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Metabolomic changes associated with elevated CO2-regulation of salt tolerance in Kentucky bluegrass

Zhuang, Lili, Yang, Zhimin, Fan, Ningli, Yu, Jingjin, Huang, Bingru
Environmental and experimental botany 2019 v.165 pp. 129-138
Poa pratensis, beta-sitosterol, biochemical pathways, campesterol, carbon dioxide, carbon dioxide enrichment, cellobiose, chlorophyll, citric acid, electrolyte leakage, fatty acid metabolism, fructose, fumaric acid, galactose, galacturonic acid, gluconic acid, glucose, glycerol, grasses, growth chambers, irrigation scheduling, isocitric acid, lactic acid, lactose, lawns and turf, leaves, linolenic acid, malic acid, malonic acid, mannitol, mannose, metabolites, metabolomics, palmitic acid, perennials, photosynthesis, pyruvic acid, quinic acid, roots, salt stress, salt tolerance, shikimic acid, sodium, sodium chloride, soil, stigmasterol, succinic acid, sucrose, tagatose, trehalose, water content
Salt stress caused by excessive sodium accumulation in the soil can result in various physiological damages in plants. Elevated CO2 concentration may cause metabolomic adjustment or reprogramming, protecting plants from salt damages. The objectives of this study were to identify CO2-reponsive metabolites in leaves and roots of Kentucky bluegrass (Poa pretensis) differently accumulated under salt stress and non-stress conditions and determine major metabolic pathways involved in CO2 responses that may contribute to CO2-enhanced salt tolerance. Plants were grown in growth chambers controlled at ambient CO2 concentration (400 ± 10 μmol mol−1) or elevated CO2 concentration (800 ± 10 μmol mol−1), and irrigated daily with 250 mL water (non-stress control) or 200 mM NaCl solution (salt stress). Elevated CO2 effectively ameliorated plant growth and physiological damages due to salt stress, as shown by the increase in turf quality, leaf relative water content, leaf chlorophyll content, shoot growth rate, net photosynthetic rate, and K + content, as well as by the reduction in electrolyte leakage and Na + content in both leaves and roots. Elevated CO2 concertation altered metabolic profiles of leaves and roots exposed to salt stress, with enhanced accumulation of organic acids (quinic acid, mucic acid, pyruvic acid, citric acid, lactic acid, malic acid, fumaric acid, and shikimic acid in leaves; citric acid, fumaric acid, gluconic acid, galacturonic acid, isocitric acid, glyceric acid, succinic acid, and malonic acid in roots), sugars (glucose, fructose, hexopyranose, gulose, tagatose, mannose, sucrose, trehalose, cellobiose in leaves; glucose, galactose, hexopyranose, sucrose, trehalose, lactose, turanose in roots), sugar alcohols (galactinol, glycerol in leaves and galactinol, glycerol, mannitol in roots), sterols (β-sitosterol in leaves and stigmasterol, β-sitosterol, campesterol in roots), and fatty acids (linolenic acid and palmitic acid in both leaves and roots). The accumulation of CO2-reponsive metabolites involved in sugar metabolism, fatty acid metabolism and respiratory metabolism could facilitate the improved salt tolerance in perennial grass due to elevated CO2 concentration.