Abstract
Seed germination is dependent on dormancy and environmental conditions. Temperature plays a decisive role on germination. Germination of Arabidopsis seeds is inhibited by high temperature (thermoinhibition) and promoted by low temperature treatment. We analyzed the genes expressed in Arabidopsis seeds by microarray, and found that expression of gibberellin (GA)-related genes was affected by temperature. Quantitative PCR analysis showed that expression of AtGA3ox2 gene, which converts inactive precursors to active GAs, was evidently lower at 34oC than at 22oC. Expression of RGL2 gene, a member of the GRAS gene family, peaked at 12h after imbibition and decreased to a lower level after 36h at 22oC, whereas it remained at high levels even after 48h at 34oC. These results suggest that the inhibition of active GA synthesis and the accumulation of a negative regulator of GA signaling play a role in inhibiting germination at high temperature.
