Abstract
The effect of salts of organic acids on washed and non-washed chloroplast membranes during freezing was investigated. Thylakoids were isolated from spinach leaves (Spinacia oleracea L.) and, prior to freezing, salts of various organic acids or inorganic salts or both were added. Freezing occurred for 3 to 4 hours at −25 C. After thawing membrane integrity was investigated by measuring the activity of cyclic photophosphorylation.
At very low NaCl levels (1 to 3 mm, washed thylakoids) salts of organic acids either could not prevent membrane inactivation in the course of freezing (succinate) or were effective only at relatively high concentrations (0.1 m or more of acetate, pyruvate, malate, tartrate, citrate). If NaCl was present at higher concentrations (e.g., 0.1 m) some organic acids, e.g. succinate, malate, tartrate, and citrate, were able to protect frost-sensitive thylakoids at surprisingly low concentrations (10 to 20 mm). Other inorganic salts such as KCl, MgCl2, NaNO3 could also induce protection by organic acids which otherwise were ineffective or poorly effective. For effective protection, a more or less constant ratio between inorganic salt and organic acid or between two or more organic acids had to be maintained. Departure to either side from the optimal ratio led to progressive inactivation.
The unspecificity of the protective effect of organic acids suggests that these compounds protect colligatively. There are also indications that, in addition, more specific interaction with the membranes contributes to protection. At temperatures above the freezing point, the presence of salts of organic acids decreased the rate of membrane inactivation by high electrolyte concentrations.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Arnon D. I. COPPER ENZYMES IN ISOLATED CHLOROPLASTS. POLYPHENOLOXIDASE IN BETA VULGARIS. Plant Physiol. 1949 Jan;24(1):1–15. doi: 10.1104/pp.24.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gerloff E. D., Stahmann M. A., Smith D. Soluble proteins in alfalfa roots as related to cold hardiness. Plant Physiol. 1967 Jul;42(7):895–899. doi: 10.1104/pp.42.7.895. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Heber U. W., Santarius K. A. Loss of Adenosine Triphosphate Synthesis Caused by Freezing and Its Relationship to Frost Hardiness Problems. Plant Physiol. 1964 Sep;39(5):712–719. doi: 10.1104/pp.39.5.712. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Heber U. Freezing injury and uncoupling of phosphorylation from electron transport in chloroplasts. Plant Physiol. 1967 Oct;42(10):1343–1350. doi: 10.1104/pp.42.10.1343. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Heber U. Freezing injury in relation to loss of enzyme activities and protection against freezing. Cryobiology. 1968 Nov-Dec;5(3):188–201. doi: 10.1016/s0011-2240(68)80163-4. [DOI] [PubMed] [Google Scholar]
- JAGENDORF A. T., AVRON M. Cofactors and rates of photosynthetic phosphorylation by spinach chloroplasts. J Biol Chem. 1958 Mar;231(1):277–290. [PubMed] [Google Scholar]
- Jung G. A., Shih S. C., Shelton D. C. Influence of Purines and Pyrimidines on Cold Hardiness of Plants. III. Associated Changes in Soluble Protein and Nucleic Acid Content and Tissue pH. Plant Physiol. 1967 Dec;42(12):1653–1657. doi: 10.1104/pp.42.12.1653. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jung G. A., Shih S. C., Shelton D. C. Seasonal changes in soluble protein, nucleic acids, and tissue pH related to cold hardiness of alfalfa. Cryobiology. 1967 Jul-Aug;4(1):11–16. doi: 10.1016/s0011-2240(67)80181-0. [DOI] [PubMed] [Google Scholar]
- LOVELOCK J. E. The mechanism of the protective action of glycerol against haemolysis by freezing and thawing. Biochim Biophys Acta. 1953 May;11(1):28–36. doi: 10.1016/0006-3002(53)90005-5. [DOI] [PubMed] [Google Scholar]
- Mazur P. Cryobiology: the freezing of biological systems. Science. 1970 May 22;168(3934):939–949. doi: 10.1126/science.168.3934.939. [DOI] [PubMed] [Google Scholar]
- Meryman H. T. Modified model for the mechanism of freezing injury in erythrocytes. Nature. 1968 Apr 27;218(5139):333–336. doi: 10.1038/218333a0. [DOI] [PubMed] [Google Scholar]
- Santarius K. A., Heber U. The kinetics of the inactivation of thylakoid membranes by freezing and high concentrations of electrolytes. Cryobiology. 1970 Sep-Oct;7(2):71–78. doi: 10.1016/0011-2240(70)90001-5. [DOI] [PubMed] [Google Scholar]