Specific features in the dose-response dependence of the zeatin effect on wheat susceptibility to powdery mildew

Abstract

Specific features in the dose-response dependence of the zeatin effect on susceptibility of 2-week-old wheat seedlings to the powdery mildew pathogen Erysiphe (syn. Blumeria) graminis DC. f. sp. tritici Marchal. were studied. The constructed dose-response curves in the majority of cases display a minimum (1–1.5 μM) flanked by two regions of higher susceptibility with the number of colonies exceeding that in the untreated control. The generalized curves for 24 independent experiments have an analogous shape. The total number of colonies on the abaxial leaf side at the minimum (1.5 μM zeatin) was considerably smaller as compared with the variants of higher and lower concentrations and with the untreated control. It is postulated that a complex dose-response dependence and the induced variation in physiological parameters play a biological role in stabilization of this pathosystem and survival of both its components.