Tobamovirus Research Articles

Updating viral agents in tomato seeds with new generation diagnostic technologies

The aim of this study is to identify and update the list of viral pathogens in tomato seeds, which plays an important role for our country's economy, and to control, on behalf of our country, viral factors like TYLCV and PepMV, which were thought not to be existing in the past but were determined by new and sensitive methods in the recent years. It is also the aim, if viral pathogens like TYLCV and PepMV are found, to share this findings with the necessary institutions and to update the viral factors which needs to be tested, and the quarantine lists. Two hundred and thirty-eight seed samples were used in this study. Serological and molecular methods were used in order to identify the viral pathogens in the seed samples. Two hundred and thirty-eight seed samples of different tomato varieties were tested in order to prove the possible existence of Tobacco mosaic tobamovirus (TMV), Tomato mosaic tobamovirus (ToMV), Cucumber mosaic cucumovirus (CMV), Tomato yellow leaf curl geminivirus (TYLCV), Tomato spotted wilt tospovirus (TSWV), Pepino mosaic potexvirus (PepMV), Pepper mild mottle tobamovirus (PMMoV), and Tomato brown rugose fruit tobamovirus (ToBRFV) and as a result 12% of the seeds were founded to be infected with TMV, 23% with ToMV and 8% with CMV. Within the scope of this study it was seen that some seed samples have mixed infections. Sixty-seven seeds of the 238 seeds has been found to be infected in this study. This is a rate of 28% were the seeds are infected at least with one viral pathogen.

Immune status of flower-ornamental plants in the collections of the Main Botanical Garden (Viral and Fungal Pathogens)

The article presents the results of studies to assess the resistance of a number of ornamental crops to viral and fungal pathogens. The objects were collections of Phlox L., Paeonia L., Dahlia L.; pathogens of powdery mildew phlox (Erysiphe cichoracearum D. C. f. phlogis Jacz.), cladosporiosis (Cladosporium paeoniae Pass.) and rust (Cronartium fl accidum (Alb. et Schw.) Wint.) peony, dominant viruses in the gene pool of these cultures. As a result of the conducted studies, it was found that the nature of interaction with pathogens at the level of plant varieties and genotypes is realized differentially. Phlox L. varieties have been isolated. with a medium and high level of resistance, and two immune varieties ‘Bright Eyes’ and ‘Karl Furst’ in conditions of a severe infectious background to Erysiphe cichoracearum D. C. f. phlogis Jacz., however, not all varieties have retained this property over the past 5 years. Two varieties have a decrease in the level of resistance, four varieties have lost this property, and three varieties have increased this property. Fife varieties with a high level of resistance to the complex of dominant viruses (Cucumber mosaic cucumovirus (CMV), Tobacco mosaic tobamovirus (TMV), Alfalfa mosaic alfamovirus (AMV), Arabis mosaic nepovirus (ArMV)) were identifi ed and 38 varieties were ranked according to the index of resistance to individual pathogens. In the Dahlia L. collection no virus-resistant varieties were found. Two out of five known viruses have been identifi ed within the Paeonia L. gene pool, to which 65% of varieties are resistant. Most varieties of Paeonia L. had weakly expressed resistance to the causative agent of Cladosporium paeoniae Pass. No varieties with a high level of resistance have been identified. Only 10 varieties susceptible to Cronartium flaccidum (Alb. et Schw.) Wint. were registered in the gene pool, 16 – medium-resistant and 30 – highly resistant. The article emphasizes the importance of finding sources of resistance and cultivating resistant varieties to harmful organisms as the safest method from the point of view of greening plant protection.

