Isoperoxidase in hairy roots and regenerated plants of horseradish ( Armoracia lapathifolia)

Abstract

Agrobacterium rhizogenes harboring an Ri plasmid was inoculated on leaves or petioles of horseradish ( Armoracia lapathifolia). After (2–4 weeks) the inoculation, adventitious roots and/or adventitious buds appeared on the inoculated sites. When the adventitious roots were cultured on hormone-freee MS medium under certain light conditions, plants regenerated from the roots. The regenerated plants were classified into three categories, i.e., normal type, wrinkled type and rooty type according to their respective morphology. In all three types, peroxidase activities in roots were 2–10 times higher than those in shoots. Peroxidase activities in roots and shoots of normal and wrinkled types were comparable to those of non-transformed plants. On the other hand, peroxidase activities of rooty type were several times higher than those of non-transformed plants. Isoenzyme patterns of peroxidases in the hairy roots resembled those in roots on non-transformed plants and the patterns in the hairy roots did not change during the culture period. Hairy roots of the rooty type grew well in liquid MS medium and total peroxidase activity in the culture reached a maximum value of about 30 units/flask after 4 weeks of culture. Peroxidase activity was also detected in the culture medium and the activity was about 1 4 of that in the hairy roots. Hairy roots can have potential use for production of peroxidase.