EXPRESSION OF THE PVYO COAT PROTEIN (CP) UNDER THE CONTROL OF THE PVXCP GENE LEADER SEQUENCE - PROTECTION UNDER GREENHOUSE AND FIELD CONDITIONS AGAINST PVYO AND PVYN INFECTION IN 3 POTATO CULTIVARS

Coat protein-mediated resistance (CPMR), resistance conferred as a res ult of the expression of viral coat proteins in transgenic plants, has been illustrated to be an effective way of protecting plants against several plant viruses. Nonetheless, consistent protection has not been achieved for transgenic plants expressing the coat protein of potato virus Y (PVY), the type member of the potyvirus family. In this report , three different potato cultivars were transformed with a chimeric co nstruct consisting of the capsid protein (CP) coding sequences of PVY flanked by the AUG codon and the translational enhancer from the coat protein gene of potato virus X (PVX). These cultivars were shown to ex press high levels of PVY CP and confer a high degree of protection aga inst PVYO and PVYN under both greenhouse and field conditions. In addi tion, transgenic plants infected with potato virus A (PVA), a related potyvirus, exhibited a delay in virus accumulation, which could be eas ily overcome with increasing virus concentrations.