ФОТОХІМІЧНА АКТИВНІСТЬ ЛИСТКІВ СОЇ ЗА ДІЇ ФІТОПАТОГЕННИХ БАКТЕРІЙ РІЗНОЇ ВІРУЛЕНТНОСТІ

Abstract

Soybean plants were grown in a greenhouse. In the phase of 4-6 leaves soybeans were artificially infected with strains of pathogens: Xanthomonas axonopodis pv. glycines 9284 and Xanthomonas axonopodis pv. phaseoli 8843. These strains were obtained from the Ukrainian collection of microorganisms of the Zabolotny institute of Microbiology and Virology of National Academy of Sciences of Ukraine. The photochemical activity of soybean leaves was determined by the biophysical method of chlorophyll fluorescence induction in 13 days after plant inoculation with bacterial strains. A portable Florotest fluorometer was use for measurements. A degree of chlorophyll degradation and suppression of photosynthetic activity in soybean leaves at artificial infection with bacterial strains isolated from different plant species of the Fabaceaeae family dependent from its virulence have been shown. The strain X. axonopodis pv. glycines 9284, isolated from soybean plants, have been highly virulent and acted more negatively than the low virulent to soybean strain X. axonopodis pv. phaseoli 8843. In particular, the value of the minimum fluorescence F0 decreased by 37.0 and 15.4 % for inoculation by strains with different virulence degree: X. axonopodis pv. glycines 9284 (from soybeans) and X. axonopodis pv. phaseoli 8843 (from beans) respectively. There was also a significant decrease in the value of Fm in these variants – by 54.9 % (X. axonopodis pv. glycines 9284) and 19.3 % (X. axonopodis pv. phaseoli 8843). At the same time, the value of maximum quantum yield of PSII (Fv / Fm) was decreased by 11.8 % in the variant with inoculation of soybean plants with the highly virulent strain X. axonopodis pv. glycines 9284, that indicates photoinhibition or damage of antenna complexes of the PSII photosynthetic apparatus of soybean plants. At the same time, only the tendency to reduce the maximum quantum yield of PSII was determined under action infection plants with X. axonopodis pv. phaseoli 8843. A parameter chlorophyll fluorescence decrease ratio Rfd, which shows the activity of CO2 assimilation in the Calvin cycle, was inhibition more at the action of artificial infection with a highly virulent strain – X. axonopodis pv. glycines 9284 – 54.5 and less – at infection with a low virulence strain – X. axonopodis pv. phaseoli 8843 – by 10.8 %. With prolonged action of the pathogenic bacterial strains X.axonopodis pv. glycines 9284 and the X. axonopodis pv. phaseoli 8843 (fortnight) showed significant inhibition of the catalase and peroxidase activity of leaf tissues, which is evidence of an increase in the formation of ROS. It was demonstrated that the highly virulent strain X.axonopodis pv. glycines 9284 most of all suppressed the catalase activity of soybean leaf tissues.