The partitioning of 14C between growth and differentiation within stem-deformed and healthy black spruce seedlings

When containerized black spruce seedlings (Picea mariana Mill.) are grown rapidly, their stems can become deformed, i.e., they bend over, grow horizontally, and obtain a permanent crook. To determine what physiological differences exist between these stem-deformed and healthy seedlings, we fed labeled amino acid,14C-phenylalanine, a precursor of lignin and phenolics as well as a constituent of proteins, to both kinds of seedlings and followed the partitioning of this 14C after a chase period of 24, 48, and 72 h. For one group of seedlings, intact plants incorporated the l4C-phenylalanine through their root systems, whereas for a second group of plants, root systems were excised and the 14C-phenylalanine was incorporated directly by stems. When the 14C was incorporated by roots, stem-deformed seedlings partitioned more l4C to protein and less to lignin and phenolics. However, when the 14C was incorporated directly by stems, the differences between stem-deformed and healthy seedlings nearly disappeared. Fur...