Abstract
Seed dormancy and germination are controlled by multiple environmental and endogenous factors. In Arabidopsis, both gibberellin (GA) and cold treatment (4˚C, dark) promote seed germination. We have previously shown that the AtGA3ox1 gene, encoding a GA 3-oxidase catalyzing the final step to produce bioactive GAs, is upregulated in response to cold treatment. Consistent with the increase in AtGA3ox1 expression, endogenous GA4 levels were elevated following cold treatment. To predict how cold treatment stimulates germination through GA action, GA-dependent gene expression was monitored using DNA microarray analysis. The GA-responsive genes during cold treatment included those previously determined to be GA-responsive at 22˚C in the light, but also included a new set of genes that appear to be unique to the low temperature environment. These results suggest that GA biosynthesis and response are modulated under different environmental conditions to control seed germination in Arabidopsis.
