Abscisic acid‐ and cold‐induced thaumatin‐like protein in winter wheat has an antifungal activity against snow mould, <i>Microdochium nivale</i>

Cold acclimation of winter wheat (Triticum aestivum L.) seedlings induces accumulation in the apoplast of taTLPs that are similar to thaumatin-like proteins (TLPs), which are pathogenesis-related proteins. We characterized a cDNA of WAS-3a encoding the major isoform of taTLPs from winter wheat cells and showed that WAS-3a transcripts were markedly increased by treatment with ABA and by treatment with elicitors (chitosan, beta-glucan and cell wall fractions of Fusarium oxysporum and Microdochium nivale) in wheat cells. To analyse the function of WAS-3a, a highly efficient expression system using wheat cells was established, and a large amount of recombinant WAS-3a protein (rWAS-3a) was obtained with near homogeneity. Antifungal assays using various fungi grown on agar plates revealed that rWAS-3a inhibits hyphal growth of pink snow mould, Microdochium nivale, at a low temperature. The results suggest that cold-induced taTLPs that accumulate in the apoplast contribute to snow mould resistance of winter wheat.