ETHYLENE AND CARBON-DIOXIDE ACCUMULATION, AND GROWTH OF CELL-SUSPENSION CULTURES OF PICEA-GLAUCA (WHITE SPRUCE)

The production of ethylene and CO2 by cell suspension cultures of white spruce under somatic embryogenic as well as non-embryogenic conditions was studied during 10-day subculture periods. The culture vessels were sealed with either gastight serum caps or foam bungs that are permeable to gases. The cultures produced significant amounts of both gases. The non-embryogenic cultures accumulated about a 3-fold higher level of ethylene than the embryogenic cultures during the initial stages of subculturing. Sealing the flasks with serum caps, with the resultant increase in the levels of these gases, inhibited growth of the cells and multiplication of the proembryos within 4 to 6 days after subculturing. Incubating the embryogenic cell suspension cultures under a continuous flow of gas mixtures of known composition suggested that the inhibition of growth was caused by the accumulation of high levels of ethylene and CO2, and not due to O2 starvation. The activity of phosphoenolpyruvate carboxylase (PEPC) was 2- to 3- fold higher in the embryogenic compared to the non-embryogenic cultures. PEPC activity declined in the embryogenic cultures within 4 days after the flasks were sealed with serum caps, coinciding with the inhibition of growth of the cells. © 1990, Gustav Fischer Verlag, Stuttgart. All rights reserved.