title: Effect of nitrogen deficiency on ascorbic acid biosynthesis and recycling pathway in cucumber seedlings.
abstract: L-Ascorbic acid (AsA, ascorbate) is one of the most abundant natural antioxidants, and it is an important factor in the nutritional quality of cucumber. In this work, key enzymes involved in the ascorbic acid biosynthesis and recycling pathway in cucumber seedlings under nitrogen deficiency were investigated at the levels of transcription and enzyme activity. The activities of myo-inositol oxygenase (MIOX) and transcript levels of MIOXs increased dramatically, while the activities of ascorbate oxidase (AO) and glutathione reductase (GR) and transcript levels of AOs and GR2 decreased significantly in N-limited leaves, as did the ascorbate concentration, in nitrogen-deficient cucumber seedlings. The activities of other enzymes and transcript levels of other genes involved in the ascorbate recycling pathway and ascorbate synthesis pathways decreased or remained unchanged under nitrogen deficiency. These results indicate that nitrogen deficiency induced genes involved in the ascorbate-glutathione recycling and myo-inositol pathway in cucumber leaves. Thus, the AO, GR and MIOX involved in the pathways might play roles in AsA accumulation.
authors.affiliation: Key Laboratory of Horticultural Crops Genetic Improvement (Ministry of Agriculture), Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Horticultural Crops Genetic Improvement (Ministry of Agriculture), Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Hong Jun
authors.initials: HJ
authors.lastname: Yu
authors.affiliation: Key Laboratory of Horticultural Crops Genetic Improvement (Ministry of Agriculture), Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Xiao Meng
authors.initials: XM
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Horticultural Crops Genetic Improvement (Ministry of Agriculture), Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Xue Yong
authors.initials: XY
authors.lastname: Yang
authors.affiliation: Beijing Key Laboratory for Agriculture Application and New Technology, Plant Science and Technology College, Beijing University of Agriculture, Beijing 102206, China.
authors.forename: Wen Chao
authors.initials: WC
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Horticultural Crops Genetic Improvement (Ministry of Agriculture), Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China. Electronic address: liqiang05@caas.cn.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.affiliation: Key Laboratory of Horticultural Crops Genetic Improvement (Ministry of Agriculture), Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China; Xinjiang Agricultural University, Urumqi 830052, Xinjiang, China. Electronic address: jiangweijie@caas.cn.
authors.forename: Wei Jie
authors.initials: WJ
authors.lastname: Jiang
mesh_terms: D001204:Ascorbate Oxidase / Q000235:genetics / Q000378:metabolism; D001205:Ascorbic Acid / Q000096:biosynthesis / Q000378:metabolism*; D018553:Cucumis sativus / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005980:Glutathione Reductase / Q000235:genetics / Q000378:metabolism; D009584:Nitrogen / Q000172:deficiency* / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D036226:Seedlings / Q000378:metabolism* / Q000502:physiology
chemical_list: D001204:Ascorbate Oxidase; D005980:Glutathione Reductase; D009584:Nitrogen; D001205:Ascorbic Acid
keywords: Ascorbate biosynthesis pathways; Ascorbate recycling pathway; Cucumber; L-ascorbic acid; Nitrogen deficiency