以烟草坏死病毒A中国分离物(Tobacco necrosis virus A Chinese isolate,TNV-AC)侵染性cDNA克隆为基础,通过基因替换、基因插入策略构建获得多种重组TNV-AC,比较了外源基因片段插入位置、插入形式及接种植物培养温度对TNV-AC诱导的基因...以烟草坏死病毒A中国分离物(Tobacco necrosis virus A Chinese isolate,TNV-AC)侵染性cDNA克隆为基础,通过基因替换、基因插入策略构建获得多种重组TNV-AC,比较了外源基因片段插入位置、插入形式及接种植物培养温度对TNV-AC诱导的基因沉默的影响.外源基因片段替换CP基因19～828 nt的重组TNV-AC丧失了在本生烟中的系统移动能力,也不能有效诱导相应基因发生明显的沉默,说明替换策略不适合于TNV-AC.向CP基因终止密码子UAG附近插入外源基因片段后,TNV-AC仍可进行复制,但最适的插入位点位于UAG之后,且容纳外源片段的长度约为120 nt.当外源片段以反向重复的形式插入UAG之后,诱导基因沉默的效率较高.接种植物的培养温度也会显著影响基因沉默的效率以及插入片段的稳定性,低温(18℃)条件下诱导NbPDS基因沉默的效率明显高于高温(24℃)条件,且沉默表型可持续110天以上.除了本生烟PDS基因,TNV-AC沉默载体还可诱导本生烟sulfur基因Su和镁离子螯合酶H亚基基因ChlH发生沉默,以上结果说明,TNV-AC具有开发为本生烟基因功能鉴定的新VIGS载体的潜力.展开更多
[Objective] The study aimed to extract the statistical features of complete tobacco necrosis virus genome and conduct clustering analysis.[Method] On the base sequence of complete tobacco necrosis virus genome,by usin...[Objective] The study aimed to extract the statistical features of complete tobacco necrosis virus genome and conduct clustering analysis.[Method] On the base sequence of complete tobacco necrosis virus genome,by using three base groups which was composed of each base and its subsequent two bases,a new sequence S was arranged;the probability of all 64 kinds of three base groups occurred on S was calculated,a 64-dimensional vector L was obtained;L-vector of each genome was compared,8 three base groups were obtained,their probabilities have significant differences.[Result] The emergence probability of 8 three base groups （CGT;CAA;TAC;TAA;AGG;ATG;ATA;AAG） has significant association with genetic variation of tobacco necrosis virus genome;according to genetic variation result,4 different sources tobacco necrosis virus complete genome formed 2 major categories.[Conclusion] The study will provide theoretical basis for the control of tobacco necrosis virus.展开更多
利用烟草坏死病毒A中国大豆分离物(Tobacco necrosis virus A Chinese isolate,TNV-AC)的全长侵染性cDNA克隆构建系列突变体进行体外转录.在枯斑寄主苋色藜(Chenopodium amaranticolor)上的侵染性检测结果表明,TNV-AC亚基因组RNA1的转...利用烟草坏死病毒A中国大豆分离物(Tobacco necrosis virus A Chinese isolate,TNV-AC)的全长侵染性cDNA克隆构建系列突变体进行体外转录.在枯斑寄主苋色藜(Chenopodium amaranticolor)上的侵染性检测结果表明,TNV-AC亚基因组RNA1的转录起始位点位于基因组RNA的G2184,亚基因组RNA2的转录起始位点位于基因组RNA的G2460.进一步分析表明,亚基因组RNA1中p8和p6基因的翻译灭活突变可导致病毒在苋色藜上的侵染症状消失,但不影响病毒在烟草原生质体中的复制,说明p8和p6基因产物可能影响病毒在细胞之间的移动,是病毒造成枯斑所必需的基因.通过原核表达产物分析,证明了亚基因组RNA2中外壳蛋白(coat protein,CP)基因的可读框起始于基因组RNA的2612~2614位AUG.CP可读框核苷酸替换或缺失突变分析表明,完整的CP蛋白虽不是病毒建立侵染所必需的,但其翻译起始密码子区域的核苷酸序列保守性及可读框核酸序列的完整性对病毒侵染苋色藜后产生枯斑的数量、显症时间和病毒RNA的积累量具有明显影响.综合以上结果,对TNV-AC的cp基因在侵染枯斑寄主苋色藜过程中的其他功能进行了讨论.展开更多
Based on a full-length infectious cDNA clone, gene modifications of Tobacco necrosis virus A Chinese isolate (TNV-AC) were made by site-directed mutagenesis or nucleotide deletions for in vitro transcrip-tion of mutan...Based on a full-length infectious cDNA clone, gene modifications of Tobacco necrosis virus A Chinese isolate (TNV-AC) were made by site-directed mutagenesis or nucleotide deletions for in vitro transcrip-tion of mutant viral RNAs. Mechanical inoculations of Chenopodium amaranticolor with in vitro tran-scripts, containing a single nucleic acid substitution at the presumed transcriptional start sites for the two subgenomic (sg) RNAs, showed that the sgRNA1 and sgRNA2 of TNV-AC were initiated at G2184 or G2460, respectively. Mutagenesis of the translational initiation-codons for the open-reading frame (ORF) P8 or P6 encoded by sgRNA1 indicated that each of the two genes was essential for formation of local lesions on C. amaranticolor leaves, perhaps by blocking virus cell-to-cell movement, but were not necessary for viral RNA replication in the protoplast of tobacco cell BY-2. Results of prokaryotic expression showed that the ORF coding for coat protein on TNV-AC sgRNA2 was initiatively translated by the first AUG codon at nucleotides 2612―2614. Site-directed mutation of translational start codons, and deletion of the entire coding region, showed that the intact TNV-AC coat protein was dispensable for establishment of TNV-AC infection in C. amaranticolor, otherwise the numbers of local lesions and the viral RNA accumulation level were reduced, or the time to symptom appearance significantly delayed. These results suggested that the nucleotide sequence around the translational start codon coding for TNV-AC coat protein gene may play an important role in the local symptoms. Aspects of the involve-ment of the coat protein in the TNV-AC life cycle were discussed.展开更多
