The rice OsGAE1 is a novel gibberellin-regulated gene and involved in rice growth

Abstract

Gibberellins (GAs) are a class of phytohormones that regulate many aspects of plant growth and development processes including stem elongation, flowering, and seed germination. A novel GA-enhanced gene, designated as OsGAE1, was identified using microarray analysis of GA-regulated genes. OsGAE1 expressed in a dose- and time course-dependent manner with minimum expression at 1 microM GA(3) and maximum expression at 50 microM GA(3) starting from 30 min and peaked at 24 h after GA(3) treatment. OsGAE1 expression was up-regulated by GA(3) at transcript level while no significant effect was observed for other hormones. OsGAE1 was expressed in Escherichia coli with N-terminal His(6) tag and the recombinant protein migrated at 38 kDa, slightly larger than the predicted 29 kDa, during SDS-PAGE. Anti-OsGAE1 antibodies immunoreacted with a protein of 40 kDa in rice leaf sheath. OsGAE1 expressed mainly in growing leaf sheath and callus compared to leaf and root. In situ hybridization and OsGAE1 promoter analysis revealed that OsGAE1 expressed in shoot apex meristem and young primary leaves. Northern blot, Western blot, and GUS activities revealed that OsGAE1 is up-regulated by GA(3). Transgenic rice expressing OsGAE1 in antisense orientation exhibited severely affected vegetative and reproductive growth. The transgenic plants were 55-70% short compared to control. These results suggest that OsGAE1 is differentially expressed in rice leaf sheath in relation to GA(3) and it encodes a functional protein which is involved in GA-regulated growth and development of rice.