In vitro regeneration of adult Pinus sylvestris L. trees

The propagation of adult conifer trees by tissue culture has been studied for the last twenty years, but problems related to the juvenile to adult phase change of trees have limited the practical applications of these tissue culture procedures. This paper describes a micropropagation protocol for the in vitro propagation of mature Scots pine trees. In this study, dormant shoot buds, which had not started to elongate, were collected from twenty-one adult Pinus sylvestris trees (> 15 years old) during the winter. The sampled buds were cut transversely into slices of 0.5 to 1 cm in thickness and were cultured on three types of culture media (DCR, WP and LPm) supplemented with four cytokinins (BA, mT, Tdz and Z), at two different concentrations (25 and 50 µM), except for Tdz, whose concentrations were diluted to 5 µM and 2.5 µM. The evaluated culture media did not show significant differences in the bud organogenesis capacity. In fact, the highest organogenic response was obtained with buds cultured on DCR and WP media and by explants cultured on medium supplemented with 25 µM meta-topolin. This protocol is a successful and efficient biotechnological approach to the micropropagation of adult P. sylvestris trees.