Analysis of the hormonal manipulation during in vitro induction of adventitious roots in Castanea Sativa

Abstract

Adventitious rooting is a complex process still poorly understood, and is a crucial step for the clonal propagation of elite genotypes of woody species. The aim of this work was to develop a new, simple and reproducible experimental system in chestnut to study the adventitious rooting process at the physiological and molecular levels. Chestnut microshoots and leaf explants excised from microshoots were used to evaluate their physiological responses to indole-3-butyric acid alone or in combination with N-1-naphthyl-phthalamic acid. Similar rooting percentages were obtained in auxin treated microshoots and leaves, however, the mean number of roots per rooted explant was higher in microshoots than in leaves. When NPA was included in the medium, the rooting capacity of both, leaves and microshoots, was reduced and root emergence was delayed at least 4 days compared with explants treated with IBA alone. Whereas in microshoots less than half of the roots were developed from the basal callus, in leaf explants the majority of the roots were originated from the callus developed in the leaf petiole, which made this system very useful for the identification of auxin-responsive genes and key regulatory genes involved in the early events of adventitious rooting process.