Abstract
To investigate the regulatory mechanism of dormancy breaking in seeds by cold treatment, we examined the dormancy of several ecotypes of Arabidopsis, generous gifts from ARBC. The dormancy of an ecotype Abd-0 was broken by cold exposure (4°C) and also by exogenous supply of gibberellins (GA) without cold treatment, suggesting that GA may be involved in the dormancy breaking. Interestingly, Abd-0 seeds exposed to 4°C were found to be more responsive to GA administered exogenously to break dormancy than non-treated control. Quantitative PCR analysis showed that accumulation of RGL2 mRNA, a negative regulator of GA signaling, significantly decreased 48h after imbibition at 22°C in Col-0 seeds, whereas it remained at a high level for at least 7 days in Abd-0 seeds. The Abd-0 phenotype was transmitted through a dominant gene(s) and further molecular studies are in progress to elucidate genes responsible for dormancy breaking in the seeds of Arabidopsis.
