Changes of pectin contents in alfalfa plants after inoculation with differently virulent isolates of Corynebacterium michiganense pv. insidiosum investigated at an early stage of disease

Six-weeks-old alfalfa plants susceptible to bacterial vascular wilt disease were inoculated with strongly, moderately or slightly virulent isolates of Corynebacterium michiganense pv. insidiosum (McCulloch) Dye and Kemp and with a mixture of all of them. On the third, 7th and 14th days after inoculation the pectin content in the overground parts and roots was determined and compared with the control non-inoculated plants. The greatest changes were revealed to be decreases of pectin contents in the overground parts and roots of plants inoculated with slightly virulent isolate of this pathogen. Minimum changes were decreases of pectin content in plants inoculated with strongly virulent isolate. Relations between these changes and defensive reactions of the plants are discussed.