[Genetic analysis of RNA-mediated virus resistance in transgenic tobacco]

RNA-mediated virus resistance is an effective way to obtain virus resistant plants and is regarded as a potential strategy with application value in plant resistant virus breeding because of its advantage of high biosafety and long duration. Whether the resistance can inherit stably is a critical factor affecting its application in agriculture. In this paper, several T0 progeny transgenic plants with different resistant levels and with different transgene copy numbers were selected for further study. The results showed that the inheritance of the transgene in T0 susceptible transgenic plants containing 1 -2 transgene copies followed Mendelian segregation pattern of single gene inheritance in their progenies. Resistant transgenic plants, which contained 4 -6 transgene copies, followed 15:1 and 63:1 segregation patterns in the T1 progeny. Transgene recombination and re-organization in the plant genome was observed, which resulted in unstable inheritance of the transgene in the progenies. Homozygous resistant transgenic plants were obtained after 3 to 4 generations in the progeny. Analysis of the transgene integration pattern indicated that most of the highly resistant plants contained inverted repeat (IR) sequences of the transgene.