The Efficiency of Southern rice black-streaked dwarf virus Transmission by the Vector Sogatella furcifera to Different Host Plant Species

Southern rice black-streaked dwarf disease is a new rice disease that severely affects rice production in South China.To understand transmission capacity of the vector Sogatella furcifera to Southern rice black-streaked dwarf virus（SRBSDV） among different host plant species,potential host plants of SRBSDV collected from the diseased rice field and/or adjacent to the field in Hunan Province,China,were determined by RT-PCR,and the transmission rates of SRBSDV by S.furcifera among different host plant species were investigated.The results showed that host plants of SRBSDV in the rice fields were five of family Gramineae（Oryza sativa,Echinochloa crusgalli,Zea mays,Paspalum distichum,Alopecurus aequali） and two of family Cyperaceae（Juncellus serotinus and Cyperus difformis）.S.furcifera could not transmit SRBSDV between gramineous plants and cyperaceous plants,and could not transmit SRBSDV between the gramineous plants,J.serotinus and C.difformis as well.However,SRBSDV could be transmitted by S.furcifera within gramineous plants.S.furcifera could transmit SRBSDV between interspecies among three species plants（O.sativa,E.crusgalli and Z.mays）,and between P.distichum and A.aequali.At 15,20,25,30,and 35°C,both macropterous and brachypterous adult of S.furcifera could transmit SRBSDV from the plants（e.g.,E.crusgalli,Z.mays and O.sativa） infected with SRBSDV to rice seedlings.The transmission rates were first increased and then decreased with the increase of temperature.Macropterous adults transmitted SRBSDV from the viruliferous E.crusgalli,Z.may and rice plants to the healthy rice seedlings,and the infected rates of rice seedlings were 26.2,18.8 and 23.7% at 15°C,56.6,64.6 and 53.6% at 25°C,and was 11.2,10.2 and 7.3% at 35°C,respectively.Transmission capacity of brachypterous adults was significantly higher than that of macropterous adults at 15,20 and 25°C（P0.05）,while transmission capacity of brachypterous adults was relatively lower compared with that of macropterous ones at 35°C.These results offer evidence on the transmission of SRBSDV via the vector S.furcifer among different host plants,which can be helpful to control Southern rice black-streaked dwarf disease by the appropriate cultural measures in South China.

Ecological Fitness of Non-vector Planthopper Sogatella furcifera on Rice Plants Infected with Rice Black Streaked Dwarf Virus

We evaluated the effects of rice black streak dwarf virus （RBSDV）-infested rice plants on the ecological parameters and its relevant defensive and detoxification enzymes of white-backed planthopper （WBPH） in laboratory for exploring the relationship between RBSDV and the non-vector planthopper. The results showed that nymph survival rate, female adult weight and fecundity, and egg hatchability of WBPH fed on RBSDV-infested rice plants did not markedly differ from those on healthy plants, whereas the female adult longevity and egg duration significantly shortened on diseased plants. Furthermore, significantly higher activities of defensive enzymes （dismutase, catalase and peroxidase） and detoxification enzymes （acetylcholinesterase, carboxylesterase and glutathione S-transferase） were found in WBPH adults fed on infected plants. Results implied that infestation by RBSDV increased the ecological fitness of non-vector planthopper population.

Transmission of Rice Black-Streaked Dwarf Virus from Frozen Infected Leaves to Healthy Rice Plants by Small Brown Planthopper (Laodelphax striatellus)

In order to preserve virus for identifying the resistance of rice varieties against rice black-streaked dwarf disease, a simple and reliable method was developed, through which virus-free small brown planthopper （SBPH） acquired rice black-streaked dwarf virus （RBSDV） from frozen infected leaves and the virus was transmitted to healthy rice plants. The experimental results showed that SBPH could obtain RBSDV from frozen infected rice leaves and the virus could be transmitted to a susceptible rice variety. For the ability to acquire RBSDV and transmit the virus to healthy plants by SBPH, there was no significant difference between frozen infected leaves and in vitro infected leaves. The novel method could be applied to identification of rice variety resistance to rice black-streaked dwarf disease, facilitating the breeding process for rice black-streaked dwarf disease resistance.

