Micropropagation of western white pine (Pinus monticola) starting with mature embryos

As part of a program to develop micropropagation protocols for western white pine, the production of adventitious shoots from mature embryos was investigated. Litvay's medium proved to be the best of the six media formulations tried. The optimum concentration of N6-benzyladenine was 30 mu M for 21 days. BiTek agar which had an optimum at 8 g/L produced significantly more shoots than GelGro gellan gum which had an optimum at 5 g/L. There was no significant difference in the shoot production between three different seed lots, two from interior British Columbia and one from coastal British Columbia, with this protocol. Harvested adventitious shoots survived best on the medium of GresshofF and Doy at half-strength. Using the protocol described here, it was possible to obtain 500 to 600 shoots for every 100 embryos explanted. Up to 80 percent of the shoots continued to grow three months after excision from the explants.