Accumulation of 19-kDa Plasma Membrane Polypeptide during Induction of Freezing Tolerance in Wheat Suspension-Cultured Cells by Abscisic Acid

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Suspension-cultured cells derived from immature embryos of winter wheat (Triticum aestivum L. cv. Chihoku) were used in experiments designed to obtain clues to the mechanism of the ABA-induced developrnent of freezing tolerance. Cultured cells treated with 50 μM ABA for 5 d at 23℃ acquired the maximum level of freezing tolerance (LT_<50>; -21.6℃). The increased freezing tolerance of ABA-treated cells was closely associated with the remarkable accumulation of 19-kDa polypeptides in the plasma membrane. The 19-kDa polypeptide components were isolated by preparative gel electrophoresis and were further separated into one major (AWPM-19) and other minor polypeptide components by Tricine-SDS-PAGE. N-terminal amino acid sequence of AWPM-19 was determined, and a cDNA clone encoding AWPM-19 was isolated by PCR from the library prepared from the ABA-treated cultured cells. The cDNA clone (WPM-1) encoded a 18.9 kDa hydrophobic polypeptide with four putative membrane spanning do-mains and with a high pI value (10.2). Expression of WPM-1 mRNA was dramatically induced by 50 μM ABA within a few hours. These results suggest that the AWPM-19 might be closely associated with the ABA-induced in-crease in freezing tolerance in wheat cultured cells.
日本植物生理学会の論文