Identification and incidence of virus diseases of Capsicum annuum in the Lusaka Province of Zambia

Commercial capsicum fields in Lusaka Province were surveyed for the presence of viruses during 1996-01/06. The survey demonstrated the occurrence of five viruses in 13 fields. Virus identification was based on field disease syndrome, host range studies, DAS-ELISA and electron microscopy. The identified viruses were alfalfa mosaic alfamovirus (AMV), potato Y potyvirus (PVY), tobacco mosaic tobamovirus (TMV), cucumber mosaic cucumovirus (CMV) and pepper mild mottle tobamovirus (PMMV). The most prevalent and widespread virus, recovered from 70% of the surveyed fields, was AMV, and this was followed by PVY and TMV, which were detected in 50% and 40% of the fields respectively. CMV and PMMV were less common and occurred in 30% of fields. The study also showed that PVY could infect capsicum plants alone or in combination with CMV or TMV. The average plant infections caused by AMV was 80–100% and by TMV and PVY 50% and 60% respectively. The disease incidence in the case of CMV was 15–60% and for PMMV 30–40%. This is a first report on the identification of viruses that infect capsicum in Zambia.     

北京地区花生病毒病防治研究

应用无毒花生种子防治黄瓜花叶病毒(CMV)和花生轻斑驳病毒(PMMV)效果显著,在与大田毒源花生隔离500米条件下基本控制住两种病毒病发生。覆膜栽培有减轻两种病毒病特别是CMV引起的黄花叶病毒病的效果。在病区大面积隔离繁殖无CMV病毒种子获得成功,应用无CMV病毒种子和覆膜栽培示范获得显著防病效果。34个花生栽培品种和资源材料田间抗性鉴定,未发现有抗性品种和材料。     

北京地区花生病毒病及流行规律研究

1985—1987年研究表明北京地区花生上流行的病害主要有黄瓜花叶病毒CA株系(CMV-CA)引起的黄花叶病害和花生轻斑驳病毒(PMMV)引起的轻斑驳病害。血清鉴定451份花生病害样品,黄花叶病害样品受CMV-CA侵染占95.7％,轻斑驳病害样品受PMMV侵染占91.3％,中后期病害样品受CMV-CA和PMMV复合感染较普遍。CMV种传率2％左右,种传病苗在花生出苗后开始出现,6月病害进入高峰。三年CMV-CA流行程度明显不同,主要取决于苗期蚜虫发生早晚、发生量及苗期降雨量。PMMV种传率低于1％,病苗出现稍晚,但病害扩散快,6月上旬进入高峰,7月上、中旬发病率达100％。三年流行程度差异不明显。     

Occurrence of viruses in irrigated wheat in Zambia

Surveys were conducted during the cool-dry months of June–August 1997 and June–July 1998 for the presence of viruses in irrigated wheat in Central, Copperbelt, Lusaka and Southern Provinces of Zambia in 14 commercial farms and four wheat cultivar plots. Virus symptoms were observed on nine wheat cultivars ( Triticum aestivum 'Deka', 'Gamtoos', 'Lorie II', 'MM2', 'Nata', 'Nkwazi', 'P7', 'Scan' and 'Sceptre') of South African, Zambian and Zimbabwean origin. Several viruses were identified on the basis of field symptomatology, symptoms developing on mechanically inoculated indicator plant species or cultivars and serology (DAS-ELISA). The study revealed the occurrence of Brome mosaic virus (BMV), Barley stripe mosaic virus (BSMV), Barley yellow dwarf virus and its strains (BYDV-PAV and RPV), Soil-borne wheat mosaic virus (SBWMV), Wheat dwarf virus (WDV), Wheat streak mosaic virus (WSMV) and Wheat spindle streak mosaic virus (WSSMV). DSA-ELISA tests confirmed these identifications. The prevalence of viruses varied annually and from field to field. BSMV, BYDV-PAV, SBWMV, WDV, WSMV and WSSMV were found to be the most prevalent viruses. Viruses generally occurred in mixed infections of 3–6 viruses and the most common virus complex consisted of 4 viruses (50%), viz. BYDV, SBWMV, WDV and WSSMV. Five- and six-virus complexes were relatively less common (20% each) whereas 3-virus complex was noticed in only 10% cases. SBWMV and WSSMV have been found to be new to Africa and Zambia and are reportedly vectored by a fungal protist – Polymyxa graminis . BYDV strains MAV and SGV were also tested but gave negative results against their antisera.     

