Li Guo-Wei, Peng Yan-Hui, Yu Xin, Zhang Min-Hua, Cai Wei-Ming, Sun Wei-Ning, Su Wei-Ai
Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, and Graduate School of the Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China.
J Plant Physiol. 2008 Dec;165(18):1879-88. doi: 10.1016/j.jplph.2008.05.002. Epub 2008 Aug 15.
The vacuole, a multifunctional organelle of most plant cells, has very important roles in space filling, osmotic adjustment, storage and digestion. Previous researches suggested that aquaporins in the tonoplast were involved in vacuolar functions. The rice genome contains 33 aquaporin genes, 10 of which encode tonoplast intrinsic proteins (TIPs). However, the function of each individual TIP isoform and the integrated function of TIPs under various physiological conditions remain elusive. Here, five rice TIP members were characterized with water and/or glycerol transport activities using the Xenopus oocyte expression system. OsTIP1;2, OsTIP2;2, OsTIP4;1 and OsTIP5;1 possessed water transport activity. OsTIP1;2, OsTIP3;2 and OsTIP4;1 were demonstrated with glycerol transport activity. Rice TIP expression patterns under various abiotic stress conditions including dehydration, high salinity, abscisic acid (ABA) and during seed germination were investigated by real-time PCR. OsTIP1s (OsTIP1;1 and OsTIP1;2) were highly expressed during seed germination, whereas OsTIP3s (OsTIP3;1 and OsTIP3;2) were specifically expressed in mature seeds with a decrease in expression levels upon germination. The results of this research provided a functional and expression profiles of rice TIPs.
液泡是大多数植物细胞中的一种多功能细胞器，在空间填充、渗透调节、储存和消化方面发挥着非常重要的作用。先前的研究表明，液泡膜水通道蛋白参与液泡功能。水稻基因组包含33个水通道蛋白基因，其中10个编码液泡膜内在蛋白（TIPs）。然而，每个单独的TIP亚型的功能以及TIPs在各种生理条件下的综合功能仍然不清楚。在此，利用非洲爪蟾卵母细胞表达系统对5个水稻TIP成员进行了水和/或甘油转运活性的表征。OsTIP1;2、OsTIP2;2、OsTIP4;1和OsTIP5;1具有水转运活性。OsTIP1;2、OsTIP3;2和OsTIP4;1被证明具有甘油转运活性。通过实时PCR研究了水稻TIP在包括脱水、高盐、脱落酸（ABA）等各种非生物胁迫条件下以及种子萌发过程中的表达模式。OsTIP1s（OsTIP1;1和OsTIP1;2）在种子萌发过程中高表达，而OsTIP3s（OsTIP3;1和OsTIP3;2）在成熟种子中特异性表达，萌发时表达水平下降。本研究结果提供了水稻TIPs的功能和表达谱。
