BASIC PEROXIDASES AND ROOTING IN MICROCUTTINGS OF MALUS

Abstract

We have examined the relation between the activity of basic peroxidases (basPox) and rooting in microcuttings of Malus. (1) A positive correlation (p <0.001) occurred between the activity of basPox in stems of shoots at the time of transfer to rooting medium and the number of roots 21 days after the transfer. This correlation, though, only occurred if the nonrooted shoots had been omitted from the calculation. (2) BasPox increased during the first stages of the rooting process (5- to 10-fold), but did not show a subsequent decrease. The increase was larger in an easy-to-root than in a hard-to-root subclone. The increase, though, also occurred in non-rooted shoots on rooting medium and in shoots cultured on propagation medium or hormone-free medium. We suggest that the increase of basPox is related to cell divisions, which may result in roots and/or callus on rooting medium, or in callus on propagation medium. In hard-to-root shoots, the outgrowth of root primordia was not inhibited as compared with easy-to-root shoots. Auxins inhibited outgrowth up to 50%. During the first days of the rooting period, 0.7% of applied radioactive auxin (indole-3-acetic acid) was taken up per day. Approx. 50% of the label taken up accumulated in the basal 3-mm portion of the stem.