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 me chanism for this induced resistance is not fully understood. The accumulati on of transcripts encoding sucrose synthase and the pathogenesis-related pr oteins (PR-proteins) chitinase, beta-1,3-glucanase, peroxidase and PR-1a we re studied in hardened and non-hardened winter wheat at several time points after inoculation with the snow mould Microdochium nivale. Sucrose synthas e was induced by the hardening treatment itself. The PR-proteins were all i nduced by infection, this response was stronger and more rapid in plants th at 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 mou ld resistance. (C) 1998 Academic Press.