Abscisic acid-induced secretion of an antifreeze-like protein in embryogenic cell lines of Picea abies
J Plant Physiol. 1996, 149, 163-170, https://doi.org/10.1016/S0176-1617(96)80190-8
Sabala I, Egertsdotter U, von Fircks H, von Arnold S

Summary
Embryogenic cell lines of Picea abies have been divided into two groups, A and B, based on the morphology and physiology of the somatic embryos. The differences between these cell lines can be related to the patterns of extracellular proteins. Group A and B embryos respond differently to abscisic acid (ABA) for maturation and transient expression of ABA-induced promoter (Dc8) after bombardment. The aim of the study was to compare changes in synthesis and secretion of proteins after an ABA treatment of embryogenic cultures of Picea abies differing in their ability to respond to ABA.

ABA was observed to induce as well as decrease synthesis and/or secretion of several proteins. Some of these changes were found in individual cell lines whereas others were characteristic for all cell lines within a group. Group B cell lines produced 64 and 42 kDa cellular proteins and most of group A cell lines produced an 88 kDa protein in response to ABA. Two extracellular proteins were found to be specifically secreted after ABA treatment; a 70 kDa protein was secreted by A-group cell lines and an 80 kDa protein by B-group cell lines. The N-terminal amino acid sequence of the 70 kDa protein showed 40 % identity over 20 amino acids to antifreeze proteins isolated from serum of several species of polar water fish. The possible roles of this protein in freezing resistance are discussed. Freezing tolerance differed between group A and B cultures. Group A cell lines typically survived down to −15 °C while those belonging to group B did not survive lower than −10 °C. The ABA treatment confers freezing resistance in group B cell lines but not in group A.

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