation in the guard cells. To re-establish the perturbed osmotic equilibrium, water follows the solutes into the cells, leading to their swelling. Numerous studies have contributed to the understanding of the mechanism and regulation of stomatal movements. However, despite the importance of transmembrane water flow during this process, only a few studies have provided evidence for the involvement of water channels, called aquaporins. Here, we microdissected Zea mays stomatal complexes and showed that members of the aquaporin plasma membrane intrinsic protein (PIP) subfamily are expressed in these complexes and that their mRNA expression generally follows a diurnal pattern. The substrate specificity of two of the expressed ZmPIPs, ZmPIP1;5 and ZmPIP1;6, was investigated by heterologous expression in Xenopus oocytes and yeast cells. Our data show that both isoforms facilitate transmembrane water diffusion in the presence of the ZmPIP2;1 isoform. In addition, both display CO2 permeability comparable to that of the CO2 diffusion facilitator NtAQP1. These data indicate that ZmPIPs may have various physiological roles in stomatal complexes.