Engineering resistance against physalis mottle tymovirus by expression of the coat protein and 3' noncoding region

Abstract

A 748 nucleotides cDNA fragment corresponding to the 3' terminal of physalis mottle virus, PhMV (formerly known as belladonna mottle virus) ($\#$Y16104) genomic RNA encompassing the tymobox, coat protein ORF and 3' noncoding region was cloned into the binary vector pKYLX 71 35 $S^2$ and introduced into N. tabacum cv. Havana plants using Agrobacterium-mediated transformation. The R0 transgenic plants showed accumulation of coat protein which self-assembled into capsids in vivo. The transgenic R1 and R2 plants showed delay in symptom expression and virus accumulation upon challenge with PhMV. 55 and 65% of the plants showed no detectable symptoms in the R1 and R2 transgenic plants respectively, when challenged with 10 $\mu$g/ml virus. Further, no detectable symptoms were observed in 75% and 25% of the R1 and R2 transgenic plants respectively, after 50 days of post infection when challenged with 10 $\mu$g/ml RNA. Thus the expression of PhMV coat protein and 3' noncoding sequence confers a high level of resistance against PhMV infection