Lakhvir K. Dhaliwal | Junghyun Shim | Rosalyn B. Angeles-shim
Seed germination is a highly regulated process that begins with the imbibition of a mature, dry seed and ends with the protrusion of the radicle from the seed coat. During imbibition, cell membranes reorganize from a hex-agonal to a lamellar phase to restore the normal metabolic functions of the seed. Perturbations in the cell membrane during this transition result in cytoplasmic leakage. Under cold stress, leakage of solutes out of the cell is exacerbat-ed, leading to membrane damage and eventually, to embryo death. In this study, we determined the effects of fatty acid composition on the germination under cold stress (12°C and 15°C) of upland cotton mutants with higher unsatu-rated: saturated fatty acid (FA) ratios. Results of the study showed a more uniform and higher germination (60-80%) of the FA mutants compared to the wild type (0-20%) under the critically low temperature of 12°C and cardinal tem-perature of 15°C. Consistent with the reported benefits of hydropriming on seed germination under cold stress, the treatment significantly improved the germination rate, mean germination time, mean daily germination, peak value, and germination index of all the experimental materials even under low temperatures. Biochemical assays showed that lipid peroxidation, an established measure of oxidative stress, was generally higher in the FA mutants after imbi-bition at 12°C and 15°C for 8 hours compared to the wild types. Conversely, electrolyte leakage was higher in the wild types than in the mutants after imbibition at 12°C and 15°C for 8 hours. Results suggest that the higher proportions of unsaturated fatty acids in the mutants enhanced the fluidity of the cell membrane during reorganization, facilitating the rapid restoration of cellular functions and allowing the faster and higher germination of the FA mutant seeds even un-der cold stress.
ISSN 2719-1990 (Print)
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