| Summary: | Germinating pea (Pisum sativum L.) roots were divided into five sequential 0.5 cm segments from the root tip. Pooled segments were analyzed for their protein, starch and lipid content as an indirect indication of plastid function. Fresh weights of root segments were lowest in the tips (4.45mug per segment) and progressively higher up to the fifth segment (11.09mug per segment). Total protein, starch and lipid content, on a per segment basis, were all highest in zone 1 (tip segment) and progressively lower up to zone 5. Plastids were isolated from each of the five root segments and analyzed for their capacity for lipid biosynthesis under several different in vitro conditions. Collectively, the observations presented here suggest that the relative contributions of plastids to the overall physiology of germinating pea roots gradually diminishes as root development proceeds, and that plastids isolated from progressively older root zones have increased capacity for glycolytic and/or pentose phosphate metabolism. (Abstract shortened by UMI.)
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