Abstract：In order to further clarify the genetic stability and the target traits of the foreign gene in the progeny of transgenic citrus, the asexual reproduction plants of transgenic Newhall navel orange(Citrus sinensis Osbeck)containing bivalent antibacterial peptide gene(Shiva A-cecropin B) were studied. In this study, the genetic stability of Shiva A gene in T0, T1, T2 and T3 progenies of transgenic citrus varieties were analyzed by PCR, Southern hybridization, Real-time quantitative PCR and greenhouse disease index statistic to Xathomonas axonopodis pv. Citri(Hasse) Dye. The results showed that the antimicrobial peptides Shiva A gene was existed and expressed in T0, T1, T2 and T3 plants. This meant target gene could be stably inherited from one generation to another through asexual propagating. There was difference of Shiva A gene copy number between transgenic T0 and its asexual propagation. Southern bloting analysis showed that T0 generation had two hybridizations, but its progenies had only one hybridization consistent with T0 generation. It could be speculated that the T0 generation plant was a transgenic multicellular mixed cytochimera. In addition, Real-time quantitative PCR results showed that, even if Shiva A gene in the T0 generation genome was double copy numbers, but its expression level was lower than a single copy of the T1, T2 and T3 generation. Therefore, in this study, exogenous gene expression and transgene copy number was a negative correlation. The results of this study provide some basic date and the material for extending the stable phenotype of transgenic citrus strains in carrying out the safety evaluation of transgenic plants.
