Effects of inactivation of the coat protein and movement genes of Tomato bushy stunt virus on early accumulation of genomic and subgenomic RNAs

Accumulation of RNA of Tomato bushy stunt virus (TBSV) was examined within the first few hours after infection of Nicotiana benthamiana protoplasts to determine the influence of the coat protein (CP), the movement-associated proteins P22 and P19 and RNA sequences at very early stages of replication. The results showed that P19 had no effect on early RNA replication, wherea s the absence of CP and/or P22 expression delayed RNA accumulation only mar ginally. Removal of CP-coding sequences had no added negative effects, but when the deletion extended into the downstream p22 gene, it not only elimin ated synthesis of subgenomic RNA2 but also delayed accumulation of genomic RNA by 10 h. At times beyond 20 h post-transfection, RNA accumulated to nor mal high levels for all mutants. This illustrates that TBSV RNA sequences t hat have negligible impact on overall RNA levels observed late in infection can actually have pronounced effects at very early stages.