中文摘要：

【目的】获得对中国甜橙茎陷点型衰退病具有防治作用的柑桔衰退病毒（Citrus tristeza virus,CTV）弱毒株。【方法】对7个国内外CTV弱毒分离株进行褐色桔蚜接种强毒株的拮抗试验,并运用p25/HinfⅠRFLP组群分析、特异性RT-PCR分析和寄主植株症状观察的方法对拮抗试验效果进行检测。【结果】本研究中所用7个弱毒株对甜橙茎陷点型衰退病均有一定的防治作用,其中弱毒株CT9、CT17和CT77对茎陷点型强毒株CT14的拮抗效果最为明显,分别为70%,50%和40%。分子检测与生物学检测的结果相一致。【结论】初步筛选出的具有拮抗作用的CTV弱毒株CT9、CT17和CT77具有应用于交叉保护的潜力,可供进一步田间区试研究。

英文摘要：

【Objective】This study was conducted to obtain the protective mild isolates of Citrus tristeza virus（CTV） to protect sweet orange plants against super-infection of the severe stem-pitting CTV isolates.【Method】Sweet orange seedlings were graft-inoculated with seven mild CTV isolates and challenge-inoculated with severe stem-pitting isolates born by brown citrus aphids（Toxoptera citricida Kirkaldy）.The effectiveness of the cross protection was evaluated by p25/Hinf ⅠRFLP groups assay,special RT-PCR assay and stem-pitting examination.【Result】Seven CTV mild isolates applied in this study were all experimentally proven to have somehow protective effectiveness against severe stem-pitting CTV isolates,of which mild isolates of CTV CT9,CT17 and CT77 had more significant effectiveness than the others.【Conclusion】The mild CTV isolates CT9,CT17 and CT77 have a potential usage in mild strain cross protection（MSCP）,and further field challenge trials are needed.