Dynamics of wheat spindle streak mosaic bymovirus in winter wheat

The dynamics of wheat spindle streak mosaic bymovirus in winter wheat were studied during two crop cycles in a field site with a history of high virus incidence. Individual plants of two susceptible cultivars were sampled from autumn to spring and the presence of virus antigen in roots and leaves was determined by ELISA. Virus incidence was higher in cv. Frankenmuth than in cv. Augusta. During year one, incidence of viral antigen in roots remained very low for four months after sowing, and did not reach maximum levels until the following spring. During year two, incidence of viral antigen in roots rose to maximum levels in autumn, only three months after sowing. These results strongly suggested that root infection occurred in spring as well as in autumn. In both cultivars and in both years, we detected the virus in roots one month prior to its detection in leaves, suggesting that virus moves slowly from roots into leaves. Maximum incidence of virus in leaves occurred in spring of both years, coinciding with the period of symptom development. Typical symptoms (yellow streaks, spindles, and mosaic) were observed in year two, whereas only mild mosaic was observed in year one. Virus antigen was detected in nonsymptomatic leaves from two months after sowing through crop senescence. Because antigen could be detected in roots throughout the crop cycle, and zoosporangia and cystosori of the fungal vector could be detected one and two months, respectively, after sowing, it is possible that wheat spindle streak mosaic bymovirus is acquired and/or spread by the vector during the majority of the crop cycle.     

Genome-wide association analysis of resistance to wheat spindle streak mosaic virus in bread wheat

Wheat spindle streak mosaic virus (WSSMV) is a major concern for cereal crops in Europe and North America. A strong increase in the occurrence of WSSMV has been observed in each French region where susceptible cultivars are cultivated. Most European bread wheat cultivars are resistant, but assessing the status of newly registered cultivars or breeding lines regarding WSSMV resistance is of importance. This paper describes a genome-wide association study carried out on a panel of 163 cultivars and tested for their resistance to WSSMV. Two regions on chromosomes 5B and 7D showed minor effects on WSSMV resistance. More importantly, a large genomic region on chromosome 2D explained most of the resistance to WSSMV. More than 99% of the cultivars carrying the AA genotype at the most associated marker (Excalibur_c15426_661) were resistant to WSSMV, while 100% of the cultivars showing the GG genotype were susceptible. This large genomic region of 45.8 Mb was found distal to the centromere and showed very high linkage disequilibrium. It is hypothesized that this region may be an alien introgression originating from a wild related species. This region contains a total of 2605 predicted genes based on the Chinese Spring IWGSC RefSeq v. 1.0 including genes potentially involved in plant disease resistance. A kompetitive allele-specific PCR (KASP) single-nucleotide polymorphism (SNP) marker was designed in order to identify breeding lines or registered cultivars resistant to WSSMV.     

An isolate of Wheat streak mosaic virus from foxtail overcomes Wsm2 resistance in wheat

Wheat streak mosaic virus (WSMV) is an economically important pathogen of wheat (Triticum aestivum) causing major yield losses in regions where severe infection occurs. To detect the presence of any new virus or new WSMV isolates, green foxtail (Setaria viridis) plants exhibiting virus-like symptoms were sampled in a summer-fallowed wheat field at the Agricultural Research Center-Hays, Kansas State University, Hays, Kansas. These plants were tested serologically for four wheat viruses: WSMV, Triticum mosaic virus (TriMV), High Plains wheat mosaic virus (HPWMoV) and Foxtail mosaic virus (FoMV). Among 38 plant samples exhibiting virus-like symptoms, 29 contained WSMV as indicated by ELISA. Four isolates from samples with relatively strong reactions were transferred to healthy wheat seedlings by mechanical inoculation in a growth chamber for pathogenicity testing. Three isolates were avirulent to a wheat variety RonL, which contains Wsm2, a gene providing temperature-sensitive resistance to currently prevalent isolates of WSMV. However, one isolate, KSH294, was able to infect RonL and showed more virulence on two other varieties/lines containing Wsm2. Further sequence and phylogenetic analysis of KSH294 confirmed that this isolate displays a sequence homology with WSMV, but has sequence differences making it distinct from previously identified WSMV isolates included in the phylogenetic analysis.     

