Metabolic responses of wheat seedlings to osmotic stress induced by various osmolytes under iso-osmotic conditions

Abstract

Many environmental stresses cause osmotic stress which induces several metabolic changes in plants. These changes often vary depending on the genotype, type and intensity of stress or the environmental conditions. In the current experiments, metabolic responses of wheat to osmotic stress induced by different kinds of osmolytes were studied under iso-osmotic stress conditions. A single wheat genotypes was treated with PEG-6000, mannitol, sorbitol or NaCl at such concentrations which reduce the osmotic potential of the culture media to the same level (-0.8MPa). The metabolic changes, including the accumulation of proline, glycine betaine (GB) and sugar metabolites (glucose, fructose, galactose, maltose and sucrose) were studied both in the leaves and roots together with monitoring the plant growth, changes in the photosynthetic activity and chlorophyll content of the leaves. In addition, the polyamine metabolism was also investigated. Although all osmolytes inhibited growth similarly, they induced different physiological and metabolic responses: the CO2 assimilation capacity, RWC content and the osmotic potential (ψπ) of the leaves decreased intensively, especially after mannitol and sorbitol treatments, followed by NaCl treatment, while PEG caused only a slight modification in these parameters. In the roots, the most pronounced decrease of ψπ was found after salt-treatments, followed by PEG treatment. Osmotic stress induced the accumulation of proline, glycine betaine and soluble sugars, such as fructose, glucose, sucrose and galactose in both the root and leaf sap. Specific metabolic response of roots and leaves under PEG included accumulation of glucose, fructose and GB (in the roots); sucrose, galactose and proline synthesis were dominant under NaCl stress while exposure to mannitol and sorbitol triggered polyamine metabolism and overproduction of maltose. The amount of those metabolites was time-dependent in the manner that longer exposure to iso-osmotic stress conditions stimulated the sugar metabolic routes. Our results showed that the various osmolytes activated different metabolic processes even under iso-osmotic stress conditions and these changes also differed in the leaves and roots.

Addition of Aegilops biuncialis chromosomes 2M or 3M improves the salt tolerance of wheat in different way

“…6 ). Starch hydrolysis, galactose or raffinose accumulation have also been detected previously in wheat under drought and different osmotic stress conditions 47 , 48 . In this experiment, an unidentified sugar compound ( S1 ) was also separated between the maltose and raffinose.…”

Metabolomic Profiling of Drought-Tolerant and Susceptible Peanut (Arachis hypogaea L.) Genotypes in Response to Drought Stress

“… 55 Sugars, such as GABA, galactose, fructose, and mannose, serve as metabolic precursors in many metabolic processes in plants. 56 In addition, starch, sucrose, and galactose metabolism was altered in Jatropha curcas drought-treated plants. 57 Also, pathways such as sucrose and starch metabolism and pentose and glucuronate interconversion were induced at the fiber initiation stage of cotton under drought stress, suggesting the regulation of sugar and energy metabolism to adapt to drought stress.…”

Comparisons of Chlorophyll Fluorescence and Physiological Characteristics of Wheat Seedlings Influenced by Iso-Osmotic Stresses from Polyethylene Glycol and Sodium Chloride

“…Nxele et al [8] observed a similar level of MDA in stressed plant under salinity and drought, but salinity stimulated more proline content. Recent study on wheat seedling also reported that NaCl stress stimulated proline accumulation dramatically, PEG induced accumulation of sugar metabolites (glucose, fructose) and glycine betaine, while polyamines' synthetic pathway was also altered by various osmolytes [26]. Furthermore, under salt stress, turgor would be maintained by transporters such as Na + /H + antiporter, H + -pyrophosphatase, high efficiency potassium transport [5], and aquaporin, which is specific transporter for water [6].…”

“…This should be attributed to roots having a higher ability to adapt to osmotic stress [23]; therefore, root growth rate can be stably maintained under various levels of PEG-induced osmotic stress [54]. Moreover, recent study revealed that the biosynthetic pathway of polyamines, including spermine, spermidine and putrescine, which participate in cell division and differentiation [55], also mediated under osmotic stress, and PEG leaded to increase of spermine, spermidine and putrescine [26].…”