Identification of a xylem sap germin-like protein and its expression under short-day and non-freezing low-temperature conditions in poplar root

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In the shoots of photoperiod-sensitive deciduous trees, including poplar, short-day and non-freezing low-temperature conditions induce bud dormancy and its break, respectively, and these conditions also induce shoot cold acclimation. In a previous study, levels of organic and inorganic components, including proteins, increased in the xylem sap of <i>Populus nigra</i> in winter, suggesting seasonal changes in root functions. Here, analysis of a major xylem sap protein (XSP24) of <i>P. nigra</i> in winter by mass spectrometry together with the whole genome sequence of <i>P. trichocarpa</i> and transcript abundance in roots under short-day conditions identified <i>PtXSP24</i> to be a germin-like protein of the cupin superfamily, which was reported to be associated with various stresses and to have oxalate oxidase and/or superoxide dismutase activities in the cell wall. Expression of <i>XSP24</i>, which corresponds to <i>PtXSP24</i> in <i>P. maximowiczii</i>, a potentially useful Japanese native poplar in the same phylogenetic clade as <i>P. trichocarpa</i>, was enhanced under short-day and non-freezing low-temperature conditions, as well as by application of abscisic acid. These results suggest that XSP24 is involved in tolerance to environmental stresses in autumn and early winter.


  • Plant Biotechnology

    Plant Biotechnology 33(2), 123-127, 2016

    Japanese Society for Plant Cell and Molecular Biology


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