Abstract
Temperature and kinetic studies were performed to examine the mechanism by which prechilling stimulates phytochrome-dependent seed germination in lettuce, Lactuca sativa, L. cv. Grand Rapids. Imbibed seeds were given a short far red irradiation and one day of dark incubation at 20 C to establish very low levels of the far red-absorbing form of phytochrome—(Pfr). Germination was greatly stimulated by subsequent prechilling treatments when they were followed by a second short far red irradiation. Prechilling therefore increased germination sensitivity to the low, normally inhibitory Pfr levels established by far red irradiation. This sensitivity increased with lowered prechilling temperature to a maximum near 4 C. It was linearly dependent upon duration of prechilling at 4 C up to a near maximal response at 10 hours, and it decayed in a converse manner when seeds were returned to 20 C after 10 hours at 4 C. Prechilling also increased germination responses to subsequent periods of high levels of Pfr which were initiated by red and terminated by far red irradiations. High Pfr periods adequate to promote the germination of unchilled seeds produced sharp inflections at 18 C in the dependence of germination on prechilling temperature. Rates of phytochrome potentiation of germination were not affected by prechilling. The response to prechilling fit a mechanism involving homeoviscous adaptation of membrane lipids to temperature.
Full text
PDF![220](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/b396/440569/901c538f7b6a/plntphys00525-0026.png)
![221](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/b396/440569/0d03d5dcd794/plntphys00525-0027.png)
![222](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/b396/440569/d6c52df1a097/plntphys00525-0028.png)
![223](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/b396/440569/ef0de530af08/plntphys00525-0029.png)
![224](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/b396/440569/404ea73bc41b/plntphys00525-0030.png)
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Duke S. O., Egley G. H., Reger B. J. Model for variable light sensitivity in imbibed dark-dormant seeds. Plant Physiol. 1977 Feb;59(2):244–249. doi: 10.1104/pp.59.2.244. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fork D. C. Effect of Growth Temperature on the Lipid and Fatty Acid Composition, and the Dependence on Temperature of Light-induced Redox Reactions of Cytochrome f and of Light Energy Redistribution in the Thermophilic Blue-Green Alga Synechococcus lividus. Plant Physiol. 1979 Mar;63(3):524–530. doi: 10.1104/pp.63.3.524. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hendricks S. B., Taylorson R. B. Dependence of thermal responses of seeds on membrane transitions. Proc Natl Acad Sci U S A. 1979 Feb;76(2):778–781. doi: 10.1073/pnas.76.2.778. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hendricks S. B., Taylorson R. B. Variation in germination and amino Acid leakage of seeds with temperature related to membrane phase change. Plant Physiol. 1976 Jul;58(1):7–11. doi: 10.1104/pp.58.1.7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ikuma H., Thimann K. V. Analysis of Germination Processes of Lettuce Seed by Means of Temperature and Anaerobiosis. Plant Physiol. 1964 Sep;39(5):756–767. doi: 10.1104/pp.39.5.756. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mancinelli A. L., Yaniv Z., Smith P. Phytochrome and Seed Germination. I. Temperature Dependence and Relative P(FR) Levels in the Germination of Dark-germinating Tomato Seeds. Plant Physiol. 1967 Mar;42(3):333–337. doi: 10.1104/pp.42.3.333. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Raison J. K. Temperature-induced phase changes in membrane lipids and their influence on metabolic regulation. Symp Soc Exp Biol. 1973;27:485–512. [PubMed] [Google Scholar]
- Roth-Bejerano N., Koller D., Negbi M. Mediation of phytochrome in the inductive action of low temperature on dark germination of lettuce seed at supra-optimal temperature. Plant Physiol. 1966 Jun;41(6):962–964. doi: 10.1104/pp.41.6.962. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Scheibe J., Lang A. Lettuce Seed Germination: Evidence for a Reversible Light-Induced Increase in Growth Potential and for Phytochrome Mediation of the Low Temperature Effect. Plant Physiol. 1965 May;40(3):485–492. doi: 10.1104/pp.40.3.485. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sinensky M. Homeoviscous adaptation--a homeostatic process that regulates the viscosity of membrane lipids in Escherichia coli. Proc Natl Acad Sci U S A. 1974 Feb;71(2):522–525. doi: 10.1073/pnas.71.2.522. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Taylorson R. B., Hendricks S. B. Action of Phytochrome During Prechilling of Amaranthus retroflexus L. Seeds. Plant Physiol. 1969 Jun;44(6):821–825. doi: 10.1104/pp.44.6.821. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Thompson G. A., Jr, Nozawa Y. Tetrahymena: a system for studying dynamic membrane alterations within the eukaryotic cell. Biochim Biophys Acta. 1977 May 31;472(1):55–92. doi: 10.1016/0304-4157(77)90014-4. [DOI] [PubMed] [Google Scholar]