β-1,3-glucanase and chitinase activities in winter triticales during cold hardening and subsequent infection by Microdochium nivale

The accumulation of pathogenesis-related proteins such as β-1,3-glucanases and chitinases was studied in cold induced snow mould resistance in two Polish cultivars of winter triticale, cv. Hewo and cv. Magnat that substantially differ in resistance to Microdochium nivale. The plants were pre-hardened at 12°C for 10 days and hardened at 4°C for 28 days. Subsequently, cold hardened plants were inoculated with fungal mycelium (M. nivale) and incubated at 4°C for 7 days in dark. Cold acclimatisation resulted in suppression of the total glucanase and chitinases activities in the resistant Hewo as well as sensitive Magnat cultivars that possibly coincides with altered metabolism. However, upon infection with M. nivale the chitinases were markedly induced in the cv. Hewo. At the same time, total β-1,3 glucanases activities did not seem to be affected by fungus in any of the tested triticale cultivars. The pattern and/or the activity of chitinases in plants might be indicative for the resistance/susceptibility against M. nivale.

Genetic studies on the resistance of winter wheat to speckled snow mould

Speckled snow mould (caused by Typhula ishikariensis) is a potential threat to winter wheat (Triticum aestivum L.) production in eastern Canada. Information on the inheritance of snow mould resistance is needed to develop an effective breeding strategy. In this study, the inheritance of resistance to the speckled snow mould was examined using crosses of a resistant genotype, PI 173438, and four susceptible cultivars, Lennox, Kitami-2, Norin-8 and Ena. The parental lines, and the F1 and F2 populations from each of the four crosses were grown in the field and in an unheated plastic greenhouse and scored for snow mould resistance. Biomass yield, survival, plant height and number of tillers/plant, all expressed as percentage of check plants, were used as indices of snow mould resistance. Generation means analysis, combining data from the field and greenhouse experiments, indicated that snow mould resistance was largely influenced by environmental conditions, and that additive genetic effects were more important than epistatic effects in controlling the expression of the disease. Dominance effects oriented towards susceptibility were detected in only one of the four crosses. Estimates of broad sense heritability in the four F2 populations ranged from 0.62 to 0.96 and from 0.34 to 0.79, respectively, when biomass yield and number of tillers/plant were used as indices of snow mould resistance. When plant height was used as an index of snow mould resistance, the heritability estimates ranged from 0.10 to 0.53. Key words: Wheat (winter), Triticum aestivum, speckled snow mould, Typhula ishikariensis, heritability