title: Over-expression of a glutamate dehydrogenase gene, MgGDH, from Magnaporthe grisea confers tolerance to dehydration stress in transgenic rice.
abstract: Heterologous expression of a fungal NADP(H)-GDH gene ( MgGDH ) from Magnaporthe grisea can improve dehydration stress tolerance in rice by preventing toxic accumulation of ammonium. Glutamate dehydrogenase (GDH; EC 1.4.1.2 and EC 1.4.1.4) may act as a stress-responsive enzyme in detoxification of high intracellular ammonia and production of glutamate for proline synthesis under stress conditions. In present study, a fungal NADP(H)-GDH gene (MgGDH) from Magnaporthe grisea was over-expressed in rice (Oryza sativa L. cv. 'kitaake'), and the transgenic plants showed the improvement of tolerance to dehydration stress. The kinetic analysis showed that His-TF-MgGDH preferentially utilizes ammonium to produce L-glutamate. Moreover, the affinity of His-TF-MgGDH for ammonium was dramatically higher than that of His-TF-OsGDH for ammonium. Over-expressing MgGDH transgenic rice plants showed lower water-loss rate and higher completely close stomata than the wild-type plants under dehydration stress conditions. In transgenic plants, the NADP(H)-GDH activities were markedly higher than those in wild-type plants and the amination activity was significantly higher than the deamination activity. Compared with wild-type plants, the transgenic plants accumulated much less NH4 (+) but higher amounts of glutamate, proline and soluble sugar under dehydration stress conditions. These results indicate that heterologous expression of MgGDH can prevent toxic accumulation of ammonium and in return improve dehydration stress tolerance in rice.
authors.affiliation: Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha, 410082, China.
authors.forename: Yanbiao
authors.initials: Y
authors.lastname: Zhou
authors.forename: Caisheng
authors.initials: C
authors.lastname: Zhang
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Lin
authors.forename: Yuanzhu
authors.initials: Y
authors.lastname: Yang
authors.forename: Yuchong
authors.initials: Y
authors.lastname: Peng
authors.forename: Dongying
authors.initials: D
authors.lastname: Tang
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Zhao
authors.forename: Yonghua
authors.initials: Y
authors.lastname: Zhu
authors.forename: Xuanming
authors.initials: X
authors.lastname: Liu
mesh_terms: D000222:Adaptation, Physiological; D000586:Amination; D064751:Ammonium Compounds / Q000378:metabolism; D050260:Carbohydrate Metabolism; D018086:Glutamate Dehydrogenase (NADP+) / Q000235:genetics* / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D007700:Kinetics; D020082:Magnaporthe / Q000235:genetics*; D012275:Oryza / Q000502:physiology*; D030821:Plants, Genetically Modified; D011392:Proline / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D013312:Stress, Physiological; D014867:Water / Q000502:physiology*
chemical_list: D064751:Ammonium Compounds; D011994:Recombinant Proteins; D014867:Water; D018698:Glutamic Acid; D011392:Proline; D018086:Glutamate Dehydrogenase (NADP+)