Abstract:Toxoptera citricida is the most efficient vector of Citrus tristeza virus (CTV). For better understand of the effect of CTV isolates and host plants on the transmissibility of CTV by single aphid of T.citricida, the transmission rates of 4 severe CTV isolates and 6 mild ones were evaluated, as Jincheng, Feng-huang pummelo and Mexican lime were used as host plants. And p20 and p25 proteins of 7 CTV isolates were compared, and p25/HinfⅠ restriction fragment length polymorphism (RFLP) groups assay was used to analyze for 10 CTV isolates and 161 aphid transmission sub-isolates which obtained by transmitted from Jincheng to Jincheng. The results indicated that Jincheng was a better host for CTV transmission by T.citricida than that of Feng-huang pummelo and Mexican lime. The transmission rate of severe CTV isolates and mild ones were similar. In this study, CTV isolates with p25/HinfⅠ RFLP group 3 had higher transmissibility by T.citricida than the others.