Transgenic plants expressing the TGB1 protein of peanut clump virus complement movement of TGB1-defective peanut clump virus but not of TGB1-defective beet necrotic yellow vein virus

The triple gene block (TGB) of peanut clump virus (PCV) is indispensable for cell-to-cell movement. To determine if the TGB gene arrangement is necessary for viral multiplication, we introduced the p51 gene corresponding to the first PCV TGB protein into Nicotiana benthamiana plants; high-level expression of P51 was obtained in regenerated transformed plants. Two lines of the R5 generation of transgenic plants were used for complementation experiments. To this end deficient PCV RNA 2 transcripts ( p51 deletion mutant, RNA 2Δ51) which could not multiply in the whole plant were co-inoculated with wild-type PCV RNA 1 transcripts into P51-transgenic plants. Viral multiplication was observed in 19%–67% of the transgenic plants, depending upon the line. However, no trans -complementation was observed when P51-transgenic plants were inoculated with beet necrotic yellow vein virus defective in the corresponding TGB1 protein, the P42 protein.