Peroxidase production in vitro by Armoracia lapathifolia (horseradish)-transformed root cultures: effect of elicitation on level and profile of isoenzymes.

Transformed roots of Armoracia lapathifolia (horseradish) were established by infection with Agrobacterium rhizogenes LBA 9402. They were used as a culture system in vitro for peroxidase production in vitro, to avoid many of the problems that affect the traditional production from field-grown species of Armoracia sp. The time course of growth of these cultures showed that total peroxidase attained maximum levels at the end of the exponential growth phase. At this stage of culture, elicitation assays were performed with AgNO3 and CuSO4 as abiotic elicitors and with fungal extracts of Verticillum sp., Monodyctis cataneae and Aspergillus niger as biotic elicitors. The best results were obtained with Verticillum sp., 24 h after elicitation, with an increase of approx. 100% in peroxidase activity. The isoenzyme pattern analysed by isoelectric focusing revealed predominantly basic and acidic isoenzymes in both plant roots and transformed root cultures. Elicited samples showed a similar isoenzyme pattern with a slight increase in basic isoenzymes.