Hypocotyl segments of white spruce seedlings, when placed with their basal end in a defined medium containing agar and 6-benzylaminopurine (BAP), formed up to 100 or more scale-like organs per segment. The organs did not arise from a preexisting apical meristem. The induction was inhibited by α-naphthaleneacetic acid (NAA). On medium containing 10−5 M BAP and no NAA, 69% of the explants formed multiple organs. When explants bearing the scale-like organs were transferred to media containing neither BAP nor NAA, the organs grew out into needles, and buds developed. Many of the buds developed into elongated shoots.

Water added to dry seeds of jack pine evoked changes at the shoot apex which reflected the mobilization and consumption of food reserves for the synthesis of new protoplasm and for the formation of the prospective shoot. In shoot apices the distal zone contained large cells having nuclei with low affinity for stains. Flank and subapical zones had smaller cells with densely stained nuclei. These features did not alter during imbibition nor after the first wave of mitosis at 96 h when radicles emerged from seeds. Cells in the distal zone divided rarely. Mitosis, most abundant in subapices, decreased acropetally to the distal zone.In dry seeds, protein bodies and amyloplasts increased in size and frequency per cell from the distal zone in the basipetal direction towards the flanks and subapical zone. During imbibition most proteinaceous reserves, rich in arginine N, disappeared from all cells of the shoot apex. Lipid bodies in distal cells were small, numerous, and disappeared slowly as germination proceeded. Proplastids, mitochondria, and unidentified pleomorphic bodies were distributed in close proximity to the nucleus particularly in apical cells.Products of imbibed tritiated water (nonexchangeable tritium), and tritiated D-glucose, thymine, thymidine, and uracil were localized at the shoot apex and revealed assimilatory patterns consistent with cytochemical zonation. The covalent incorporation of tritium from water, while spread through most cells, was greatest in nuclei of flank and subapical cells. The radioactivity from glucose was found mainly in cell walls. Labelling by uracil, thymine, and thymidine by salvage mechanisms was especially abundant in nuclei of the flanks. These events coincided with dense RNA and DNA staining during germination. Collectively, observations indicated that at the flanks, water and seed reserves were concentrated at specific binding sites for the synthesis and dispersion of macromolecules before the visual production of leaf primordia.

Resting, vegetative buds of white spruce, black spruce, Norway spruce, balsam fir, and Douglas-fir were grown under aseptic conditions on agar with various supplements. While an inorganic source of nitrogen was sufficient for the rapid growth of buds, the addition of organic nitrogen to the medium consistently promoted growth, but changes in weight and axis length were not always significant. For white spruce, all levels of growth regulators inhibited bud development. Coconut milk supported organized growth. Malt extract and casein hydrolysate were not beneficial. Levels of sugar above 2% (w/v) greatly improved the weight and length of the emerging shoot.The extent of shoot formation depended on the portion of dormant bud which was used as starting material. Buds isolated with an attached crown and intact embryonic shoot grew faster than those excised above this nodal diaphragm. By 40 days, the fresh weight of isolated buds increased 15–20 times, and their axes elongated 5–6 fold. Needles of some species (Douglas-fir) were well-developed. Changes in the free amino acids of developing white spruce shoots in culture corresponded in kind, and sequence to changes found during late winter, and spring in growing buds on trees under field conditions. Initially, buds contained low levels of total soluble N, and high percentages of proline N. Subsequently both invitro and in the field, the total soluble N increased and the content of proline N decreased. Amides now dominated the composition of the soluble N. Reduced growth and axis length usually reflected high percentages of arginine N and increased scale development in a way that resembled bud formation during late summer under field conditions.

In early fall, the high levels of free arginine nitrogen in spruce buds were eventually replaced by proline nitrogen, and in late spring, glutamine nitrogen accumulated. In late October when levels of free proline nitrogen were high, bud primordia from terminal shoots were excised and exposed to uniformly labeled 14C-L-proline and 14C-L-glutamine. The main early products from 14C-L-proline were Δ1-pyrroline-5-carboxylic acid, glutamic-γ-semialdehyde, and glutamic acid. Later products included glutamine, γ-aminobutyric acid, and to a much lesser extent pyrrolidone carboxylic acid, ornithine, and arginine. In protein, radioactivity was recovered from proline, glutamic acid, and hydroxyproline.Products from 14C-glutamine were mainly glutamic and α-ketoglutaric acid as well as proline, γ-aminobutyric acid, alanine, and pyrrolidone carboxylic acid. In protein, glutamic acid, aspartic acid, and proline contained carbon-14. Results indicated that proline and glutamine were related by their carbon metabolism through a common path involving glutamic acid. However, the main feature of glutamine metabolism was the removal of its α-amino and the amide nitrogen to yield α-keto acids especially α-ketoglutaric acid. The occurrence of α-ketoglutaramic acid could have accounted for succinamic acid and succinimide derived from 14C-L-glutamine.

In germinating jack pine, changes in nitrogenous compounds were separated into two phases, the first, where through imbibition, seeds expanded but the prospective seedling remained enclosed by the haploid and nutritive female gametophyte (0 to 3 days), and second, when radicles emerged and only cotyledons remained in contact with the gametophyte (4 to 11 days).During imbibition, total soluble N in seeds dropped and the amino acid pool was dominated by high levels of free arginine. As levels of arginine N declined the greatest changes in percentage composition involved glutamic acid (gametophyte) and glutamine (embryo). Thereafter, arginine N accumulated. By 7 days, arginine N was recovered in seedlings primarily from cotyledons. High asparagine levels were observed in stems and roots as glutamine N in the emerging seedling declined.Protein reserves in the seedling were nearly depleted by 4 days. Total protein and, at later stages, the ratio of hexone bases to dicarboxylic acids was generally higher in the gametophyte than in the seedling. Soluble proteins of the embryo were separated into at least 18 bands by disc electrophoresis and contained peroxidase activity which increased strongly after the first week of germination. The increase of nine isoenzymes of peroxidase with mobilities towards the anode correlated with the histochemical localization of peroxidase at the emerging shoot and root tips and throughout the vascular tissues.