Auxin–Ethylene Interaction in Adventitious Rooting and Related Changes in Anodic Peroxidase Isozymes in Sunflower Hypocotyls

Culturing the hypocotyl explants from 7-day-old, light-grown seedlings of sunflower (Helianthus annuus L.) on auxin-supplemented MS medium leads to a marked stimulation in callus induction and root initiation. NAA proved more effective than IAA for both responses. Experiments employing ethylene precursors (methionine and ACC) and action inhibitor (AgNO₃) revealed a significant role of endogenous ethylene levels in auxin-induced rooting. The auxin-ethylene interaction in root morphogenesis is accompanied with specific changes in anodic peroxidase isozymes.