Virology, Nebraska Center for


Date of this Version



Phytopathology Nov 2011, Volume 101, Number 11


© 2011 The American Phytopathological Society


Transgenic plants expressing double-stranded RNA (dsRNA) of virus

origin have been previously shown to confer resistance to virus infections

through the highly conserved RNA-targeting process termed RNA silencing

or RNA interference (RNAi). In this study we applied this strategy to

soybean plants and achieved robust resistance to multiple viruses with a

single dsRNA-expressing transgene. Unlike previous reports that relied

on the expression of one long inverted repeat (IR) combining sequences

of several viruses, our improved strategy utilized a transgene designed to

express several shorter IRs. Each of these short IRs contains highly conserved

sequences of one virus, forming dsRNA of less than 150 bp. These

short dsRNA stems were interspersed with single-stranded sequences to

prevent homologous recombination during the transgene assembly

process. Three such short IRs with sequences of unrelated soybean-infecting

viruses (Alfalfa mosaic virus, Bean pod mottle virus, and Soybean

mosaic virus) were assembled into a single transgene under control of the

35S promoter and terminator of Cauliflower mosaic virus. Three independent

transgenic lines were obtained and all of them exhibited strong

systemic resistance to the simultaneous infection of the three viruses.

These results demonstrate the effectiveness of this very straight forward

strategy for engineering RNAi-based virus resistance in a major crop

plant. More importantly, our strategy of construct assembly makes it easy

to incorporate additional short IRs in the transgene, thus expanding the

spectrum of virus resistance. Finally, this strategy could be easily adapted

to control virus problems of other crop plants.