Transgenic plant generated by RNAi-mediated knocking down of soybean Vma12 and soybean mosaic virus resistance evaluation

Abstract

Soybean mosaic virus (SMV) is one of the most destructive viral diseases in soybean and causes severe reduction of soybean yield and destroys the seed quality. However, the production of SMV resistant plants by transgenic is the most effective and economical means. Based on our previous yeast two-hybrid assay, the GmVma12 was selected as a strong candidate gene for further function characterization. Here we transformed soybean plants with a construct containing inverted repeat of-GmVma12 sequence to analyze the role of GmVma12 during SMV invasion. Totals of 33 T0 and 160 T1 plants were confirmed as positive transgenic plants through herbicide application, PCR detection and LibertyLink® strip screening. Based on the segregation ratio and Southern Blot data, T1 lines No. 3 and No. 7 were selected to generate T2 plants. After SMV-SC15 inoculation, 41 T1 and 38 T2 plants were identified as highly resistant, and their quantification disease levels were much lower than non-transformed plants. The transcript level of GmVma12 in T2 plants decreased to 70% of non-transformed plants. The expression level of SMV-CP transcript in T2 transgenic plants was lower than that in non-transformed plants and SMV CP protein in T2 plants could not be detected by Enzyme-linked Immunosorbent assay, which indicated that SMV production would be inhibited in transgenic plants. Moreover, coat mottles of T2 seeds were obliterated significantly. In conclusion, inverted repeat of the hairpin structure of GmVma12 interfered with the transcription of GmVma12, which can induce resistance to SMV in soybean. This research lays the foundation for the mechanism of SMV pathogenesis, and provides new ideas for SMV prevention and control.