柑橘衰退病毒基因RNAi载体的构建

基于转化病毒基因介导抗性,通过在植物表达载体p CAMBIA 2301上插入启动子–内含子–终止子的方式,构建一种含有发夹结构的、通用型强的RNAi载体骨架结构;以柑橘衰退病毒(citrus tristeza virus,CTV)的p25、p20和p23基因保守序列为模板设计正向片段和反向片段,先后与骨架载体连接,成功构建了3个RNAi载体(分别命名为ds2301–p25、ds2301–p20和ds2301–p23),并将载体ds2301–p23注射入墨西哥莱蒙叶片。制作p23基因的地高辛标记探针,用Northern杂交检测是否有si RNA产生。结果表明:用Northern杂交可以检测到p23特异的si RNA,在墨西哥莱蒙叶片中瞬时表达的农杆菌ds2301–p23可以发生RNAi,表达有效的si RNA。本研究中构建的骨架载体可以广泛用于RNAi载体的构建,含有柑橘衰退病毒基因片段的3个载体可以用于基因功能分析及具有CTV抗性的柑橘种质资源获得。     

柑橘CsERF1基因RNAi载体的构建及转化

用RT-PCR克降柑橘的CsERF1基因cDNA序列,并连接到TA克隆载体pMD-19T上;经限制性内切酶2次双酶切,CsERF1基因的正、反向片段被分别插入到双元质粒pFGC5941查耳酮合成酶A(CHSA)内含子的两端,构成反向重复序列;经菌液PCR和测序验证,成功构建了Cs ERF1基因的RNA干涉载体;通过农杆...     

抗CMV和ToMV RNAi载体的构建及加工番茄遗传转化

【目的】利用农杆菌介导法将抗CMV和ToMV的RNAi表达载体pBi35STC12转入红番3号加工番茄,获得抗CMV和ToMV的加工番茄植株,为加工番茄病毒病的防治奠定基础。【方法】采用RT-PCR扩增,选取新疆加工番茄CMV分离物NS0-4 1a复制酶第1 051-1 350bp序列和ToMV分离物SCS-2 130/180ku复制酶第1 920-2 200bp序列,作为干扰片段CR12和To12。通过T克隆载体将CR12和To12连接成拼接片段TC12,构建成含反向重复结构拼接片段的RNAi表达载体pBi35STC12。通过农杆菌介导法,用其转化红番3号加工番茄,经过筛选、PCR检测得到转基因植株。【结果】成功构建了抗CMV和ToMV的RNAi表达载体pBi35STC12,并用其转化番茄植株,从转化的1 500个愈伤组织中获得33株再生植株,利用PCR对再生植株进行检测,显示从33株再生植株中获得了19株转基因植株,转化率为1.26%。【结论】构建了抗CMV和ToMV的RNAi表达载体pBi35STC12,用其转化红番3号加工番茄,获得了转基因植株。     

水稻TWH基因RNAi载体的构建及遗传转化

根据RNAi表达载体的设计原则,以TWH基因为靶基因,将长度253 bp目的片段通过正反两个方向插入表达载体pR1301中,构建RNAi表达载体pR1301-TWH.通过根癌农杆菌EHA 105介导法将其导入水稻品种武育粳3号,获得34株阳性转基因植株,为进一步深入研究TWH基因功能奠定了基础.     

橘蚜传播柑橘衰退病毒的研究进展

就橘蚜传播柑橘衰退病毒 (CTV)的传毒特性、传毒率、影响传毒率因素、与柑橘衰退病流行的关系、对混合株系的虫传分离作用以及带毒橘蚜的分子生物学检测等研究进展作一综述 .橘蚜传播 CTV的方式为非循回型半持久式 ,其从甜橙和墨西哥莱檬植株上传播 CTV的效率高于棉蚜、橘二叉蚜和绣线菊蚜等蚜虫 .橘蚜对 CTV不同株系的传毒率有所差异 ,对重型株系的传毒率较轻型株系高 .影响传毒率的因素有蚜虫发育虫态、毒源植物、接毒植物和环境条件等 .橘蚜与酸橙砧甜橙衰退病的发生与流行 ,特别是衰退型强株系衰退病的发生与流行有密切相关性 ,它是甜橙衰退病发生与流行的最主要传播介体 .橘蚜对 CTV具有分离株系的作用 ,通过单虫传播 ,可以将混合感染状态的 CTV不同株系分离而获得纯化株系 .检测橘蚜携带 CTV的分子生物学反转录 -聚合酶链式反应技术已建立 ,并已应用于检测橘蚜等蚜虫的单虫带毒情况 .讨论认为 ,不同发育虫态、毒源植物、接毒植物和环境条件等因素对橘蚜传播 CTV的影响 ,特别是毒源植物和温度条件对橘蚜传毒率的影响 ,及利用橘蚜单虫传播分离 CTV株系等方面的研究有待进一步加强     

