Detection of Tomato yellow leaf curl Sardinia virus in Tunisia

Surveys were undertaken for tomato yellow leaf curl viruses in the main Tunisian tomato-growing areas in fields and plastic houses. Symptoms included yellowing, leaf curling and stunting. Collected samples were submitted to molecular analysis using two approaches: (1) hybridization tests with two DNA probes corresponding to an intergenic region derived from a cloned dimer of an Egyptian full-length TYLCV and to the coat region of a Tunisian TYLCV isolate; (2) PCR amplification coupled to RFLP allowing both identification and clustering of Tunisian isolates. Only Tomato yellow leaf curl Sardinia virus was detected in Tunisia.     

河北省番茄黄化曲叶病毒病的分子鉴定初报

双生病毒是一类具有孪生颗粒形态的植物单链病毒,目前双生病毒病害已在多个国家和地区的作物上造成严重危害。近年来,我国多省报道作物上有这类病毒的发生,且有逐年加重和扩散的趋势。根据危害番茄的双生病毒DNA A序列保守区设计简并引物,对2009年4月采自河北省魏县表现叶片黄化、曲叶症状的4个番茄样品进行PCR检测,均为双生病毒阳性,对样品的扩增片断进行了克隆测序,经序列比对分析,与番茄黄化曲叶病毒（Tomato leaf curl virus,TYLCV）山东分离物（FJ646611.1）序列相似性为99.25%~99.55%,说明河北番茄黄化曲叶病由TYLCV引起。     

Control of the Bemisia tabaci/Tomato yellow leaf curl virus complex in tomato nurseries in Portugal*

According to EU and Portuguese law, inspection of horticultural nurseries is an important task for the Phytosanitary Inspection Services of the NPPO, which requires the introduction of some rules: official registration of producers and production of plant material of EC quality. Mainly as a result of the introduction of Tomato yellow leaf curl virus (TYLCV) in 1995, tight control of registered nurseries was implemented in Algarve in order to ensure the production of young horticultural plants of good varietal and phytosanitary quality. A survey system was established in order to contain pests by trying to eradicate them in nurseries. Nurseries were obliged to adopt new technologies, including for example the compulsory use of screen nets, the improvement of the existing glasshouses and the implementation of strict rules for access of people to these places. The Administration (MADRP/DRAALG) has provided financial support in order to have new nursery glasshouses (without increasing the area) suitable for the control of Bemisia tabaci and other pests which may be disease vectors. It should be stressed that about 50% of nursery production in Algarve is used in other regions of Portugal, considered as EU Protected Zones for B. tabaci.     

侵染广西番茄的番茄黄化曲叶病毒的分子鉴定

番茄黄化曲叶病毒病是番茄生产上的毁灭性病害,严重影响番茄产量及品质。2019年从广西百色市采集疑似番茄黄化曲叶病叶片样品,采用滚环扩增(RCA)及基因克隆等方法,获得了4个烟粉虱传双生病毒的全基因序列,4个分离物的全长序列分别为2 776、2 781、2 752、2 781 bp,均编码6个开放阅读框;核苷酸相似性比较发现,4个分离物彼此间的相似性均在90%以上,与已报道的番茄黄化曲叶病毒Tomato yellow leaf curl virus (TYLCV)各分离物间的相似性也在91%以上;系统进化分析表明,TYLCV广西分离物BS-2和BS-4与TYLCV-Hunan、BS-1和BS-3与TYLCV-YN6553等分离物处于独立的小分支,说明TYLCV广西分离物与TYLCV-Hunan、TYLCV-YN6553具有较近的亲缘关系。本研究首次报道TYLCV在广西发生。     

Tomato yellow leaf curl virus: host range and virus-vector relationships

The Jordanian isolate of tomato yellow leaf curl virus has a narrow host range restricted to a few solanaceous plants. Severe symptoms developed on tomatoes and Datura stramonium , whereas Nicotiana glutinosa and N. tabacum cvs Samsun and Havana 423 were infected without showing symptoms. The whitefly Bemisa tabaci is an efficient vector; a single whitefly was able to transmit the virus. The minimum acquisition and inoculation feeding periods were 60 and 30 min, respectively, and the latent period was 20–24 h. The virus was retained by Bemisia tabaci for 11 days. The host range and virus vector relationships of the Jordanian isolate are reported for the first time.     