酶联免疫吸附法(ELISA)检测花生种子带毒的研究

 利用花生上分离到的花生轻斑驳病毒(PMMV),黄瓜花叶病毒CA株系(CMV-CA),花生矮化病毒Mi株系(PSV-Mi)所制备的抗血清,从中提取IgG、应用ELISA间接法检测花生种子,在花生种子中不程度地都检测出带有PMMV、CMV、PSV病毒,而且有复合带毒现象。经催芽的花生种子子叶、胚芽及胚根分别用PMMV和CMV免疫制备的抗体进行检测,花生的上述三部分均带有PMMV和CMV病毒,且胚芽中病毒量最高。萌发种子及未萌发种子的子叶无论从带毒率还是病毒含量上均看不出明显的差异。ELISA间接法由于直接利用商品酶标抗体,简化了试验程序,利于对种子带毒进行快速检测。     

Association of the inhibitor of virus replication with resistance mechanisms in pepper cultivars

The kinetics of accumulation of tobacco mosaic virus (TMV) and the S strain of pepper mild mottle virus (PMMV) in resistant and susceptible pepper cultivars was analyzed by enzyme-linked immunosorbent assay (ELISA). Crude protein extracts from noninoculated leaves of the resistant cultivar significantly inhibited TMV replication in tobacco protoplasts. Inoculation with either TMV or PMMV-S caused a slight increase in its inhibitory potency. In contrast, protein extracts from either inoculated or noninoculated leaves of the susceptible cultivar did not inhibit TMV replication in tobacco protoplasts. The protein extracts from the resistant cultivar gave a positive reaction with antibodies against the tobacco inhibitor of virus replication (IVR) in western blotting. The putative role of this IVR-like protein from the resistant cultivar in resistance against TMV is discussed.     

Systemic necrosis in tomato induced by a Japanese isolate of rehmannia mosaic virus in a temperature-sensitive manner

The Japanese isolate of rehmannia mosaic virus (ReMV-J) was initially isolated from chilli pepper in Japan. The leaves of diseased chilli pepper plants, which hold no tobamovirus-resistance genes, have mosaic symptoms. As the symptoms progress, the infected plants develop prominent leaf necrosis and severe leaf fall, followed by stem necrosis and fruit distortion. Additionally, ReMV-J systematically infects tomato and this reportedly leads to mottle in tomato when incubated at 20 °C. This study found that ReMV-J induces systemic necrosis of tomato – except for cultivar Micro-Tom – when incubated at 25 °C. To determine the virus factor involved in the induction of temperature-sensitive systemic necrosis on tomato, intergenic recombinants between ReMV-J and tomato mosaic virus were constructed. All recombinant viruses systemically infected tomato similar to ReMV-J. Recombinant viruses with the movement protein (MP) gene of ReMV-J induced systemic necrosis on tomato. Incubation at 20 °C significantly reduced the ability of recombinant viruses with the MP gene of ReMV-J to induce systemic necrosis. Thus, the ReMV-J MP gene is involved in the temperature-sensitive induction of systemic necrosis on most tomato cultivars tested. This study is the first to report the involvement of the MP gene in temperature-sensitive induction of systemic necrosis by tobamovirus on tobamovirus-susceptible tomato.     

