RT Journal Article
SR Electronic
T1 Effect of Fusicoccin on Dark <sup>14</sup>CO<sub>2</sub> Fixation by <em>Vicia faba</em> Guard Cell Protoplasts
JF Plant Physiology
JO Plant Physiol.
FD American Society of Plant Biologists
SP 1700
OP 1703
DO 10.1104/pp.70.6.1700
VO 70
IS 6
A1 Brown, Peter H.
A1 Outlaw, William H.
YR 1982
UL http://www.plantphysiol.org/content/70/6/1700.abstract
AB When Vicia faba guard cell protoplasts were treated with fusicoccin, dark 14CO2 fixation rates increased by as much as 8-fold. Rate increase was saturated with less than 1 micromolar fusicoccin. Even after 6 minutes of dark 14CO2 fixation, more than 95% of the incorporated radioactivity was in stable products derived from carboxylation of phosphoenolpyruvate (about 50% and 30% in malate and aspartate, respectively). The relative distribution of 14C among products and in the C-4 position of malate (initially more than 90% of [14C]malate) was independent of fusicoccin concentration. After incubation in the dark, malate content was higher in protoplasts treated with fusicoccin. A positive correlation was observed between the amounts of 14CO2 fixed and malate content. It was concluded that (a) fusicoccin causes an increase in the rate of dark 14CO2 fixation without alteration of the relative fluxes through pathways by which it is metabolized, (b) fusicoccin causes an increase in malate synthesis, and (c) dark 14CO2 fixation and malate synthesis are mediated by phosphoenolpyruvate carboxylase.