First report of Chili pepper mild mottle virus in calibrachoa in the United States

Beginning in January 2022, plants of the popular solanaceous ornamental calibrachoa (Calibrachoa spp.) from commercial producers in the United States were observed with various viral disease symptoms including chlorosis, purple mottling and tip necrosis of leaves, and colour-break of flowers (Figures 1, 2). Seventy cuttings of the affected plants were submitted to Agdia Testing Services (Agdia Inc., USA) for analysis and produced positive results with Tobacco mosaic virus ImmunoStrip® (lateral flow immunoassay) and ELISA, Pepper mild mottle virus ImmunoStrip® and ELISA, and Tomato mosaic virus ELISA suggesting the presence of a tobamovirus. To confirm and extend these serological results, total RNA was isolated from seven samples using a modified RNeasy protocol (Qiagen, Germany) and tested using a tobamovirus group RT-PCR (Maroon & Zavriev, 2002). The sequence of the RT-PCR amplicons indicated the presence of the recently described tobamovirus, Chili pepper mild mottle virus (CPMMoV; Vélez-Olmedo et al., 2021). For further characterisation, total RNA from four calibrachoa samples (two each from two different greenhouses located in two different states) representing four different calibrachoa varieties were selected for additional RT-PCR testing at USDA-ARS with degenerate tobamovirus primers. Amplicons of c. 200 bp were observed from all samples with the tob4404v and tob4593 primers (Adkins et al., 2018) designed to amplify a conserved portion of the replicase gene. Similarly, amplicons of c. 800 bp were observed from all samples with the SolACPv and SolACPvc primers (Chellemi et al., 2011) designed to amplify the 3′ terminus of the movement protein gene, the entire coat protein (CP) gene, and part of the 3′ UTR. Amplicons were directly sequenced (GenBank Accession Nos. ON381946-ON381953) and those from each primer set shared 99–100% nucleotide identity with each other, and 99–100% nucleotide identity with the corresponding regions of CPMMoV isolate Oxampampa4 (MN164455) confirming the presence of this tobamovirus. CPMMoV-specific CP gene primers (Vélez-Olmedo et al., 2021) also produced amplicons of the expected size, c. 1,100 bp. No other tobamovirus sequences were detected with any of these primer sets. We additionally tested the same four samples with degenerate potyvirus (Gibbs & Mackenzie, 1997) and orthotospovirus (Chu et al., 2001) primers; no amplicons were observed. CPMMoV was first reported in 2021 from field-grown pepper in Peru (Vélez-Olmedo et al., 2021). To the best of our knowledge, this is the first report of CPMMoV in calibrachoa or any other greenhouse-grown ornamental host. Further research is necessary to determine the prevalence of CPMMoV in ornamental and vegetable crop hosts, and the potential impact this tobamovirus may have on these crops. Salvador Lopez and Carrie Vanderspool are acknowledged for their excellent technical assistance.

Physiological and morphological response of tomato plants to nano-chitosan used against bio-stress induced by root-knot nematode (Meloidogyne incognita) and Tobacco mosaic tobamovirus (TMV)

Root-knot nematodes (Meloidogyne spp.) have been reported to be responsible for large economic losses of agricultural crops due to their wide host range and variety of suitable climates. The control measures of these parasitic nematodes depend upon synthetic nematicides and a small number bio-based products. Chemical nematicides are eliciting adverse effects on the environment and human health. In the present study, an alternative tool, nano-chitosan was tested for the control the root-knot nematodes, Meloidogyne incognita, and Tobacco mosaic tobamovirus (TMV) in greenhouse-cultivated tomato. The effect of nano-chitosan on morphological (weight and length of shoot and root systems) and biochemical responses (Polyphenol oxidase, Peroxides, Total soluble phenol and Total protein) was assessed. The obtained results indicated that densities of Meloidogyne incognita alone or in the presence of TMV were decreased by nano-chitosan at a range of 45.89 to 66.61%, while root gall desntiy was reduced between 10.63 and 67.87%. Moreover, the density of TMV on tomato leaves singly or in the presence of M. incognita was suppressed at range of 10.26 to 65.00% after 20 days of infection, and reached up to 58.00% after 40 days of infection. However, soil application of nano-chitosan pre infection reduced TMV density only by 5.48%. Morphogenesis of tomato plants such as shoot and root systems were significantly improved. The impacts of nano-Chitosan applications on total soluble phenol, total protein, polyphenol oxidase and peroxides after 20 and 40 days of infections varied.

