Transposon Tagging In the Diploid Strawberry

Fragaria vesca PI 551572 was transformed with a transposon tagging construct with maize transposase and EGFP on the Ac element as well as nptII, p35S driving transposase and pmas driving EGFP on the Ds element. We obtained 122 primary transformants, of which 38 were potential launch pads, 30 were multiple insertions or chimaeras, and 54 exhibited somatic transposition. Multiplex PCR was used to screen sets of 24 T1 progeny of putative launch pads for transposition of Ds. Although transposition occurred in 14 putative launch pads only four exhibited sufficient transposition rate (22% to 34%) to warrant further analysis. Flanking genomic sequence obtained by hi-TAIL PCR originating from nested primers in the TPase gene revealed that the four functional launch pads occurred on three different linkage groups. Putative transposants were identified by the presence of Ds elements and absence of Ac elements. Sequencing hi-TAIL PCR products derived from nested primers at either end of the Ds element revealed transposition of the Ds element globally in the strawberry genome. Premature excision of Ds prior to gametogenesis resulted in the frequent recovery of similar transposants within T0 families. From these four launch pads, we have identified 52 independent transposants occurring on all linkage groups among 1,252 T1 plants screened. A Filemaker Pro database houses the mutant data.