Plant and Cell Physiology, 1984, Vol. 25, No. 7 1233-1239
© 1984
Article |
Adenine and Pyridine Nucleotide Status of Isolated Vicia Guard Cell Protoplasts During K+-Induced Swelling
1Universität Tübingen, Biologie I, Auf der Morgenstelle 1 D-7400 Tübingen 1, F.R.G.
2Technische Universität München, Lehrstuhl f. Botanik Arcisstr. 21, D-8000 Munchen 2, F.R.G.
The levels of ATP, ADP, and reduced and oxidized pyridine nucleotides were determined in guard cell protoplasts of Vicia faba during their swelling in 10 mu potassium iminodiacetate. Upon addition of K+, the ATP/ADP ratio dropped from 9 to about 6 (0 to 1 min of incubation), followed by a steep increase up to 15 between 1 and 3 min. After 3 min, the protoplasts began to increase in diameter from about 15 µm to nearly 17 µm after 5 min of incubation, accompanied by a rapid decrease of the ATP/ADP ratio to about 7. During this time, NAD and NADPH showed oppositely directed oscillations, while the pools of NADH and NADP stayed rather constant. As the sum of all pyridine nucleotides did not change, an interconversion of NAD and NADPH must have occurred during the swelling. The levels.of glucose-6-P dehydrogenase activity, which were assayed under the same conditions, showed oscillations parallel to those of the ATP/ADP ratios and opposite to those of the NADPH/NAD ratios. The results are discussed with respect to the regulatory mechanisms during guard cell swelling.
(Received April 21, 1984; Accepted August 1, 1984)
![]()
CiteULike
Connotea
Del.icio.us What's this?