Action Mechanism of Synthesized Nitrogen Base Analogues that inhibit Tomato Mosaic tobamovirus

Synthetic Nitrogen Base Analogues (SNBA) fused heterocyclic purine and pyrimidine derivatives are of great biological interest, especially as antiviral, antitumor and antimicrobial agents. The viruses are one of the risk factors for plants resulting in gigantic economic losses . Four SNBA compounds were assayed antiviral activity, plant cytotoxicity as well as determining their mode of action against Tomato mosaic tobamovirus (ToMV) by using the local lesion on Datura metel as well as infectivity assayed on tomato plants . The cytotoxicity of Ph-Oxanzolo and Oxazalone compounds at concentrations 15 and 20μg/mL showed chlorosis, mottling, necrosis, wilting, and curling at three to four days after spraying while Hippuric acid and Benzotriazolo compounds were safe on test plants and didn’t show any signs of toxicity on D.metel and tomato plants . Ph-Oxanzolon and Oxazalone had virucidal activity where showed high percentage of inhibition at simultaneous- ToMV inoculation at 5,10,15,20 ppm concentration and low percentage of inhibition at pre-and –post ToMV inoculation , as well as they showed high ToMV concentration and low percentage disease severity at 10 ppm concentration . While another Hippuric acid and Benzotriazol had affect the ToMV replication process , where showed weak inhibitory activity of inhibition at simultaneous - ToMV inoculation at 5,10,15,20 ppm concentration and low percentage of inhibition at pre-and –post ToMV inoculation , as well as they showed very low doubtful ToMV concentration and disease severity percentage at 15 ppm concentration .

Biosynthesis of novel phytochemicals in tobacco plant infected with tobacco mosaic tobamovirus (TMV)

The main purpose of this work was to study the effect of TMV infection on physiology of active gradient photochemicals and protein expression in infected tobacco plants. Impact of Tobacco mosaic tobamovirus (TMV) on active gradient photochemicals quantitative and qualitative was evaluated in Nicotiana tobaccum cv. white burly. First, the TMV samples were isolated from single local lesions of infected leaves of N. glutinosa. Then, the N. tobaccum cv. white burly plants were inoculated with TMV. The infected plants showed severe systemic mosaic symptoms and reduction of leave size. We used Datura metel as a diagnostic tool-plant (indicator) for mosaic virus because of its vast exhibitory ability to show the symptoms incited by viruses. It was confirmed that these symptoms were due to the effect of TMV virus, comparing with Datura plant (as control). Analysis of TMV infected leaves by GC-mass detected biosynthesis of novel photochemicals (2-cyclopenten-1-one, Furfural, Indene, Pyrrole, Benzonitrile, Guaiacol and Oxime, methoxy-phenyl) that could not be detected in healthy plants. Furthermore, a 56.17% decreased in nicotine content was observed in infected plants compared with healthy ones. Also, increase of soluble protein contents was observed in infected leaves in response to TMV infection, compared with healthy ones. Alterations in protein patterns were observed in N. tabaccum leaves in response to TMV infection using SDS PAGE. Several secondary bioactive compounds were also found to hold important functions in infected plants. For example, flavonoids could protect against free radicals generated during photosynthesis. Terpenoids may attract pollinators or seed dispersers, or inhibit competing plants. Alkaloids usually ward-off herbivore animals or insect attacks (phytoalexins).

First report of broad bean wilt virus 2 and Youcai mosaic virus infecting woolly foxglove (Digitalis lanata).

