Sugar beet - Patent granted to Biosem

Method for transforming plant cells belonging to species Beta vulgaris, characterized in that it comprises the bringing into contact of the dispersion of friable white calluses in a liquid plant cell culture medium containing 0 to about 3.0 mg/liter of the cytokinin, or of a suspension of friable white calluses in a liquid plant cell culture medium containing about 0.1 to about 3.0 mg/liter of the cytokinin, with Agrobacterium containing a vector carrying a gene intending to be introduced into the plant cells, following by co-culturing the plant cells and the bacteria in order to give rise to transformed friable calluses.

Transgenic plant belonging to the Beta vulgaris species and resistance to infection by the sugar beet necrotic yellow vein virus (BNYVV), the said plant being transformed in a stable manner by a nucleic acid fragment whose expression product is capable of conferring the said resistance, the said fragment being derived from the 5' end of genomic or subgenomic RNA2 of BNYVV, or from the corresponding cDNA, this fragment encoding at least a portion of the proteins encoded by nucleotides 145 to 3285 of the wild type sequence of RNA2, and being under the control of a promoter allowing the expression of the fragment in the plant cells and being in this sense or antisense orientation.