Viral suppression in transgenic plants expressing chimeric transgene from tomato leaf curl virus and cucumber mosaic virus

The genes CMV-cp and ToLCV-cons-rep from the isolates of cucumber mosaic virus (CMV) and tomato leaf curl virus (ToLCV) were transcriptionally fused under the control of CaMV 35 S promotor. This construct was used to transform tobacco and tomato using Agrobacterium. We show transforming ToLCV and CMV infected plants with the homologous chimeric gene construct, that produces RNAs, capable of duplex formation, confers gene silencing. We proposed that the antisense suppression in ToLCV infected plants provides a threshold level of dsRNA needed to induce gene silencing where as sense suppression in CMV infected plants may be operating through cosuppression, leading to delayed and attenuated symptoms.