A twin T-DNA system is a convenient strategy for creating selectable marker-free transgenic plants. The standard transformation plasmid, pCAMBIA 1300, was modified into a binary vector consisting of two separate T-DNAs, one of which contained the hygromycin phosphotransferase (hpt) marker gene. Using this binary vector, we constructed two vectors that expressed inverted-repeat (IR) structures targeting the rice stripe virus (RSV) coat protein (CP) gene and the special-disease protein (SP) gene. Transgenic rice lines were obtained via Agrobacterium-mediated transformation. Seven independent clones harbouring both the hpt marker gene and the target genes (RSV CP or SP) were obtained in the primary transformants of pDTRSVCP and pDTRSVSP, respectively. The segregation frequencies of the target gene and the marker gene in the T₁ plants were 8.72% for pDTRSVCP and 12.33% for pDTRSVSP. Two of the pDTRSVCP lines and three pDTRSVSP lines harbouring the homozygous target gene, but not the hpt gene, were strongly resistant to RSV. A molecular analysis of the resistant transgenic plants confirmed the stable integration and expression of the target genes. The resistant transgenic plants displayed lower levels of the transgene transcripts and specific small interfering RNAs, suggesting that RNAi induced the viral resistance.

Stable transgenic rice line (named KRSV-1) with strong resistance against rice stripe virus was generated using the genesequence of disease-specific protein by RNA interference. Comprehensive safety assessment of transgenic plants has turnedinto a significant field of genetic modification food safety. In this study, a safety assessment of KRSV-1 was carried out in astepwise approach. The molecular analysis exhibited that KRSV-1 harbored one copy number of transgene, which wasintegrated into the intergenic non-coding region of chromosome 2 associated with inter-chromosomal translocations of 1.6-kb segments of chromosome 8. Then, transcriptomics and proteomics analyses were carried out to detect the unintendedeffects as a result of the integration of the transgene. Although 650 dramatically differentially expressed genes (DDEGs)and 357 differentially expressed proteins were detected between KRSV-1 and wild-type (WT) by transcriptomics andproteomics analyses, no harmful members in the form of toxic proteins and allergens were observed. Encouragingly, thenutritional compositions of seeds from KRSV-1 were comparable with WT seeds. The results of this entire study ofmolecular analysis, transcriptome and proteome profile of KRSV-1 revealed that no detrimental changes in the form of toxicproteins and allergens were detected in the transgenic rice line due to the integration of the transgene.