title: Populus euphratica HSF binds the promoter of WRKY1 to enhance salt tolerance.
abstract: Poplar species increase expressions of transcription factors to deal with salt environments. We assessed the salt-induced transcriptional responses of heat-shock transcription factor (HSF) and WRKY1 in Populus euphratica, and their roles in salt tolerance. High NaCl (200mM) induced PeHSF and PeWRKY1 expressions in P. euphratica, with a rapid rise in roots than in leaves. Moreover, the salt-elicited PeHSF reached its peak level 6h earlier than PeWRKY1 in leaves. PeWRKY1 was down-regulated in salinized P. euphratica when PeHSF was silenced by tobacco rattle virus-based gene silencing. Subcellular assays in onion epidermal cells and Arabidopsis protoplasts revealed that PeHSF and PeWRKY1 were restricted to the nucleus. Transgenic tobacco plants overexpressing PeWRKY1 showed improved salt tolerance in terms of survival rate, root growth, photosynthesis, and ion fluxes. We further isolated an 1182-bp promoter fragment upstream of the translational start of PeWRKY1 from P. euphratica. Promoter sequence analysis revealed that PeWRKY1 harbours four tandem repeats of heat shock element (HSE) in the upstream regulatory region. Yeast one-hybrid assay showed that PeHSF directly binds the cis-acting HSE. To determine whether the HSE cluster was important for salt-induced PeWRKY1 expression, the promoter-reporter construct PeWRKY1-pro::GUS was transferred to tobacco plants. β-glucuronidase activities increased in root, leaf, and stem tissues under salt stress. Therefore, we conclude that salinity increased PeHSF transcription in P. euphratica, and that PeHSF binds the cis-acting HSE of the PeWRKY1 promoter, thus activating PeWRKY1 expression.
authors.affiliation: College of Biological Sciences and Technology (Box 162), Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Zedan
authors.initials: Z
authors.lastname: Shen
authors.affiliation: College of Biological Sciences and Technology (Box 162), Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Yao
authors.affiliation: Institute of Integrative Plant Biology, School of Life Science, Jiangsu Normal University, Xuzhou 221116, Jiangsu Province, PR China.
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.affiliation: College of Biological Sciences and Technology (Box 162), Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Liwei
authors.initials: L
authors.lastname: Chang
authors.affiliation: College of Biological Sciences and Technology (Box 162), Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Shaojie
authors.initials: S
authors.lastname: Wang
authors.affiliation: College of Agricultural and Food Science, Zhejiang Agricultural and Forestry University, Hangzhou, Zhejiang 311300, PR China.
authors.forename: Mingquan
authors.initials: M
authors.lastname: Ding
authors.affiliation: College of Biological Sciences and Technology (Box 162), Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Zeyong
authors.initials: Z
authors.lastname: Qian
authors.affiliation: College of Biological Sciences and Technology (Box 162), Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Huilong
authors.initials: H
authors.lastname: Zhang
authors.affiliation: College of Biological Sciences and Technology (Box 162), Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Nan
authors.initials: N
authors.lastname: Zhao
authors.affiliation: College of Biological Sciences and Technology (Box 162), Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Gang
authors.initials: G
authors.lastname: Sa
authors.affiliation: National Engineering Research Center for Information Technology in Agriculture, Beijing 100097, PR China.
authors.forename: Peichen
authors.initials: P
authors.lastname: Hou
authors.affiliation: College of Biological Sciences and Technology (Box 162), Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Tao
authors.initials: T
authors.lastname: Lang
authors.affiliation: College of Biological Sciences and Technology (Box 162), Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Feifei
authors.initials: F
authors.lastname: Wang
authors.affiliation: College of Biological Sciences and Technology (Box 162), Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhao
authors.affiliation: College of Biological Sciences and Technology (Box 162), Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Xin
authors.initials: X
authors.lastname: Shen
authors.affiliation: College of Biological Sciences and Technology (Box 162), Beijing Forestry University, Beijing 100083, PR China. Electronic address: Lschen@bjfu.edu.cn.
authors.forename: Shaoliang
authors.initials: S
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D032107:Populus / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D011401:Promoter Regions, Genetic; D055049:Salt Tolerance / Q000235:genetics*; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects
chemical_list: D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D014157:Transcription Factors; D012965:Sodium Chloride; D005966:Glucuronidase
keywords: Gene silencing; Heat shock element; Heat-shock transcription factor; NaCl; PeWRKY1; PeWRKY1 promoter