Recombination with host transgenes and effects on virus evolution: an overview and opinion

This commentary relates to the work by M. Borja et al. (M. Borja, T. Rubio, H.B. Scholthof, and A.O. Jackson, MPMI 12:153-162, 1999) that shows that wild-type virus can be restored frequently by double recombination events between a tomato bushy stunt virus mutant with deletions inactivating the coat protein gene and a coat protein transgene. Here, we focus on evidence suggesting that new viruses might evolve via recombination with transgenes used for disease resistance, and discuss the potential effects of widespread use of these sources of resistance on virus evolution. We argue that the benefits arising from using transgenic sources of resistance for virus disease control outweigh potential negative consequences of evolution of novel hybrid viruses with destructive disease potential.