Influence of Abscisic Acid on Nitrate Accumulation and Nitrate Reductase Activity in Potato Tuber Slices

概要

論文の詳細を見る
Abscisic acid (ABA) at concentrations of 1 to 10 μg・ml^<-1> suppressed development of nitrate reductase activity in fresh tuber slices of Solanum tuberosum L. incubated in KNO_3. Suppression of activity was evident after 3 hr and continued for 20 hr before recovery. This recovery may be due to inactivation of the hormone. Nitrate accumulation was enhanced by ABA. At exogenous NO_3 levels of 0.1 to 5 mM, the hormone enhanced both NO_3 accumulation and nitrate reductase activity. When applied 24 hr after incubation in NO_3, ABA promoted a marked decline in enzyme activity in the absence of exogenous NO_3, but was less effective in the presence of NO_3. Slices incubated in NO_3 and ABA also exhibited increased loss of enzyme activity upon removal of NO_3. Preincubating slices in the hormone for 24 hr in a NO_3-free medium resulted in stimulation of nitrate reductase activity. Addition of NO_3 resulted in a marked stimulation of enzyme activity over a period of 8-10 hr. The ABA response is not related to tissue levels of free amino acids and is not affected by different NO_3 sources. These results suggest the ABA effect on nitrate reductase activity is influenced by NO_3 status of the cells. Where external NO_3 levels are low it stimulated NRA while it inhibited activity where NO_3 content is high.
日本植物生理学会の論文