In vitro adventitious shoot formation on mature-phase leaves and petioles of Liquidambar styraciflua L.

Adventitious shoots were induced to form on leaves and petiole segments of mature-phase Liquidambar styraciflua L. Shoot organogenesis occurred directly, without the formation of a distinct callus stage, and well-defined shoots were visible in 6–9 weeks. Prolific shoot production was supported by Woody Plant Medium supplemented with relatively high levels of benzyladenine (2.5 mg/l). Changes in benzyladenine concentration and the addition of 0.1 mg/l naphthaleneacetic acid to the medium altered the relative abundance of shoots on various parts of a leaf. Shoot formation occurred most frequently at or near breaks in major vasculature. Wounding of the leaves by slashing across the lamina and vasculature significantly increased the total number of shoots formed per explant and also altered the pattern of organogenesis. Differences in organogenic response were seen between the cultivars ‘Moraine’ and ‘Variegata’. Shoots derived from leaves were easily rooted and acclimated to greenhouse conditions. Three new variegation types arose in vitro as a result of adventitious shoot formation on ‘Variegata’ leaves.