Broad bean wilt virus 2 (BBWV2), a member of genus Fabavirus, in the family Secoviridae, is an economically important virus in China (Zhou et al., 1994). Similarly, Youcai mosaic virus (YoMV), a member of genus Tobamovirus in the family Virgaviridae, causes serious disease in many plants (Aguilar et al., 1996). In April of 2017, woolly foxglove (Digitalis lanata) plants displaying foliar virus-like mottling symptoms were found at the Beijing Medicinal Plant Garden. To detect possible pathogenic virus(es), total RNA was extracted from symptomatic leaves and used in reverse transcription (RT)-PCR with six pairs of primers for the detection of BBWV2 (BBWV-F: 5′-TTGGGHTCWAGYYTGGGACGYTTRT-3′ and BBWV-R: 5′-TTRTARAACTTCTTGCTCCCACGM-3′), Cucumber mosaic virus (CMVCPf: 5′-ATGGACAAATCTGAATCAACCA-3′ and CMVCPr: 5′-TCAGACTGGGAGCACCCCAGACGT-3′), tobamo- (Tob-Uni1: 5′-ATTTAAGTGGASGGAAAAVCACT-3′ and Tob-uni2: 5′-GTYGTTGATGAGTTCRTGGA-3′), poty- (PotyF: 5′-ATGGTHTGGTGYATHGARAAYGG-3′ and PotyR: 5′-TGCTGCKGCYTTCATYTG-3′), potex- (Potex5: 5′-CAYCARCARGCMAARGAYGA-3′ and Potex2RC: 5′-AGCATRGCNSCRTCYTG-3′), and polerovirus (PoconF: 5′-TGYTCYGGTTTTGACTGG-3′ and PocoCPR: 5′-CGTCTACCTATTSGGRTTN-3′). A 1, 347 bp fragment (GenBank accession No. MF671980) partially covering the coat protein (CP) gene was amplified from symptomatic plants using BBWV2 primers. This fragment shared the highest identity (92.2% and 98.2% at the nucleotide and amino acid levels, respectively) with a BBWV2 isolate from Rehmannia glutinosa in China (GQ202215). In addition, a 680 bp fragment (MF671981) covering the complete CP gene was also amplified from symptomatic plants with tobamovirus primers. This fragment showed the highest identity (100%) with YoMV isolate Shanghai (AF254924). No RT-PCR product was amplified from asymptomatic plants. To our knowledge, this is the first report of BBWV2 and YoMV in Digitalis lanata.

FIRST REPORT OF A NEW PEPPER MILD MOTTLE VIRUS PATHOTYPE 1,2 ON PEPPER IN SPAIN

During the summer of 2015, leaf deformations and chlorotic mosaic symptoms on leaves and unusual necrotic lesions on leaves, stems and fruits were observed on pepper (Capsicum annuum) plants grown in Almeria (Spain). Symptomatic leaf and fruit samples from eight collected plants, carrying L3 and L4 resistance against tobamovirus, were analyzed by ELISA specific for potyviruses, Cucumber mosaic virus and each of the following possible pepper-infecting viruses: Paprika mild mottle virus, Tobacco mosaic virus, Tomato mosaic virus, Tobacco mild green mosaic virus, and Pepper mild mottle virus (PMMoV). The eight plants tested negative for all viruses except for PMMoV. Mechanically inoculated extracts from two PMMoV-positive, singly infected symptomatic pepper plants systemically infected C. annuum cv Mazo (Unigenia), but not C. chinense PI159236, C. chacoense PI260429, four commercial L4, and two L3 resistant pepper plants, which exhibited local necrosis symptoms. Total RNAs from two plants inoculated with single infections were extracted, analyzed by reverse transcription PCR using primers designed to specifically amplify the coat protein gene (CP) of PMMoV (Antignus et al., 2008) and directly sequenced. Two independent samples yielded identical nt sequences (GenBank accession No. KT962848) and BLAST analysis showed the highest deduced aa identities of 99.4% with P1,2 isolates (M81413, AB000709, EF434393) of PMMoV. However, the predicted aa sequence possessed an Ala→Thr mutation at residue 66 of the CP. To our knowledge, although PMMoV has been shown to have variants that fail to infect L3 and L4 resistant pepper plants, based on unique CP coding sequences, this is the first report of a new P1,2 pathotype in Spain.

