Abstract
Gibberellin (GA) plays an essential role in seed germination and shoot growth in Arabidopsis. To understand how GA stimulates seed germination and shoot growth, we have analyzed GA-dependent gene expression using oligonucleotide-based microarray.
We have identified SCARECROW-LIKE 3 (SCL3) as a GA down-regulated gene in both seeds and shoots. SCL3 belongs to the GRAS family which includes SCR, SHR and negative regulators of GA response, RGA and GAI. To examine the role of SCL3, we performed phenotypic analyses of scl3 T-DNA insertion mutants and transgenic plants overexpressing SCL3. The scl3 mutant was more sensitive to a GA biosynthetic inhibitor, uniconazole during seed germination and root growth than wild-type. This phenotype was complemented by introducing genomic fragment including SCL3 to T-DNA insertion mutant. Moreover, Overexpression of SCL3 caused longer hypocotyls in the presence of GA relative to non-transgenic plants. These results suggest that SCL3 acts in GA response as a positive regulator.
