title: Melatonin mediates the regulation of ABA metabolism, free-radical scavenging, and stomatal behaviour in two Malus species under drought stress.
abstract: Melatonin pre-treatment significantly increases the tolerance of both drought-tolerant Malus prunifolia and drought-sensitive M. hupehensis plants. Its beneficial effects include better water conservation in leaves, less electrolyte leakage, steady chlorophyll contents, and greater photosynthetic performance under stress conditions. Melatonin selectively down-regulates MdNCED3, an abscisic acid (ABA) synthesis gene, and up-regulates its catabolic genes, MdCYP707A1 and MdCYP707A2, thereby reducing ABA contents in drought-stressed plants. Melatonin also directly scavenges H2O2 and enhances the activities of antioxidant enzymes to detoxify H2O2 indirectly. These two mechanisms work synergistically to improve the functions of stomata, i.e. causing them to re-open. Plants can effectively regulate their water balance under drought conditions by up-regulating the expression of melatonin synthesis genes MdTDC1, MdAANAT2, MdT5H4, and MdASMT1. Therefore, inducing melatonin production is an important mechanism by which plants can counteract the influence of this abiotic stressor.
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A and F University, Yangling, Shaanxi 712100, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Cellular and Structural Biology, The University of Texas, Health Science Center at San Antonio, 7703 Floyd Curl, San Antonio, TX 78229, USA.
authors.forename: Dun-Xian
authors.initials: DX
authors.lastname: Tan
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A and F University, Yangling, Shaanxi 712100, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Liang
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A and F University, Yangling, Shaanxi 712100, China.
authors.forename: Cong
authors.initials: C
authors.lastname: Chang
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A and F University, Yangling, Shaanxi 712100, China.
authors.forename: Dongfeng
authors.initials: D
authors.lastname: Jia
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A and F University, Yangling, Shaanxi 712100, China fwm64@nwsuaf.edu.cn fwm64@sina.com.
authors.forename: Fengwang
authors.initials: F
authors.lastname: Ma
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D027845:Malus / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D008550:Melatonin / Q000235:genetics* / Q000378:metabolism; D010937:Plant Growth Regulators / Q000235:genetics* / Q000378:metabolism; D054046:Plant Stomata / Q000378:metabolism; D018526:Plant Transpiration; D013045:Species Specificity; D013312:Stress, Physiological / Q000502:physiology*
chemical_list: D000975:Antioxidants; D010937:Plant Growth Regulators; D000040:Abscisic Acid; D008550:Melatonin
keywords: ABA; H2O2; Malus; abiotic stress; antioxidant.; drought; melatonin; stomata