Diverse conserved domains and a positively selected site in the sugarcane streak mosaic virus P1 protein are essential for RNA silencing suppression and protein stability

RNA silencing is one of the conserved antiviral mechanisms in plants, and viruses encode RNA silencing suppressors (RSS) to overcome host RNA silencing and facilitate virus infection. Sugarcane streak mosaic virus (SCSMV; species Sugarcane streak mosaic virus, genus Poacevirus, family Potyviridae) is a major causal agent of sugarcane mosaic disease in many countries in Asia, including China. In this study, we used Agrobacterium co-infiltration to show that the SCSMV P1 protein, rather than the helper component-proteinase (HC-Pro), functions as a strong RSS to suppress local RNA silencing in Nicotiana benthamiana. Mutational analysis indicated that the 15 amino acids (aa; aa 1–15) of the SCSMV P1 N-terminus were not important for RNA silencing suppression, but rather another 15 aa domain (aa 108–122) containing a conserved motif (LFR/KNKQAYIST) was essential for efficient silencing suppression by P1. In addition to the 15 aa (aa 344–358) domain in the P1 N-terminus, another 15 aa domain (aa 65–79) of P1, containing the LXKA motif and one conserved aa (D78), were associated with P1 protein stability. Furthermore, substituting the histidine (H263) residue in P1 with threonine (H263T) or alanine (H263A) also affected P1 protein stability. Notably, the H263 residue is both a positively selected site and part of the serine protease catalytic triad (HDS). Taken together, our data demonstrate that SCSMV P1, and not HC-Pro, plays a functional role in suppressing RNA silencing, and also show that some conserved motifs and a positivelyselected site in the P1 protein are associated with RSS activity and protein stability.     

甘蔗线条花叶病毒P1蛋白基因原核表达及抗血清制备

甘蔗线条花叶病毒Sugarcane streak mosaic virus(SCSMV)是引起甘蔗花叶病的主要病原之一,在世界各大蔗区普遍发生,严重威胁甘蔗产业的发展.建立快速有效的检测方法对于SCSMV的防控有着重要意义.本研究依据SCSMV P1基因序列合成一对引物,扩增获得1 074 bp的目的基因,将目的基因与...     

甘蔗线条花叶病毒HC-Pro基因的分子变异分析

为了解析甘蔗线条花叶病毒Sugarcane streak mosaic virus(SCSMV)不同分离物HC-Pro基因的分子变异规律,本研究利用RT-PCR法扩增获得SCSMV HC-Pro基因的序列,通过生物信息学分析,分别从重组、系统发生、选择压力等方面研究SCSMV HC-Pro基因的分子变异特征。共测定了44条SCSMV HC-Pro基因序列,相似性最低值为70%;HC-Pro基因重组频率较低,仅发现3个重组位点,其中一个系首次报道;与先前报道相比,部分新测定云南蔗区的SCSMV分离物在HC-Pro基因上形成一个新组-第Ⅲ组;HC-Pro基因处于很强的负选择压力作用,未发现正向选择作用位点。本研究结果进一步证明SCSMV HC-Pro基因具有高度的遗传多样性。     

进境玉米种子中小麦花叶病毒的检测及其RNA3序列全长扩增分析

小麦花叶病毒（wheat mosaic virus,WMoV）是严重危害小麦、玉米等禾本科作物的种传病毒,在我国尚无发生,具有重要检疫意义。本研究利用引物WMoV-283F/R全国首次检测出玉米种子中的WMoV,成功扩增出了两个不同典型毒株NP序列,并分析其序列特征。根据WMoV-RNA3、WMoV-RNA3A和WMoV-RNA3B序列特点设计特异性引物,经RT-PCR扩增玉米种子样品2211-2和8044-10的RNA,扩增产物测序得到283 bp基因序列,分别与WMoV分离物GG1-RNA3B(GenBank登录号KT988872.1)、WMoV分离物K1-RNA 3(GenBank登录号KT988889.1)同源性为96.11%、96.47%。设计引物分别扩增玉米种子样品2211-2和8044-10的RNA核衣壳全长序列,得到WMoV-Germany RNA3、WMoV-Malaysia RNA3A和WMoV-Malaysia RNA3B全长序列。使用MEGA6软件采用Maximum likelihood法建立系统发育树,它们分别属于3个同源性差异明显的簇。通过DNAMAN序列比...     

