A detached seedling leaf technique to study resistance to Mycosphaerella graminicola (anamorph Septoria tritici) in wheat

A detached seedling leaf technique was developed to screen for resistance t o septoria tritici blotch of wheat and to detect specific interactions betw een cultivars and isolates, Wheat seedlings were inoculated with spore susp ensions of Mycosphaerella graminicola. Detached primary leaves were then pl aced in a clear plastic box such that their cut ends were sandwiched betwee n layers of agar containing benzimidazole, with a gap below the middle of t he leaves. Mean levels of disease were affected by light and temperature, a nd also by the concentration of benzimidazole, such that higher concentrati ons resulted in less disease. Second leaves were more susceptible than seed ling primary leaves. However, none of these factors affected ranking of dis ease among cultivars or cultivar-by-isolate interactions. Kavkaz-K4500 1.6. a.4, Synthetic 6x and Triticum macha showed specific susceptibility and res istance to different isolates. The detached leaf technique could be a usefu l complement to field trials and an alternative to whole seedling assays in assessing cultivar resistance and investigating the genetics of the host-p athogen interaction.