OsWAX2基因的植物表达载体构建及遗传转化

利用拟南芥的WAX2基因序列,BLAST检索出3个水稻同源基因,分别命名为OsWAX2-1,OsWAX2-2,OsWAX2-3,与拟南芥WAX2基因的同源性分别为56.0%,55.2%,52.0%;其预测的编码蛋白与WAX2蛋白的同源性分别为61.5%,60.5%,64.7%.这3个蛋白都存在4个跨膜结构和2个固醇去饱和酶的保守区,说明这3个蛋白质都属于跨膜蛋白,并可能与角质层的蜡质合成有关.从全长cDNA数据库检索获得了3个OsWAX2的全长cDNA.以pCAMBIA-1300-multi为载体,构建了CaMV35S启动子驱动的3个OsWAX2的过表达载体pOEOSW2-1,pOEOSW2-2,pOEOSW2-3及3个RNAi表达载体pCROSW2-1,pCROSW2-2,pCROSW2-3,并通过冻融法将6个表达载体转化到根癌农杆菌EHA105,LBA4404和GV3101中,采用农杆菌介导法进行水稻日本晴品种的遗传转化,得到了具有Hyg抗性的水稻转基因苗,PCR检测到阳性植株.     

柑橘衰退病毒柚类分离物CP基因的克隆及原核表达分析

以来自湖北省的HB柚柑橘衰退病毒(Citrus tristeza virus,CTV)分离物(CTV-HB1)为材料,利用RT-PCR技术对其CP基因进行克隆,序列分析结果表明:CTV-HB1与典型茎陷点分离物SY568和NUagA的核苷酸和推定氨基酸的序列相似性均在97%以上,而与CTV速衰分离物T36和弱毒分离物T385和T30的核苷酸和氨基酸序列相似性较低,均在95%以下。将CP基因片段连接到表达载体,转化大肠杆菌后诱导重组蛋白的表达。SDS-PAGE和Westen-blot分析结果表明,经IPTG诱导后产生了预期大小的重组蛋白,该蛋白可与CTV-L5提纯病毒制备的多克隆抗体发生特异性免疫反应。     

玉米sbe2a基因RNAi载体的构建及转化玉米的初步研究

采用PCR技术克隆了玉米淀粉分支酶sbe2a基因的cDNA片段,将其克隆到pMD18-T载体,对重组子进行PCR检测和限制性内切酶分析,并进行序列分析.结果表明:克隆片段长度为562bp,将该基因的正义和反义片段插入到pCAMBIA1301改造过的载体p35-1301的35S启动子下游,构建高效RNAi表达载体,通过花...     

抗黄瓜花叶病毒RNAi载体的构建及烟草的转化

[目的]构建抗黄瓜花叶病毒RNAi载体,并将载体转入烟草。[方法]采用RT-PCR方法,扩增黄瓜花叶病毒NS04加工番茄分离物的RNA2基因组的序列。选取CMVRAN2基因组中的复制酶片段作为靶序列,构建pBi35SCR2真核表达载体,并对表达载体进行鉴定;通过农杆菌介导的方法将表达载体转入烟草,用PCR的方法检测载体是否转入。[结果]系统进化树分析结果表明,RNA2中编码CMV-2a的序列与中国浙江的DQ412731分离物有较高核苷酸及氨基酸同源性,分别达到98.0%和96.5%;PCR结果表明,试验成功构建了pBi35SCR2真核表达载体,并成功将表达载体转入烟草。[结论]试验获得的转基因烟草可作为后期攻毒试验的材料,并为研究加工番茄抗黄瓜花叶病毒奠定了基础。     

