Jang Ji Young, Lee Seong Hee, Rhee Ji Ye, Chung Gap Chae, Ahn Sung Ju, Kang Hunseung
Department of Plant Biotechnology, Agricultural Plant Stress Research Center and Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju, 500-757, Korea.
Plant Mol Biol. 2007 Aug;64(6):621-32. doi: 10.1007/s11103-007-9181-8. Epub 2007 May 24.
Despite the high isoform multiplicity of aquaporins in plants, with 35 homologues including 13 plasma membrane intrinsic proteins (PIPs) in Arabidosis thaliana, the individual and integrated functions of aquaporins under various physiological conditions remain unclear. To better understand aquaporin functions in plants under various stress conditions, we examined transgenic Arabidopsis and tobacco plants that constitutively overexpress Arabidopsis PIP1;4 or PIP2;5 under various abiotic stress conditions. No significant differences in growth rates and water transport were found between the transgenic and wild-type plants when grown under favorable growth conditions. The transgenic plants overexpressing PIP1;4 or PIP2;5 displayed a rapid water loss under dehydration stress, which resulted in retarded germination and seedling growth under drought stress. In contrast, the transgenic plants overexpressing PIP1;4 or PIP2;5 showed enhanced water flow and facilitated germination under cold stress. The expression of several PIPs was noticeably affected by the overexpression of PIP1;4 or PIP2;5 in Arabidopsis under dehydration stress, suggesting that the expression of one aquaporin isoform influences the expression levels of other aquaporins under stress conditions. Taken together, our results demonstrate that overexpression of an aquaporin affects the expression of endogenous aquaporin genes and thereby impacts on seed germination, seedling growth, and stress responses of the plants under various stress conditions.
尽管植物中水通道蛋白具有高度的亚型多样性，拟南芥中有35个同源物，包括13个质膜内在蛋白（PIPs），但水通道蛋白在各种生理条件下的个体功能和综合功能仍不清楚。为了更好地了解水通道蛋白在各种胁迫条件下在植物中的功能，我们检测了在各种非生物胁迫条件下组成型过表达拟南芥PIP1;4或PIP2;5的转基因拟南芥和烟草植株。在适宜的生长条件下生长时，转基因植株和野生型植株在生长速率和水分运输方面没有发现显著差异。过表达PIP1;4或PIP2;5的转基因植株在脱水胁迫下表现出快速的水分流失，这导致在干旱胁迫下种子萌发和幼苗生长受到抑制。相反，过表达PIP1;4或PIP2;5的转基因植株在冷胁迫下表现出水分流动增强和种子萌发促进。在脱水胁迫下，拟南芥中PIP1;4或PIP2;5的过表达显著影响了几种PIPs的表达，这表明一种水通道蛋白亚型的表达在胁迫条件下会影响其他水通道蛋白的表达水平。综上所述，我们的结果表明，水通道蛋白的过表达会影响内源性水通道蛋白基因的表达，从而影响植物在各种胁迫条件下的种子萌发、幼苗生长和胁迫反应。
