Extreme resistance to cucumber mosaic virus (CMV) in transgenic tomato expressing one or two viral coat proteins

For the production of broad commercial resistance to cucumber mosaic virus (CMV) infection, tomato plants were transformed with a combination of two c oat protein (CP) genes, representing both subgroups of CMV. The CP genes we re cloned from the CMV-D strain and Italian CMV isolates (CMV-22 of subgrou p I and CMV-PG of subgroup II) which have been shown to produce severe dise ase symptoms. Four plant transformation vectors were constructed: pMON18774 and pMON18775 (CMV-D CP), pMON18831 (CMV-PG CP) and pMON18833 (CMV-22 CP a nd CMV-PG CP). Transformed Ro plants were produced and lines were selected based on the combination of three traits: CMV CP expression at the Ro stage , resistance to CMV (subgroup I and/or II) infection in growth chamber test s in R-1 expressing plants, and single transgene copy, based on R-1 segrega tion. The results indicate that all four vector constructs generated plants with extremely high resistant to CMV infection. The single and double gene vector construct produced plants with broad resistance against strains of CMV from both subgroups I and II at high frequency. The engineered resistan ce is of practical value and will be applied for major Italian tomato varie ties.