Development of resistant transgenic soybeans with inverted repeat-coat protein genes of soybean dwarf virus

In an attempt to generate soybean plants resistant to soybean dwarf virus (SbDV), we transformed a construct containing inverted repeat-SbDV coat protein (CP) genes spaced by β-glucuronidase (GUS) sequences into soybean somatic embryos via microprojectile bombardment. Three T₀ plants with an introduced CP gene were obtained, and one generated T₁ seeds. The presence of the transgene in T₁ plants was confirmed by PCR and Southern blot hybridization analysis, but expression of CP was not detected by northern blot hybridization analysis. Two months after inoculation of SbDV by aphid, T₂ plants contained little SbDV-specific RNA and remained symptomless. These plants contained SbDV-CP-specific siRNA. These results suggest that the T₂ plants achieved resistance to SbDV by an RNA-silencing-mediated process.