Behavior of Watermelon Cultivars after Inoculation with Watermelon mosaic virus in Saudi Arabia

All seven watermelon cultivars that were screened for their reactions to a severe Saudi Arabian isolate of Watermelon mosaic virus(WMV-SA)that was found inducing a severe disease in watermelon in Riyadh region,were found to be susceptible and showed different virus-like symptoms upon mechanical inoculation.Sugar Baby,Crimson Sweet 1 and Crimson Sweet 2 cultivars showed milder symptoms and,therefore,got lower grand mean of weekly symptom ratings than Charleston Gray No.502,Jubilee,Black Diamond and Charleston Gray No.133 in both first and second experiments.Artificial inoculation with this isolate significantly reduced the plant height,fresh and dry weights of the tested cultivars.The reduction percentages in plant height of Sugar Baby and Crimson Sweet 2 were significantly lower than those of Crimson Sweet 1,Charleston Gray No.502 and Charleston Gray No.133 in both experiments.Also the reduction in percentages of fresh weights of Sugar Baby,Crimson Sweet 2 and Jubilee were significantly lower than reduction percentages of Crimson Sweet 1,Black Diamond and Charleston Gray No.133.The dry weight reduction percentages of Jubilee,Sugar Baby and Crimson Sweet 2 were lower than those of Charleston Gray No.502,Charleston Gray No.133,Black Diamond and Crimson Sweet 1 in both experiments.No correlation existed between the virus titer in the infected cultivars and their performances.In general,Sugar Baby and Crimson Sweet 2 performed better than the other cultivars as they had the lowest symptom severity ratings,the lowest percentages of plant height,fresh and dry weight reductions compared to the other tested cultivars.

Characterization of a Watermelon mosaic virus Isolate Inducing a Severe Disease in Watermelon in Saudi Arabia

In one of the field visits to cucurbits-growing areas in vicinity of Riyadh city during 2013-2015,severe virus disease-like symptoms were observed on watermelon in Al-Ammariyah area.Mechanical inoculation of the different plant species used in the host range study,from the collected symptomatic watermelon samples,produced mosaic symptoms on Citrullus lanatus,Cucumis sativus,Cucurbita pepo,C.melo,C.melo subsp.melo and Nicotiana benthamiana,but chlorotic local lesions on Chenopodium amaranticolor.No symptoms were observed on the rest of the other inoculated plant species.The virus was transmitted by Aphis gossypii and A.craccivora in a non-persistent manner.Transmission electron microscopic examination of watermelon samples using the leaf dip method revealed only microscopic filamentous shaped virus particles measuring 750 nm in length and 12 nm in diameter in average.ELISA revealed positive results only to Watermelon mosaic virus(WMV)and negative to Zucchini yellow mosaic virus(ZYMV),Papaya ringspot virus(PRSV),Cucumber mosaic virus(CMV)and Squash mosaic virus(SqMV).Specific bands of approximately 825 bp were formed on agarose gel following electrophoresis of the reverse transcriptase-polymerase chain reaction(RT-PCR)products of each of the naturally infected C.lanatus,and artificially infected C.lanatus,C.pepo,C.sativus,and N.benthamiana.The homology tree that was constructed from multiple sequence alignments of the detected Saudi Arabian isolate of WMV(WMV-SA)with 18 other isolates of WMV from nine different countries indicated close relationships between them.Two isolates from Spain and two other isolates from Iran were more closely related to the WMV-SA whereas the isolate from Poland was the least.

转WMV-2外壳蛋白基因西瓜植株的病毒抗性

西瓜是夏季的重要水果 ,病毒病是影响其品质和产量的重要原因之一。植物基因工程的发展为抗病育种提供了新途径。利用外壳蛋白 (coatprotein)基因转化高等植物 ,赋予转基因植物以相应抗病性的成功例子已很多。本文报道WMV - 2CP基因在转基因西瓜植株中的遗传、分离、表达以及转基因植株对病毒病的抗性实验结果。通过自交结合PCR检测 ,发现WMV - 2CP基因在自交子一代的分离符合孟德尔 3∶1的分离比。经过连续 4代的选择鉴定 ,已从T7、T11和T32 3个独立转化子的后代中筛选获得 8个转基因纯合株系 ,性状表现整齐一致。Westernblot结果表明 ,R4 T7-1、R4 T11-3以及R4 T32 -73个不同来源的株系均能表达产生外壳蛋白。转基因纯合株系WMV - 2感染后的病毒抗性实验表明 ,与未转基因对照相比 ,转基因株系可以推迟发病时间 ,减轻发病程度。实验筛选获得的转基因株系R4 T32 -7表现出对WMV - 2的高度抗性 。

