Abstract
Seed germination is controlled by a variety of environmental and endogenous signals. In Arabidopsis, severe gibberellin (GA)-deficient mutants are defective in seed germination, indicating an essential role of GA in this process. Using DNA microarray, gas chromatography-mass spectrometry and in situ hybridization analyses, we have been studying how bioactive GAs are synthesized and how seeds respond to GA during germination of Arabidopsis seeds. Our data show that both light and temperature signals regulate a subset of GA biosynthesis and catabolism genes that determine the level of bioactive GAs. For example, a GA biosynthesis gene AtGA3ox1 is upregulated in response to low temperature, resulting in an increase in the level of bioactive GAs. Besides temperature, AtGA3ox1 is also positively regulated by active phytochrome. Our DNA microarray results suggest that the GA response pathway also is modulated at varying environmental parameters.
