Beneficial Effects of Silicon on Drought Tolerance in Plants
Soil drought is major abiotic factors that limit crop growth and productivity worldwide.Indeed,soil drought disrupts the cellular ionic and osmotic balance.Although silicon(Si) is generally considered nonessential for plant growth and developments,Silicon uptake by plants can alleviate both biotic and abiotic stresses.Silicon applica-tion could therefore improve crop production under adverse climate and soil conditions.Several reports have reviewed the benefits of silicon application on crop growth,but the mechanisms of silicon action have not been systematically discussed.Here,the authors review recent advances on silicon uptake,transport,and accumulation in plants and how silicon alleviates salinity toxicity and drought stress.The major points are the following:① both passive and active silicon uptake may coexist in plants,but more silicon transporters remain to be identified,and the process of silicon transport needs further clarification;② the mechanisms for silicon mediated tolerance of salinity and drought have been extensively investigated at both physiological and biochemical levels,further more including increasing water uptake,i.e.,roots,maintaining nutrient balance,decreasing water loss from leaves,promoting photosynthetic rate.And it may improve antioxidant defense abilities by increasing the activities of antioxidant enzymes and the contents of non enzymatic antioxidants;③ silicon can regulate the levels of endogenous plant hormones under stress conditions,whereas silicon involvement in signaling and regulation of gene expression related to increasing stress tolerance remains to be explored.
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