Productivity of wheat is affected by drought stress; however, the correlation between drought stress and metabolism is still not clear. The aim of this study was to investigate physiological adaptive mechanisms and reveal physiological processes related to drought tolerance. The results indicated that the wheat metabolome is dominated by sugars, organic acids and amino acids; the wheat metabolome plays important roles in enhancing the drought tolerance of shoots. Drought caused system alterations in widespread metabolic networks involving transamination, tricarboxylic acid cycle, glycolysis, glutamate-mediated proline biosynthesis, shikimate-mediated secondary metabolisms and GABA metabolisms.

BackgroundIt 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.ResultsThe 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.ConclusionsCa 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.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0546-x) contains supplementary material, which is available to authorized users.

Toward an understanding of the protein interaction network of the human liverAn extensive interaction network of human liver-expressed proteins is described, composed of 3484 interactions among 2582 proteins. Proteins associated with liver disease tend to be central and highly connected in the network.