Conidial sporulation of <Emphasis Type="Italic">Stemphylium solani</Emphasis> under laboratory conditions and infectivity of the inoculum produced <Emphasis Type="Italic">in vitro</Emphasis>

Potato virus Y (PVY) is the type-species of the genus Potyvirus, family Potyviridae, being reported as a major tomato (Solanum lycopersicum L.) pathogen in several regions of the world. Pepper yellow mosaic virus (PepYMV) was originally described as a resistance-breaking Potato virus Y (PVY) isolate on Capsicum annuum L. cultivars, and afterwards it was also reported infecting tomatoes in Brazil. In the present work, a search for sources of resistance to both PepYMV and PVY was conducted in a collection of 119 accessions belonging to seven Solanum (section Lycopersicon) species. This germplasm was initially evaluated to PepYMV reaction by mechanical inoculation followed by symptom observations and ELISA. Potential PepYMV resistance sources were identified for the first time in S. habrochaites, S. peruvianum, S. corneliomuelleri, S. chilense, S. pimpinellifolium, and one accession derived from an interspecific cross (S. lycopersicum x S. peruvianum). A sub-group of 24 accessions with negative serology for PepYMV was also challenged with a PVY isolate, followed by serological and molecular detection with universal primers. Solanum habrochaites ‘L.03683’ and ‘L.03684’ were the only accessions found with stable resistance to both viruses. These results confirm S. habrochaites as the most important source of multiple resistance factor(s) to distinct Potyvirus species.     

Occurrence of maize lethal necrosis in Ecuador: a disease without boundaries?

Maize plants displaying severe mosaic, chlorosis and, in some cases, necrosis were observed in two provinces of Ecuador. Shotgun sequencing of cDNA obtained from double-stranded RNA extracted from symptomatic samples revealed the presence of Sugarcane mosaic virus (SCMV) and Maize chlorotic mottle virus (MCMV), two components of maize lethal necrosis. In 2015, a survey conducted in Los Ríos, Manabí and Guayas, major maize production areas in the country, showed that the two viruses were present in a significant number of plants. Mixed infections were detected and associated with severe symptoms. MCMV was also detected in two hybrid seed lots, a significant finding for the epidemiology of the disease in Ecuador. The report of maize lethal necrosis, today the most significant virus disease of maize, in Ecuador is of great concern for producers in the South American continent because of the potential of an epidemic as that observed in east Africa in recent years.     

Natural infection of <Emphasis Type="Italic">Nicandra physaloides</Emphasis> by <Emphasis Type="Italic">Tomato severe rugose virus</Emphasis> in Brazil

Nicandra physaloides, a common weed in South America, was found to be infected by an isolate of Tomato severe rugose virus (ToSRV), a bipartite begomovirus. The plants developed severe yellow rugose mosaic and were collected in São Paulo State, Brazil. This isolate of ToSRV was transmitted by Bemisia tabaci B biotype from infected plants of N. physaloides to healthy plants of N. physaloides and tomato in a glasshouse. This is the first report of natural infection of N. physaloides by ToSRV in Brazil.     

Bioassay of insecticides on mortality of <Emphasis Type="Italic">Bemisia tabaci</Emphasis> biotype B and transmission of <Emphasis Type="Italic">Tomato severe rugose virus</Emphasis> (ToSRV) on tomatoes

Tomato severe rugose virus (ToSRV) is a serious and prevalent begomovirus that causes severe mosaic and yield loss of tomato plants in Brazil. The virus is transmitted by Bemisia tabaci bitotype B (MEAM1) in a persistent circulative manner. This study evaluated the efficacy of cyantraniliprole foliar spray, cyantraniliprole root drenching, spiromesifen, thiamethoxam, and cartap on the mortality of Bemisia tabaci byotipe B and simulated primary and secondary transmission of ToSRV. None of the insecticides were effective in controlling primary transmission of ToSRV by B. tabaci. Cyantraniliprole root drenching, cartap, and cyantraniliprole foliar spray were effective in controlling secondary transmission of the virus, and infections were reduced by 94.5, 89.6, and 81%, respectively, compared to each of their controls. Thiamethoxam and spiromesifen did not provide effective control of secondary infection. Elimination of external sources of inoculum before starting new plantings and rational use of insecticides to reduce secondary infection may contribute to better disease management of tomato crops.     

