Abstract：In order to find the potential influence of Citrus tristeza virus (CTV) isolates in Jianyang Tangelo on Gannan navel orange, the CTV isolates were characterized at the molecular level. Jianyang Tangelo (Citrus paradisi × C. reticulata) is a new citrus hybrid cultivar with excellent quality. CTV isolate JY-5 was inoculated in Newhall navel orange (C. sinensis) and the HinfⅠrestriction fragment length polymorphism(RFLP) and single-strand conformation polymorphism(SSCP) of its coat protein(cp) gene was comparatively analyzed. The results of RFLP analysis revealed that the single group of the CTV isolate in Jianyang Tangelo changed into mixed groups when it inoculated in Newhall navel orange. DNA bands of cp/SSCP of CTV isolates increased when the CTV isolate was graft inoculated from Jianyang Tangelo to Newhall navel orange. The results of HinfⅠRFLP and SSCP showed that the replication of some composition of CTV isolate was inhibited in Jianyang Tangelo but enhanced in Newhall navel orange. By analyzing and comparing the nucleotide and amino acid sequences of cp, p23 and k17 of isolate JY-5 in Jianyang Tangelo and isolate JY-5R from inoculated Newhall navel orange, the identity of genomic regions were 92.5%, 90.3% and 82.3%, respectively, and of their amion acid sequences were 95.9%, 90.9% and 77.9%, respectively. Phylogenetic analysis revealed that the isolate JY-5 in Jianyang Tangelo and JY-5R in inoculated Newhall classified into different clusters in phylogenetic trees of cp, p23 and k17. Sequence comparisons and phylogenetic analysis indicated that no high homology and closer relationships between the isolates JY-5 and JY-5R, the isolate JY-5R was inhibited in Jianyang Tangelo but enhanced in Newhall navel orange. The results suggest that if the CTV isolate from Jianyang Tangelo infects Gannan's Newhall navel orange and spreads in Ganzhou, maybe cause some damage to Gannan's navel oranges. Therefore, it is necessary to take a survey on the CTV occurence and Jianyang Tangelo plantation in Ganzhou.