IDENTIFICATION AND MOLECULAR CHARACTERIZATION OF TOBACCO MILD GREEN MOSAIC VIRUS IN HUNGARY

Pepper (Capsicum annuum L.), an important crop in Hun- gary, is frequently infected by Cucumber mosaic virus (CMV), Tobacco mosaic virus (TMV) and, recently, also by Pepper mild mottle virus (PMMoV) and Tomato spotted wilt virus (TSWV). In the spring of 2015, mild mosaic symptoms were observed on cv. Ho F1. Symptoms on the fruits were more obvious, consisting of reduction in size, mottling and color changes, brown necrotic streaks and spots. To identify the putative pathogen(s), symptomatic fruits were collected and used for host range determination. Symptoms on mechani- cally inoculated Nicotiana tabacum cv. Samsun, N. tabacum cv. Xanthi-nc, Nicotiana benthamiana, Capsicum annuum cv. Albaregia (L+ gene), C. annuum cv. Feherozon (L1) and C. annuum cv. Brendon F1 (L3) suggested the presence of a tobamovirus belonging to pathotype 0 (Boukema, 1980). Moreover, total RNA was extracted from a symptomatic pepper fruit with the RNeasy plant mini kit (Qiagen, Ger- many) and used in RT-PCR using universal tobamovirus primers for the coat protein gene (Kalman et al., 2001). A products of the expected size (700 bp) was obtained, cloned into pGEM-T Easy Vector (Promega, USA) and sequenced (Biomi, Hungary). The sequence was deposited in GenBank under the accession No. KT374283. Blast analysis showed a 99% identity at nucleotide level with a Spanish isolate (P04/17, accession No. FN594859) of Tobacco mild green mosaic virus (TMGMV). To our knowledge, this is the first report of TMGMV on pepper in Hungary.

Effects of Different Treatments on the Inactivation of Various Seedborne Viruses in Some Vegetables

In this study, we considered the efficacy of seed treatments for the inactivation of some seedborne viruses in tomato, pepper, melon, squash, bean and lettuce seeds, which are essential for human nutrition and seed production in our country. A total of 325 seed samples obtained from various farmers and foundations were tested by DAS-ELISA and RT-PCR procedures. Eight seed lots infected with Tomato mosaic tobamovirus (ToMV), Tobacco mosaic tobamovirus (TMV), Cucumber mosaic cucumovirus (CMV), Soybean mosaic potyvirus (SMV) and Lettuce mosaic potyvirus (LMV) were selected as research materials. Virus inactivation treatments were made by using acetic acid (CH3COOH), hydrogen peroxide (H2O2), hydrochloric acid (HCl), sodium hypochlorite (NaClO), Triton X 100, dry heat, heated water, ozone (O3), and UV (305 nm wavelength). The most effective treatments for reducing virus concentration were HCl, heated water (65 °C) and ozone (10 g m−3). These treatments reduced concentrations of seed-borne viruses in ranges of 51%, 42%, and 32%, respectively. Other treatments were less effective and reduced virus concentrations in the range of 27%–12%. HCl and ozone treatments were the most effective and applicable methods because they did not have negative effect on seed germination.

