Phenolic accumulation and peroxidase activity inin vitro selected alfalfa callus cultures resistant to filtrate ofFusarium spp.

Changes in the phenylalanine ammonia-lyase (PAL) activity, accumulation of phenolic acids and ionically-bound peroxidase activity in thein vitro selected embryogenic and nonembryogenicMedicago sativa callus cultures resistant to the filtrate ofFusarium spp. were found. The PAL activity in bothin vitro selected cultures during a 4-week cultivation on a medium with phytotoxins was higher than in the control calli grown on a medium without toxin. The filtrate fromFusarium spp. evoked an increase in the contents of all determined phenolic acids in the selected calli. They occurred predominantly bound as esters. The most pronounced portions in the elevated acids level were of ester-bound p-hydroxybenzoic, vanillic, p-coumaric and ferulic acids. The ionic cell wall-bound peroxidase activity in both selected calli cultivated on a medium with a filtrate was twice as high as the activity determined in the control cultures. The activity of soluble peroxidase was not influenced by challenge with a filtrate. No significant differences were found between thein vitro selected embryogenic and nonembryogenic alfalfa callus cultures in the response to the phytotoxic filtrate.