文摘以烟草坏死病毒A中国分离物(Tobacco necrosis virus A Chinese isolate,TNV-AC)侵染性cDNA克隆为基础,通过基因替换、基因插入策略构建获得多种重组TNV-AC,比较了外源基因片段插入位置、插入形式及接种植物培养温度对TNV-AC诱导的基因沉默的影响.外源基因片段替换CP基因19～828 nt的重组TNV-AC丧失了在本生烟中的系统移动能力,也不能有效诱导相应基因发生明显的沉默,说明替换策略不适合于TNV-AC.向CP基因终止密码子UAG附近插入外源基因片段后,TNV-AC仍可进行复制,但最适的插入位点位于UAG之后,且容纳外源片段的长度约为120 nt.当外源片段以反向重复的形式插入UAG之后,诱导基因沉默的效率较高.接种植物的培养温度也会显著影响基因沉默的效率以及插入片段的稳定性,低温(18℃)条件下诱导NbPDS基因沉默的效率明显高于高温(24℃)条件,且沉默表型可持续110天以上.除了本生烟PDS基因,TNV-AC沉默载体还可诱导本生烟sulfur基因Su和镁离子螯合酶H亚基基因ChlH发生沉默,以上结果说明,TNV-AC具有开发为本生烟基因功能鉴定的新VIGS载体的潜力.
基金Supported by"Eleventh Five-year" Education Science Development Plan of Hubei Province (2006B131)~~
文摘[Objective] The study aimed to extract the statistical features of complete tobacco necrosis virus genome and conduct clustering analysis.[Method] On the base sequence of complete tobacco necrosis virus genome,by using three base groups which was composed of each base and its subsequent two bases,a new sequence S was arranged;the probability of all 64 kinds of three base groups occurred on S was calculated,a 64-dimensional vector L was obtained;L-vector of each genome was compared,8 three base groups were obtained,their probabilities have significant differences.[Result] The emergence probability of 8 three base groups （CGT;CAA;TAC;TAA;AGG;ATG;ATA;AAG） has significant association with genetic variation of tobacco necrosis virus genome;according to genetic variation result,4 different sources tobacco necrosis virus complete genome formed 2 major categories.[Conclusion] The study will provide theoretical basis for the control of tobacco necrosis virus.
文摘利用烟草坏死病毒A中国大豆分离物(Tobacco necrosis virus A Chinese isolate,TNV-AC)的全长侵染性cDNA克隆构建系列突变体进行体外转录.在枯斑寄主苋色藜(Chenopodium amaranticolor)上的侵染性检测结果表明,TNV-AC亚基因组RNA1的转录起始位点位于基因组RNA的G2184,亚基因组RNA2的转录起始位点位于基因组RNA的G2460.进一步分析表明,亚基因组RNA1中p8和p6基因的翻译灭活突变可导致病毒在苋色藜上的侵染症状消失,但不影响病毒在烟草原生质体中的复制,说明p8和p6基因产物可能影响病毒在细胞之间的移动,是病毒造成枯斑所必需的基因.通过原核表达产物分析,证明了亚基因组RNA2中外壳蛋白(coat protein,CP)基因的可读框起始于基因组RNA的2612~2614位AUG.CP可读框核苷酸替换或缺失突变分析表明,完整的CP蛋白虽不是病毒建立侵染所必需的,但其翻译起始密码子区域的核苷酸序列保守性及可读框核酸序列的完整性对病毒侵染苋色藜后产生枯斑的数量、显症时间和病毒RNA的积累量具有明显影响.综合以上结果,对TNV-AC的cp基因在侵染枯斑寄主苋色藜过程中的其他功能进行了讨论.
基金the National Natural Science Foundation of China (Grants Nos. 30470077 and 30325001).
文摘Based on a full-length infectious cDNA clone, gene modifications of Tobacco necrosis virus A Chinese isolate (TNV-AC) were made by site-directed mutagenesis or nucleotide deletions for in vitro transcrip-tion of mutant viral RNAs. Mechanical inoculations of Chenopodium amaranticolor with in vitro tran-scripts, containing a single nucleic acid substitution at the presumed transcriptional start sites for the two subgenomic (sg) RNAs, showed that the sgRNA1 and sgRNA2 of TNV-AC were initiated at G2184 or G2460, respectively. Mutagenesis of the translational initiation-codons for the open-reading frame (ORF) P8 or P6 encoded by sgRNA1 indicated that each of the two genes was essential for formation of local lesions on C. amaranticolor leaves, perhaps by blocking virus cell-to-cell movement, but were not necessary for viral RNA replication in the protoplast of tobacco cell BY-2. Results of prokaryotic expression showed that the ORF coding for coat protein on TNV-AC sgRNA2 was initiatively translated by the first AUG codon at nucleotides 2612―2614. Site-directed mutation of translational start codons, and deletion of the entire coding region, showed that the intact TNV-AC coat protein was dispensable for establishment of TNV-AC infection in C. amaranticolor, otherwise the numbers of local lesions and the viral RNA accumulation level were reduced, or the time to symptom appearance significantly delayed. These results suggested that the nucleotide sequence around the translational start codon coding for TNV-AC coat protein gene may play an important role in the local symptoms. Aspects of the involve-ment of the coat protein in the TNV-AC life cycle were discussed.