西瓜花叶病毒(WMV—2)两株系寄主的病生理研究

以沈阳农大植保系植物病毒研究室提供的WMV—2两株系WMV—2(1)和WMV—2(2)为试材。它们除寄主范围及在某些指示植物上有症状反应的差异外,亦导致其寄主的病生理反应不同。如接种到西葫芦叶片后,株系的强弱差别亦能反应到叶片叶绿素含量多少、光合作用强度、电导率及过氧化物同工酶活性等指标上。试验初步观察到WMV—2的两个株系其寄主病生理上,存在某些可以分辨的差异,WMV—2(1)对西葫芦叶片内叶绿素的破坏程度、降低光合强度以及过氧化物酶活性升高的程度等均大于WMV—2(2)。由此,作者等初步认为这些病生理指标可作为区分西瓜花叶病毒株系较好的辅助手段。

几种诱抗剂对西瓜ZYMV的防治效果评价

为探索对西瓜病毒病具有防效作用的植物免疫诱抗剂,以小西葫芦黄花叶病毒(zucchini yellow mosaic virus,ZYMV)为防治对象,植株的显症率及相对防效为指标,评价了6种不同浓度的哌啶酸(Pip)、N-羟基哌啶酸(NHP)、没食子酸、苯并噻二唑(BTH)、壳寡糖、β–氨基丁酸(β-aminobutyric acid,BABA)及其2种药剂和3种药剂复配后对该病毒的防治效果。结果显示,单一药剂喷施后对西瓜ZYMV的防效从高到低依次为:NHP(0.5 mmol·L^(-1))、Pip(2 mmol·L^(-1))、壳寡糖(1 g·L^(-1))、没食子酸(0.5 g·L^(-1))、BABA(1 mmol·L^(-1))、BTH(0.1 mmol·L^(-1));复配药剂试验中,2种药剂复配防效最好的是2-Ⅶ(NHP 0.5 mmol·L^(-1)+Pip 2 mmol·L^(-1)),接种后11 d、无菌水对照植株显症率达到100.00%时,该组合处理的植株显症率为10.00%,相对防效达89.99%,但该复配药剂会影响植株生长;3种药剂复配防效较好的组合是3-Ⅰ(没食子酸0.5 g·L^(-1)+NHP 0.5 mmol·L^(-1)+BABA 1 mmol·L^(-1))和3-Ⅱ(没食子酸0.5 g·L^(-1)+NHP 0.5 mmol·L^(-1)+Pip 2 mmol·L^(-1)),显症率分别为27.27%、33.33%,相对防效分别为79.49%、68.27%,显著高于其他组合,其中3-Ⅱ处理的植株显症率增加缓慢,防病效果较其他处理持久,防治效果最优。综上,NHP、Pip和没食子酸3种诱抗剂在预防西瓜病毒病害中具有潜在的应用价值。

罗汉果花叶病毒(WMV-2-Luo)抗血清制备及ELISA检测技术研究

用西葫芦作为罗汉果花叶病毒 (WMV 2 Luo)的繁殖寄主 ,通过差速离心和PEG二次沉淀法得到WMV 2 Luo的提纯液 ,用该病毒提纯液免疫日本大白兔 ,获得了WMV 2 Luo兔抗血清。经ELISA测定 ,其效价为 1/5 12 0 ,以 0 1mol/L磷酸盐缓冲液 (pH7 8,含 1 5 %NaDIECA)作为样品制备缓冲液 ,用间接ELISA法检测WMV 2 Luo的灵敏度为 1/32 0 0。用此方法检测罗汉果组培苗带毒情况和田间病株均获得成功。