A DNA probe mix for the multiplex detection of ten artichoke viruses

Artichoke Italian latent virus (AILV), Artichoke latent virus (ArLV), Artichoke mottled crinkle virus (AMCV), Bean yellow mosaic virus (BYMV), Cucumber mosaic virus (CMV), Pelargonium zonate spot virus (PZSV), Tomato infectious chlorosis virus (TICV), Tobacco mosaic virus (TMV), Tomato spotted wilt virus (TSWV) and Turnip mosaic virus (TuMV) are damaging to artichoke. We have developed a protocol enabling the simultaneous detection of these artichoke viruses by non-isotopic dot blot hybridisation with DNA probes. The probe mix detected all viruses with high specificity and identical to that obtained using individual probes. The approach is proposed for the routine assessment of phytosanitary status for certified nursery production of globe artichoke.     

Fast detection by loop-mediated isothermal amplification (LAMP) of the three begomovirus species infecting tomato in Panama

Potato yellow mosaic Panama virus (PYMPV), Tomato leaf curl Sinaloa virus (ToLCSiV) and Tomato yellow mottle virus (TYMoV) of genus Begomovirus (family Geminiviridae) are the only three begomovirus species detected infecting tomato (Solanum lycopersicum L.) in Panama. PYMPV, ToLCSiV and TYMoV induce symptoms of stunting, yellowing, curling, distortion of leaves and reduction of fruit size and cause important economic loses. A loop-mediated amplification under isothermal conditions (LAMP) assay was developed for the individual detection of these three begomovirus species by using a set of three primer pairs specific per each one of them. Amplification products were visualized by gel electrophoresis or direct Gel-Red staining of DNA into the reaction tube. PYMPV, ToLCSiV and TYMoV were detected in total DNA extracts obtained from different plant tissues such as leaves, stems, flowers, fruits and roots of infected tomato plants collected in different production regions of Panama. LAMP sensitivity was similar to that of conventional PCR but, the first procedure was faster and cheaper than the last one. Moreover, all three viruses were successfully detected by LAMP and not by conventional PCR from sap extracts obtained from leaf tissues of infected tomato plants which were embedded into 3MM Whatman paper and stored several days, facilitating the samples processing as well as the material movement among different laboratories. Therefore, LAMP is a specific, rapid and cheap procedure to detect all three begomoviruses infecting tomato in Panama and it is suitable for field surveys and sanitation programs.     

Occurrence and distribution of viruses infecting tomato and pepper in Alibori in northern Benin

In surveys conducted in 2011 and 2012 to identify the viruses causing diseases on pepper and tomato in the department of Alibori in northern Benin, 451 samples of pepper and tomato were analyzed by ELISA using 11 specific antibodies. The highest virus incidence among the surveyed districts was recorded on pepper in Malanville (56.18%), followed by Karimama (39.32%). The most frequently found viruses were Pepper veinal mottle virus (PVMV), Cucumber mosaic virus (CMV), and Potato virus Y-necrotic (PVY-n), accounting respectively for 22.39%, 21.73% and 15.96% of the collected samples. Tomato yellow leaf curl virus (TYLCV) was detected in only 2.43% of the samples, whereas Alfalfa mosaic virus (AMV), Chilli veinal mottle virus (ChiVMV), Tomato mosaic virus (ToMV) and Tomato spotted wilt virus (TSWV) were not detected in any of the samples tested. Double and triple infections involving different virus combinations were found, respectively, in 14.86% and 4% of the samples. Five plant species (Euphorbia hirta Linnaeus, Moringa oleifera Lam, Leucas martinicencis (Jacquin) R. Brown, Combretum micranthum G. Don, Abelmoschus esculentus L. Moench.) out of 30 samples belonging to 13 botanical families, collected within or nearby tomato and pepper fields, were found infected with PVMV, PVY-n, and CMV. Control measures to reduce the impact of viruses on pepper and tomato production are discussed. This is the first report of viruses infecting pepper and tomato in Benin.     

Occurrence of viruses in field-grown pepper crops and some of their reservoir weed hosts in Samsun, Turkey

Pepper production is affected by several viral diseases in Samsun, Turkey. To determine the identity of these viruses, a total of 313 samples from field-grown peppers were collected during surveys in 1998 and 1999, and tested by enzyme linked immunosorbent assay (ELISA). Six viruses,Alfalfa mosaic virus (AMV),Cucumber mosaic virus (CMV),Potato virus Y (PVY),Tomato mosaic virus (ToMV),Tobacco mosaic virus (TMV) andTomato spotted wilt virus (TSWV) were detected in the samples. Of 313 plants tested, 42 were doubly infected, and TMV+PVY (15.4%) was the most common double infection. This is also the first report of AMV in pepper fields in Turkey. The effect of some weed species that may act as reservoir of these viruses was also investigated in the region and of 24 weed species belonging to 15 families tested, 16 were found to be infected with at least one virus.Amaranthus retroflexus (Redroot pigweed) appeared to be a common host of CMV, PVY, ToMV, TMV and TSWV, whereasHibiscus trionum (Venice mallow) was recorded as a new weed host of PVY and TSWV. The majority of weed species found to be virus infected were very common in the pepper growing areas of the region. This indicates that pepper fields contaminated with these weeds are under risk of viral infections. http://www.phytoparasitica.org posting July 21, 2005.     

