title: Saline stress enhanced accumulation of leaf phenolics in honeysuckle (Lonicera japonica Thunb.) without induction of oxidative stress.
abstract: Honeysuckle (Lonicera japonica Thunb.) is a traditional medicinal plant in Chinese, and chlorogenic acid and luteolosid are its specific bioactive phenolic compounds. This study was to investigate leaf antioxidant responses in honeysuckle to saline stress with emphasis on phenolics through hydroponic experiments and field trials. NaCl stress did not stimulate antioxidant system including superoxide dismutase, ascorbate peroxidase, catalase and ascorbate, and had no significant effect on lipid peroxidation in the leaves. Consistently, no inhibition on photochemical capacity of photosystems suggested that reactive oxygen species (ROS) was maintained at a normal level under NaCl stress. However, leaf phenolic synthesis was activated by NaCl stress, indicated by elevated genes transcription and activity of phenylalanine ammonia-lyase and increased phenolics concentration. Specifically, leaf chlorogenic acid concentration was increased by 67.43% and 48.86% after 15 days of 150 and 300 mM NaCl stress, and the increase of luteolosid concentration was 54.26% and 39.74%. The accumulated phenolics hardly helped detoxify ROS in vivo in absence of oxidative stress, but the elevated phenolic synthesis might restrict ROS generation by consuming reduction equivalents. As with NaCl stress, soil salinity also increased concentrations of leaf phenolics including chlorogenic acid and luteolosid without exacerbated lipid peroxidation. In conclusion, leaf phenolics accumulation is a mechanism for the acclimation to saline stress probably by preventing oxidative stress in honeysuckle; leaf medicinal quality of honeysuckle can be improved by saline stress due to the accumulation of bioactive phenolic compounds.
authors.affiliation: Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China. Electronic address: kyan@yic.ac.cn.
authors.forename: Kun
authors.initials: K
authors.lastname: Yan
authors.affiliation: State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China.
authors.forename: Shijie
authors.initials: S
authors.lastname: Zhao
authors.affiliation: College of Life Sciences, Yantai University, Yantai, China.
authors.forename: Lanxing
authors.initials: L
authors.lastname: Bian
authors.affiliation: Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.
authors.forename: Xiaobing
authors.initials: X
authors.lastname: Chen
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D001713:Biphenyl Compounds / Q000737:chemistry; D002726:Chlorogenic Acid / Q000032:analysis; D002734:Chlorophyll / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D005453:Fluorescence; D016166:Free Radical Scavengers / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018527:Hydroponics; D031239:Lonicera / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D008315:Malondialdehyde / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D010636:Phenols / Q000378:metabolism*; D010650:Phenylalanine Ammonia-Lyase / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D010851:Picrates / Q000737:chemistry; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012015:Reference Standards; D012621:Seasons; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological / Q000187:drug effects* / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D010636:Phenols; D010851:Picrates; D002734:Chlorophyll; D002726:Chlorogenic Acid; D012965:Sodium Chloride; D008315:Malondialdehyde; C004931:1,1-diphenyl-2-picrylhydrazyl; D010650:Phenylalanine Ammonia-Lyase
keywords: Antioxidant enzyme; Ascorbate; Phenolics; Phenylalanine ammonia-lyase; Photosynthetic electron transport