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Recently, exogenous α-Lipoic acid (ALA) has been suggested to improve the tolerance of plants to a wide array of abiotic stresses. However, there is currently no definitive data on the role of ALA in wheat plants exposed to sodic alkaline stress. Therefore, this study was designed to evaluate the effects of foliar application by ALA at 0 (distilled water as control) and 20 µM on wheat seedlings grown under sodic alkaline stress (50 mM 1:1 NaHCO3 & Na2CO3; pH 9.7. Under sodic alkaline stress, exogenous ALA significantly (p ≤ 0.05) improved growth (shoot fresh and dry weight), chlorophyll (Chl) a, b and Chl a + b, while Chl a/b ratio was not affected. Moreover, leaf relative water content (RWC), total soluble sugars, carotenoids, total soluble phenols, ascorbic acid, K and Ca were significantly increased in the ALA-treated plants compared to the ALA-untreated plants. This improvement was concomitant with reducing the rate of lipid peroxidation (malondialdehyde, MDA) and H2O2. Superoxide dismutase (SOD) and ascorbate peroxidase (APX) demonstrated greater activity in the ALA-treated plants compared to the non-treated ones. Conversely, proline, catalase (CAT), guaiacol peroxidase (G-POX), Na and Na/K ratio were significantly decreased in the ALA-treated plants. Under sodic alkaline stress, the relative expression of photosystem II (D2 protein; PsbD) was significantly up-regulated in the ALA treatment (67% increase over the ALA-untreated plants); while Δ pyrroline-5-carboxylate synthase (P5CS), plasma membrane Na+/H+ antiporter protein of salt overly sensitive gene (SOS1) and tonoplast-localized Na+/H+ antiporter protein (NHX1) were down-regulated by 21, 37 and 53%, respectively, lower than the ALA-untreated plants. These results reveal that ALA may be involved in several possible mechanisms of alkalinity tolerance in wheat plants. [ABSTRACT FROM AUTHOR]

Recently, exogenous α-Lipoic acid (ALA) has been suggested to improve the tolerance of plants to a wide array of abiotic stresses. However, there is currently no definitive data on the role of ALA in wheat plants exposed to sodic alkaline stress. Therefore, this study was designed to evaluate the effects of foliar application by ALA at 0 (distilled water as control) and 20 µM on wheat seedlings grown under sodic alkaline stress (50 mM 1:1 NaHCO3 & Na2CO3; pH 9.7. Under sodic alkaline stress, exogenous ALA significantly (p ≤ 0.05) improved growth (shoot fresh and dry weight), chlorophyll (Chl) a, b and Chl a + b, while Chl a/b ratio was not affected. Moreover, leaf relative water content (RWC), total soluble sugars, carotenoids, total soluble phenols, ascorbic acid, K and Ca were significantly increased in the ALA-treated plants compared to the ALA-untreated plants. This improvement was concomitant with reducing the rate of lipid peroxidation (malondialdehyde, MDA) and H2O2. Superoxide dismutase (SOD) and ascorbate peroxidase (APX) demonstrated greater activity in the ALA-treated plants compared to the non-treated ones. Conversely, proline, catalase (CAT), guaiacol peroxidase (G-POX), Na and Na/K ratio were significantly decreased in the ALA-treated plants. Under sodic alkaline stress, the relative expression of photosystem II (D2 protein; PsbD) was significantly up-regulated in the ALA treatment (67% increase over the ALA-untreated plants); while Δ pyrroline-5-carboxylate synthase (P5CS), plasma membrane Na+/H+ antiporter protein of salt overly sensitive gene (SOS1) and tonoplast-localized Na+/H+ antiporter protein (NHX1) were down-regulated by 21, 37 and 53%, respectively, lower than the ALA-untreated plants. These results reveal that ALA may be involved in several possible mechanisms of alkalinity tolerance in wheat plants.

Abstract Alkali (high-pH) stress is an important factor limiting agricultural production and has complex effects on plant metabolism. Transcriptomics is widely used in the discovery of stress-response genes, but it provides only a rough estimation for gene expression. Proteomics may be more helpful than transcriptomics for the discovery and identification of stress-response genes. In this study, wheat plants were treated with sodic alkaline stress (50 mM, NaHCO 3 : Na 2 CO 3 = 1:1; pH 9.7), and then proteomic analysis was carried out on control and stressed plants. We detected 3,104 proteins, including 69 alkaline stress-response proteins. Five superoxide dismutases, three malate dehydrogenases, three dehydrin proteins, and one V-ATPase protein were upregulated in sodic alkaline-stressed wheat roots. We propose that these salinity response proteins may be important for ion homeostasis and osmotic regulation of sodic alkaline-stressed wheat. Additionally, two malic enzymes and many enzymes involved in the tricarboxylic acid cycle (TCA) were downregulated in the roots. The upregulation of malate dehydrogenase and the downregulation of TCA enzymes and malic enzymes may enhance the accumulation of malate in sodic alkaline-stressed wheat roots. Previous studies have demonstrated that the accumulation of malate in roots is a crucial adaptive mechanism of wheat to sodic alkaline stress. Herein, our proteomics results provided molecular insights into this adaptive mechanism. Highlights • Proteomics data are based on the newly released reference genome of common wheat. • Most salinity-tolerance proteins were downregulated by sodic alkaline stress. • Achieved molecular dissection of crucial adaptive mechanism in wheat to sodic alkaline stress. • Wheat exhibited A-subgenome-preference for translation under both control and stress conditions. [ABSTRACT FROM AUTHOR]

Previous studies have noted lower L* (lightness) values for both dark-cutting beef and normal-pH beef enhanced with lactate. In the current study, absorption-coefficient, scattering-coefficient, CIE L*a*b* values, refractive index of sarcoplasm, and inter-muscle bundle space were evaluated for dark-cutting beef, normal-pH beef enhanced with lactate, normal-pH beef enhanced with water, and normal-pH beef not enhanced with either water or lactate. Compared with non-enhanced loins, lactate-enhancement had lower a* , chroma, oxymyoglobin, reflectance, scattering, and inter-muscle bundle space as well as greater absorption and refractive index. Dark-cutting steaks had lower a* , chroma, oxymyoglobin values, reflectance, and scattering as well as less inter-muscle bundle space compared with lactate-enhanced steaks. Sarcoplasm refractive index values were greater in lactate-enhanced steaks than dark-cutting steaks. The results suggest that changes in muscle structure and optical properties due to either pH or lactate addition can alter muscle darkening and blooming properties. • Compared failure to bloom in dark-cutting and lactate-enhanced steaks • Dark-cutting steaks had lower reflectance than lactate-enhanced • Lactate-enhanced had greater refractive index values than dark-cutting steaks [ABSTRACT FROM AUTHOR]