Promoter trapping in Arabidopsis using T-DNA insertional mutagenesis

A new promoter trap vector was constructed based on the juxtaposition of T-DNA right border to coding sequence of GUS. The new vector pRN-1 carried an intron in the GUS coding region. Promoter trap vectors pGKB5 and pRN-1 vectors were used to transform Arabidopsis ecotype Columbia using the floral dip transformation system. The transformants were selected on appropriate selection media and the primary transformants were confirmed by PCR using gene specific primers. Approximately 50% of the T-2 lines segregated for a 3:1 ratio indicating presence of T-DNA at single locus. Approximately 15% of the transformed lines showed expression of GUS. Morphological mutants for male sterility and dwarfism were also identified in the T-2 population. A T-DNA tagged line was identified in T-2 with GUS expression specifically in the floral parts. The number of T-DNA loci in this line was confirmed by Southern blot hybridization. T-DNA flanking region isolated from this line suggested insertions into chromosome 2 at two closely linked loci. The results demonstrate that the population generated can be used effectively to identify and characterize gene regulatory elements.