山东省侵染西瓜的西瓜花叶病毒（WMV－2）和黄瓜花叶病毒（CMV）的研究

从采自平度、临沂两地的西瓜病叶中得到两个病毒分离物Ｗ—ＰＤ和Ｗ—ＬＹ。Ｗ—ＰＤ可侵染３科８种植物，可由桃蚜以非持久性方式传播。钝化温度６５℃，稀释限点１０￣（－４）～１０￣（－５），体外存活期２０～２５ｄ。提纯病毒呈典型的核蛋白吸收，最大吸收峰为２６０ｎｍ，最小吸收峰为２４６ｎｍ。Ａ２６０／Ａ２８０＝１．２４。病毒外壳蛋白分子量为３３．３４ＫＤ。Ｗ—ＰＤ的粒子线状，长度为６００～７５０ｎｍ。在病组织超薄切片中可以看到风轮状和环状内含体。Ｗ—ＰＤ与ＷＭＶ—２的抗血清有明显的沉淀反应。以上结果表明，Ｗ—ＰＤ为ＷＭＶ—２的一个分离物。Ｗ—ＬＹ可侵染５科１３种植物。钝化温度７０℃，稀释限点１０￣（－３）～１０￣（－４），体外存活期３～５ｄ，可由桃蚜以非持久方式传播，与ＣＭＶ的抗血清有明显的沉淀反应。Ｗ—ＬＹ应为ＣＭＶ的一个分离物。ＷＭＶ—２是我省西瓜病毒病的主要毒原，其分出率为７５％，ＣＭＶ的分出率为１６．３５％。

西瓜花叶病毒(WMV)单克隆抗体的制备及其应用

【目的】制备抗西瓜花叶病毒(Watermelon mosaic virus,WMV)的特异性单克隆抗体,并以其为核心建立能快速有效地检测WMV的血清学方法,从而为中国田间西瓜花叶病毒病的诊断和检测、预测预警及科学防控体系的建立提供物质和技术支撑。【方法】用提纯的WMV病毒粒子免疫BALB/c小鼠,经细胞融合和细胞培养、抗体筛选和细胞克隆等杂交瘤细胞技术,获得能稳定分泌抗WMV单克隆抗体的杂交瘤细胞株,将杂交瘤细胞注射入BALB/c小鼠腹腔制备其单抗腹水,并以制备的单抗为核心建立能准确、特异、灵敏地检测田间植物中WMV的ACP-ELISA、DAS-ELISA、dot-ELISA、Tissue blot-ELISA和IC-RT-PCR方法,以及能检测单头传毒介体蚜虫体内WMV的dot-ELISA方法。【结果】3株能稳定分泌WMV单克隆抗体的杂交瘤细胞株(2C8、15A8和16C12)及其单抗腹水被制备,3株杂交瘤细胞分泌的单抗腹水的间接ELISA效价均达到了10^(-6)以上,抗体类型及亚类均为IgG1、kappa轻链。Western blot分析发现,这3个单抗均与WMV的外壳蛋白亚基有特异性反应。灵敏度分析结果表明,ACP-ELISA、DAS-ELISA、dot-ELISA和IC-RT-PCR方法检测WMV病叶的灵敏度分别达到1﹕163 840、1﹕327 680、1﹕5 120和1﹕1 310 720倍稀释(w/v,g/m L)。特异性分析结果表明,以这3个单抗为核心建立的ACP-ELISA、DAS-ELISA、dot-ELISA、Tissue blot-ELISA和IC-RT-PCR 5种血清学检测方法均能与感染WMV的病叶发生特异性免疫反应,而与感染小西葫芦黄花叶病毒(Zucchini yellow mosaic virus,ZYMV)、黄瓜花叶病毒(Cucumber mosaic virus,CMV)、黄瓜绿斑驳花叶病毒(Cucumber green mottle mosaic virus,CGMMV)、马铃薯Y病毒(Potato virus Y,PVY)的植物样品、健康白南瓜、西瓜、葫芦和烟草的植物组织均呈阴性反应,且dot-ELISA方法还能特异性地检测单头蚜虫体内的WMV,而在检测无毒蚜虫时呈阴性反应。利用建立的血清学检测方法对采自浙江省、江苏省、山东省和海南省的275株葫芦科疑似病株进行检测,结果发现187株植物感染WMV,发病率达68%,说明WMV在中国田间葫芦科植物中广泛流行发生,且血清学方法的检测结果与RT-PCR方法的检测结果完全一致,将部分PCR产物进行核酸测序和序列比对分析,结果表明这些PCR产物是WMV CP基因片段,证明血清学方法检测阳性的样品确实感染WMV。【结论】获得了3株特异、灵敏的WMV单克隆抗体,以其为核心建立的5种血清学方法能准确、灵敏、可靠地应用于田间样品中WMV的检测,从而为中国WMV田间样品的大规模快速检测和诊断、该病害预报预警和科学防控提供物质和技术支撑。