Distinct association of an alphasatellite and a betasatellite with <Emphasis Type="Italic">Tomato leaf curl New Delhi virus</Emphasis> in field-infected cucurbit

Leaf samples of Cucurbita pepo with yellow mosaic disease symptoms were collected in 2012. Rolling circle amplification and PCR amplification with begomovirus-specific primers confirmed the presence of an Old World bipartite begomovirus, an alphasatellite and a betasatellite. Molecular analysis of full-length sequences showed that Tomato leaf curl New Delhi virus (DNA-A) is associated with its cognate DNA-B, Papaya leaf curl betasatellite and a novel alphasatellite. To the best of our knowledge, this is the first report of an alphasatellite and a betasatellite associated with a bipartite begomovirus.     

Phylogeny of Egyptian isolates of <Emphasis Type="Italic">Cucumber mosaic virus</Emphasis> (CMV) and <Emphasis Type="Italic">Tomato mosaic virus</Emphasis> (ToMV) infecting <Emphasis Type="Italic">Solanum lycopersicum</Emphasis>

Four Cucumber mosaic virus (CMV) (CMV-HM 1–4) and nine Tomato mosaic virus (ToMV) (ToMV AH 1–9) isolates detected in tomato samples collected from different governorates in Egypt during 2014, were here characterized. According to the coat protein gene sequence and to the complete nucleotide sequence of total genomic RNA1, RNA2 and RNA3 of CMV-HM3 the new Egyptian isolates are related to members of the CMV subgroup IB. The nine ToMV Egyptian isolates were characterized by sequence analysis of the coat protein and the movement protein genes. All isolates were grouped within the same branch and showed high relatedness to all considered isolates (98–99%). Complete nucleotide sequence of total genomic RNA of ToMV AH4 isolate was obtained and its comparison showed a closer degree of relatedness to isolate 99–1 from the USA (99%). To our knowledge, this is the first report of CMV isolates from subgroup IB in Egypt and the first full length sequencing of an ToMV Egyptian isolate.     

A myosin passenger protein gene (<Emphasis Type="Italic">FaSmy1</Emphasis>) is an essential regulator of cell development,pathogenicity, DON biosynthesis,and resistance to the fungicide phenamacril in <Emphasis Type="Italic">Fusarium asiaticum</Emphasis>

Wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TriMV) are important viruses of wheat (Triticum aestivum L.) in the Great Plains of United States. In addition to agronomic practices to prevent damage from these viruses, temperature sensitive resistance genes Wsm1, Wsm2 and Wsm3, have been identified. However, threshold temperatures for Wsm1 and Wsm3 have not been clearly defined. To better understand these two resistance genes, wheat lines C.I.15092 (Wsm1), KS96HW10–3 (Wsm1), and KS12WGGRC59 (Wsm3) were evaluated for WSMV resistance at 27, 30, 33 and 35 °C and for TriMV resistance at 18, 21, 24, 27, 30, 33 and 35 °C. The results showed that only C.I.15092 remained resistant at 30 °C for both viruses. This line also tolerated TriMV at 33 and 35 °C with less sever symptom and lower infection rates. Wheat lines KS96HW10–3 and KS12WGGRC59 hold resistance to TriMV up to 21 °C. Molecular marker results suggested that the resistance in C.I.15092 is most probably conditioned by the resistance gene Wsm1 and additional gene(s) other than Wsm2 and Wsm3.     

Identification and partial characterization of a <Emphasis Type="Italic">Carica papaya</Emphasis>-infecting isolate of <Emphasis Type="Italic">Alfalfa mosaic virus</Emphasis> in Brazil

A Carica papaya plant with severe yellow leaf mosaic, leaf distortion, and systemic necrosis was found in the municipality of Piracicaba, state of São Paulo, Brazil. Transmission electron microscopy (TEM) analysis revealed the presence of potyvirus-like particles and bacilliform particles similar to those of the Alfamovirus genus. The potyvirus was identified as Papaya ringspot virus-type P (PRSV-P). Biological, serological, and molecular studies confirmed the bacilliform virus as an isolate of Alfalfa mosaic virus (AMV). Partial nucleotide and amino acid sequences of the coat protein gene of this AMV isolate shared 97–98% identity with the AMV isolates in the GenBank database. This report is the first of the natural infection of papaya plants by AMV.