小麦黄花叶病毒罗田分离物细胞质内含体蛋自基因的序列分析

利用RT-PCR,获得了小麦黄花叶病毒湖北罗田分离物细胞质内含体(CI)蛋白基因的cDNA克隆。序列分析结果表明,湖北罗田分离物CI基因由1977个核苷酸组成,编码一个由659个氨基酸组成的蛋白质。与已报道的河南潢川、四川雅安、江苏扬州及日本分离物序列比较,不同分离物之间核苷酸序列同源性在95.0％～97.5％之间,相应推导的氨基酸序列同源性在93.2％～97.1％之间。并对CI蛋白的功能进行了讨论。     

Influence of wheat streak mosaic virus infection on phenylpropanoid metabolism and the accumulation of phenolics and lignin in wheat

Wheat plants infected with wheat streak mosaic virus were studied for their physiological response to infection. Previous histological data suggest that wheat streak mosaic virus-induced deposits of phenolic nature are present along the bundle sheath and mesophyll cell walls. In this study, we examined this phenomenon further by analysis of phenolic compounds and enzymes involved in their synthesis. In infected plants, the amounts of free and wall-bound phenolic compounds increased slightly, and chromatography showed that the type of free phenolic compounds present had changed. The amount of lignin did not change due to infection. Enzyme assays showed that while phenylalanine ammonia lyase and tyrosine ammonia lyase activities decreased as they do in healthy plants, cinnamyl alcohol dehydrogenase activity stayed high throughout infection. In addition, peroxidase activities in infected plants decreased around the time that the leaves ceased to expand. These results suggest that the general phenylpropanoid pathway is stimulated upon infection, but that lignification is not.     

The complete nucleotide sequence of RNA2 of barley mild mosaic virus (BaMMV)

Barley mild mosaic virus is a member of theBymoviruses, a genus of the familyPotyviridae. The virus consists of two types of flexuous rod-shaped particles. Each of them contains one single-stranded polyadenylated RNA in plus orientation of approximately 7.6 kb (RNA1) and 3.6 kb (RNA2). Complementary DNAs of both RNAs have been synthesised and cloned. The nucleotide sequence of RNA2 has been determined. It is 3524 nucleotides in length, excluding the 3 poly(A) tail, and contains one large open reading frame (2679 nts), coding for a polyprotein of approximately 98 kDa. There are indications that a putative proteolytic activity in the N-terminal part can cleave the polyprotein autocatalytically into a 25 kDa protein (putative proteinase) and a 73 kDa polypeptide of unknown function.     

卫星RNA SatC382对辅助病毒的影响

 通过体外转录将黄瓜花叶病毒(CMV)卫星RNASatC382与不带卫星的黄瓜花叶病毒CNa株系进行假重组,获取带卫星的CMV重组株(CNa-SatC382)。经dsRNA提取及RT PCR检测,证实CNa和SatC382在假重组株中能稳定共存。测定CNa和CNa-SatC382的14种寄主生物学反应,并统计两者接种昆诺藜、假酸浆、心叶烟、西葫芦7、14、21、28d的病情指数,结果显示:带卫星和不带卫星的CMV在各供试寄主上表现的症状差别不明显,病情指数也无显著差异。由此推测卫星RNASatC382没有改变辅助病毒CMV-CNa株系对寄主症状的影响。     

甜菜花叶病毒新疆分离物基因组3′末端序列分析

甜菜花叶病毒(Beet mosaic virus,BtMV)属马铃薯Y病毒科、马铃薯Y病毒属,可经多种蚜虫以非持久性方式传播,病毒粒子为弯曲线状,核酸为单分子正义ssRNA。目前只有美国华盛顿分离物的全序列以及斯洛伐克和英国少数几个分离物3′端的部分序列被报道[1,2]。美国分离物全长9591nt,3′端具有PolyA尾,编码一个由3086个氨基酸组成的多聚蛋白,与其它Potyvirus病毒一样可切割成10个蛋白,从N到C端依次为P1、HC-Pro、P3、6K1、CI、6K2、NIa-Vpg、NIa-Pro、NIb和CP[2]。对于我国发生的BtMV,1981年Liu等[3]报道了发生于北京地区菠菜上的Bt…     

甜菜花叶病毒新疆分离物基因组3'末端序列分析

甜菜花叶病毒（Beet mosaic virus，BtMV）属马铃薯Y病毒科、马铃薯Y病毒属，可经多种蚜虫以非持久性方式传播，病毒粒子为弯曲线状，核酸为单分子正义ssRNA。目前只有美国华盛顿分离物的全序列以及斯洛伐克和英国少数几个分离物3’端的部分序列被报道。美国分离物全长9591 nt，3’端具有PolyA尾，编码一个由3086个氨基酸组成的多聚蛋白，与其它Potyvirus病毒一样可切割成10个蛋白，从N到C端依次为P1、HC—Pro、P3、6K1、CI、6K2、NIa—Vpg、NIa～Pro、NIb和CP。对于我国发生的BtMV，1981年Liu等报道了发生于北京地区菠菜上的BtMV，之后研究人员相继报道了黑龙江、内蒙古和新疆等甜菜主产区甜菜花叶病的发生及危害情况，并陆续开展了对BtMV的生物学特性、外壳蛋白分子量测定和氨基酸组分分析、细胞病理学等研究，目前对于我国发生的BtMV的分子结构特征还未见报道。本文报道了甜菜花叶病毒新疆分离物（BtMV—XJ）3’端的核酸序列，并与国外已报道序列进行了比较分析，为从分子水平上明确我国BtMV的分子结构特点、深入研究其编码蛋白的功能打下了基础。     

