Initiation of embryogenic callus and suspension cultures of eastern white pine (Pinus strobus L.)

Embryogenic callus and suspension cultures of eastern white pine (Pinus strobus) have been obtained. The whole female gametophyte was plated on a medium containing 50 mg/l glutamine, 500 mg/l casein hydrolysate, 3% sucrose, 2 mg/1 2,4-D, 1 mg/1 BA and 0.2% Gelrite as a solidifying agent. Embryogenic calli could be seen as early as 5 days following culture. Histological studies indicate proliferation of pre-existing embryogenic tissue in the corrosion cavity followed by extrusion of embryogenic callus through the micropylar end of the gametophyte. Embryogenic suspension cultures were obtained by placing embryogenic callus into liquid medium. Embryogenic suspension cultures were subcultured weekly and proliferated as early-stage embryos with attached suspensors. Embryo development was obtained following transfer of the embryogenic tissue to an auxin-free medium containing 50 mM glutamine, 38 μM abscisic acid, and 6% sucrose. Although embryo development could be consistently obtained, whole plants have not yet been recovered from these somatic embryos.