美洲南瓜(Cucurbit pepo)WMV-2抗性遗传及分子标记研究

以美洲南瓜(Cucurbita pepo)抗病自交系‘0504’和感病自交系‘0223’为亲本杂交获得的157个F2单株为材料,研究南瓜对西瓜花叶病毒2号(WMV-2)抗性的遗传规律和分子标记。对亲本、F1及F2苗期接种WMV-2进行抗病性鉴定,结果表明,美洲南瓜对WMV-2的抗性由单隐性基因控制。采用集团分离分析法(BSA)和SSR技术,筛选出与WMV-2抗性基因连锁的标记CMTm157和CMTm158,遗传距离分别为10.9cM和6.2cM,其可以作为南瓜抗WMV-2育种的辅助选择分子标记。

WMV-2感染引起甜瓜植株苯丙氨酸解氨酶和叶绿素的变化

研究了西瓜花叶病毒-2新疆株(Watermelon mosaic virus-2-XJ,WMV-2-XJ)感染抗性不同的甜瓜品种后苯丙氨酸解氨酶和叶绿素含量的变化.与健康对照植株相比,受感染植株的酶活性均有所增高,但抗性品种“新玉”增高的幅度是感性品种“网纹香”的2倍,酶活性峰早出现12天,即抗性品种酶活性增高幅度大,酶活性峰出现早,叶绿素的变化则与抗性呈负相关,抗性品种“新玉”受WMV-2-XJ感染后的叶绿素含量与健康对照差异不大,而感性品种“网纹香”的叶绿素含量则比健康对照下降了62.9%.苯丙氨酸解氨酶和叶绿素含量的变化均与甜瓜品种对WMV-2-XJ的抗性呈现规律性的相关性,这种规律性可用于甜瓜品种对WMV-2-XJ抗性鉴定的生物化学分析.

Markers for Rapid Evaluation of Virus Resistance for TYLCV in Tomato, ZYMV and PRSV-W in Zucchini and LMV in Lettuce and Hybrid Seeds in Pumpkin

Screening for the source of virus resistance in horticultural plants or specific characterization as hybridization, through symptoms, requires time and depends on the weather and knowledge of plant characteristics. So, it is important to develop specific gene markers to allow rapid diagnosis by PCR. Markers were developed based on sequences homology comparison of susceptible and resistant plants provided by HORTEC SEEDS in tomato for Tomato yellow leaf curl virus (TYLCV) by the resistance gene Ty-1, in zucchini for Zucchini yellow mosaic virus (ZYMV) and Papaya ringspot virus estirpe watermelon (PRSV-W), and in lettuce for Lettuce mosaic virus (LMV). Fragments of 249 bp were amplified only by resistant plants to TYLCV as the hybrids 2648 and Aguamiel, and not for varieties as Santa Cruz or Carina. It were observed for ZYMV the amplification of 791 bp by the resistant hybrid Px7051 and not for the susceptible cultivar La Belle;for PRSV-W using the same zucchini plants the amplification of 650 bp for susceptible and 750 bp for resistant;for LMV the 421 bp amplification only for the resistant cultivar Brasil 303 and not for susceptible Babá de Verão. Finally, it was observed that primers PK47F/R were able to check the Cabotiá seed hybrids of pumpkin Jabras.

