[Influence of exogenous cytokinins on dynamics of development and differentiation of infection structure of the causal organism of wheat powdery mildew].

Using methods of light and electron scanning microscopy, development and infection structures differentiation of the causal organism of wheat powdery mildew, Erysiphe graminis DC. f. sp. tritici March., was investigated under influence of exogenous zeatin. It has been shown for the first time that physiologically active materials, in particular, cytokinin type phytohormons affect on the dimensions of halo revealed at the site of pathogen penetration by cytochemical staining. Treatment with zeatin influenced conidia germination and pathogen growth at the ectophytic stage. Dose response dependence of zeatin for number of mature colonies of pathogen (6 days after an infection) has been presented by multiphase curve with two maxima (1 and 3 microM) and minimum (1.5 microM). Similar curves have been received for the number of normal appressoria and the diameters of the large halo that possibly shows the existence of factors affecting both parameters, and the final number of pathogen colonies, as well. The obtained data demonstrate that multiphase dose response curve for development of the causal organism of powdery mildew under effect of cytokinins is originated from the factors acting at early stages of pathogenesis.