Differences in the elicitation of soluble and ionic bound enzymes in tomato leaves using chitin derivatives

Abstract

The ability of chitin or chitosan oligomers and chitosan polymers with 5 or 30% degree of acetylation (DA) to induce hydrolytic enzymes in tomato plant leaves was examined. Changes in the activities of the ionic bound and the soluble forms of chitosanase, chitinase, and b-1,3-glucanase were determined during a 7-day period after the leaves of the plants were sprayed with the chitin and chitosan compounds. Chitosan oligomers were unable to induce any of the enzymes, while chitin oligomers were an effective inducer. The activities of the ionic bound forms of the above three enzymes were increased significantly by chitin oligomers and chitosan polymer, whereas those of the soluble forms hardly changed. In light of the finding that chitosan oligomers with low levels of acetylation were non-elicitors while chitin oligomers with 95% acetylation were effective elicitors, it is suggested that the elicitation activity of the oligomers is determined by the DA. In addition, since the chitosan polymer acted as an eli...