北京地区番茄黄化曲叶病毒病的鉴定及防治对策

番茄黄化曲叶病毒病是一种由烟粉虱传播的病毒病,给番茄生产造成严重威胁。2009年在北京郊区调查时发现部分保护地种植的番茄植株表现典型黄化曲叶症状。通过提取典型症状样品总DNA利用粉虱传双生病毒检测简并引物PA/PB,进行PCR扩增到541bp的特异条带。通过测序和核苷酸序列比对表明该序列与番茄黄化曲叶病毒序列相似性最高为99%。分子检测结果表明北京郊区部分保护地种植的番茄已被烟粉虱传播的番茄黄化曲叶病毒侵染危害。     

番茄黄化曲叶病毒在湖北首次报道

2014年春季,在湖北省武汉市发现种植的番茄表现植株矮缩,叶片上卷,叶缘黄化等症状。PCR检测结果显示,所有采集的病样中均存在菜豆金色花叶病毒属病毒。进一步通过滚环扩增方法获得了该病毒的湖北分离物HB01的全基因组。基因克隆及序列分析结果表明,该病毒基因组全长为2 781nt,与已报道的番茄黄化曲叶病毒(TYLCV)各分离物同源性在89.0%以上,而与来自中国不同地区的TYLCV分离物的同源率均在97.0%以上。因此,HB01属于TYLCV的一个分离物。     

Tomato yellow leaf curl virus effects on chloroplast biogenesis and cellular structure

Tomato yellow leaf curl virus (TYLCV) is a begomovirus causing significant crop losses in tomatoes worldwide. TYLCV infection has several defined symptoms that are characterized at the whole plant level that include yellowing and curling of the leaves, stunting and growth retardation, and severe yield losses that can reach 100%. While the etiology and phenotypic symptoms of TYLCV infection were characterized, little is known about the cellular basis of these symptoms. Our goal in the present study is to describe some of the microscopic features of the disease while comparing TYLCV-susceptible and resistant near-isogenic tomato plants under infection. We depict the cellular changes that occur in susceptible line as a result of TYLCV infection that include: epidermal cell sizes reduction, accompanied with modifications in cell shape; reduction in plastid number, plastid size and chlorophyll content; diminished expression genes encoding LHC, Rub L, CAB4, and CAB8 and a surge in plasmodesmata number after infection. We conclude that TYLCV affect many targets or that it has a very critical target in cellular development.     

番茄褪绿病毒与番茄黄化曲叶病毒复合侵染对番茄褪绿病毒传播的影响

番茄褪绿病毒Tomato chlorosis virus(ToCV)是一种由烟粉虱Bemisia tabaci传播的正义单链RNA病毒,在田间常与番茄黄化曲叶病毒Tomato yellow leaf curl virus(TYLCV)复合侵染而造成番茄生产上重大的经济损失。为了明确ToCV与TYLCV的复合侵染对烟粉虱传播ToCV所造成的影响,本文采用RT-PCR以及qRT-PCR检测了复合侵染的番茄对烟粉虱获取和传播ToCV的影响。研究表明,烟粉虱取食复合侵染的番茄后对ToCV的传播效率显著提高,仅25头烟粉虱的传毒率即可达到100%,ToCV在烟粉虱以及番茄体内的累积量均显著提高。说明这种复合侵染促进了烟粉虱对ToCV的传播,在田间应当及时防控烟粉虱,警惕病毒与烟粉虱的蔓延。     

Detection of Tomato yellow leaf curl virus in imported tomato fruit in northern Europe

Imported tomato fruits infected with Tomato yellow leaf curl virus (TYLCV) were identified on the market in northern Europe using paper‐based FTA Classic Cards (Whatman), polymerase chain reaction (PCR) and partial DNA sequence analysis. Trade tomatoes originating from southern Europe, Africa and the Middle East were sampled in Estonia and Sweden, and tested for infection with begomoviruses. Out of 100 batches analysed with five fruits sampled in each batch (58 batches from Estonia and 42 from Sweden), 20 batches were positive (16 from Estonia and four from Sweden). Rolling circle amplification (RCA) and full‐length genome sequence analysis of one isolate collected in Estonia and one isolate in Sweden, revealed highest nucleotide sequence identity at 99% to TYLCV‐IL for the Estonian isolate and at 97% to TYLCV‐Mld for the Swedish isolate. In this study, TYLCV was identified for the first time in imported tomato fruits on the market in northern Europe. FTA cards proved to be an effective means to collect, extract and store begomovirus DNA from tomato fruits and the subsequent molecular analysis.     