Differential reaction of sweet pepper to infection with the crinivirus tomato chlorosis virus probably depends on the viral variant

The tomato chlorosis virus (ToCV), transmitted by whitefly species of the genera Bemisia and Trialeurodes in a semipersistent manner, causes significant losses in solanaceous crops including tomato (Solanum lycopersicum) and sweet pepper (Capsicum annuum). Worldwide reports of natural and experimental infection of sweet pepper plants with ToCV are contradictory, raising the question of whether the critical factor determining infection is related to the susceptibility of sweet pepper cultivars or the genetics of virus isolates. In this work, ToCV isolates obtained from different hosts and geographical origins were biologically and molecularly analysed, transmitted by B. tabaci MEAM1 and MED, and the reaction of different sweet pepper cultivars was evaluated under different environmental conditions. Brazilian ToCV isolates from tomato, potato (S. tuberosum), S. americanum, and Physalis angulata did not infect plants of five sweet pepper cultivars when transmitted by B. tabaci MEAM1. Temperatures did not affect the sweet pepper susceptibility to tomato-ToCV isolates from São Paulo, Brazil, and Florida, USA. However, sweet pepper-ToCV isolates from Spain and São Paulo, Brazil, were transmitted efficiently to sweet pepper plants by B. tabaci MEAM1 and MED. Although the results indicated that ToCV isolates from naturally infected sweet pepper plants seem to be better adapted to plants of C. annuum, phylogenetic analyses based on the complete nucleotide sequences of RNA1 and RNA2 as well as the p22 gene did not reveal significant nucleotide differences among them. Additional studies are needed to identify intrinsic characteristics of ToCV isolates that favour infection of sweet pepper plants.     

Viruses of pepper in plastic houses in Crete

During a survey of virus diseases affecting pepper grown in plastic houses in Crete, during 1984–1986, tomato mosaic virus (ToMV) and tobacco mosaic virus (TMV) were detected. The most common virus was TMV, being present in samples of alle pepper cultivars carrying the L₁ resistance gene, while ToMV was isolated only from susceptible pepper cultivars. According to responses ofCapsicum spp. the isolates from 640 samples checked were classified into three pathotypes: P₀, P_1.2 and P_1.2.3. Results of this study show that P_1.2 represents at present the major threat to the Cretan pepper industry.Samenvatting Bij een in de jaren 1984–1986 gehouden inventarisatie van virusziekten in paprika in plastic-foliekassen op Kreta werd zowel het tabaksmozaïekvirus (TMV) als het tomatemozaïekvirus (ToMV) aangetoond. TMV kwam zeer algemeen voor: het werd aangetroffen in alle monsters van de paprikarassen met het resistentiegen L₁. ToMV werd alleen geïsoleerd uit planten van vatbare paprikarassen. Volgens de waargenomen symptomen die de isolaten van 640 monsters opCapsicum spp. vertoonden, konden de isolaten in drie pathotypen, nl. P₁, P_1,2 en P_1,2,3, worden geklassificeerd. Uit het onderzoek is gebleken dat P_1,2 de belangrijkste bedreiging vormt voor de teelt van paprika op Kreta.     

Endophytes of <Emphasis Type="Italic">Lippia citriodora</Emphasis> (Syn. <Emphasis Type="Italic">Aloysia triphylla</Emphasis>) enhance its growth and antioxidant activity