Resistance of Major Rice Cultivars in Hangzhou Area of China against Southern Rice Black-streaked Dwarf Virus

Resistance of 17 major rice cultivars in Hangzhou region of China against southern rice black-streaked dwarf virus was tested in the paper. The results showed that the incidence rate of southern rice black-streWed dwarf virus had certain positive correlation with quantity of white-backed planthopper （Sogatellafurci-fera） and resistance among various cultivars was significant. Two varieties, Yueyou 9113 and Tianyouhuazhan, were most susceptible ; Yongyou 8, Jiayou 2 and Xi-ushui 134 had best resistance and could be used as disease-resistant varieties to prevent the disease.

Detection,Occurrence,and Survey of Rice Stripe and BlackStreaked Dwarf Diseases in Zhejiang Province,China

The major viral diseases that occur on rice plants in Zhejiang Province, eastern China, are stripe and rice black-streaked dwarf diseases. Rice stripe disease is only caused by rice stripe tenuivirus （RSV）, while rice black-streaked dwarf disease can be caused by rice black-streaked dwarf fijivirus （RBSDV） and/or southem rice black-streaked dwarf fijivirus （SRBSDV）. Here we review the characterization of these viruses, methods for their detection, and extensive surveys showing their occurrence and spread in the province.

Screening of Rice Genes Interacting with p5b of Rice BlackStreaked Dwarf Virus

Rice black-streaked dwarf virus （RBSDV） is a recognized member of the genus Fijivirus, family Reoviridae. Its genome has ten double-stranded RNA （dsRNA） segments （$1-$10）, in which the fifth genome segment （$5） contains two open reading frames （ORFs） with a partially overlapping region. The second ORF of RBSDV S5 encodes a viral nonstructural protein named p5b with unknown function. To reveal the function of p5b, its gene was ligated into the bait plasmid pGBKT7 and an expression library containing rice cDNAs was constructed using plasmid pGADT7 for yeast two-hybrid assay. The bait protein p5b was detected in yeast by western blot, and the result of an auto-activation test showed that p5b could not autonomously activate the expression of reporter genes in yeast. Then the bait protein p5b was used for screening the cDNA expression libraries of rice. Gene fragments of some pivotal enzymes involved in photosynthesis, respiration and other important metabolic processes, were identified to interact with p5b in yeast, suggesting that these interactions may play roles in symptom development in infected plants.

Disaster Prevention and Mitigation Technologies of Rice Virus Diseases Spread by Small Brown Planthopper (SBPH)

Rice stripe virus disease （RSVD） and rice black-streaked dwarf virus disease （RBSDVD） are two epidemic diseases in Yancheng City, Jiangsu Province in the last decade. The authors investigated the disaster regularity, prevention and control technology of RSVD and RBSDVD systematically. The occurrence and virus transmission of SBPH and disaster regularity of virus diseases were studied; the resistance of some rice varieties was cleared; the effects of physical and agricultural measures such as insect net blocking, appropriate late sowing and plowing on controlling occurrence and virus transmission of SBPH were figured out; a hatch of chemical agents were screened, providing efficient and harmless pesticides for effective control against SBPH and prevention against virus diseases. A set of disaster control and mitigation technologies was proposed in this paper, which was practical, sustainable, and easy to operate for the local planting patterns.

Epidemiological Characteristics of Maize Rough Dwarf Disease in Huang-Huai-Hai Plain

Maize rough dwarf disease is a common epidemic disease in large areas.Its epidemic and occurrence mechanism is a complex process.In this paper,the epidemiological characteristics and influencing factors of maize rough dwarf disease in Huang-Huai-Hai plain were elaborated based on the research results of maize rough dwarf disease at home and abroad for many years.The epidemic of maize rough dwarf disease is affected by many factors,such as the occurrence and virus carrying rate of the first generation small brown planthopper,accumulation of virus sources on gramineous crops and weed hosts,maize variety resistance,maize sowing date,maize growth period,crop layout,tillage system,climate and ecological environment.The key factors causing the outbreak and epidemic of maize rough dwarf disease are the planting of maize susceptible varieties,the meeting of maize seedling stage and the peak period of adult spread of the first generation of small brown planthopper.

