Abstract
Alfalfa was grown hydroponically in 0, 0.6, and 4.8 millimolar K in order to determine the influence of tissue level of K on photosynthesis, dark respiration, photorespiration, stomatal and mesophyll resistance to CO2, photosystem I and II activity, and synthesis and activity of ribulose 1,5-bisphosphate carboxylase (RuBPc).
A severe (0.0 millimolar) and mild (0.6 millimolar) K deficiency, compared to plants grown at 4.8 millimolar K, produced a significant decrease in photosynthesis and photorespiration, but an increase in dark respiration. Both deficient K levels increased hydrophyllic resistance to CO2, but only the severe deficiency increased stomatal resistance.
Photosystem I and II activity of isolated chloroplasts was not affected by K deficiency. The apparent activity of a crude RuBPc preparation was significantly reduced in severely deficient plants. Activity of the enzyme could not be restored to normal rates by the addition of K to the reaction medium.
The specific activity of RuBPc isolated from severely K-deficient and K-sufficient leaflets was not significantly different, suggesting that K does not function in RuBPc activity. Incorporation of [14C]leucine into RuBPc, as a measure of synthesis, by K-deficient leaflets was reduced to 15% of K-sufficient leaflets. The addition of K to the reaction medium stimulated [14C]leucine incorporation into RuBPc and 10 millimolar KNO3 increased incorporation to 80% of K-sufficient leaflets. Actinomycin D and cycloheximide suppressed the K-stimulated incorporation of [14C]leucine into RuBPc, suggesting that the K-stimulated synthesis of RuBPc most likely represents de novo synthesis.
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- Baszynski T., Brand J., Barr R., Krogmann D. W., Crane F. L. Some Biochemical Characteristics of Chloroplasts from Mineral-deficient Maize. Plant Physiol. 1972 Sep;50(3):410–411. doi: 10.1104/pp.50.3.410. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fischer R. A. Stomatal opening: role of potassium uptake by guard cells. Science. 1968 May 17;160(3829):784–785. doi: 10.1126/science.160.3829.784. [DOI] [PubMed] [Google Scholar]
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- Loustalot A. J., Gilbert S. G., Drosdoff M. THE EFFECT OF NITROGEN AND POTASSIUM LEVELS IN TUNG SEEDLINGS ON GROWTH, APPARENT PHOTOSYNTHESIS, AND CARBOHYDRATE COMPOSITION. Plant Physiol. 1950 Jul;25(3):394–412. doi: 10.1104/pp.25.3.394. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Peoples T. R., Koch D. W., Smith S. C. Relationship between Chloroplast Membrane Fatty Acid Composition and Photosynthetic Response to a Chilling Temperature in Four Alfalfa Cultivars. Plant Physiol. 1978 Mar;61(3):472–473. doi: 10.1104/pp.61.3.472. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Terry N., Ulrich A. Effects of Potassium Deficiency on the Photosynthesis and Respiration of Leaves of Sugar Beet under Conditions of Low Sodium Supply. Plant Physiol. 1973 Jun;51(6):1099–1101. doi: 10.1104/pp.51.6.1099. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Terry N., Ulrich A. Effects of potassium deficiency on the photosynthesis and respiration of leaves of sugar beet. Plant Physiol. 1973 Apr;51(4):783–786. doi: 10.1104/pp.51.4.783. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Trebst A. Measurement of Hill reactions and photoreduction. Methods Enzymol. 1972;24:146–165. doi: 10.1016/0076-6879(72)24065-4. [DOI] [PubMed] [Google Scholar]
- Zelitch I. Comparison of the effectiveness of glycolic Acid and glycine as substrates for photorespiration. Plant Physiol. 1972 Jul;50(1):109–113. doi: 10.1104/pp.50.1.109. [DOI] [PMC free article] [PubMed] [Google Scholar]