THE CONTENTS OF ZEATIN, INDOLEACETIC ACID AND ABSCISIC ACID IN THE LEAVES AND ROOTS OF WHEAT WITH DIFFERENT RESISTANCE TO <i>BIPOLARIS SOROKINIANA</i>
The influence of root rot pathogen Bipolaris sorokiniana on the phytohormones content (zeatin, indole-3-acetic acid and abscisic acid) in roots and leaves of wheat with different resistance to the pathogen was studied. Infection of seedlings was performed by watering with a conidia suspension of the fungus in a concentration of 10 3 spores/ml. Contents of phytohormones was determined in 3, 6 and 9 days after inoculation by immunoassay. Also the rate of disease development was assessed. Inoculation of B. sorokiniana significantly changed the level of IAA and ABA in the aerial parts and roots of wheat susceptible cultivar. Thus, the level of IAA in the roots of susceptible plants on 9th day after the infection was lower and the level of ABA was two times higher than that of healthy plants. The degree of infestation of susceptible plants within the specified period was two times higher than in resistant ones. Infected wheat plants of resistant cultivar differed in minor fluctuation of IAA and ABA in the roots and leaves. In resistant wheat plants in response to infection there was an increase of zeatin in several times. In infected plants of susceptible cultivar zeatin concentration decreased during pathogenesis. Analysis of the ratio of IAA, ABA and zeatin in infected (roots) and uninfected (leaves) parts suggests that high level of zeatin in plants contribute the formation of wheat resistance to necrotrophic pathogen B. sorokiniana.