Overexpression of BnGA2ox2, a rapeseed gibberellin 2-oxidase, causes dwarfism and increased chlorophyll and anthocyanin accumulation in Arabidopsis and rapeseed

Abstract

Plant height is one of the important agronomic traits of crops. Gibberellins (GAs) play an important role in the regulation of plant height. Gibberellin 2-oxidase (GA2ox) inactivates active GAs or their precursors and plays a key role in the catabolism of GAs. Here, we isolated and characterized a fragment from rapeseed (Brassica napus L.), designated BnGA2ox2, that is highly expressed in the silique and flower. Overexpression of BnGA2ox2 in Arabidopsis resulted in GA-deficient phenotypes, including a short hypocotyl, reduced plant height, increased chlorophyll and anthocyanin accumulation, late flowering, and partial sterility. Similarly, when BnGA2ox2 was overexpressed in rapeseed, the transgenic plants had a dwarf phenotype with dark-green leaves and increased chlorophyll and anthocyanin accumulation. In addition, similar dwarf phenotypes were observed in Arabidopsis overexpressing AtGA2ox2. Genetic analysis showed that the atga2ox2 mutation could partially rescue the phenotype of BnGA2ox2 transgenic Arabidopsis plant, indicating that BnGA2ox2 and AtGA2ox2 have conserved functions in vegetative plant growth and stem elongation. These results suggest that BnGA2ox2 regulates stem elongation and chlorophyll and anthocyanin accumulation in rapeseed and Arabidopsis. Therefore, BnGA2ox2 is a new candidate gene for breeding dwarf varieties of rapeseed.