Abstract
Gibberellins (GAs) are essential endogenous regulators of growth and developmental processes throughout the life cycle of higher plants. We are interested in genetic engineering of the biosynthesis of GAs to control the growth of lombardy poplar (Populus nigra). We isolated twenty-eight genes for the putative GA oxygenase enzymes belonged to the 2-oxoglutarate dependent oxygenase superfamily in lombardy poplar. Phylogenetic analysis revealed that the genes fall into four clades: eight into the GA20ox clade, four into the GA3ox clade, seven into the C19GA2ox clade and six into the C20GA2ox clade. We have isolated transgenic poplar over-expressing the gene for PnGA2ox1 in the C19GA2ox clade. The transgenic poplar showed dwarf phenotypes. To explore the expression of the genes of GA biosynthesis in transgenic poplar, we performed an analysis by real-time RT-PCR using primers specific for each gene.