用rolB基因转化大红甜橙的初步研究

为建立大红甜橙的再生及遗传转化体系,提高转化芽的成株率,以30d龄的大红甜橙（Citrus sineasis Osbeck）实生苗上胚轴为材料,导入rolB基因,进行遗传转化研究．结果表明：MS＋3．0mg/L 6-BA培养基诱导不定芽的效果最好,达95％以上,．遗传转化时,采用培养基Ⅱ（MS＋3mg／L 6-BA＋200μmol／L As）＋培养基Ⅳ（MT＋3mg／L 6-BA＋50mg／L Kan＋500mg/L Cef）组合的抗性芽诱导最快,诱导率为51％．用微芽嫁接的方法,将抗性芽嫁接到卡里佐枳橙上,成苗良好,已获得19株转rolB基因植株,盆栽在温室中生长良好．     

Preliminary Studies on CPG/Hinf Ⅰ RFLP Groups of Citrus tristeza virus Infected Sweet Oranges in China

Citrus tristeza virus (CTV) causes economically important losses to the citrus industry worldwide. Mild strain cross protection (MSCP) against tristeza has hardly been practised due to mixed infection of different CTV-strains and little background of its molecular biology in China. For better cognition on CTV, 192 sweet orange samples collected from eight provinces (Chongqing, Sichuan, Fujian, Hunan, Guangxi, Yunnan, Guangdong and Jiangxi) were tested by direct tissue blot immuno-assay (DTBIA), and 158 of them were tested positively, which therefore were subjected to coat protein gene (CPG)/Hinf Ⅰ restriction fragment length polymorphism (RFLP) analysis. Sample bulks were compared between Chongqing and Fujian by some statistical data, including ratios of single infection and mixed infection to local samples, proportions of CTV isolates with single RFLP groups, and rates of each RFLP group. The simplified analysis of samples from the other six provinces were then conducted. This study suggests that CTV isolates with CPG/Hinf Ⅰ RFLP groups Ⅲ and Ⅰ are the main epidemic ones in China, and mixed infection of CTV in fields are popular. Based on observation of severity of stem-pitting symptom in field trees, CTV isolates with CPG/Hinf Ⅰ RFLP groups Ⅲ and Ⅰ caused severe stem-pittings in sweet oranges in China.     

柑桔衰退病毒基因组学研究进展

柑桔衰退病毒(CTV)是柑桔普遍存在的一种重要病毒病害,因其自身基因变异和寄主的不同而产生不同的症状,给防治CTV带来一定困难.为防治柑桔衰退病,需要研究CTV本身的相关特征.从CTV的基因组学上的特征综述了国内外在CTV基因组学最新的科研进展.     

Characterization of Citrus tristeza virus Isolates by Indicators and Molecular Biology Methods

Citrus tristeza virus （CTV） exists in citrus as a large number of distinct strains differing in biological characters. The control strategies such as mild strains cross protection （MSCP） require a clear understanding of the characterization of CTV. For better understanding of the structure of CTV population and the relationship between molecular and biological characterization, 72 CTV samples collected from five provinces in China were studied, using biological indexing, p25/Hinf I restriction fragment length polymorphism （RFLP）, multiple molecular markers, and bidirectional RT-PCR assay. The mixture of severe stem pitting isolates was found to be dominant in the field. CTV isolates with p25/Hinf Ⅰ RFLP group 3 and p23/BD-PCR group Ⅰ, Ⅲ were the main cause of epidemics, and most CTV isolates were found to be the mixture of T30 and VT genotypes. More accurate identification of strain mixtures in the field and better understanding of the biological traits of the isolates may be achieved by applying the three molecular detection methods simultaneously.     

Expressing p20 hairpin RNA of Citrus tristeza virus confers Citrus aurantium with tolerance/resistance against stem pitting and seedling yellow CTV strains

