Peroxidase activity during adventitious root formation in avocado microcuttings

Abstract

Peroxidases seem to play an important role in the regulation of auxin levels during the rooting of cuttings. In avocado, leaf peroxidase activity remained constant throughout the rooting process in the three fractions analyzed (soluble, ionically, and covalently bound to cell wall). Soluble peroxidase activity in stem basal parts increased twofold after 3 days and then remained constant until the end of the process. Cationic and anionic electrophoresis revealed a lower number of isoenzymes in the stems than in the leaves. Histological stainings at stem basal parts were also carried out to localize the enzyme activity. Peroxidase was active in all tissues at the time the cutting was taken, with vascular bundles and epidermis giving the strongest reactions. During the process of root formation peroxidase activity was closely associated with growth and differentiation processes, e.g., cambial cell division and xylogenesis; a strong reaction was also found in the developing root primordia. The possible role of peroxidases in the regulation of auxin levels during the rooting process in avocado is discussed. Key words: auxin, avocado, peroxidase, rooting.