Influence of rice black streaked dwarf virus on the ecological fitness of non-vector planthopper Nilaparvata lugens （Hemiptera： Delphacidae）

Rice black streak dwarf virus （RBSDV） is transmitted by the small brown planthopper （SBPH）, Laodelphax striatellus （Fallen）. Non-vector rice brown planthopper （BPH）, Nilaparvata lugens （Stal）, shares the same host rice plants with SBPH in paddy fields. The changes in nutritional composition of rice plants infected by RBSDV and the ecological fitness of BPH feeding on the infected plants were studied under both artificial climate chamber and field conditions. Contents of 16 detected amino acids and soluble sugar in RBSDV infected rice plants were higher than those in the healthy ones. On the diseased plants BPH had significantly higher nymphal survival rates, nymphal duration of the males, weight of the female adults, as well as egg hatchability compared to BPH being fed on healthy plants. However, there was no obvious difference in female nymph duration, longevity and fecundity. Defense enzymes （superoxidase dismutase, SOD and catalase, CAT） and detoxifying enzymes （carboxylesterase, CAE and glutathione S-transferase, GST） in BPH adults fed on diseased plants had markedly higher activities. The results indicate rice plants infected by RBSDV improved the ecological fitness of the brown planthopper, a serious pest but not a transmitter of the RBSDV virus.

Southern rice black-streaked dwarf virus:A new proposed Fijivirus species in the family Reoviridae

For the past several years, a novel dwarf disease has been observed on rice (Oryza sativa) in some regions of Guangdong Province and Hainan Province, southern China. Infected plants showed stunting, dark leaf and small enations on stem and leaf back. Typical Fijivirus viroplasma containing crystalline arrayed spherical virons approximately 70―75 nm in diameter and tubular structures were detected in ultrathin sections by an electron microscope in parenchyma phloem cells of the infected plants. The virus was transmitted to rice seedlings by white-backed planthoppers, Sogatella furcifera (Hemiptera: Delphacidae), collected in the diseased fields. Analysis of dsRNA extracts from infected plants revealed ten linear segments, which were similar to the electrophoretic profile of Rice black-streaked dwarf virus (RBSDV). RT-PCR with a single primer which matched to a linker sequence ligated to both 3′ ends of the viral genomic dsRNAs resulted in amplification of genome segments 9 (S9) and 10 (S10) cDNA products. The complete nucleotide sequences of S9 and S10 were obtained from clones of the RT-PCR amplicon exhibited characteristic properties of Fijivirus including low GC content (34.5% and 35.6%), genus conserved 5′ and 3′ termini sequences and similar genome organization. Blast searches indicated that the sequences of S9 and S10 shared 68.8%―74.9% and 67.1%―77.4% nucleotide identities with those of viruses in the Fijivirus group 2, respectively. These values were similar to those among other viruses in the Fijivirus group 2 and considerably lower than those among RBSDV isolates. Phylogenetic trees based on S9 and S10 nucleotide sequences and their putative amino acid sequences showed that this virus represented a separate branch among other Fijiviruses. The virus was also detected by a nested RT-PCR assay in corn (Zea mays), barnyard grass (Echinochloa crusgalli), Juncellus serotinus and flaccidgrass (Pennisetum flaccidum) in and/or adjacent to the infected rice fields. It is proposed that this virus be considered as a new species, Southern rice black-streaked dwarf virus, in the group 2 of the genus Fijivirus in the family Reoviridae.

Two virus-encoded RNA silencing suppressors,P14 of Beet necrotic yellow vein virus and S6 of Rice black streak dwarf virus

Functional analysis for gene silencing suppres- sor of P14 gene of Beet necrotic yellow vein virus and S6 gene of Rice black streak dwarf virus was carried out by agro- in- filtration with recombinant vectors of Potato virus X. The phenotype observation of green fluorescent protein (GFP) expression and Northern blot showed that the gene silencing of gfp transgenic Nicotiana benthamiana induced by ho- mologous sequence was strongly suppressed by the immix- ture infiltration of either the P14 or the S6. In the suppressed plants, the gfp mRNA accumulation was higher than that in the non-suppressed controls and the symptoms caused by PVX infection became more severe, especially the gfp DNA methylation of plant genome was significantly inhabited when co-infiltrated with RBSDV S6 gene. These results sug- gested that these two virus genes were potentially to encode for proteins as RNA silencing suppressors.

水稻黑条矮缩病毒RT-LAMP快速检测方法的建立

【目的】建立一种快速、灵敏的逆转录环介导等温扩增方法(RT-LAMP)检测寄主植物和传毒介体体内的水稻黑条矮缩病毒(Rice black-streaked dwarf virus,RBSDV)。【方法】合成4条针对RBSDV S10核苷酸序列6个位点的特异性引物。分别对引物浓度、MgSO4浓度、反应温度和时间进行优化。将感病水稻总RNA梯度稀释后进行灵敏性检验并与RT-PCR比较分析。选择RBSDV和南方水稻黑条矮缩病毒(SRBSDV)验证该方法的特异性。用本RT-LAMP方法检测田间病株。【结果】RT-LAMP检测方法可排除SRBSDV的干扰而特异地检测植物和飞虱体内的RBSDV,与RT-PCR灵敏性基本一致。检测结果易于判定。【结论】RT-LAMP检测方法适合寄主植物和介体体内RBSDV的快速检测。

