Morphogenic responses and in vitro regeneration of canelo (Drimys winteri JR et Forster), a forest species used in Chilean traditional medicine

Drimys winteri (canelo) is an important native forest tree common to southe rn latitudes of Chile and Argentina. Micropropagation and selection work of this species is important for reforestation; however, best characters from different populations have to be determined, fixed, and asexually multipli ed for use. The aim of the present work is to evaluate the regeneration pot ential being expressed by different in vitro cultured explants of this spec ies. Using shoot-tips, root formation was obtained leading to plantlet rege neration. Rooting was obtained in a two-step culture, the first consisted i n a WPM-liquid medium, including 1.61 mu M alpha-naphthaleneacetic acid (NA A), 0.43 mu M 6-benzyladenine (BA) and 0.03 mu M of gibberellic acid (GA3) for 60 days at low light intensity (10 mu mol m(-2) s(-1)) followed by a su bculture in half-strength liquid MS-medium in presence of 26.85 mu M NAA an d 0.5 mg/l Ca-panthotenate. Roots were not formed in permanent darkness. Sh oot organogenesis and multiple shoot formation were obtained from internoda l explants and internodal-derived callus respectively. Single shoots were c ommonly observed in internodes after 1-2 months and multiple shoots formed mainly on callus after 4 months, in presence of 0.54, 5.37 and 53.71 mu M N AA or 0.46 and 4.65 CIM 6-furfurylaminopurine (K), in 90% of explants. Unde r continuous darkness, callus formed more than 40 shoots/explant. Direct sh oot-formation also occurred in leaf sections up to 70%, in presence of 0.45 or 11.35 mu M thidiazuron (TDZ) in combination with 0.54 or 5.37 mu M NAA.