西瓜花叶病毒西葫芦分离物的基因组及其侵染性克隆

西瓜花叶病毒(watermelon mosaic virus,WMV)是危害瓜类作物的一种主要病毒,笔者分析了西葫芦分离物CH99/69的基因组序列和分子变异,构建了具有侵染性的全长cDNA克隆。结果显示,CH99/69分离物基因组全长为10047 nt,与其他分离物的全基因组核苷酸、多聚蛋白核苷酸和多聚蛋白氨基酸的序列一致性分别为81.40%~94.80%、81.40%~94.70%、88.40%~97.20%。基于全基因组序列的系统进化分析显示,CH99/69与中国的Urumqi火参果分离物、WMV-WS西葫芦分离物和法国的WMV-Fr西葫芦分离物亲缘关系较近,它们均聚于Ⅰ组中,而与中国的WMV-Pg人参分离物、WMV-GZca臭椿分离物、hollyhock蜀葵分离物亲缘关系最远。接种试验显示,CH99/69分离物的克隆具有侵染性,能系统侵染甜瓜、西瓜、西葫芦和瓠瓜,经接种产生的病毒后代能够通过摩擦接种进行侵染。

Host Reaction of Watermelon mosaic virus Isolates Infecting Melon from Different Geographical Origins in Xinjiang of China

Watermelon mosaic virus(WMV) is one of the major viruses infecting cucurbit crops worldwide. Although WMV is very common worldwide,little is known about the biological traits of WMV isolates from China. Hence, this study aimed to characterize 11 WMV isolates infecting melon from different geographical origins in Xinjiang based on experimental hosts. Sap inoculation of the 11 WMV isolates onto a range of 13 plant species revealed some differences compared to the WMV isolates collected from other countries. Our results showed that, overall, there were no obvious correlations of host responses to inoculation with WMV isolates from different geographical origins. However, isolate JS-1 caused mild mosaic on Cucurbita moschata, whereas the remaining 10 isolates were asymptomatic on this plant species. Moreover, in Datura stramonium, isolate TYG-1 induced mosaic, whereas the remaining 10 isolates did not infect this species. All isolates infected systemically Cucurbita pepo and Cucumis melo plants, causing severe symptoms. All isolates did not induce any symptoms on Cucumis sativus, but the virus could be detected using RT-PCR. Additionally, all isolates infected systemically Nicotiana tabacum plants, causing mild mosaics. Chenopodium amaranticolor and Chenopodium quinoa reacted to all isolates by chlorotic local lesions in the inoculated leaves, and the virus was detected in the inoculated leaves using RT-PCR. In addition, the attempts to transmit the isolates to Luffa cylindrica, Vicia faba, Phaseolus vulgaris, Vigna unguiculata or Pisum sativum failed as confirmed by negative RT-PCR. Our results would be useful for understanding the biological variability of WMV.

黄瓜绿斑驳花叶病毒生物学特性及对西瓜生长的影响

对黄瓜绿斑驳花叶病毒(cucumber green mottle mosaic virus,CGMMV)在辽宁省的分布、生物学特性及病毒侵染对西瓜产量和品质的影响进行了研究。结果表明:CGMMV在辽宁省的营口、鞍山、沈阳、丹东、大连、辽阳等地均有分布;在供试的5科21种植物中,病毒仅可侵染葫芦科的西瓜、黄瓜、葫芦、南瓜、角瓜、甜瓜、瓠瓜7种植物,并表现系统花叶症状。该病毒致死温度95～100℃,稀释限点10-4～10-5,体外保毒期119d。电镜观察病毒粒子直棒状,长300nm,宽15nm。RT-PCR检测表明,盖州、台安、新民的西瓜花叶样品为黄瓜绿斑驳花叶病毒西瓜株系。利用春秋两季大棚栽培西瓜接种试验表明,西瓜感染CGMMV后,导致植株生长缓慢,结瓜稍小,自根西瓜产量减产幅度很大,秋季大棚减产38.7%～47.6%,春季大棚减产11.4%～19.4%;采用葫芦嫁接的西瓜产量损失变化较小,秋季大棚减产3.4%～17.5%,春季大棚减产2.5%～9.1%。另外,研究结果表明,CGMMV侵染直接导致西瓜倒瓤,使西瓜丧失食用价值,血清学检测倒瓤西瓜携带CGMMV。

