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A Wheat (Triticum aestivum) Protein Phosphatase 2A Catalytic Subunit Gene Provides Enhanced Drought Tolerance in Tobacco

Xu, Chongyi, Jing, Ruilian, Mao, Xinguo, Jia, Xiaoyun, Chang, Xiaoping
Annals of botany 2007 v.99 no.3 pp. 439-450
Escherichia coli, Nicotiana benthamiana, Triticum aestivum, complementary DNA, drought tolerance, genes, leaves, onions, phosphoprotein phosphatase, protein subunits, recombinant proteins, seedlings, serine, signal transduction, stress response, tobacco, transgenic plants, water content, water stress, water use efficiency, wheat
BACKGROUND AND AIMS: 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. KEY 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.