High efficiency regeneration of grapevine plants transformed with the GFLV coat protein gene

Genetically transformed grapevines were obtained through co-cultivation of embryogenic cell suspensions with an engineered A. tumefaciens strain. Two economically important rootstocks, 41B and SO4, as well as a well-known grapevine vinifera variety, Chardonnay were regenerated. For the first time transformation of a scion variety is reported. A chimeric coat protein gene (CP) was integrated in order to protect grapevine against grapevine fanleaf virus (GFLV) infection. A neomycin phosphotransferase II (NPT II) gene allowed the selection of large number of transformed embryogenic calli and plants for the three varieties. Percentages of transformed material were first estimated with GUS activity. Presence of the CP gene was assessed by PCR and Southern analysis and gene expression by ELISA. Transformed calli have now been subcultured in vitro for 3 years without losing their embryogenic ability. GUS activity assays on leaves and roots of acclimatized plants showed transformation to be stable.