江苏水稻黑条矮缩病病毒的RT-PCR分析和快速检测

为了明确江苏新发生的矮缩病害为水稻黑条矮缩病,采用RT-PCR和序列测定方法对其病原进行了精确鉴定。根据水稻黑条矮缩病病毒基因组序列的信息,设计扩增RNA聚合酶基因、外壳蛋白基因和RNA沉默抑制子基因以及核心蛋白基因部分编码区的4对引物,提取感染水稻黑条矮缩病病毒的水稻植株总RNA并进行RT-PCR扩增,可以在感病植株中分别扩增出水稻黑条矮缩病病毒基因组特有的4个条带,测序结果表明,来源于江苏南京的分离物的4个基因部分编码片段与已登录的对应基因片段核苷酸序列同源性达99%以上,共发现7个碱基的突变。经生物信息学分析发现7个单碱基突变都是同义突变,氨基酸序列没有改变。根据以上结果确认该病病原为水稻黑条矮缩病病毒。利用该方法可以对水稻和其他寄主进行早期病毒检测。

双重RT-PCR法同时快速检测南方水稻黑条矮缩病毒和水稻黑条矮缩病毒

南方水稻黑条矮缩病毒(SRBSDV)和水稻黑条矮缩病毒(RBSDV)在病害症状、传播介体及寄主等方面非常相似,田间很难对其进行诊断及鉴定。根据SRBSDV与RBSDV外壳蛋白(CP)基因核苷酸序列差异设计特异性引物,建立一种快速、准确的双重PT-PCR鉴别方法,为SRBSDV和RBSDV的流行监测提供技术支持。

2011-2012年三种水稻矮缩病在我国的分布及发生调查

水稻黑条矮缩病毒、南方水稻黑条矮缩病毒和水稻锯齿矮缩病毒均可以引起水稻矮缩病。于2011-2012年,利用dot-ELISA和RT-PCR方法对江苏、浙江、江西、广西、海南、云南、贵州、四川、重庆、湖南等省的水稻矮缩病进行调查。检测结果表明,2011年水稻中3种矮缩病的病毒感染率分别为:水稻黑条矮缩病毒10.92%,南方水稻黑条矮缩病毒30.67%,水稻齿叶矮缩病毒4.62%。2012年水稻中3种矮缩病的病毒感染率分别为:水稻黑条矮缩病毒0.40%,南方水稻黑条矮缩病毒48.38%,水稻齿叶矮缩病毒26.32%。检测结果说明2012年的南方水稻黑条矮缩病害、水稻齿叶矮缩病害重于2011年,水稻黑条矮缩病害轻于2011年。水稻黑条矮缩病主要发生于江苏、浙江等省;南方水稻黑条矮缩病主要在广西、海南、云南、贵州、重庆、浙江等省区流行;水稻齿叶矮缩病在广西、海南、云南等地均有发生,且往往与南方水稻黑条矮缩病毒复合感染。

水稻黑条矮缩病暴发流行原因分析--以河南开封为例

水稻黑条矮缩病最早于1963年在浙江省余姚的早稻上发现,1964-1966年在浙江、江苏和上海等地流行或局部危害,1967年后华东地区发病迅速减轻,20世纪70年代在浙江病区难以找到病株,但1991-2002年浙江杂交稻区水稻黑条矮缩病又再次流行成灾,随后发病面积下降。2006年以来在江苏、浙江、山东等稻区大面积发生,并迅速上升为当地水稻主要病害之一,给水稻生产造成了巨大的经济损失。2013-2014年,水稻黑条矮缩病在河南沿黄部分稻区严重发生。本文从稻-麦连作的耕作制度,介体灰飞虱的越冬基数大、带毒率高,田间毒源丰富、易感水稻品种多,介体灰飞虱发生高峰与秧苗敏感期高度重合等方面,分析了水稻黑条矮缩病间歇性暴发流行的原因,以期为该病科学防控提供理论依据。

