Tobacco-acquired resistance induced by an exopolysaccharide of Paenibacillus kribbensis PS04 against bacterial wilt

Abstract

ABSTRACTInduction of host resistance is commonly considered to be the most effective disease control strategy, but no cultivar has yet been bred to effectively manage tobacco bacterial wilt. An alternative tactic is to induce host-acquired resistance against the pathogen, Ralstonia solanacearum. In this study, tobacco-acquired resistance was induced by an exopolysaccharide (EPS) fructan produced by Paenibacillus kribbensis PS04, and disease severity was reduced in pot trials. The photosynthetic pigment and leaf carbohydrate contents in tobacco leaves verified that tobacco scorch symptoms disappeared under the action of EPS. Further, when the malondialdehyde (MDA) content declined by two-thirds, lipid peroxidation was eliminated. Compared to the untreated control, the contents of non-enzymatic antioxidants, ascorbate (AsA) and glutathione (GSH), rose by 69% and 64%, respectively; while the activities of defense enzymes, superoxide dismutase (SOD) and peroxidase (POD), were enhanced by 22% and 82%, respectively, at the end of leaf sampling. This evidence was further supported by native PAGE on isoforms of SOD and POD. The results of this study demonstrate that tobacco-acquired resistance can be triggered by the EPS produced by P. kribbensis PS04.