Tissue and cell-specific localization of rice aquaporins and their water transport activities.
Tissue and cell-specific localization of rice aquaporins and their water transport activities.
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DOI：
10.1093/pcp/pcm162
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发表时间：
2008
影响因子：
4.9
通讯作者：
J. Sakurai;A. Ahamed;M. Murai;M. Maeshima;M. Uemura
中科院分区：
文献类型：
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作者：
J. Sakurai;A. Ahamed;M. Murai;M. Maeshima;M. Uemura
植物中的水运输很大程度上取决于水运输通道（称为水通道蛋白）的表达和活性。在这里，我们使用七种亚型特异性水通道蛋白抗体通过免疫印迹和免疫细胞化学阐明了水通道蛋白在水稻中的组织和细胞特异性定位。我们还使用酵母表达系统结合停流分光光度测定法检查了典型水通道蛋白家族成员的水运输活性。 OsPIP1成员OsPIP2;1、OsTIP1;1和OsTIP2;2在叶片和根中均表达，而OsPIP2;3、OsPIP2;5和OsTIP2;1仅在根中表达。在根中，大量水通道蛋白积聚在根尖附近的区域（距根尖约 1.5-4 毫米）。在该区域中，观察到各种水通道蛋白成员的细胞特异性定位。 OsPIP1 成员和 OsTIP2;2 分别主要在内皮层和中央圆柱中积累。 OsTIP1;1 在根皮层和外皮层中表现出特异性定位。 OsPIP2;1、OsPIP2;3 和 OsPIP2;5 在所有根细胞中积累，但它们在内皮层中的积累水平高于其他细胞。在距离根尖 35 毫米的区域，通气组织发育，水通道蛋白积聚水平较低。在叶片中，OsPIP1 成员和 OsPIP2;1 主要位于叶肉细胞中。酵母中表达的OsPIP2;1、OsPIP2;3、OsPIP2;5 和OsTIP2;2 表现出高水转运活性。这些结果表明，具有各种水运输活性的水稻水通道蛋白可能在促进水通量和维持不同组织和细胞中的水势方面发挥不同的作用。
Water transport in plants is greatly dependent on the expression and activity of water transport channels, called aquaporins. Here, we have clarified the tissue- and cell-specific localization of aquaporins in rice plants by immunoblotting and immunocytochemistry using seven isoform-specific aquaporin antibodies. We also examined water transport activities of typical aquaporin family members using a yeast expression system in combination with a stopped-flow spectrophotometry assay. OsPIP1 members, OsPIP2;1, OsTIP1;1 and OsTIP2;2 were expressed in both leaf blades and roots, while OsPIP2;3, OsPIP2;5 and OsTIP2;1 were expressed only in roots. In roots, large amounts of aquaporins accumulated in the region adjacent to the root tip (around 1.5-4 mm from the root tip). In this region, cell-specific localization of the various aquaporin members was observed. OsPIP1 members and OsTIP2;2 accumulated predominantly in the endodermis and the central cylinder, respectively. OsTIP1;1 showed specific localization in the rhizodermis and exodermis. OsPIP2;1, OsPIP2;3 and OsPIP2;5 accumulated in all root cells, but they showed higher levels of accumulation in endodermis than other cells. In the region at 35 mm from the root tip, where aerenchyma develops, aquaporins accumulated at low levels. In leaf blades, OsPIP1 members and OsPIP2;1 were localized mainly in mesophyll cells. OsPIP2;1, OsPIP2;3, OsPIP2;5 and OsTIP2;2 expressed in yeast showed high water transport activities. These results suggest that rice aquaporins with various water transport activities may play distinct roles in facilitating water flux and maintaining the water potential in different tissues and cells.