Metabolic and structural responses of pine buds under climate chamber conditions

Scots pine ( Pinus sylvetris L.) plants, about 2 m high, were placed in controlled conditions for 2 weeks in January, April and November. During the experiments made in January, the conditions in the climate chambers simulated either a gradual or abrupt advancement of spring. In April they simulated either the advancement of the season or its reversal back to January. In November the plants were transferred to conditions that resembled spring. In January, pieces of buds collected at the end of the experiment were also fixed for electron microscope studies.
Isolation of the ribosomes and the determination of their in vitro translation capacity revealed that in January the response to environmental changes was evident. An increase in synthesized proteins was caused by a rise in the translation capacity of ribosome assemblies rather than by an increase in their quantity. The cellular ultras-structure changed in conformity with the changes characteristic of the spring. In April, the plants transferred to the climate chambers maintained their ability to synthesize proteins, but the buds were judged to be under stress. In November die ability of the buds to respond to environmental changes was retarded or inhibited.