Cloning and sequence analysis of orchids CymMV and ORSV CP gene isolated in northern of Vietnam

Orchids are ones of indoor decorated plants with beautiful and fragrant flowers. It is not only varied in styles, but also high economic valuable flower. However, the cultivation of orchids meets several difficulties, especially viral infection that caused reducing the productivity and quality of orchid flowers. Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot tobamo virus (ORSV) are considered as viruses that cause the largest damage to orchids. In this study, we cloned and sequenced the coating protein genes (CP) of the two viruses CymMV and ORSV isolated from some provinces in northern Vietnam. These sequences were aligned out by BioEdit 7 software. The CP nucleotide sequences of the isolates were compared with those of previously published isolates in GenBank originating from different countries. The results showed the CP gene sequences of CymMV were quite diverse, in contrast, the CP genes of ORSV were very conservative. These results contributed to the study of genetic diversity of the CymMV and ORSV viruses and as a basis for selection genetic materials to create disease resistant orchids in Vietnam.

The Role of Hydrogen Peroxide and Nitric Oxide in the Induction of Plant-Encoded RNA-Dependent RNA Polymerase 1 in the Basal Defense against Tobacco Mosaic Virus

Plant RNA-dependent RNA Polymerase 1 (RDR1) is an important element of the RNA silencing pathway in the plant defense against viruses. RDR1 expression can be elicited by viral infection and salicylic acid (SA), but the mechanisms of signaling during this process remains undefined. The involvement of hydrogen peroxide (H2O2) and nitric oxide (NO) in RDR1 induction in the compatible interactions between Tobacco mosaic tobamovirus (TMV) and Nicotiana tabacum, Nicotiana benthamiana, and Arabidopsis thaliana was examined. TMV inoculation onto the lower leaves of N. tabacum induced the rapid accumulation of H2O2 and NO followed by the increased accumulation of RDR1 transcripts in the non-inoculated upper leaves. Pretreatment with exogenous H2O2 and NO on upper leaf led to increased RDR1 expression and systemic TMV resistance. Conversely, dimethylthiourea (an H2O2 scavenger) and 2-(4-carboxyphenyl)- 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (an NO scavenger) partly blocked TMV- and SA-induced RDR1 expression and increased TMV susceptibility, whereas pretreatment with exogenous H2O2 and NO failed to diminish TMV infection in N. benthamiana plants with naturally occurring RDR1 loss-of-function. Furthermore, in N. tabacum and A. thaliana, TMV-induced H2O2 accumulation was NO-dependent, whereas NO generation was not affected by H2O2. These results suggest that, in response to TMV infection, H2O2 acts downstream of NO to mediate induction of RDR1, which plays a critical role in strengthening RNA silencing to restrict systemic viral infection.

Detection of viruses in seeds of some vegetables by reverse transcriptase polymerase chain reaction (RT-PCR)

The present study was carried out to detect the presence of Alfalfa mosaic alfamovirus (AMV), cucumber mosaic cucumovirus (CMV), lettuce mosaic potyvirus (LMV), cucumber green mottle mosaic virus (CGMMV), tomato bushy stunt tombusvirus (TBSV), tobacco mosaic tobamovirus (TMV), tomato black ring nepovirus (TBRV) and tomato mosaic tobamovirus (ToMV) in seeds of pepper, tomato, cucumber and lettuce which are essential for human nutrition and seed production in Turkey. 50 seed samples for each vegetable obtained from various foundations and farmers were tested by reverse transcriptase polymerase chain reaction (RT-PCR) and double-antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA) was conducted to compare the results. Besides, two total nucleic acid (TNA) extraction methods and a commercial RNA purification kit was compared to get high quality RNA for optimized RT-PCR. Purified total RNA extracts were used as template for cDNA synthesis, PCR products were analyzed by gel electrophoresis, and visualized by ethidium bromide staining. As a result of all, the optimum TNA extraction method was silica capture which is practical and easy to use for getting viral agents from tested vegetable seeds. RT-PCR was found rapid and sensitive in detecting viruses in seeds of vegetables when compared to DAS-ELISA. This study shows that RT-PCR can be successfully applied in certification programs and quarantine tests of vegetable seeds. Keywords : Seed, reverse transcriptase polymerase chain reaction (RT-PCR), total nucleic acid (TNA) extraction, optimization African Journal of Biotechnology Vol. 12(25), pp. 3891-3897

