COMPARISON OF OXIDATIVE STRESS PARAMETERS IN SOYBEAN SEEDLINGS INOCULATED WITH MACROPHOMINA PHASEOLINA FROM DIFFERENT ISOLATES

The research was focused on biotic stress caused by Macrophomina phaseolina (Tassi) Goid., a plant pathogen that causes charcoal rot by infecting the root and lower stem of soybean. Differences in pathogenicity of fungi cultures from five isolates (two from sugar beet, one from maize, one from soybean and one from sunflower) have been investigated in seedlings of two soybean cultivars (Meli and Balkan). Comparison of antioxidant systems of soybean seedlings showed different reactions of plants infected with M. phaseolina isolates of different origin. The highest pathogenicity showed isolate from sugar beet ŠR62/4 (2.80), while no
significant difference was found for isolates ŠR55(3)/09 (2.58), MphSo (2.32) and MphSu (2.26). The isolate from maize, MphK, showed lowest pathogenicity (1.94). For the most of the biochemical parameters tested (lipid peroxidation, phenylalanine
ammonium-lyase activity, total polyphenols, tannins and proanthocyanidins contents) the isolate from sugar beet (ŠR55(3)/09) induced the most significant reaction in soybean seedlings among all isolates investigated. Presence of this pathogen in the
field conditions should be further monitored and the crop rotation should be seriously taken into account.