‘赣南早’与‘纽荷尔’脐橙对柑橘衰退病病毒变异的影响

Evaluation on the Effects of ‘Gannanzao’ and ‘Newhall’ Naval Oranges on Mutation of Citrus tristeza virus

研究‘纽荷尔’脐橙及其芽变品种‘赣南早’对柑橘衰退病病毒(Citrus tristeza virus,CTV)分离株变异的影响及抗性差异。将CTV分离株YC-3接种后分析‘赣南早’上的分离株YC-3Z和‘纽荷尔’上的分离株YC-3N外壳蛋白(CP)基因的限制性片段长度多态性(RFLP)和单链构象多态性(SSCP)及序列差异,测定两个品种体内CTV的复制水平及与抗性相关防御酶活性的变化。结果表明CTV分离株YC-3Z、YC-3N与接种前的YC-3相比,RFLP组群和SSCP谱带数无变化;密码子的替换主要发生在第3位的碱基位点上,其次为第1位,第2位未发生替换;密码子转换数多于颠换数;CTV分离株YC-3N密码子发生了非同义突变;CTV分离株在‘纽荷尔’上的复制水平是在‘赣南早’上的3.3倍。酶活性测定表明‘赣南早’和‘纽荷尔’接种CTV后,体内过氧化物酶(POD)、超氧化物歧化酶(SOD)活性增加了78.2%以上,苯丙氨酸解氨酶(PAL)和多酚氧化酶(PPO)活性均有提升,过氧化氢酶(CAT)活性降低,但两个品种间5种防御酶活性不存在显著差异。

To evaluate the resistance of two navel orange varieties,‘Newhall＇and its bud mutant ‘Gannanzao＇,to Citrus tristeza virus（CTV）,and their effect on virus mutation,an isolate of CTV（YC-3）was inoculated to both varieties by graft. CTV isolates YC-3Z and YC-3N were then re-isolated from‘Gannanzao＇and‘Newhall＇,respectively. The HinfⅠrestriction fragment length polymorphism（RFLP） of coat protein（CP）,single-strand conformation polymorphism（SSCP）,and the sequence variation of CP genes of both isolates YC-3Z and YC-3N were analyzed and compared. The replication level of the each isolate in its corresponding variety and activity changes of the enzymes in each variety,including the superoxide dismutase（SOD） were measured. No difference was found between two isolates for HinfⅠRFLP analysis and DNA bands of CP/SSCP. Sequence analysis of CP gene indicated that the most substitution occurred at the third nucleotide in a codon,followed by the first nucleotide,while no substitution occurred at the second nucleotide. The number of codons transition is higher than that of transversion,non-synonymous mutation occurred in the YC-3N isolate,but not YC-3Z. The replication level of CTV in‘Newhall＇is 3.3 times higher than that in‘Gannanzao＇. The POD and SOD activities increased by more than 78.2%,PAL and PPO activities also increased,while CAT activity decreased in both varieties. However,there was no significant difference between two varieties for activities changes of those five enzymes.