title: Comparative metabolic responses and adaptive strategies of wheat (Triticum aestivum) to salt and alkali stress.
abstract: BACKGROUND
  It is well known that salinization (high-pH) has been considered as a major environmental threat to agricultural systems. The aim of this study was to investigate the differences between salt stress and alkali stress in metabolic profiles and nutrient accumulation of wheat; these parameters were also evaluated to determine the physiological adaptive mechanisms by which wheat tolerates alkali stress.
  
  
  RESULTS
  The harmful effect of alkali stress on the growth and photosynthesis of wheat were stronger than those of salt stress. High-pH of alkali stress induced the most of phosphate and metal ions to precipitate; as a result, the availability of nutrients significantly declined. Under alkali stress, Ca sharply increased in roots, however, it decreased under salt stress. In addition, we detected the 75 metabolites that were different among the treatments according to GC-MS analysis, including organic acids, amino acids, sugars/polyols and others. The metabolic data showed salt stress and alkali stress caused different metabolic shifts; alkali stress has a stronger injurious effect on the distribution and accumulation of metabolites than salt stress. These outcomes correspond to specific detrimental effects of a highly pH environment.
  
  
  CONCLUSIONS
  Ca had a significant positive correlation with alkali tolerates, and increasing Ca concentration can immediately trigger SOS Na exclusion system and reduce the Na injury. Salt stress caused metabolic shifts toward gluconeogenesis with increased sugars to avoid osmotic stress; energy in roots and active synthesis in leaves were needed by wheat to develop salt tolerance. Alkali stress (at high pH) significantly inhibited photosynthetic rate; thus, sugar production was reduced, N metabolism was limited, amino acid production was reduced, and glycolysis was inhibited.
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, P.R. 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. 540073148@qq.com.
authors.forename: Zongze
authors.initials: Z
authors.lastname: Yang
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, P.R. China. lif@ieda.org.cn.
authors.forename: Feng
authors.initials: F
authors.lastname: Li
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, P.R. China. yancr@ieda.org.cn.
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, P.R. China. zhongxl@ieda.org.cn.
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, P.R. China. happy555qiqi@163.com.
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, P.R. China. xuxubuwei@126.com.
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, P.R. China. lihr@ieda.org.cn.
authors.forename: Haoru
authors.initials: H
authors.lastname: Li
authors.affiliation: Key laboratory of Molecular Epigenetics of Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China. 309592407@qq.com.
authors.forename: Long
authors.initials: L
authors.lastname: Zhao
mesh_terms: D000468:Alkalies / Q000378:metabolism / Q000494:pharmacology*; D009997:Osmotic Pressure / Q000502:physiology; D055049:Salt Tolerance / Q000187:drug effects*; D012965:Sodium Chloride / Q000378:metabolism / Q000494:pharmacology*; D013312:Stress, Physiological / Q000502:physiology*; D014908:Triticum / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000468:Alkalies; D012965:Sodium Chloride