title: UPLC-QTOF analysis reveals metabolomic changes in the flag leaf of wheat (Triticum aestivum L.) under low-nitrogen stress.
abstract: Wheat is one of the most important grain crop plants worldwide. Nitrogen (N) is an essential macronutrient for the growth and development of wheat and exerts a marked influence on its metabolites. To investigate the influence of low nitrogen stress on various metabolites of the flag leaf of wheat (Triticum aestivum L.), a metabolomic analysis of two wheat cultivars under different induced nitrogen levels was conducted during two important growth periods based on large-scale untargeted metabolomic analysis using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF). Multivariate analyses-such as principle components analysis (PCA) and orthogonal partial least square discriminant analysis (OPLS-DA)-were used for data analysis. PCA yielded distinctive clustering information among the samples, classifying the wheat flag samples into two categories: those under normal N treatment and low N treatment. By processing OPLS-DA, eleven secondary metabolites were shown to be responsible for classifying the two groups. The secondary metabolites may be considered potential biomarkers of low nitrogen stress. Chemical analyses showed that most of the identified secondary metabolites were flavonoids and their related derivatives, such as iso-vitexin, iso-orientin and methylisoorientin-2″-O-rhamnoside, etc. This study confirmed the effect of low nitrogen stress on the metabolism of wheat, and revealed that the accumulation of secondary metabolites is a response to abiotic stresses. Meanwhile, we aimed to identify markers which could be used to monitor the nitrogen status of wheat crops, presumably to guide appropriate fertilization regimens. Furthermore, the UPLC-QTOF metabolic platform technology can be used to study metabolomic variations of wheat under abiotic stresses.
authors.affiliation: College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China. Electronic address: Mxinming@163.com.
authors.forename: Xin-Ming
authors.initials: XM
authors.lastname: Ma
authors.affiliation: College of Life Science, Henan Agricultural University, Zhengzhou, Henan 450002, China.
authors.forename: Xiao-Chun
authors.initials: XC
authors.lastname: Wang
authors.affiliation: Institute of Agricultural Quality Standards and Testing Techniques, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China.
authors.forename: Ji-Hong
authors.initials: JH
authors.lastname: Liu
authors.affiliation: Industrial Crops Research Institute, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China.
authors.forename: Bing-Yan
authors.initials: BY
authors.lastname: Huang
authors.affiliation: College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China.
authors.forename: Xiao-Yang
authors.initials: XY
authors.lastname: Guo
authors.affiliation: College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China.
authors.forename: Shu-Ping
authors.initials: SP
authors.lastname: Xiong
authors.affiliation: Industrial Crops Research Institute, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China.
authors.forename: Gui-Xiao
authors.initials: GX
authors.lastname: La
mesh_terms: D015415:Biomarkers / Q000032:analysis; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D016002:Discriminant Analysis; D005419:Flavonoids / Q000378:metabolism; D016018:Least-Squares Analysis; D055442:Metabolome / Q000187:drug effects; D055432:Metabolomics / Q000379:methods*; D009584:Nitrogen / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism*; D025341:Principal Component Analysis; D013312:Stress, Physiological / Q000187:drug effects*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014908:Triticum / Q000187:drug effects / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D005419:Flavonoids; D009584:Nitrogen
keywords: Low nitrogen stress; Metabolomics; OPLS-DA; PCA; UPLC-QTOF; Wheat