Control of the Bemisia tabaci/Tomato yellow leaf curl virus complex on protected tomato crops in Algarve (Portugal)*

The whitefly Bemisia tabaci has been a serious pest in protected tomato crops since 1995 in the south of Portugal (Algarve), causing severe losses mainly resulting from Tomato yellow leaf curl virus (TYLCV), first reported in the autumn/winter season. In order to manage and control the B. tabaci/TYLCV complex, experimental field trials were carried out between 1997 and 2000. Several control methods were tested, such as the application of white screen nets to windows and doors, chemical treatments against B. tabaci and the use of cucumber as a trap crop. The results show that the percentage of plants with TYLCV symptoms mainly reflects B. tabaci infestation level in the first 6 weeks. Screen net protection was the control method that clearly provided a low incidence of plants with TYLCV symptoms in the autumn/winter season. Additionally, insecticide treatments, made weekly in the first 6 weeks, may give improved protection. In the winter/spring season, the B. tabaci/TYLCV complex is a minor problem because of the low populations of B. tabaci and the climatic conditions. Information about the work in progress and results was given to growers through visits to the experimental fields and oral presentations.     

Capsicum Species: Symptomless Hosts and Reservoirs of Tomato yellow leaf curl virus

ABSTRACT Five Capsicum species were tested for susceptibility to Tomato yellow leaf curl virus (TYLCV) and the mild strain of TYLCV (TYLCV-Mld). TYLCV was able to infect 30 of 55 genotypes of C. annuum, one of six genotypes of C. chinense, one of two genotypes of C. baccatum, and the only genotype of C. frutescens tested but was unable to infect the one genotype of C. pubescens tested. This is the first evidence for the susceptibility of C. baccatum, C. chinense, and C. frutescens to TYLCV. Unlike TYLCV isolates, TYLCV-Mld was unable to infect C. chinense. No host differences were observed between the Israeli and Florida isolates of TYLCV. None of the Capsicum species showed symptoms after infection with TYLCV or TYLCV-Mld. TYLCV was detected in fruits of C. annuum, but whiteflies were unable to transmit virus from fruits to plants. White-flies were able to transmit both TYLCV and TYLCV-Mld from infected pepper plants to tomato plants. Pepper plants in research plots were found infected with TYLCV at rates as much as 100%. These data demonstrate the ability of some genotypes of pepper to serve as reservoirs for the acquisition and transmission of TYLCV and TYLCV-Mld.     

侵染新疆加工番茄的中国番茄黄化曲叶病毒 DNA-A的基因组特征

 从新疆加工番茄上分离到病毒分离物XJ26-4,对其基因组DNA-A 全序列测定表明,XJ26-4 DNA-A 全长2 737 个核苷酸(GenBank 登录号:FN985163),具有典型的双生病毒基因组特征。进一步序列比较发现,XJ26-4 DNA-A 与中国番茄黄化曲叶病毒(Tomato yellow leaf curl China virus, TYLCCNV)各分离物的同源性最高,达到91. 2% ~ 99. 5% ,而与其他双生病毒的序列相似性均在79. 5% 以下,表明XJ26-4 是TYLCCNV 的一个分离物。这是首次明确新疆加工番茄受到粉虱传双生病毒的侵染。     

A simple, efficient agroinoculation soaking procedure for Tomato yellow leaf curl virus

Tomato yellow leaf curl virus (TYLCV, genus Begomovirus, family Geminiviridae), poses a serious threat to tomato crops in tropical and subtropical regions. We developed a simple agroinoculation method with an infectious clone of TYLCV. Dipping of excised sections of susceptible tomato shoots in an Agrobacterium suspension successfully introduced the replicating virus with high efficiency. An additional vacuum treatment for 5 min ensured uniform infection without escapes, allowing evaluation of differences in TYLCV resistance among tomato cultivars. The method can be used in laboratory experiments for virological studies and in breeding programs for resistant cultivars.     

Development of a Scale for Evaluation of Tomato yellow leaf curl virus Resistance Level in Tomato Plants

ABSTRACT We have developed a scale of differential hosts that enables the determination and comparison of level of resistance to Tomato yellow leaf curl virus (TYLCV) expressed by resistant tomato lines or by individual plants in a segregating population. The scale is composed of seven different homozygous tomato genotypes that exhibit different levels of TYLCV resistance, ranging from fully susceptible to highly resistant. The differential hosts composing the scale were inoculated with TYLCV under greenhouse conditions. Four weeks after inoculation the plants were evaluated for disease symptom severity, and virus DNA titer was determined. The different genotypes were arranged in the scale according to symptom severity score. The different genotypes were then tested under different environmental conditions, inoculated at different ages, and tested in a field experiment assaying TYLCV-induced yield reduction. While the symptom severity score of each individual resistant genotype changed under different environmental conditions, the relative position on the scale did not alter, except for one genotype. Thus, to evaluate disease resistance of a given tomato genotype, the genotype in question should be inoculated alongside the differential hosts composing the scale, and within 4 weeks one can determine the relative level of resistance of the tested genotype.