Changes in extracellular, cellular, and subcellular proteins during abscisic acid and low temperature induced cold hardening of alfalfa (Medicago sativa L. cv. Wisconsin 22C) cell suspension cultures were investigated by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Extracellular proteins from 4- to 6-day-old ABA and low temperature grown alfalfa cells showed decreased electrophoretic mobilities, lacked a 190-kDa glycoprotein, and had reduced amounts of four other polypeptides. In total cell protein analyses, a 42-kDa protein was enriched in both ABA and low temperature treated alfalfa cells. Several proteins increased or induced by exogenous ABA treatment were identified in the extracellular (12.5 and 13 to 15 kDa), total cell and cell wall (24 kDa), and soluble (20, 37, and 41 kDa) fractions. However, no major protein changes were resolved by one-dimensional electrophoretic analyses of crude membrane proteins.
Factors Influencing the Induction of Freezing Tolerance by Abscisic Acid in Cell Suspension Cultures of Bromus inermis Leyss and Medicago sativa L.