Glycyrrhiza uralensis Fisch (G. uralensis) is a key species for windbreak and sand fixation, possessing notable pharmacological and economic value. However, the yield of G. uralensis is considerably impacted due to its cultivation in arid, semi-arid, and salt-affected regions. Silicon (Si) has been reported to improve plant tolerance to drought and salt stress by regulating nitrogen and secondary metabolism. Herein, the effects of Si treatment on nitrogen and secondary metabolism of G. uralensis seedlings under drought (D), salt (S), and drought-salt (SD) stresses were investigated in combination with physiological and transcriptomic analyses. The results indicated that stress conditions significantly inhibited the growth of G. uralensis seedlings by suppressing nitrogen and secondary metabolism. Si treatment counteracted these inhibitions to some extent. Specifically, Si treatment increased soluble protein content by approximately 15% by regulating the nitrogen metabolism of G. uralensis under D stress. Furthermore, Si treatment elevated the content of glycyrrhetinic acid by about 89% under SD stress by increasing the content of primary metabolites and regulating the expression of enzymes involved in the biosynthesis of glycyrrhizic acid and liquiritin, including 3-hydroxy-3-methylglutaryl CoA reductase (HMGR), squalene synthase (SQS), and β-amyrin synthase (β-AS). In summary, our findings suggest that Si could alleviate the adverse effects induced by drought and/or salt stresses on the growth of G. uralensis seedlings by regulating nitrogen metabolisms, which further triggered the accumulation of secondary metabolites, ultimately improving the stress resistance of cultivated G. uralensis seedlings. This work provides direction for Si to improve stress resistance.
To investigate the effect and action mechanism of resveratrol on the vascular endothelial cell by high glucose treatment. Primarily cultured human umbilical vein endothelial cells (HUVECs) were pretreated by resveratrol (0.2 μmol/L) and holding for 6 h, and then cultured in Dulbecco Modified Eagle Medium (DMEM) within 0.45 mmol/L of palmimte acid and 32.8 mmol/L of glucose, which is holding for 12 h. The cells were collected to analyze the expression of E-selected element. Supernatant of cultured cells, induced by 100 nmol/L insulin for 30 min, was used to analyze the nitric oxide content. Compared with normal control cells, the secretion of nitric oxide is stimulated by insulin decrease, however, the expression of E-selected element increased in HUVEC. Resveratrol treatment increased the secretion of nitric oxide stimulated by insulin and decreased the expression of E-selected element and partly counteracts the impairment of high glucose and palmitate acid on the function of endothelial cells. Resveratrol can improve and protect the function of high glucose and fatty acid cultured endothelial cell, and therefore may be a promising medicine in the prevention or therapy of diabetic macrovascular diseases.