Dwarfism in Brassica napus L. induced by the over-expression of a gibberellin 2-oxidase gene from Arabidopsis thaliana

Gibberellins (GAs) are endogenous hormones that play an important role in regulating plant stature by increasing cell division and elongation in stem internodes. The GA2-oxidase gene from Arabidopsis thaliana (AtGA2ox8) was introduced into Brassica napus L. by Agrobacterium-mediated floral-dip transformation with the aim of decreasing the amount of bioactive GA and hence reducing plant stature. As anticipated, the transgenic plants exhibited dwarf phenotype. Compared with the wild type, the transgenic plants had increased primary branches (by 14.1-15.3%) and siliques (by 10.8-15.2%), which resulted in a significant increase in the seed yield (by 9.6-12.4%). Moreover, the contents of anthocyanin in leaves of 60-day-old transgenic plants was about 9.4-fold higher in winter and about 6.8-fold higher in summer than the wild type. These excellent agronomic traits of the transgenic plants could not only improve the lodging resistance and seed yields, but also protect them against stress. Therefore, the over-expression of AtGA2ox8 might be used to produce dwarf varieties and increase seed yield in Brassica napus L.