DISEASE RESISTANCE IN TOBACCO AND TOMATO PLANTS TRANSFORMED WITH THE TOMATO SPOTTED WILT VIRUS NUCLEOCAPSID GENE

The nucleocapsid protein (N) gene was cloned from the tomato spotted wilt virus (TSWV) Hawaiian L isolate. The 777-nucleotide N gene had 97 and 99% homology with a tomato (CNPHI) and two lettuce (L3 and BL) isolates, respectively. Leaf disks of Nicotiana tabacum cv. Xanthi nc and cotyledons of Lycopersicon esculentum cv. VF36 were transformed with Agrobacterium tumefaciens harboring a binary vector with a chimeric TSWV N gene cassette. Significantly lower numbers of local lesions and several days delay of symptom development were observed when R1 transgenic tobacco plants expressing the TSWV N gene were challenged with TSWV. The R1 transgenic tobacco plants transformed to produce an antisense RNA were as resistant as plants producing sense RNA. Only 50-80% of the transgenic tomato plants became infected after mechanical inoculation with TSWV in the greenhouse. These results demonstrate that expression of the sense or antisense RNA of the TSWV N gene can be used in both tobacco and tomato plants to achieve genetically engineered resistance.