The Citrus tristeza virus(CTV) uses 3 silencing suppressor genes, p20, p23 and p25, to resist the attacks from its Citrus hosts. Inactivating these genes is therefore obviously a potential defensive option in addition to the current control strategies including aphid management and the use of mild strain cross protection. In this study, we cloned partial DNA fragments from the three genes, and used them to construct vectors for expressing hairpin RNAs(hp RNAs). To facilitate the formation of hp RNAs, the constructs were introduced in a loop structure. Following transformation of sour orange(Citrus aurantium) with these constructs, 8 p20 hp RNA(hp20) and 1 p25 hp RNA(hp25) expressing lines were obtained. The 7 hp20 transgenic lines were further characterized. Their reactions to CTV were tested following inoculation with CT14 A and/or TR-L514, both of which are severe strains. Results showed that 3 lines(hp20-5, hp20-6 and hp20-8) were completely resistant to TR-L514 under greenhouse conditions for no detectable viral load was found in their leaves by PCR. However, they exhibited only partial suppression of TR-L514 under screen house conditions since the virus was detected in their leaves, though 2 months later compared to non-transgenic controls. Further tests showed that hp20-5 was tolerant also to CT14 A under screen house conditions. The growth of hp20-5 was much better than others including the controls that were concurrently challenged with CT14 A. These results showed that expressing p20 hp RNA was sufficient to c onfer sour orange with CTV resistance/tolerance.     

四川安岳柑橘衰退病病原鉴定及序列分析

[目的]探明引起四川安岳柑橘衰退病的病原。[方法]利用RT-PCR、克隆、测序等技术对四川安岳地区的柑橘类果树进行柑橘衰退病毒(CTV)检测,并对其外壳蛋白(CP)全序列进行了分析。[结果]81个疑似CTV侵染的样品中共有18个检测呈阳性,检出率为22.2%,表明安岳地区柑橘类果树衰退病由CTV引起。基于CP全序列同源性比较及进化分析表明,危害该地区柑橘类果树的CTV分属5个组群,亲缘关系较复杂。[结论]为安岳地区CTV的防控与防治提供了理论依据。     

Preliminary Studies on CPG/Hinf Ⅰ RFLP Groups of Citrus tristeza virus Infected Sweet Oranges in China

Citrus tristeza virus （CTV） causes economically important losses to the citrus industry worldwide. Mild strain cross protection （MSCP） against tristeza has hardly been practised due to mixed infection of different CTV-strains and little background of its molecular biology in China. For better cognition on CTV, 192 sweet orange samples collected from eight provinces （Chongqing, Sichuan, Fujian, Hunan, Guangxi, Yunnan, Guangdong and Jiangxi） were tested by direct tissue blot immuno-assay （DTBIA）, and 158 of them were tested positively, which therefore were subjected to coat protein gene （CPG）/Hinf Ⅰ restriction fragment length polymorphism （RFLP） analysis. Sample bulks were compared between Chongqing and Fujian by some statistical data, including ratios of single infection and mixed infection to local samples, proportions of CTV isolates with single RFLP groups, and rates of each RFLP group. The simplified analysis of samples from the other six provinces were then conducted. This study suggests that CTV isolates with CPG/Hinf Ⅰ RFLP groups Ⅲ and Ⅰ are the main epidemic ones in China, and mixed infection of CTV in fields are popular. Based on observation of severity of stem-pitting symptom in field trees, CTV isolates with CPG/Hinf Ⅰ RFLP groups Ⅲ and Ⅰ caused severe stem-pittings in sweet oranges in China.     

