Interactions between cold hardening and Microdochium nivale infection on expression of pathogenesis-related genes in winter wheat

Cold hardening induces snow mould resistance in cereals and grasses. The mechanism for this induced resistance is not fully understood. The accumulation of transcripts encoding sucrose synthase and the pathogenesis-related proteins (PR-proteins) chitinase, beta-1,3-glucanase, peroxidase and PR-1a were studied in hardened and non-hardened winter wheat at several time points after inoculation with the snow mould Microdochium nivale. Sucrose synthase was induced by the hardening treatment itself. The PR-proteins were all induced by infection, this response was stronger and more rapid in plants that had been hardened prior to inoculation. The present results suggest that cold hardening has a conditioning effect on snow mould induced expression of PR-proteins. This may partly explain how cold hardening induces snow mould resistance. (C) 1998 Academic Press.