Analysis of Inheritability and Expression Profile of Single and Multi-copy Transgene(s) in Rice Over Generations

Transformation of Oryza sativa subsp indica variety Pusa Basmati 1 with Agrobacterium tumefaciens strain LBA4404(pTOK233) carrying genes coding for neomycin phosphotransferase (nptII), β-glucuronidase (gus) and hygromycin phosphotransferase (hph) under the control of plant-specific promoters (pnos and pCaMV35S) within its T-DNA region produced transgenics with single and multiple copies of T-DNA. Simple Mendelian as well as complex patterns of the inheritance for hygromycin resistance trait were observed in R1 and R2 generations. Non-segregating lines selected in R2 generation did not show further segregation of the resistance trait in R3 and R4 generations accompanied by stabilization of integrated transgenes. One of these lines showed the presence of truncated T-DNA in R1 generation. The single copy transgenics showed high stability of expression of gus gene, whereas multi-copy transgenics were prone to silencing up to R3 generation after which no further reduction in gene expression was observed.