Potential of marker-assisted selection for Tobacco mosaic tobamovirus resistance in tobacco breeding

Tobacco mosaic tobamovirus (TMV) is one of the most destructive virus threatening worldwide tobacco production. Use of host resistance is the best method of control. The N -gene was introgressed into tobacco from Nicotiana glutinosa to confer hypersensitive resistance to TMV. Phenotypic selection of TMV resistant germplasm is expensive, slow and unreliable. Use of N -gene specific primers is efficient in selecting TMV resistant germplasm in marker-assisted breeding. This study aimed at assessing the utility of N -gene specific primers in flue cured and dark-fire cured tobacco breeding materials in Zimbabwe. Four specific primers namely N1/N2, AS1/AS2, E1/E2 and SD1/SD2 were used to detect the N -gene in flue cured and dark-fire cured tobacco. DNA was extracted from young leaves of tobacco plants and quantified by a spectrophotometer. Polymerase chain reaction (PCR) mix and amplifying conditions for the four specific primer pairs were optimized. Results show that out of the four sets of primers used, AS1/AS2 and SD1/SD2 did not produce expected band products, while N1/N2 and E1/E2 detected the N -gene in flue cured and dark-fire cured tobacco. Therefore, the use of N1/N2 and E1/E2 primers will be relatively cheap, effective and quick in the foreground selection of the N -gene. Keywords: N -gene, specific primers, resistance, molecular markers, Nicotiana tabacum . African Journal of Biotechnology Vol. 12(24), pp. 3783-3789

Induction of Resistance in Tomato Plants Against Tomato mosaic tobamovirus Using Beneficial Microbial Isolates

The possibility of making use of the phenome non of Systemic Acquired Resistance (SAR) to control viruses achieved by the soaking treatment of tomato seeds cv. Castl Rock with three growth forms to Bacillus circulans, Pseudomonas fluorescens 2 and Trichoderma harzianum against Tomato mosaic tobamovirus (ToMV) infection. All the application forms of beneficial biotic inducers were reduced the mean number of ToMV local lesions on Datura metel. P. fluorescens 2 was found to be the best treatment in three forms on reduction of local lesion number 42.2, 32.7 and 38.1 of microbial liquid culture, microbial cells or spores and microbial culture filtrate forms, respectively, while the highest mean numbers of local lesions were 51.5, 61.7 and 73.5 of microbial liquid culture, microbial cells or spores and microbial culture filtrate, respectively for T. harzianum. The microbial culture filtrate form was more effective than other microbial forms to reduce mean number of ToMV local lesions to B. circulans, P. fluorescens 2 and T. harzianum isolates, 40.7, 32.1 and 51.5, respectively. The individual microbial isolates on all three microbial forms able to vary ToMV local lesions similarity (homologous or heterologous) and morphology (size center and surrounded with halo or without halo) compared with TMV mother strain.

The Rubisco Small Subunit Is Involved in Tobamovirus Movement and Tm-22-Mediated Extreme Resistance

The multifunctional movement protein (MP) of Tomato mosaic tobamovirus (ToMV) is involved in viral cell-to-cell movement, symptom development, and resistance gene recognition. However, it remains to be elucidated how ToMV MP plays such diverse roles in plants. Here, we show that ToMV MP interacts with the Rubisco small subunit (RbCS) of Nicotiana benthamiana in vitro and in vivo. In susceptible N. benthamiana plants, silencing of NbRbCS enabled ToMV to induce necrosis in inoculated leaves, thus enhancing virus local infectivity. However, the development of systemic viral symptoms was delayed. In transgenic N. benthamiana plants harboring Tobacco mosaic virus resistance-2² (Tm-2²), which mediates extreme resistance to ToMV, silencing of NbRbCS compromised Tm-2²-dependent resistance. ToMV was able to establish efficient local infection but was not able to move systemically. These findings suggest that NbRbCS plays a vital role in tobamovirus movement and plant antiviral defenses.