甜橙和柚中CTV强弱毒株系p20的遗传变异

【目的】对7个柑橘衰退病毒(CTV)株系进行遗传变异研究,明确寄主甜橙和柚中CTV强弱毒株系p20的变异水平。【方法】运用RT-PCR、克隆及测序等技术建立CTV p20种群,并借助MEGA6构建单倍型系统发育树,运用软件DNAStar对两种寄主中CTV强弱毒种群的遗传结构、变异水平进行分析,运用DnaSP软件对各种群进行单倍型多样性、核苷酸多样性分析和中性检验分析。【结果】构建了7个CTV p20种群,由162条序列构成,包含11个单倍型,单个种群有1个或更多单倍型出现。序列分析发现,来自不同种群的单倍型对应的原始核苷酸序列一致性为88.2%—100.0%,对应的氨基酸序列的一致性为92.3%—100.0%,最低的氨基酸序列一致性发生在CT23-1和CT9-2之间;其中单倍型PeraIAC-4、CT22和CT9-1共有50条序列,对应的原始核苷酸序列一致性为100.0%,属优势单倍型,与标准株系T36亲缘关系较近;单倍型多样性最丰富的是甜橙种群PeraIAC,单倍型多样性为0.800,而单倍型多样性最低的是柚种群CT22,单倍型多样性为0.170;相比柚种群的单倍型多样性(0.170—0.552)和核苷酸多样性(0.00032—0.05919),甜橙种群具有更为丰富的单倍型多样性(0.513—0.800)和核苷酸多样性(0.04208—0.05677)。系统发育树分析表明,来自甜橙的分离株种群结构复杂,甜橙种群中检测到的单倍型与标准株系T30、T36、VT和T3均有相关性;与标准株系T3相距很近的CT31-2与优势单倍型在系统发育树上距离最远,对应的原始核苷酸序列一致性仅为88.3%。中性检验结果表明,CTV甜橙种群趋于平衡或收缩状态,而CTV柚种群除CT23外则趋于扩张状态;其中TR-514Y、CT31和CT23种群的Tajima’s D值、Fu和Li’s D*值以及Fu和Li’s F*值均为正值且达到显著水平,而CT9种群的Tajima’s D值、Fu和Li’s D*值以及Fu和Li’s F*值均为负值且达到显著水平。运用DnaSP软件对各种群进行重组分析表明,在各种群中均未检测到重组事件发生。种群变异分析发现,各种群突变克隆百分比在0—30.8%,碱基突变频率在0—7.706×10~(-4),其中CTV甜橙强毒种群有最高的突变克隆百分比(30.8%),最高的碱基突变频率(7.706×10~(-4)),最多的碱基突变数量(11个)和最多的突变位点(7个);CTV甜橙弱毒种群的突变克隆百分比和碱基突变频率均明显低于甜橙强毒种群,CTV柚弱毒种群的突变克隆百分比和碱基突变频率略低于柚强毒种群。碱基突变类型分析发现碱基突变以碱基替代为主,其中A→G突变为优势类型,仅在柚强毒种群CT3的156和157位点间检测到一个碱基插入突变类型,为碱基A插入,未检测到碱基缺失突变类型。【结论】在寄主甜橙和柚中CTV强弱毒p20种群结构及变异存在差异,CTV甜橙种群有着更复杂的种群结构和更高的种群变异水平,且CTV强毒种群变异更大。     

基于柑橘叶斑驳病毒的表达载体构建及应用

【目的】 构建基于柑橘叶斑驳病毒（citrus leaf blotch virus,CLBV）的表达载体,通过系统表达抗菌肽提高植物抗病性,为柑橘溃疡病、柑橘黄龙病等病害的防控提供新型技术手段。【方法】 基于前期构建的侵染性克隆pCY-CLBV201,在外壳蛋白基因终止子后插入亚基因组启动子序列及多克隆位点,构建病毒表达载体pCLBV202。在多克隆位点插入绿色荧光蛋白（green fluorescent protein）基因（gfp）,通过农杆菌介导接种、荧光观察验证pCLBV202-GFP表达GFP的情况。克隆天蚕的抗菌肽（cecropin B,CB）基因并构建重组载体pCLBV202-CB,通过农杆菌介导分别注射接种本氏烟和真空浸润接种柑橘实生苗,筛选阳性植株并分别注射接种和根灌接种烟草青枯病菌及针刺离体叶片接种柑橘溃疡病菌,同时设空载体接种植株为对照,通过症状观察、发病率及病情指数评价接种植株的烟草青枯病抗性;通过柑橘叶片的病斑数量、发病率及菌落浓度评价其溃疡病抗性。【结果】 pCLBV202-GFP接种烟草和尤力克柠檬后,均可以在系统新叶上观察到绿色荧光,在烟草上表现更为明亮,说明基于CLBV的表达载体构建成功。接种青枯病菌后,处理组（pCLBV202-CB）较对照组（pCLBV202）发病时间延迟4 d。在接种后第24天（24 dpi）,处理组发病率为14.3%,对照组发病率为100%,差异显著。处理组相对于对照组的抗性指数为-2.66,抗性评价为高抗,表明利用pCLBV202-CB系统表达CB增强了对烟草青枯病的抗性。尤力克柠檬叶片针刺接种柑橘溃疡病菌,7 dpi时,处理组病斑数为47个,发病率为43.5%,对照组病斑个数为73个,发病率为67.6%。菌群数变化检测发现,处理组菌群数小于对照组菌群数,表明利用pCLBV202-CB系统表达CB增强了尤力克柠檬的溃疡病抗性。【结论】 构建了基于CLBV的病毒表达载体pCLBV202。利用pCLBV202在本氏烟和柑橘中系统表达CB可以提高植株对细菌性病害的抗性,这为柑橘细菌性病害的防控提供了新技术。