Levan differentially primes barley defence against infections by Fusarium graminearum, Rhizoctonia solani and Pyricularia oryzae

Abstract

AbstractThe widespread use of pesticides poses significant challenges to the safety of agricultural products and the ecological environment. Levan‐type fructans have the ability to act as an induced resistance stimulus, enhancing plant disease resistance, which aligns with the principles of green development. This study showed that levan polysaccharide, produced by Halomonas smyrnnensis levansucrase, could induce the resistance of barley to Fusarium graminearum much better than inulin‐type fructans or low‐molecular‐weight chitosan oligosaccharide. Three different application methods of levan, namely seed soaking, leaf spraying or their combination, all decreased the necrotic areas caused by F. graminearum and Rhizoctonia solani. When inoculated with F. graminearum, the content of hydrogen peroxide, proline or jasmonic acid and the activities of peroxidase and ascorbate peroxidase in levan‐treated barley were higher than those in the control. In contrast, when inoculated with R. solani, the hydrogen peroxide content and peroxidase activity in levan‐treated leaves showed a faster induction than the control at the early priming and the content of proline and methyl salicylate was higher than that of the control. Thus, levan induces distinct pathways in response to different pathogens.