Polymerization degree of chitosan affects structural and compositional changes in the cell walls, membrane lipids, and proteins in the leaves of Ipomoea purpurea: An FT-IR spectroscopy study

This research aimed to investigate the polymerization degree (DP) -dependent effects of chitosan treatments on structural and compositional changes in certain cell wall polysaccharides (mainly lignin), membrane lipids, and proteins of in vitro-propagated Ipomoea purpurea leaves through FT-IR spectroscopy. The chitosan oligomer mixture (DP 2-15; CHI-OM) and chitosan polymer (DP 70; CHI-P) applied at 5, 10, and 20 mg L-1 concentrations induced different patterns of biomolecular changes in I. purpurea leaves. The chitosan variants enhanced the destabilization of cell membrane structures. CHI-P treatments increased the lipid structure and protein content of the membranes more than CHI-OM treatments. CHI-OM treatment was found to have the ability to induce the formation of beta-sheet structures with a low number of strands, whereas CHI-P treatment was found to have the ability to trigger the formation of more extended alpha-helix structures in the secondary structure of proteins. CHI-P treatments increased lignin synthesis more than CHI-OM treatments. However, CHI-OM at 10 mg L-1 concentration was more effective than CHI-P treatments in the induction of cell wall polysaccharide synthesis. These findings suggest that the polymerization degree of chitosan plays a role in changing structures and compositions of the biomolecules present in the leaves of I. purpurea. (c) 2020 Elsevier B.V. All rights reserved.