title: A novel Glycine soja homeodomain-leucine zipper (HD-Zip) I gene, Gshdz4, positively regulates bicarbonate tolerance and responds to osmotic stress in Arabidopsis.
abstract: Wild soybean (Glycine soja) is a highly adaptive plant species which can grow well in saline-alkaline soils. In soybean genome, there exist about 140 HD-Zip (Homeodomain-leucine Zipper) genes. HD-Zip transcription factor family is one of the largest plant specific superfamilies and plays important roles in response to abiotic stresses. Although HD-Zip transcription factors have been broadly reported to be involved in plant resistance to abiotic stresses like salt and drought, their roles in response to bicarbonate stress is largely unknown.
  
  
  
  From our previous transcriptome profile analysis of wild soybean treated by 50 mM NaHCO3, we identified an HD-Zip gene (Gshdz4) which showed high response to the alkaline stress. Our result of qRT-PCR showed that the expression of Gshdz4 was induced by alkaline stress (NaHCO3) in both leaves and roots of wild soybean. Overexpression of Gshdz4 in Arabidopsis resulted in enhanced tolerance to NaHCO3 and KHCO3 during the process of plant growth and development. However, the growths of transgenic and WT plants were not significantly different on the medium with high pH adjusted by KOH, implicating Gshdz4 is only responsible for resisting HCO3 (-) but not high pH. The transgenic plants had less MDA contents but higher POD activities and chlorophyll contents than the WT plants. Moreover, the transcript levels of stress-related genes, such as NADP-ME, H (+) -Ppase, RD29B and KIN1 were increased with greater extent in the transgenic plants than the wild plants. On the contrary, Gshdz4 overexpression lines were much sensitive to osmotic stress at seed germination and stocking stages compared to the wild plants.
  
  
  
  We revealed that the important and special roles of Gshdz4 in enhancing bicarbonate tolerance and responding to osmotic stress. It is the first time to elucidate these novel functions of HD-ZIP transcription factors. All the evidences broaden our understanding of functions of HD-Zip family and provide clues for uncovering the mechanisms of high tolerance of wild soybean to saline-alkaline stresses.
authors.affiliation: Key Laboratory of Agricultural Biological Functional Genes, Northeast Agricultural University, Harbin, 150030, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Cao
authors.affiliation: Key Laboratory of Agricultural Biological Functional Genes, Northeast Agricultural University, Harbin, 150030, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Key Laboratory of Agricultural Biological Functional Genes, Northeast Agricultural University, Harbin, 150030, China.
authors.forename: Huizi
authors.initials: H
authors.lastname: DuanMu
authors.affiliation: Key Laboratory of Agricultural Biological Functional Genes, Northeast Agricultural University, Harbin, 150030, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
authors.affiliation: Key Laboratory of Agricultural Biological Functional Genes, Northeast Agricultural University, Harbin, 150030, China.
authors.forename: Xiangbo
authors.initials: X
authors.lastname: Duan
authors.affiliation: Key Laboratory of Agricultural Biological Functional Genes, Northeast Agricultural University, Harbin, 150030, China.
authors.forename: Pinghui
authors.initials: P
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Agricultural Biological Functional Genes, Northeast Agricultural University, Harbin, 150030, China.
authors.forename: Ranran
authors.initials: R
authors.lastname: Chen
authors.affiliation: Key Laboratory of Agricultural Biological Functional Genes, Northeast Agricultural University, Harbin, 150030, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.affiliation: Key Laboratory of Agricultural Biological Functional Genes, Northeast Agricultural University, Harbin, 150030, China. ymzhu2001@neau.edu.cn.
authors.forename: Yanming
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Agricultural Biological Functional Genes, Northeast Agricultural University, Harbin, 150030, China. xiaodong.ding@neau.edu.cn.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Ding
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D001639:Bicarbonates / Q000378:metabolism*; D055864:Droughts; D007887:Fabaceae / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D009997:Osmotic Pressure; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D013025:Glycine max / Q000235:genetics*
chemical_list: D001639:Bicarbonates; D010940:Plant Proteins
keywords: Arabidopsis; Bicarbonate tolerance; Glycine soja; Gshdz4; Osmotic stress; Transcription factor