title: A wheat (Triticum aestivum) protein phosphatase 2A catalytic subunit gene provides enhanced drought tolerance in tobacco.
abstract: OBJECTIVE
  Multiple copies of genes encoding the catalytic subunit (c) of protein phosphatase 2A (PP2A) are commonly found in plants. For some of these genes, expression is up-regulated under water stress. The aim of this study was to investigate expression and characterization of TaPP2Ac-1 from Triticum aestivum, and to evaluate the effects of TaPP2Ac-1 on Nicotiana benthamiana in response to water stress.
  
  
  METHODS
  TaPP2Ac-1 cDNA was isolated from wheat by in silico identification and RT-PCR amplification. Transcript levels of TaPP2Ac-1 were examined in wheat responding to water deficit. Copy numbers of TaPP2Ac-1 in wheat genomes and subcellular localization in onion epidermal cells were studied. Enzyme properties of the recombinant TaPP2Ac-1 protein were determined. In addition, studies were carried out in tobacco plants with pCAPE2-TaPP2Ac-1 under water-deficit conditions.
  
  
  RESULTS
  TaPP2Ac-1 cDNA was cloned from wheat. Transcript levels of TaPP2Ac-1 in wheat seedlings were up-regulated under drought condition. One copy for this TaPP2Ac-1 was present in each of the three wheat genomes. TaPP2Ac-1 fused with GFP was located in the nucleus and cytoplasm of onion epidermis cells. The recombinant TaPP2Ac-1 gene was over-expressed in Escherichia coli and encoded a functional serine/threonine phosphatase. Transgenic tobacco plants over-expressing TaPP2Ac-1 exhibited stronger drought tolerance than non-transgenic tobacco plants.
  
  
  CONCLUSIONS
  Tobacco plants with pCAPE2-TaPP2Ac-1 appeared to be resistant to water deficit, as shown by their higher capacity to maintain leaf relative water content, leaf cell-membrane stability index, water-retention ability and water use efficiency under water stress. The results suggest that the physiological role of TaPP2Ac-1 is related to drought stress response, possibly through its involvement in drought-responding signal transduction pathways.
authors.affiliation: The National Key Facility for Crop Gene Resources and Genetic Improvement, Key Laboratory of Crop Germplasm & Biotechnology, Ministry of Agriculture, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
authors.forename: Chongyi
authors.initials: C
authors.lastname: Xu
authors.forename: Ruilian
authors.initials: R
authors.lastname: Jing
authors.forename: Xinguo
authors.initials: X
authors.lastname: Mao
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Jia
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Chang
mesh_terms: D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000201:enzymology; D003593:Cytoplasm / Q000201:enzymology; D004926:Escherichia coli / Q000235:genetics; D018628:Gene Dosage; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D019697:Onions / Q000235:genetics; D010749:Phosphoprotein Phosphatases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology; D054648:Protein Phosphatase 2; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis; D016415:Sequence Alignment; D014026:Nicotiana / Q000235:genetics*; D014908:Triticum / Q000201:enzymology* / Q000235:genetics; D014867:Water / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D021122:Protein Subunits; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D014867:Water; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2