title: Ionomic and metabolic responses to neutral salt or alkaline salt stresses in maize (Zea mays L.) seedlings.
abstract: Soil salinity and alkalinity present a serious threat to global agriculture. However, most of the studies have focused on neutral salt stress, and the information on the metabolic responses of plants to alkaline salt stress is limited. This investigation aimed at determining the influence of neutral salt and alkaline salt stresses on the content of metal elements and metabolites in maize plant tissues, by using mixtures of various proportions of NaCl, NaHCO3, Na2SO4, and Na2CO3.
  
  
  
  We found that alkaline salt stress suppressed more pronouncedly the photosynthesis and growth of maize plants than salinity stress. Under alkaline salt stress conditions, metal ions formed massive precipitates, which ultimately reduced plant nutrient availability. On the other hand, high neutral salt stress induced metabolic changes in the direction of gluconeogenesis leading to the enhanced formation of sugars as a reaction contributing to the mitigation of osmotic stress. Thus, the active synthesis of sugars in shoots was essential to the development of salt tolerance. However, the alkaline salt stress conditions characterized by elevated pH values suppressed substantially the levels of photosynthesis, N metabolism, glycolysis, and the production of sugars and amino acids.
  
  
  
  These results indicate the presence of different defensive mechanisms responsible for the plant responses to neutral salt and alkaline salt stresses. In addition, the increased concentration of organic acids and enhanced metabolic energy might be potential major factors that can contribute to the maintenance intracellular ion balance in maize plants and counteract the negative effects of high pH under alkaline salt stress.
authors.affiliation: Institute of Environment and Sustainable Development in Agriculture (IEDA), Chinese Academy of Agricultural Sciences (CAAS) / Key Laboratory of Dryland Agriculture, Ministry of Agriculture, Beijing, 100081, People's Republic of China. guor219@yahoo.com.
authors.forename: Rui
authors.initials: R
authors.lastname: Guo
authors.affiliation: Key laboratory of Molecular Epigenetics of Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China.
authors.forename: LianXuan
authors.initials: L
authors.lastname: Shi
authors.affiliation: Institute of Environment and Sustainable Development in Agriculture (IEDA), Chinese Academy of Agricultural Sciences (CAAS) / Key Laboratory of Dryland Agriculture, Ministry of Agriculture, Beijing, 100081, People's Republic of China.
authors.forename: Changrong
authors.initials: C
authors.lastname: Yan
authors.affiliation: Institute of Environment and Sustainable Development in Agriculture (IEDA), Chinese Academy of Agricultural Sciences (CAAS) / Key Laboratory of Dryland Agriculture, Ministry of Agriculture, Beijing, 100081, People's Republic of China.
authors.forename: Xiuli
authors.initials: X
authors.lastname: Zhong
authors.affiliation: Institute of Environment and Sustainable Development in Agriculture (IEDA), Chinese Academy of Agricultural Sciences (CAAS) / Key Laboratory of Dryland Agriculture, Ministry of Agriculture, Beijing, 100081, People's Republic of China.
authors.forename: FengXue
authors.initials: F
authors.lastname: Gu
authors.affiliation: Institute of Environment and Sustainable Development in Agriculture (IEDA), Chinese Academy of Agricultural Sciences (CAAS) / Key Laboratory of Dryland Agriculture, Ministry of Agriculture, Beijing, 100081, People's Republic of China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Institute of Environment and Sustainable Development in Agriculture (IEDA), Chinese Academy of Agricultural Sciences (CAAS) / Key Laboratory of Dryland Agriculture, Ministry of Agriculture, Beijing, 100081, People's Republic of China.
authors.forename: Xu
authors.initials: X
authors.lastname: Xia
authors.affiliation: Institute of Environment and Sustainable Development in Agriculture (IEDA), Chinese Academy of Agricultural Sciences (CAAS) / Key Laboratory of Dryland Agriculture, Ministry of Agriculture, Beijing, 100081, People's Republic of China.
authors.forename: Haoru
authors.initials: H
authors.lastname: Li
mesh_terms: D008401:Gas Chromatography-Mass Spectrometry; D055442:Metabolome / Q000502:physiology; D008670:Metals / Q000378:metabolism; D015999:Multivariate Analysis; D009997:Osmotic Pressure; D010788:Photosynthesis / Q000187:drug effects; D054712:Salinity; D055049:Salt Tolerance; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000502:physiology*; D013431:Sulfates / Q000494:pharmacology; D003313:Zea mays / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology
chemical_list: D008670:Metals; D013431:Sulfates; C012036:sodium sulfate; D012965:Sodium Chloride
keywords: Alkaline salt stress; Growth; Maize; Metabolites; Metal elements; Neutral salt stress; Photosynthesis