黄瓜绿斑驳花叶病毒西瓜、甜瓜种子的带毒率和传毒率

【目的】加强种子带毒检测,防止黄瓜绿斑驳花叶病毒(Cucumber green mottle mosaic virus,CGMMV)通过种子传播而导致该病害的扩散和流行。【方法】以感染CGMMV的西瓜、甜瓜病株收获的种子为材料,应用DAS-ELISA检测感染CGMMV的种子带毒率和传毒率。【结果】250粒西瓜种子全部为阳性,带毒率达100%;623株西瓜幼苗14株为阳性,传毒率为2.25%。130粒甜瓜种子122粒为阳性,带毒率达93.85%;2 050株甜瓜幼苗58株为阳性,传毒率为2.83%。灵敏度检测种子带毒量在感染种子研磨样体积与健康种子研磨样体积为1/1 000时仍检测是阳性;叶片带毒量在病叶研磨样体积与健康叶研磨样体积为1/10 000时仍检测是阳性。【结论】感染CGMMV西瓜、甜瓜种子带毒率高而传毒率相对较低,说明CGMMV主要以种子表面带毒为主。灵敏度检测表明DAS-ELISA能进行大批量的种子检测。

罗汉果花叶病病原病毒鉴定

从典型病株上分离到 1种大小为 12 nm× (6 0 0～ 80 0 ) nm的线状病毒 ;该病毒可通过汁液摩擦和棉蚜(Aphis gossypii)传播 ,人工接种可侵染罗汉果 (Siraitia grosvenorii)、西葫芦 (Cucurbita pepo)、南瓜 (C.moschata)、黄瓜 (Cucumis sativus)、西瓜 (Citrullus vulgaris)、毛节瓜 (Citrullus vulgaria)和瓠瓜 (L agenariasiceraria)等葫芦科植物引起花叶症状 ,侵染苋色藜 (Chenopodium amaranticolor)引起局部褪绿斑点 ,接种番木瓜(Carica papaya)、普通烟草 (N icotiana tabacum)、心叶烟 (N .glutinosa)、曼陀罗 (Datura stramonium)、洋酸浆(Physalisf loridana)、番杏 (Tetragonia tetragonioides)、豇豆 (Vigna sinensis)未见有任何症状 ;病毒的致死温度为5 5℃～ 6 0℃ ,稀释终点为 10 - 3～ 10 - 4 ,在 17℃～ 2 5℃下放置 10 d还有侵染活力 ;EL ISA测定结果表明 ,该病毒与西瓜花叶病毒 - 2 (WMV- 2 )有密切的血清学关系。上述结果表明 ,引起广西罗汉果花叶病的病原病毒是 WMV-2的一个株系。本研究还表明 ,罗汉果花叶病毒与番木瓜环斑病毒 (PRSV)、马铃薯 Y病毒 (PVY)、烟草蚀纹病毒 (TEV)、大豆花叶病毒 (SMV)及莴苣花叶病毒 (L MV)

西瓜花叶病毒中国分离株全基因组核苷酸序列测定

Watermelon and melon mosaic disease is the important disease in agricultural production,mostly caused by watermelon mosaic virus.In this paper,the complete nucleotide sequence of watermelon mosaic virus Chinese isolate(WMV-Ch)was firstly determined.Excluding the 3’-terminal poly(A)tail,the genome was 10037 nt long,containing 5’-and 3’-terminal untranslated regions and a large open reading frame.The genome encoded a polyprotein of 3217 amino acids with a predicted Mr of 365.8 kD.Based on comparison with the proposed location of cleavage sites of other potyvirus polyproteins,10 mature proteins were predicted.There were 92.5% nucleotide and 96.4% amino acid identities over entire genome between WMV-Ch and France isolate(WMV-Fr),respectively.The nucleotide identity of the coat protein genes among WMV-Ch and WMV from different countries was all less than 95%,and phylogenetic tree revealed that WMV-Ch was most close to Japanese isolate.