Characterization of Tobacco Mosaic Tobamovirus (TMV-S) Isolated from Sunflower (Helianthus annuus L.) in Egypt

Characterization of Tobacco Mosaic Tobamovirus (TMV-S) Isolated from Sunflower (Helianthus annuus L.) in Egypt

Application of Multiplex RT-PCR for Detection of Cucurbit-infecting Tobamovirus

Cucumber green mottle mosaic virus (CGMMV) and Kyuri green mottle mosaic virus (KGMMV) are seed borne viruses and they are also transmitted mechanically during agricultural practice and through water. Hence, these viruses have potential diseases widely distributed throughout the world. To detect different strains of CGMMV and KGMMV, several specific primers for each virus were designed for single and multiplex RT-PCR. The results of single and multiplex RT-PCR showed that CGMMV was detected in zucchini isolated in Bali-Indonesia, while KGMMV was detected both in zucchini isolated in Bali-Indonesia and Cucumis metuliferus isolated in Thailand. Furthermore, artificial co-infection of these two viruses was prepared and carried out using two different ways of viral RNAs extraction. Based on the results, it could be reported that viral RNAs for cDNA amplification by multiplex RT-PCR could be extracted from a mixture of infected leaves or separate extraction of each viruses infected leaves. In addition, results presented in this study demonstrated the application of multiplex RT-PCR to simultaneously detect CGMMV and KGMMV from cucurbit leaves using a mixture of four primers and its feasibility as a sensitive and rapid laboratory assay. Since, no multiplex RT-PCR technique has been described for the detection of CGMMV and KGMMV, this technique can be a good option for sensitive and reliable tool for detection of two major cucurbit infecting Tobamoviruses. Keywords : Cucurbit infecting Tobamovirus, multiplex RT-PCR, seed borne viruses

Bazı biber hat ve çeşitlerinin tobacco mosaic tobamovirus (TMV)’e dayanıklılığının mekanik inokulasyon ve elisa testleri ile belirlenmesi

The virus Tobacco mosaic tobamovirus (TMV) disease causes major losses in yield and quality in pepper cultivation. No chemical control of the virus disease forces growers to use resistant varieties in the world. This study was carried out in the frame of “Improvement of Turkey F1 Hybrid Vegetable Variety and Public-Private Sector Collaboration in Seed Production Project” between 2005 and 2009. 156 Pepper lines in gene pool of Institute and 36 varieties of private sector were screened against TMV resistance in greenhouse in autumn and spring seasons. Plants sown two plants per pot were infected with pathogen by mechanical inoculation at 2-4 true leaf period. The symptoms were weekly observed and recorded. Observations were evaluated at 4-6 weeks after inoculation by symptomatologic and ELISA. As a result of this study, 15 lines of Institute and 2 varieties of private sector were determined resistant.

New asperxanthone and asperbiphenyl from the marine fungus Aspergillus sp.

Marine fungi are of great importance as potential sources of agricultural pesticide leads. To continue work on new and biologically active metabolites from marine fungi, culture extracts of selected isolates were screened for inhibitory activity against tobacco mosaic virus (TMV), a typical member of the tobamovirus group of plant viruses. A new difuranxanthone, asperxanthone (1), and a new biphenyl, asperbiphenyl (2), as well as seven known unsaturated fatty acid glycerol esters, were isolated from a selected marine fungus, identified as Aspergillus sp. (MF-93), collected in the Quan-Zhou Gulf. Two-dimensional NMR methods and FAB-MS established the structures of the new compounds. Among the compounds, 1 and 2 showed moderate activity (inhibitory rates 62.9 and 35.5% respectively) in inhibiting multiplication of TMV, higher than that of the other seven known lipids but much lower than that of the extract at the identical concentration of 0.2 mg mL(-1). Two new compounds, asperxanthone and asperbiphenyl, were identified as active components from Aspergillus sp. (MF-93).