Influence of Xanthomonas campestris pv. campestris on the growth of etiolated and photosynthetic seedlings of Brassica oleracea

Relevance. In recent years, physiologists are very interested in studying the characteristics of the growth and development of seedlings under conditions of etiolation. Etiolated seedlings, as a model object, are interesting in studying the responses of a plant organism to the effects of various biotic environmental factors. In this regard, a comprehensive study of the characteristics of the influence of Xanthomonas campestris pv. campestris (Хсс) on growth processes in the early stages of development of white cabbage plants, depending on the racial composition of the pathogen, is very important.Material and method. The study was carried out on the basis of the immunity and plant protection laboratory of the Federal State Budgetary Scientific Institution of the Federal Scientific Vegetable Center (FSVC). The material of research were seeds of two varieties of white cabbage with different resistance to vascular bacteriosis and four races of Xanthomonas campestris pv. campestris (Хсс1, Хсс3, Хсс4 и Хсс6). Sterile seeds of each variety were laid out in Petri cups. Infection with different races of Xcc was carried out by introducing into each Petri cup 1 ml of a bacterial suspension of a two-day culture at a concentration of 106 cells/ml. Half of the Petri cups were placed in a thermostat without illumination, the other was exposed to light under a 16- hour regime of illumination with diffused light. The magnitude and orientation of biological effects of studied factors on biometric parameters of seedlings were evaluated by the relative deviation of the difference between parameters of the experimental and control variants.Results. A different degree of influence of the resistance of the variety and the aggressiveness of the pathogen race on the growth of individual parts of the seedling has been established, and the response of etiolated and photosynthetic seedlings to infection is often the opposite. In the susceptible cultivar Slava 1305, acceleration of root and hypocotyl growth in the dark (Хсс3, Хсс4 and Хсс1) and inhibition of these processes in the light (Хсс1, Хсс4 and Хсс6) were noted. Relatively stable SB-3 F1 hybrid has more pronounced raspecificity of the effect of Xcc on root growth and stimulation of hypocotyl growth in all variants, which was 2-8 times lower in etiolated seedlings when infected with Xcc6 and Xcc1 races than in light ones, and when infected by the races Xcc1 and Xcc4, the effect was comparable.