江苏省葫芦科作物西瓜花叶病毒的分子鉴定和序列分析

[目的]对江苏各地具典型褪绿花叶症状的多种葫芦科作物是否为西瓜花叶病毒（Watermelon mosaic virus,WMV）侵染进行分子鉴定,明确该病毒在江苏的遗传分化.[方法]提取样品总RNA,利用西瓜花叶病毒的cp基因特异性引物进行RT-PCR扩增,克隆测序,应用DNASTAR和Clustal X软件进行序列分析.[结果]来自南瓜、瓠瓜、西瓜和西葫芦的11个分离物的RNA模板中均检测到1200 bp左右的片段;序列测定表明该片段含1154个核苷酸,包含完整的编码281个氨基酸的WMV-cp基因.序列比对结果表明,11个分离物和来自不同地区的17个分离物WMV-cp基因核苷酸和推导的编码CP蛋白氨基酸序列同源性分别为90.5％～100.0％和92.9％～100.0％.[结论]WMV的遗传变异与地缘相关性较强而与寄主相关性较弱.江苏分离物WMV-CP氨基酸均具有蚜传株系的特征结构域DAG,暗示其田间流行与蚜虫有关.

侵染南瓜的西瓜花叶病毒和黄瓜花叶病毒CP基因的克隆和序列分析

为从分子水平鉴定山东聊城的一表现明显花叶、黄化、蕨叶及果实畸形的南瓜病毒病的病原,采用RT-PCR的方法,用马铃薯Y病毒属病毒3′-末端序列的简并引物和黄瓜花叶病毒(Cucumber mosaic virus,CMV)外壳蛋白(CP)基因的特异引物,对该样品进行了检测,并对克隆到的基因序列进行分析。结果表明,该样品受西瓜花叶病毒(Watermelon mosaic virus,WMV)和CMV2种病毒的复合侵染,分别命名为WMV-liaocheng和CMV-liaocheng,与其他相应病毒分离物CP基因核苷酸序列的同源性分别为91.2%～98.0%和77.0%～97.9%,推导的氨基酸序列同源性分别为96.4%～98.5%和81.2%～99.1%。根据完整CP基因核苷酸序列构建的系统进化树显示:18个WMV分离物可分为3组,其中WMV-liaocheng与HLJ、CHN及Habenaria等分离物表现出较近的亲缘关系,形成Ⅲ组;30个CMV分为2个亚组,其中CMV-liaocheng属于亚组I,CMV-liaocheng可能发生过重组。

多羟基双萘醛提取物WCT抗病毒的生理病理学研究

本文研究了多羟基双萘醛提取物WCT处理西葫芦后,对西瓜花叶病毒的防效和抗病毒相关酶活性及超微结构变 化。结果发现,先喷WCT 24 h后接种的相对预防效果为83．7％,高于先喷病毒A 24 h后接种的预防效果和先接种24 h后 喷WCT的治疗效果。WCT预防处理能在喷药后第3 d或第9 d相对于接种未喷药处理的PPO、POD和PAL的活性显著 提高,且3种酶活性随时问推移都有一个上升一下降-上升的交替起伏的变化趋势;能诱导西葫芦在Rf值为0．33、0．36、 0．43处多出3条新的PPO同工酶带,能增强2条在Rf值为0．73和0．79的POD同工酶带。WCT治疗处理酶活性变化规 律与接种未喷药处理的对照相近,对寄主植物没有诱导作用。在西葫芦发病初期,相对于接种未喷药处理的对照,WCT预 防处理的西葫芦叶肉细胞内病毒内含体数量减少,内含体的形状主要以风轮状为主,叶绿体和线粒体没有解体现象,且叶 绿体中淀粉粒膨大积累,叶绿体附近嗜锇颗粒增多。WCT治疗处理与接种未喷药处理的几乎没有明显差异。