Binding experiments as well as affinity labeling with an 125I-labeled 2-(4-aminophenyl)ethylamino derivative of N-acetylchitooctaose revealed the presence of high-affinity binding sites/proteins for N-acetylchitooligosaccharide elicitor in the plasma membrane preparation from suspension-cultured carrot cells, barley cells and wheat leaves. Their binding specificity corresponded with the elicitor activity of N-acetylchitooligosaccharides and related sugars in these plant cells/tissues, and was similar to that reported for the binding site/protein previously reported for suspension-cultured rice cells. The molecular size of the binding proteins identified in carrot, barley and wheat was slightly smaller than that of rice. These plant cells were shown to respond to N-acetylchitooligosaccharides and generate reactive oxygen species, induced medium alkalinization, or previously shown to initiate lignification (wheat leaves, Barber et al. (1989) Physiol. Mol. Plant Pathol. 34: 3). No elicitor-binding protein nor the elicitor-induced cellular responses was detected for a cell line of tobacco BY-2 (BY-2T). On the other hand, another cell line of tobacco BY-2 (BY-2N) showed the presence of elicitor-binding protein and also elicitor-induced medium alkalinization. Thus, there was a good correlation between the existence of high-affinity binding proteins for the elicitor and elicitor-induced cellular responses among tested plant cells. These results indicated the wide distribution of N-acetylchitooligosaccharide elicitor-binding protein among various plants and added further support for the function of these plasma membrane proteins in the perception of the elicitor signal.
Keywords: Key words: N-acetylchitooligosaccharides — Barley — Carrot — Elicitor — Receptor — Wheat.; Abbreviations: BSA, bovine serum albumin; DTT, dithiothreitol; EGTA, ethylene glycol bis(2-aminoethylether)-tetraacetic acid; 125I-(GlcNAc)8-APEA, 125I-labeled 2-(4-aminophenyl)ethylamino derivative of N-acetylchitooctaose; PEG, polyethyleneglycol; PMSF, phenylmethanesulfonyl fluolide; SHAM, salicylhydroxamic acid.
Journal Article. 4637 words. Illustrated.
Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry
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