title: Dark CO(2) Fixation and its Role in the Growth of Plant Tissue.
abstract: Experiments were designed to determine the significance of dark CO(2) fixation in excised maize roots, carrot slices and excised tomato roots grown in tissue culture. Bicarbonate-(14)C was used to determine the pathway and amounts of CO(2) fixation, while leucine-(14)C was used to estimate protein synthesis in tissues aerated with various levels of CO(2).Organic acids were labeled from bicarbonate-(14)C, with malate being the major labeled acid. Only glutamate and aspartate were labeled in the amino acid fraction and these 2 amino acids comprised over 90% of the (14)C label in the ethanol-water insoluble residue.Studies with leucine-(14)C as an indicator of protein synthesis in carrot slices and tomato roots showed that those tissues aerated with air incorporated 33% more leucine-(14)C into protein than those aerated with CO(2)-free air. Growth of excised tomato roots aerated with air was 50% more than growth of tissue aerated with CO(2)-free air. These studies are consistent with the suggestion that dark fixation of CO(2) is involved in the growth of plant tissues.
authors.affiliation: Department of Horticulture, University of Illinois, Urbana, Illinois.
authors.forename: W E
authors.initials: WE
authors.lastname: Splittstoesser