Abstract
GAMYB was firstly identified as a transcriptional regulator of gibberellin (GA)-responsive genes in barley aleurone. Previously, we revealed that OsGAMYB-dependent CYP703A3 expression is essential for the GA-mediated exine formation in the rice. Our recent studies have also shown that the GID1/DELLA-mediated GA perception system appeared after the divergence of vascular plants. In this study, we tested whether the regulation of CYP703A expression by GAMYB is also conserved in Selaginella.
In situ hybridization showed that SmGAMYB and SmCYP703A were expressed in the tapetum. SmGAMYB could specifically interact with the SmCYP703A promoter region in vitro. Moreover, introduction of these genes from Selaginella rescued the male sterility of rice gamyb and cyp703a3 mutants. The treatment of GA biosynthetic inhibitor to Selaginella inhibited its normal exine formation. Taken together, these results suggest that the GA signaling for exine formation is conserved after the divergence of vascular plants.
