Studies on the O-specific polysaccharide of the lipopolysaccharide from the Pseudomonas mediterranea strain C5P1 radi, a bacterium pathogenic. of tomato and chrysanthemum

An O-specific polysaccharide (OPS) was isolated from the lipopolysaccharide of Pseudomonas mediterranea strain C5Plrad1, the causal agents of tomato pith necrosis and Chrysanthemum stem rot, and studied by one- and two-dimensional H-1 and C-13 NMR spectroscopy. The following structure of the trisaccharide repeating unit of the OPS was established, which, to our knowledge, is unique among the known bacterial polysaccharide structures: -> 4)-beta-o-ManpNAc3NAcA-(1 -> 4)-beta-o-ManpNAc3NAcA-(1 -> 3)-alpha-D-QuipNAc4NAc-(1 -> where QuiNAc4NAc and ManNAc3NAcA indicate 2,4-diacetamido-2,4,6-trideoxyglucose and 2,3diacetamido-2,3-dideoxymannuronic acid, respectively. Pre-treatment of leaves with LPS or OPS preparations at 250 and 50 mu g mL(-1) did not inhibit development of a hypersensitivity reaction induced by P. mediterranea C5P1rad1 on tobacco, tomato and chrysanthemum plants. The same preparations at 250 mu g mL(-1) partially prevented elicitation of the hypersensitivity reaction by Pseudomonas syringae KVPT7RC on chrysanthemum but not tobacco and tomato. (C) 2017 Published by Elsevier Ltd.