单头灰飞虱体内两种水稻病毒的双重一步法 RT-PCR检测

灰飞虱传播的水稻条纹病毒(Rice stripe virus,RSV)和水稻黑条矮缩病毒(Rice black-streaked dwarf virus,RBSDV)是危害我国水稻生产最主要的2种病毒,建立灰飞虱体内RSV和RBSDV快速、可靠的检测方法是水稻生产中的重要问题。本研究根据RSV RNA3和RBSDV S10序列分别设计了2个病毒的特异性引物,通过退火温度和PCR循环数等条件的优化,建立了灰飞虱体内RSV和RBSDV快速鉴定的双重一步法RT-PCR体系。对一步法和两步法RT-PCR检测结果进行比较,表明2种方法均能准确有效鉴定灰飞虱体内的2种病毒,且两步法的检测效果略好于一步法。而灵敏度实验表明一步法RT-PCR可以从0.005 ng·μL-1的灰飞虱RNA初始模板中准确检测到病毒,完全满足单头灰飞虱体内病毒检测的需要。应用本研究建立的双重一步法RT-PCR体系对200头获毒灰飞虱样品中的RSV和RBSDV进行了检测,结果进一步证实了此方法的稳定性和可靠性。

南方水稻黑条矮缩病毒安徽分离物S5片段的克隆及S5-2基因的原核表达

【目的】探讨南方水稻黑条矮缩病毒(Southern rice black-streaked dwarf virus,SRBSDV)安徽分离物(SRBSDVAn Hui-HN2)的遗传特性,并获得原核表达的P5-2蛋白。【方法】RT-PCR扩增SRBSDV S5片段,克隆、测序并进行序列分析。将S5-2基因插入原核表达载体,重组载体转化大肠埃希菌并用IPTG诱导,Ni2+-NTA亲和柱纯化融合蛋白,SDS-PAGE分析P5-2蛋白的表达情况。【结果】SRBSDV-An Hui-HN2 S5片段全长3 167 bp,包含S5-2基因全长612 bp,编码204个氨基酸。序列比对结果显示,SRBSDV-An Hui-HN2 S5片段与其他SRBSDV分离物S5片段的序列相似性极高,达99.0%~99.7%,而与斐济病毒属(Fijivirus)其他成员S5片段的序列相似性较低,仅为38.0%~71.3%;构建的S5片段系统发育树表明SRBSDV和RBSDV聚成1个分支,其中6个SRBSDV分离物聚成1个亚分支。原核表达获得相对分子质量约为47 000的重组蛋白,Western blot分析显示,GST单抗能够与重组融合蛋白发生特异性反应。【结论】SRBSDV各分离物之间亲缘关系非常近,而与Fijivirus其他成员亲缘关系较远,原核表达获得的融合蛋白为靶标蛋白。

山东水稻黑条矮缩病毒dsRNA提取与RT-PCR检测研究

水稻黑条矮缩病是由灰飞虱和白背飞虱等传播的病毒性病害,给水稻生产带来严重危害。通过提取水稻黑条矮缩病毒dsRNA发现,感病植株的dsRNA凝胶电泳存在8条带,而健康植株是空白结果,与报道的玉米粗缩病毒结果相同。根据水稻黑条矮缩病毒基因组序列的信息,在其S1和S10片段分别设计合成两对引物,对感染病毒植株和健康植株进行扩增,可在感病植株中分别扩增出水稻黑条矮缩病毒基因组特有的条带,而在健康植株中未能扩增出条带。利用此种方法可以建立水稻黑条矮缩病检测体系,对水稻黑条矮缩病进行早期检测和预报。

水稻黑条矮缩病毒P7-1基因对水稻的遗传转化及转基因植株的抗病性分析

【目的】通过在水稻中过量表达水稻黑条矮缩病毒(Rice black streaked dwarf virus,RBSDV)P7-1基因,分析RBSDV P7-1是否是导致水稻不育的重要致病因子,并明确过量表达P7-1转基因植株对病毒的抗性。【方法】采用RT-PCR方法从感病植物中扩增获得RBSDV P7-1基因,构建p CAMBIA-1300-P7-1载体,通过农杆菌转化法获得转基因水稻,观察水稻是否能够正常结实,并采用人工接种病毒方法分析转基因植株的抗性。【结果】过量表达RBSDV P7-1的转基因水稻生长、结实正常。在接种7 d和14 d时转基因植株中病毒积累量显著低于野生型对照,但在28 d时部分转基因株系中病毒积累量高于对照,接种30 d时转基因植株的发病率与对照无明显差异。【结论】在水稻中过量表达RBSDV P7-1不影响水稻的结实;转基因水稻在RBSDV侵染早期可抑制病毒的积累,但在后期对病毒的抗性与对照没有明显差异。