烟草品种对烟草花叶病毒和黄瓜花叶病毒的抗性鉴定

 2010-2011年采用大田人工接种鉴定的方法,对生产中大面积推广使用的24份烟草品种进行了烟草花叶病毒（TMV）和黄瓜花叶病毒（CMV）的抗性鉴定。结果表明,供试品种对TMV和CMV的抗病性存在较大差异,对TMV表现抗病的有Coker86、吉烟5号、Coker176、CV87、辽烟8号、CV91、中烟90等7份材料;表现中抗的有秦烟98、双抗70、C151等3份材料;表现中感的有秦烟96、G80、金星6007、龙江981、K326、秦烟201、NC89等7份材料;表现感病的有G28、云烟97、净叶黄、红花大金元、RG11、云烟85、云烟87等7份材料。对CMV表现抗病的有Coker86、龙江981、C151、秦烟201、云烟87等5份材料;表现中抗的材料是金星6007;表现中感的有CV91、RG11、Coker176、中烟90、K326、红花大金元、净叶黄、G80、G28等9份材料;表现感病的有秦烟98、云烟85、秦烟96、NC89、双抗70、云烟97、CV87、辽烟8号、吉烟5号等9份材料。其中兼抗TMV和CMV两种病毒病的材料有2份,分别是Coker86和C151。同时研究还发现,抗病性不同的烟草品种在受到病毒危害以后,对烟叶的产量和品质的影响也不同。明确了中国24个烟草品种的抗病性水平,为抗病品种的利用与品种合理布局提供科学依据,同时为烟草抗病毒病育种的亲本选择提供抗源信息。     

中国小麦花叶病毒弱毒突变体筛选与鉴定

中国小麦花叶病毒(Chinese wheat mosaic virus,CWMV)是我国小麦土传花叶病毒病的重要病原.将CWMV RNA1、RNA2片段分别连接到pCB301-Rz载体,得到重组质粒pCWMV-RNA1和pCWMV-RNA2,这2个质粒可在本氏烟上引起花叶和畸形症状,在小麦上引起黄花叶症状.在pCWMV...     

油菜花叶病毒武汉株系基因组全序列分析

 油菜花叶病毒(Oilseed rape mosaic virus,ORMV)武汉株系(Wh)基因组全序列分析表明,该株系基因组全长6301nt,与烟草花叶病毒属(Tobamovirus)亚组Ⅲ病毒基因组结构相似,含4个开放阅读框架(open reading frame,ORF),ORF2与ORF3有77nt的重叠区。与该属其他病毒对应ORF的核苷酸及编码蛋白氨基酸序列比对,ORMV-Wh与亚组Ⅲ的ORMV、车前草花叶病毒上海株系(Ribgrass mosaic virus,RMV-Sh)、车前草花叶病毒凤仙花株系(RMV-Imp)和烟草花叶病毒十字花科和大蒜株系(Tobacco mosaic virus,TMV-Cg)一致性最高,均超过95%。4种蛋白的氨基酸序列系统进化树构建将Tobamovirus亚组Ⅲ株系分为3个群,ORMV-Wh归为ORMV代表的株系群。     

Taxonomy of Wisteria vein mosaic virus and extensions to its host range and geographical distribution

Wisteria mosaic, a serious disease of Wisteria spp. in horticultural production in many parts of the world, is caused by a virus, Wisteria vein mosaic virus (WVMV). This paper reports the presence of the virus in a new host, Wisteria venusta , and a new geographical distribution, New South Wales, Australia. A partial sequence (1329 nucleotides) of this isolate of WVMV was obtained, which represents the first available sequence data for the virus. Alignment of the nucleotide and predicted amino acid sequences with those of members of the Potyviridae showed closest identity with viruses of the Potyvirus genus. The predicted amino acid sequence has one open reading frame, open at the 5' end, corresponding to part of the nuclear inclusion b protein and the capsid protein, followed by a 251-nucleotide untranslated region and a polyadenylated tail at the 3' end.