Sweet pepper (Capsicum annuum) is a popular crop worldwide and an asymptomatic host of the begomovirus (Geminiviridae) Tomato yellow leaf curl virus (TYLCV). A previous study showed that TYLCV could be transmitted by the seeds of tomato plants, but this phenomenon has not been confirmed in other plants. In 2015, four different cultivars of sweet pepper (‘Super Yellow,’ ‘Super Red,’ ‘Sunnyez’ and ‘Cupra’) known to be susceptible to TYLCV were agro-inoculated with a TYLCV infectious clone. Three months after inoculation, the leaves of the ‘Super Yellow’ cultivar showed 80% (8/10) susceptibility and the other three sweet pepper cultivars showed 30 to 50% susceptibilities. All of the ‘Super Yellow’ seed bunches (five seeds per bunch) from plants whose leaves were confirmed to be TYLCV-infected were also TYLCV-infected (8/8). The seeds of other cultivars showed 20 to 40% susceptibilities. Virus transmission rates were also verified with 10 bunches of seedlings for each cultivar (five seedlings per pool). Eight bunches of ‘Super Yellow’ seedlings (8/10) were confirmed to be TYLCV-infected and one to three bunches of each of the other cultivar seedlings were also infected. Viral replication in TYLCV-infected seeds and seedlings was confirmed via strand-specific amplification using virion-sense- and complementary-sense-specific primer sets. This is the first report of TYLCV seed transmission in sweet pepper plants and among non-tomato plants. Because sweet pepper is an asymptomatic host of TYLCV, seeds infected with TYLCV could act as a silent invader of tomatoes and other crops.     

Phenotype and spectrum of action of the Pvr4 resistance in pepper against potyviruses, and selection for virulent variants

The dominant Pvr4 gene identified in Capsicum annuum cv. Criollo de Morelos 334 (CM334) is frequently used in pepper cultivars because it possesses one of the largest spectra of action among plant virus resistance genes. This gene was previously shown to confer efficient resistance to all known Potato virus Y isolates, to Pepper mottle virus , to Pepper yellow mosaic virus and to Ecuadorian rocoto virus. This study showed that the W4 line, derived from CM334 and carrying Pvr4 , was also resistant to Peru tomato mosaic virus and Pepper severe mosaic virus , but not to Pepper veinal mottle virus , Chilli veinal mottle virus or Tobacco etch virus . It was noticed that the phenotype of the resistance was atypical since, in the W4 line, hypersensitive reaction or extreme resistance could be observed, depending on virus isolates and inoculated organs. Despite the large deployment of Pvr4 in hybrid cultivars, the numerous tests performed in controlled conditions and the use of W4 serial back-inoculations with potyvirus isolates controlled by this line, no virulent variant isolates were obtained. However, it was shown that the use of graft inoculation experiments allow PVY virulent variants to be selected.     

蚜虫迁飞动态与辣椒病毒病流行的关系

在江苏省泰县和南京城郊辣椒病毒病的优势病原为黄瓜花叶病毒(CMV),次为烟草花叶病毒(TMV),此外还鉴定了一种蚕豆萎蔫病毒(BBWV)。辣椒病毒病发病株率随迁入辣椒田内有翅蚜总量的增长而增高,两者呈显著正相关,蚜虫迁飞高峰后20天左右出现辣椒发病高峰。田间最有效的传毒介体为桃蚜、萝卜蚜、禾谷缢管蚜,它们的迁飞高峰都在5月中、下旬,此时正值辣椒感病阶段,对发病率和产量影响较大。5月中旬至6月中旬置放田间的辣椒苗发病率最高,说明此时迁入田间的有翅蚜传毒最为有效,此期间是阻断蚜虫传毒的关键时期。     

花脸蘑蛋白粗提液控制辣椒病毒病及促生作用研究

本研究提取野生食用菌——花脸蘑Lepista sordida的蛋白粗提液,并在室内测定其对辣椒病毒病的控制作用及其对辣椒植株生长的促进作用。结果表明,以25、50和100μg·mL^-1的花脸蘑蛋白粗提液分别茎叶喷雾处理后再接种黄瓜花叶病毒,防治效果分别为72.11%、79.53%和94.86%;以100μg·mL^-1的花脸蘑蛋白粗提液通过茎叶喷雾,浸种与茎叶喷雾结合两种方法处理辣椒后,辣椒根系的湿重及干重、辣椒地上部湿重和干重、叶片数、叶面积、叶绿素指数、株高、茎粗和壮苗指数均比对照明显提高。综上所述,花脸蘑蛋白粗提液在室内对黄瓜花叶病毒引起的辣椒病毒病有很好的控制作用,同时对辣椒生长具有良好的促进作用。     

