Overexpression of the Wheat Aquaporin Gene, TaAQP7, Enhances Drought Tolerance in Transgenic Tobacco

Abstract

Aquaporin (AQP) proteins have been shown to transport water and other small molecules through biological membranes, which is crucial for plants to combat stress caused by drought. However, the precise role of AQPs in drought stress response is not completely understood in plants. In this study, a PIP2 subgroup gene AQP, designated as TaAQP7, was cloned and characterized from wheat. Expression of TaAQP7-GFP fusion protein revealed its localization in the plasma membrane. TaAQP7 exhibited high water channel activity in Xenopus laevis oocytes and TaAQP7 transcript was induced by dehydration, and treatments with polyethylene glycol (PEG), abscisic acid (ABA) and H2O2. Further, TaAQP7 was upregulated after PEG treatment and was blocked by inhibitors of ABA biosynthesis, implying that ABA signaling was involved in the upregulation of TaAQP7 after PEG treatment. Overexpression of TaAQP7 increased drought tolerance in tobacco. The transgenic tobacco lines had lower levels of malondialdehyde (MDA) and H2O2, and less ion leakage (IL), but higher relative water content (RWC) and superoxide dismutase (SOD) and catalase (CAT) activities when compared with the wild type (WT) under drought stress. Taken together, our results show that TaAQP7 confers drought stress tolerance in transgenic tobacco by increasing the ability to retain water, reduce ROS accumulation and membrane damage, and enhance the activities of antioxidants.

Overexpression of EsMcsu1 from the halophytic plant Eutrema salsugineum promotes abscisic acid biosynthesis and increases drought resistance in alfalfa (Medicago sativa L.)

“…Therefore, EsMcsu1overexpression increased the ability of transgenic alfalfa plants to eliminate cellular ROS, indicating that the transgenic lines experienced less oxidative damage than the WT plants. IL, which is an index of physical damage to cell membranes (Zhou et al, 2012), was significantly lower in the leaves of TG2 and TG7 than in those of the WT plants, while no difference was observed before drought treatment (Figure 7a). In addition, MDA, which is a key indicator of ROS-mediated damage to plant cells (Moore and Roberts, 1998), exhibited a similar tendency to IL (Figure 7b).…”

“…Leaf water loss and water potential was measured as described by Li et al (2013). Levels of ion leakage (IL) and malondialdehyde (MDA) were detected according to the method described by Zhou et al (2012). In vivo localization and quantification of reactive oxygen species (ROS), including H 2 O 2 and O 2 − , was determined according to the methods reported by Yadav et al (2012).…”

Aspergillus glaucus Aquaglyceroporin Gene glpF Confers High Osmosis Tolerance in Heterologous Organisms

“…It also presents the subsequent phenotypic characterization of this transgenic plant under conditions of salt and drought stress. While transgenic methods used to explore the role of plant AQPs have been reported previously (54)(55)(56), this is the first report describing the in planta heterologous expression of an aquaglyceroporin derived from a filamentous fungus. Recently, a viral aquaglyceroporin of Chlorovirus (encoded by aqpv1) has been expressed in tobacco (57).…”

Constitutive and stress-inducible overexpression of a native aquaporin gene (MusaPIP2;6) in transgenic banana plants signals its pivotal role in salt tolerance

“…Indeed, recent studies conducted on important monocot species have reported that the heterologous overexpression of AQP genes in transgenic plants imparts improved tolerance to cold, salt and drought stress. TaAQP8 overexpression in transgenic tobacco improved salt stress tolerance whereas ectopic expression of TaAQP7 improved the drought tolerance in tobacco plants indicating specific roles and functions of each AQP isoform in the overall management of water balance in plant cells (Zhou et al 2012). Similarly, constitutive overexpression of OsPIP1;1 improved salt tolerance in transgenic rice (Liu et al 2012) and constitutive and stress-inducible overexpression of a native plasma membrane AQP in banana improved drought, salt and cold tolerance in transgenic banana plants (Sreedharan et al 2013).…”