Responses of hybrid aspen over-expressing a PIP2;5 aquaporin to low root temperature

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• 作者：Kapilan Ranganathan^a ; Walid El Kayal^b ; ¹ ; Janice E.K. Cooke^b ; Janusz J. Zwiazek^a ; ^{jzwiazek@ualberta.ca" class="auth_mail" title="E-mail the corresponding author}
• 关键词：E ; transpiration ; Ea ; activation energy ; Lp ; hydraulic conductivity ; PIP ; plasma membrane intrinsic protein ; Pn ; net photosynthesis ; PtdPIP2 ; 5ox ; PtdPIP2 ; 5 over-expressing hybrid aspen lines ; PtdPIP2 ; 5 ; PIP2 ; 5 isolated from Populus trichocarpa  ; × ;   ; deltoides
• 刊名：Journal of Plant Physiology
• 出版年：2016
• 出版时间：15 March 2016
• 年：2016
• 卷：192
• 期：Complete
• 页码：98-104
• 全文大小：1309 K

文摘

Aquaporins mediate the movement of water across cell membranes. Plasma membrane intrinsic protein 2;5 from Populus trichocarpa × deltoides (PtdPIP2;5) was previously demonstrated to be a functionally important water conducting aquaporin. To study the relevance of aquaporin-mediated root water transport at low temperatures, we generated transgenic Populus tremula × alba over-expressing PtdPIP2;5 under control of the maize ubiquitin promoter, and compared the physiological responses and water transport properties of the PtdPIP2;5 over-expressing lines (PtdPIP2;5ox) with wild-type plants. We hypothesized that over-expression of PtdPIP2;5 would reduce temperature sensitivity of root water transport and gas exchange. Decreasing root temperatures to 10 and 5 °C significantly decreased hydraulic conductivities (L_p) in wild-type plants, but had no significant effect on L_p in PtdPIP2;5ox plants. Recovery of L_p in the transgenic lines returned to 20 °C from 5 °C was faster than in the wild-type plants. Low root temperature did not induce major changes in transcript levels for other PIPs. When roots were exposed to 5 °C in solution culture and shoots were exposed to 20 °C, wild-type plants had significantly lower net photosynthetic and transpiration rates compared to PtdPIP2;5ox plants. Taken together, our results demonstrate that over-expression of PtdPIP2;5 in P. tremula × alba was effective in alleviating the effects of low root temperature on L_p and gas exchange.