Disinfection of pepper seed infected with different strains of capsicum mosaic virus by trisodium phosphate and dry heat treatment

Disinfection of pepper seed infected with capsicum mosaic virus (CaMV) by immersion in 100 g/1 Na₃ P0₄ solution was compared with dry heat treatment at 76°C. The virus content of the seed varied with the CaMV strains used to infect the pepper cultivars and the time of harvest of seeds from infected plants. Immersion times in Na₃PO₄ had to be increased from 15 min to 2 h to obtain near-complete virus inactivation; these treatments had no effects on germination.
Heating seed in an oven at 76°C for 3 days following a waiting period of 3 months after harvest always eliminated all the virus present, but adversely affected germination. This resulted in delayed emergence and a reduction in the number of seedlings suitable for further raising. The viability of heat-treated seeds also decreased with continued storage after treatment.
There were inconsistent differences in germination of seed from healthy plants and plants infected with the CaMV strains P8 or P11. The possibility of internal seed infection and practical consequences are discussed.     

云南辣椒正番茄斑萎病毒属病毒的分子鉴定

辣椒是云南省主要经济作物之一,近年来病毒病尤其是正番茄斑萎病毒属病毒发病严重,影响了辣椒产量和品质。利用RT-PCR技术对从云南辣椒主产区采集的疑似感染正番茄斑萎病毒属病毒的25份辣椒样品进行分子鉴定,结果显示,12份样品检测出正番茄斑萎病毒属病毒,检出率为48.0%,其中6份是番茄斑萎病毒tomato spotted wilt orthotospovirus (TSWV),检出率为24.0%;5份是番茄环纹斑点病毒tomato zonate spot orthotospovirus (TZSV),检出率为20.0%;有1份是TSWV和TZSV复合侵染,检出率为4.0%,这是在云南辣椒生产上首次发现TSWV和TZSV的复合侵染。通过鉴定,初步了解正番茄斑萎病毒属病毒在云南辣椒生产中的发生情况和种类,为制定云南地区该属病毒的防治策略提供理论依据。     

黑龙江省不同来源稻瘟病菌致病性分析

将从黑龙江‘龙粳17’、‘吉特639’和‘垦稻10’病田中分离的9、8、8个稻瘟病菌菌株喷雾接种到4套鉴别寄主上,结果表明,中国稻瘟病菌生理小种鉴别寄主将这3个来源的菌株分别划分成8、7和4个生理小种,日本清泽鉴别品种则将其分别划分成9、8和8个生理小种,以黑龙江本地水稻品种作为鉴别品种,则可将其分别划分成8、7和5个致病型,以24个水稻抗稻瘟病单基因系为鉴别品种,则将上述菌株分别划分为9、7和8个致病型。     

RNA 3 deletion mutants of beet necrotic yellow vein virus do not cause rhizomania disease in sugar beets

ABSTRACT Two mutant strains of beet necrotic yellow vein virus (BNYVV) containing deletions in RNA 3 were obtained by single lesion transfers in Tetragonia expansa. The deleted regions encode either 94 or 121 amino acids toward the C-terminal part of the 25-kDa protein (P25). Wild-type and mutant virus strains were inoculated by Polymyxa betae to sugar beet seedlings of susceptible and partially resistant cultivars. No differences were found in virus content in rootlets between mutant and wild-type viruses or between susceptible and resistant cultivars after culture for 4 weeks in a growth cabinet. However, when virus-inoculated seedlings were grown in the field for 5 months, the wild-type virus caused typical rhizomania root symptoms (69 to 96% yield loss) in susceptible cultivars, but no symptoms (23% loss) developed in most plants of the resistant cultivar, and BNYVV concentrations in the roots were 10 to 20x lower in these plants than in susceptible plants. In contrast, the mutant strains caused no symptoms in susceptible or resistant cultivars, and the virus content of roots was much lower in both cultivars than in wild-type virus infections. Wild-type RNA 3 was not detectable in most of the taproots of a resistant cultivar without any symptoms, suggesting that replication of undeleted RNA 3 was inhibited. These results indicate that the P25 of BNYVV RNA 3 is essential for the development of rhizomania symptoms in susceptible cultivars and suggest that it may fail to facilitate virus translocation from rootlets to taproots in the partially resistant cultivar.     

