title: MsZEP, a novel zeaxanthin epoxidase gene from alfalfa (Medicago sativa), confers drought and salt tolerance in transgenic tobacco.
abstract: The zeaxanthin epoxidase gene ( MsZEP ) was cloned and characterized from alfalfa and validated for its function of tolerance toward drought and salt stresses by heterologous expression in Nicotiana tabacum. Zeaxanthin epoxidase (ZEP) plays important roles in plant response to various environment stresses due to its functions in ABA biosynthetic and the xanthophyll cycle. To understand the expression characteristics and the biological functions of ZEP in alfalfa (Medicago sativa), a novel gene, designated as MsZEP (KM044311), was cloned, characterized and overexpressed in Nicotiana tabacum. The open reading frame of MsZEP contains 1992 bp nucleotides and encodes a 663-amino acid polypeptide. Amino acid sequence alignment indicated that deduced MsZEP protein was highly homologous to other plant ZEP sequences. Phylogenetic analysis showed that MsZEP was grouped into a branch with other legume plants. Real-time quantitative PCR revealed that MsZEP gene expression was clearly tissue-specific, and the expression levels were higher in green tissues (leaves and stems) than in roots. MsZEP expression decreased in shoots under drought, cold, heat and ABA treatment, while the expression levels in roots showed different trends. Besides, the results showed that nodules could up-regulate the MsZEP expression under non-stressful conditions and in the earlier stage of different abiotic stress. Heterologous expression of the MsZEP gene in N. tabacum could confer tolerance to drought and salt stress by affecting various physiological pathways, ABA levels and stress-responsive genes expression. Taken together, these results suggested that the MsZEP gene may be involved in alfalfa responses to different abiotic stresses and nodules, and could enhance drought and salt tolerance of transgenic tobacco by heterologous expression.
authors.affiliation: Department of Grassland Science, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Grassland Science, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Yafang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Grassland Science, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Leqin
authors.initials: L
authors.lastname: Chang
authors.affiliation: Department of Grassland Science, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Department of Grassland Science, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Jie
authors.initials: J
authors.lastname: An
authors.affiliation: Department of Grassland Science, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Yushi
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Grassland Science, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Yuman
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Department of Grassland Science, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Department of Grassland Science, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, Shaanxi, China.
authors.forename: Xuyang
authors.initials: X
authors.lastname: Sha
authors.affiliation: Department of Grassland Science, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, Shaanxi, China. hutianming@126.com.
authors.forename: Tianming
authors.initials: T
authors.lastname: Hu
authors.affiliation: Department of Grassland Science, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, Shaanxi, China. yangpeizhi@126.com.
authors.forename: Peizhi
authors.initials: P
authors.lastname: Yang
mesh_terms: D055864:Droughts; D018506:Gene Expression Regulation, Plant; D000455:Medicago sativa / Q000201:enzymology* / Q000235:genetics*; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D055049:Salt Tolerance / Q000235:genetics*; D014026:Nicotiana / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology*
chemical_list: D010088:Oxidoreductases; C097153:zeaxanthin epoxidase
keywords: Abscisic acid; Drought; Medicago sativa; Nodule; Overexpression; Salt