ARABIDOPSIS REQUIRES POLYUNSATURATED LIPIDS FOR LOW-TEMPERATURE SURVIVAL

Mutants of Arabidopsis that contain reduced levels of polyunsaturated fatty acids showed growth characteristics at 22-degrees-C that were ve ry similar to wild type. By contrast, at 12-degrees-C, the mutants fai led to undergo stem elongation during reproductive growth although the y produced normal flowers and fertile seeds. After transfer to 6-degre es-C, rosette leaves of the mutants gradually died, and the plants wer e inviable. These different responses of the mutant plants at 12-degre es-C and 6-degrees-C suggest that distinct functions may be affected a t these two temperatures. The gradual development of symptoms at 6-deg rees-C and other lines of evidence argue against a general collapse of membrane integrity as the cause of the lethal phenotype. Rather, they indicate that the decrease in polyunsaturated membrane lipids may ini tially have relatively limited effects in disrupting cellular function .