TOWARDS AN EFFICIENT REGENERATION PROTOCOL FOR <em>EUCALYPTUS</em> <em>UROPHYLLA</em>

Abstract

The aim of the present study was to establish an efficient regeneration system for Eucalyptus urophylla by means of organogenesis. The hypocotyls from seedlings of E. urophylla clone U6 were used as explants and cultured in a modified Murashige and Skoog (MS) medium, supplemented with 13.2 μM L^-1 N-phenyl-N’-[6-(2-chlorobenzothiazol)-yl] urea (PBU) and 0.285μM L^-1 indole-3-acetic acid (IAA). After culture for 5 days, 98.8% explants formed callus. After 30 days, the calli obtained were transferred to Schwarz differential medium (SDM) containing different combinations of 6-benzyladenine (6-BA) and naphthalene acetic acid (NAA). Compared with other growth regulator combinations, PBU stimulated more vigorous calli and restrained browning. In addition, a large percentage (58.6%) of the calli induced by PBU showed adventitious bud formation. Proliferation of adventitious buds was obtained on SDM medium supplemented with 2.2 μM L^-1 6-BA and 0.25 μM L^-1 NAA and shoot elongation was then stimulated on SDM medium supplemented with 5.28 μM L^-1PBU and 0.25 μM L^-1 NAA for 20 days. For rooting, the elongated shoots were cultivated on root induction medium containing 2.46 μM L^-1 indole-3-butyric acid (IBA). Plantlets were then successfully transplanted to a greenhouse. This paper presents an efficient procedure for regeneration of E. urophylla.