Silicon Modulates the Production and Composition of Phenols in Barley under Aluminum Stress

Abstract

Silicon (Si) exerts beneficial effects in mitigating aluminum (Al) toxicity in different plant species. These include attenuating oxidative damage and improving structural strengthening as a result of the increased production of secondary metabolites such as phenols. The aim of this research was to evaluate the effect of Si on phenol production and composition in two barley cultivars under Al stress. Our conceptual approach included a hydroponic experiment with an Al-tolerant (Sebastian) and an Al-sensitive (Scarlett) barley cultivar treated with two Al doses (0 or 0.2 mM of Al) and two Si doses (0 or 2 mM) for 21 days. Chemical, biochemical and growth parameters were assayed after harvest. Our results indicated that the Al and Si concentration decreased in both cultivars when Al and Si were added in combination. Silicon increased the antioxidant activity and soluble phenol concentration, but reduced lipid peroxidation irrespective of the Al dose. Both barley cultivars showed changes in culm creep rate, flavonoids and flavones concentration, lignin accumulation and altered lignin composition in Si and Al treatments. We concluded that Si fertilization could increase the resistance of barley to Al toxicity by regulating the metabolism of phenolic compounds with antioxidant and structural functions.

Closing Biogeochemical Cycles and Meeting Plant Requirements by Smart Fertilizers and Innovative Organic Amendments

“…Mineral fertilization may also lead to soil acidification thereby increasing aluminum (Al 3+ ) toxicity [7,24,25]. In this context, Vega et al [26] studied the beneficial effects of silicon application for mitigating Al 3+ toxicity in sensitive barley cultivars. Their findings revealed that silicon fertilization could increase the resistance of barley to Al 3+ toxicity by regulating the metabolism of phenolic compounds with antioxidant and structural functions.…”

Comprehensive Study of Si-Based Compounds in Selected Plants (Pisum sativum L., Medicago sativa L., Triticum aestivum L.)

“…Figure 5 illustrates the chemical structures of selected phenolic compounds, focusing on the flavonoids and phenolic acids described in the literature [72,109,232].…”

“…Figure 5 illustrates the chemical structures of selected phenolic compounds, focusing on the flavonoids and phenolic acids described in the literature [72,109,232]. Researchers have suggested the presence of several potential links between silicon and phenol metabolism: (i) silicon could interact with the OH groups of phenols by condensing with Si(OH) in biological systems, (ii) silicon may be involved with lignincarbohydrate complexes present in cell walls, and (iii) silicon might play a role in signal transduction pathways responsible for inducing lignin production [193,233,234].…”

Silicon attenuates aluminum toxicity in sugarcane plants by modifying growth, roots morphoanatomy, photosynthetic pigments, and gas exchange parameters

“…Si application is important in mitigating Al toxicity by minimizing transpiration and maximizing photosynthesis 28 , 29 , increasing phenolic compounds, especially lignin 10 , 21 , 22 , enhancing enzyme activity 6 , 30 , and macros- and micronutrients uptake 6 , 10 , 12 . Several studies with various species found that, Si supplementation enhances plant responses to the toxic effects of Al in plants such as wheat 31 , maize 32 , rice 33 , and barley 21 , 22 .…”

“…Sugarcane was selected in this study due to its hyperaccumulation of Si 8 , 34 , which is suitable for studying the mechanisms of Si-mediated Al tolerance. Currently, most studies on the amelioration of Al toxicity by Si are based on growth and physiological levels 22 , 35 , while the role of Si in root morphoanatomy under Al stress is still limited. Therefore, the objective of this study was to evaluate the interactive role of Si in increasing the growth, physiological and morphoanatomy responses of sugarcane plants under Al toxicity.…”