Influence of the amount of blackgram mottle virus in different tissues on transmission through the seeds of Vigna mungo

Blackgram mottle virus (BMoV) was transmitted via up to 16% of seeds of different cultivars of blackgram, as determined by seedling symptom tests. The percentage of seed infection by BMoV as determined by EL1SA was even higher. Seed transmission was highest in cv. PLU-277 (15.9%), followed by cvs T-9 (11.8%), PLU-213 (7.0%) and UH-81-7 (1.3%). Seed transmission was correlated with the amount of virus present in the embryonic axis and later in primary leaves. The presence of virus in the testa alone did not result in its transmission through seeds. Virus concentration in different tissues varied; the mean amount of virus in the three cultivars was found to be 48–1234 ng per embryonic axis, 15–24 ng per cotyledon, and 12–20 ng per testa. The infection of primary leaves through the seed also resulted in systemic infection if the amount of virus in primary leaves exceeded 100 ng/100 mg of tissue. Close agreement was found between the percentage of seedlings with systemic infection and the percentage of seeds and embryonic axes containing more than 100 ng virus. The cultivars that resisted seed transmission contained relatively small amounts of the virus in embryonic axes.     

Reduction of yield losses in pepper crops caused by potato virus Y in KwaZulu-Natal,South Africa,using plastic mulch and Yellow sticky traps

Potato virus Y is the major cause of crop losses in pepper in KwaZulu-Natal Province, South Africa. An evaluation of the efficacy of five treatments to reduce transmission of the virus to pepper by aphids was conducted. The use of white plastic mulch was the most effective, resulting in a 32% yield increase over the untreated control. Yellow sticky plastic traps also had a significant beneficial effect on the yield, but mineral oil sprays as well as a neem-derived product were ineffective. Weekly mercaptothion (malathion) sprays caused an increase in virus incidence, and yields were only 49% that of the untreated control.     

Genetic diversity and mixed infections of begomoviruses infecting tomato, pepper and cucurbit crops in Nicaragua

Begomoviruses were detected in Nicaraguan fields of tomato ( Lycopersicon esculentum ) and adjacently growing plants of pepper ( Capsicum annuum ), chilli pepper ( C . baccatum ), cushaw ( Cucurbita argyrosperma ) and Mexican fireplant ( Euphorbia heterophylla ) using polymerase chain reaction (PCR) and universal begomovirus primers. All tomato and Mexican fireplant plants showing symptoms were infected with begomoviruses, while only 30–46% of the pepper, chilli pepper and cushaw plants showing symptoms tested virus-positive. No begomoviruses were found in potato. The virus species were provisionally identified by sequencing 533 bp of the viral coat protein gene ( AV1 ). Tomato severe leaf curl virus (ToSLCV), Tomato leaf curl Sinaloa virus (ToLCSinV) and Pepper golden mosaic virus (PepGMV) were found to infect both tomato and pepper. A new provisional species designated Tomato leaf curl Las Playitas virus (ToLCLPV) was detected in a tomato plant. Squash yellow mottle virus (SYMoV) and PepGMV were found in cucurbits, the latter for the first time in this host. Euphorbia mosaic virus (EuMV) was detected in Mexican fireplant. Sequencing of a larger number of PCR-amplified clones from selected plants revealed intraspecific viral sequence variability, and also multiple begomovirus infections which could represent up to three species in a single tomato or cushaw plant. Phylogenetic grouping of virus sequences did not correlate with the host of origin.