Fatty Acids, Temperature and Growth

Hugly & Somerville (1992) A Role for Membrane Lipid Polyunsaturation in Chloroplast Biogenesis at Low Temperature, Plant Physiol. 99:197-202
Two different mutants of Arabidopsis thaliana deficient in chloroplast membrane lipid polyunsaturation were indistinguishable in appearance from the wild-type when grown at 22°C. By contrast, leaf tissues of the mutants that developed during growth at 5°C were chlorotic, whereas the wild type was not. This is the first direct evidence that chloroplast lipid polyunsaturation contributes to low-temperature fitness. Chloroplasts from mutant lines grown at 5°C were much smaller than those of the wild-type, and the thylakoid membrane content was reduced by up to 70%. However, there was no discernible effect of low temperature on chloroplasts that developed prior to exposure to low temperatures. These and related observations suggest that the high degree of chloroplast membrane lipid polyunsaturation is required for some aspect of chloroplast biogenesis.

Bartkowski, et al., (1978) Influence of exogenous Fatty Acids on cottonseed germination. Physiologia Plantarum, 44(3): 153-156
Effects of exogenous free fatty acid application on percentage germination and radicle length were investigated with more chill sensitive (Pima S-4) and less chill sensitive (Pima S-5) cottonseed (Gossypium barbadense L.) at chilling (14°C) and optimal (34°C) temperatures. Of the organic solvents able to solubilize free fatty acids, aqueous solutions as high as 5% dimethyl sulfoxide did not adversely affect germination at 34°C. Palmitic, oleic and linoleic acids (120 μM) were solubilized in 5% DMSO.
    At 14°C, percent germination of fatty acid treated Pima S-5 significantly increased, while no difference was observed for Pima S-4. Conversely, radicle length of fatty acid treated Pima S-4 significantly increased especially with oleate and linoleate, while no difference was detected for Pima S-5. Fatty acid supplementation influenced neither germination nor radicle length for Pima S-4 and Pima S-5 at 34°C.

Bartkowski, et al., (1977) Dry Seed Fatty Acid Composition and Seedling Emergence of Pima Cotton at Low Soil Temperatures, Agron. J. 69: 37-40
The development of a rapid test to predict cotton lines (Gossypium spp.) which exhibit increased resistance to chilling injury would be a valuable breeding tool. The objective of this study was to evaluate the relationship of Pima cottonseed (G. barbadense L.) lipid composition to seed germination and seedling emergence under field conditions with low soil temperatures. Seed fatty acid methyl esters of selected genotypes were analyzed by gas-liquid chromatography. Total seed lipid was fractionated into polar and neutral components and their associated fatty acid methyl esters were similarly analyzed. Low correlations were obtained between unsaturated/ saturated (U/S) fatty acid ratios of total seed lipid and laboratory germination percentages. However, seedling emergence under field conditions with low soil temperatures correlated strongly with U/S fatty acid ratios of total seed and polar lipids (r = 0.97** and 0.95% respectively)3. No advantage was realized by using polar lipids over total seed lipid for the analysis. Results of this study suggest the feasibility of using the rapid analysis of total seed lipid associated U/S fatty acid ratios for identifying cotton lines with chilling resistance during seed germination and emergence.

Clay, et al., (2006) Nuclear Deoxyribonucleic Acid Metabolism and Membrane Fatty Acid Content Related to Chilling Resistance in Germinating Cotton (Gossypium barbadense), Physiologia Plantarum. 38(3): 171-175
Chilling damage was examined in the chilling-sensitive plant Gossypium barbadense. Between 30 and 36 h of germination at 34°C, the seedlings are extremely sensitive to temperatures below 10°C. The initiation of chilling damage by exposure to 2°C for 5 h during the sensitive period resulted in a large reduction in DNA synthesis. The reduction was correlated with a reduced efficiency of nuclear DNA polymerase activity. Comparing a more chilling resistant genotype to a more sensitive variety indicated that the resistant genotype nuclear DNA polymerase activity is more efficient when exposed to a chilling stress. Resistance was also correlated with a higher degree of unsaturated fatty acid content in the nuclear membranes of the resistant variety.

Javed (1994) Studies on composition and metabolism of lipids in seeds of Citrullus species. Doctoral Thesis.

Jungman (2000) The effect of Fatty Acid profiles on peanut seed germination at low temperatures. Master's Thesis.

Linder (2000) Adaptive Evolution of Seed Oils in Plants: Accounting for the Biogeographic Distribution of Saturated and Unsaturated Fatty Acids in Seed Oils. Am. Nat. 156: 442-458
Structural, energetic, biochemical, and ecological information suggests that germination temperature is an important selective agent causing seed oils of higher-latitude plants to have proportionately more unsaturated fatty acids than lower-latitude plants. Germination temperature is predicted to select relative proportions of saturated and unsaturated fatty acids in seed oils that optimize the total energy stores in a seed and the rate of energy production during germination. Saturated fatty acids store more energy per carbon than unsaturated fatty acids; however, unsaturated fatty acids have much lower melting points than saturated fatty acids. Thus, seeds with lower proportions of saturated fatty acids in their oils should be able to germinate earlier and grow more rapidly at low temperatures even though they store less total energy than seeds with a higher proportion of saturated fatty acids. Seeds that germinate earlier and grow more rapidly should have a competitive advantage. At higher germination temperatures, seeds with higher proportions of saturated fatty acids will be selectively favored because their oils will provide more energy, without a penalty in the rate of energy acquisition. Macroevolutionary biogeographical evidence from a broad spectrum of seed plants and the genus Helianthus support the theory, as do microevolutionary biogeography and seed germination performance within species of Helianthus.

Martz, et al., (2002) Genetic control of fatty acid desaturation during cold acclimation and de-acclimation of birch. Acta Hort. (ISHS) 618

Munshi, et al., (2007) Lipid composition in fast and slow germinating sunflower (Helianthus annuus L) seeds. Gen. Appl. Plant Physiology. 33 (3-4), 235-246
The physiochemical characteristics and lipid composition in fast and slow germinating sunflower (Helianthus annuus L.) seeds were studied. The quantity of phospholipids, glycolipids and sterols in cotyledons and embryonic axes in fast germinating seeds (FG-embryo emerged within 24 h after sowing) increased progressively between the 1st-6th days after sowing (DAS) compared with the slow growing seeds (SG-embryo emerged after the 4th DAS). The fatty acid composition in cotyledons of FG seeds showed increased levels of palmitic and oleic acids 6 and 8 DAS, while a decline in palmitic and stearic acids as well as accumulation of oleic and linoleic acids were observed in SG seeds. However, higher content of linolenic acid was found in the embryonic axes of FG seeds compared with SG seeds 6 and 8 DAS. The FG seeds located in the peripheral whorls of the inflorescence, with high quantity of storage lipids, contributed to the enhanced rate of germination compared with SG seeds located in the central whorls.

Yaniv and Perl (1987) The effect of temperature on the fatty acid composition of evening primrose (Oenothera) seeds during their development, storage and germination. Acta Hort. (ISHS) 215:31-38

Ngamau (2006) Selection for early flowering, temperature and salt tolerance of Zantedeschia aethiopica 'Green Goddess'. ISHS Acta Horticulturae 766.

Risley (1958) Male Controls Sprouting. American Rose Annual