Whiteflies are a key pest of crops in open-field production throughout the tropics and subtropics... more Whiteflies are a key pest of crops in open-field production throughout the tropics and subtropics. This is due in large part to the long and diverse list of devastating plant viruses transmitted by these vectors. Open-field production provides many challenges to manage these viruses and in many cases adequate management has not been possible. Diseases caused by whitefly-transmitted viruses have become limiting factors in open-field production of a wide range of crops, i.e., bean golden mosaic disease in beans, tomato yellow leaf curl disease in tomato, cassava mosaic disease and cassava brown streak disease in cassava, and cotton leaf crumple disease in cotton. While host resistance has proven to be the most cost-effective management solution, few examples of host resistance have been developed to date. The main strategy to limit the incidence of virus-infected plants has been the application of insecticides to reduce vector populations aided to some extent by the use of selected cultural practices. However, due to concerns about the effect of insecticides on pollinators, consumer demand for reduced pesticide use, and the ability of the whitefly vectors to develop insecticide-resistance, there is a growing need to develop and deploy strategies that do not rely on insecticides. The reduction in pesticide use will greatly increase the need for genetic resistance to more viruses in more crop plants. Resistance combined with selected IPM strategies could become a viable means to increase yields in crops produced in open fields despite the presence of whitefly-transmitted viruses.
Five Capsicum species were tested for susceptibility to Tomato yellow leaf curl virus (TYLCV) and... more 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. Whiteflies 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.
and 8 Dec. The sprayer was operated at 60 psi and delivered 100 gpa using a single nozzle fitted ... more and 8 Dec. The sprayer was operated at 60 psi and delivered 100 gpa using a single nozzle fitted with a D-5 disk and #45 core. Fruit were harvested on 15, 28 Nov and 12 Dec. The number and weight of undamaged fruit and the number of fruit damaged by armyworm larvae were determined. The southern armyworm population was low throughout the trial. No treatment resulted in fewer or more fruit yielded per plot compared to the check. Fewer fruit damaged by armyworm larvae were harvested from all sprayed plots, except those sprayed with the lowest rate of CM-006, relative to plots sprayed with water. No foliar symptoms of phytotoxicity were observed with any treatment. This is Florida Agricultural Experiment Station Journal Series No. N-01289.
Current knowledge of plant virus diversity is biased towards agents of visible and economically i... more Current knowledge of plant virus diversity is biased towards agents of visible and economically important diseases. Less is known about viruses that have not caused major diseases in crops, or viruses from native vegetation, which are a reservoir of biodiversity that can contribute to viral emergence. Discovery of these plant viruses is hindered by the traditional approach of sampling individual symptomatic plants. Since many damaging plant viruses are transmitted by insect vectors, we have developed ''vector-enabled metagenomics'' (VEM) to investigate the diversity of plant viruses. VEM involves sampling of insect vectors (in this case, whiteflies) from plants, followed by purification of viral particles and metagenomic sequencing. The VEM approach exploits the natural ability of highly mobile adult whiteflies to integrate viruses from many plants over time and space, and leverages the capability of metagenomics for discovering novel viruses. This study utilized VEM to describe the DNA viral community from whiteflies (Bemisia tabaci) collected from two important agricultural regions in Florida, USA. VEM successfully characterized the active and abundant viruses that produce disease symptoms in crops, as well as the less abundant viruses infecting adjacent native vegetation. PCR assays designed from the metagenomic sequences enabled the complete sequencing of four novel begomovirus genome components, as well as the first discovery of plant virus satellites in North America. One of the novel begomoviruses was subsequently identified in symptomatic Chenopodium ambrosiodes from the same field site, validating VEM as an effective method for proactive monitoring of plant viruses without a priori knowledge of the pathogens. This study demonstrates the power of VEM for describing the circulating viral community in a given region, which will enhance our understanding of plant viral diversity, and facilitate emerging plant virus surveillance and management of viral diseases.
The Abstracts that follow are arranged in numerical sequence by the abstract number. For Poster S... more The Abstracts that follow are arranged in numerical sequence by the abstract number. For Poster Sessions, the number preceded by PB (i.e., PB XXX) indicates the poster board number on which the poster will be mounted. Abstracts for Oral Sessions, Colloquia,and Workshops are grouped by sessions. To determine when a paper is to be presented, check the session number in the Program Schedule or the Conference at a Glance charts. The author presenting the paper is indicated by an asterisk.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Virus-like symptoms of leaf deformation and rugosity, especially of younger leaves, and a mild mo... more Virus-like symptoms of leaf deformation and rugosity, especially of younger leaves, and a mild mosaic were observed on fresh market common (green) bean (Phaseolus vulgaris L.) plants in Hendry County in southwest Florida in December of 2007 and again in February of 2008. All bean fields were adjacent to watermelon fields in which Cucurbit leaf crumple virus (CuLCrV), Squash vein yellowing virus (SqVYV), and Papaya ringspot virus type W (PRSV-W) infections had previously been confirmed (fall of 2007) by PCR, reverse transcription (RT)-PCR, and/or ELISA. Whiteflies, Bemisia tabaci, were observed on both bean and watermelon plants in December and February. Fifteen samples (eleven with symptoms) were collected in December and two (both with symptoms) in February. Initial ELISA assays using commercially available antisera for potyviruses or Cucumber mosaic virus (Agdia, Elkhart, IN) were negative. Total nucleic acids were extracted and used for PCR testing. All samples tested negative by RT-PCR using specific primers for SqVYV, PRSV-W, and Cucurbit yellow stunting disorder virus, and degenerate primers for potyviruses. Ten of fifteen December samples (ten of eleven symptomatic samples) and both February samples yielded PCR products of the expected size with the degenerate begomovirus primers, PAR1c496/PAL1v1978, which amplify a portion of the begomovirus A component (3). PCR products from three December and both February samples were cloned and sequenced. The 1,159-nt PCR products shared 99% identity with each other and 96% identity with the corresponding region of A component sequences of Arizona and California CuLCrV isolates (GenBank Accession Nos. AF256200 and AF224760, respectively). Additional degenerate begomovirus primers PBL1v2040/PCRc154, which amplify a 381-nt portion of the hypervariable region of the begomovirus B component (3), and AC1048/AV494, which amplify a 533-nt portion of a conserved region of the coat protein gene (4), were used to confirm the identity of CuLCrV in the three December samples. The PBL1v2040/PCRc154 PCR products shared 98 to 99% identity with each other and 94 to 95% identity with the corresponding region of B component sequences of Arizona and California CuLCrV isolates (GenBank Accession Nos. AF327559 and AF224761, respectively), whereas the AC1048/AV494 PCR products shared 99% identity with each other and 97% identity with the corresponding region of A component sequences of Arizona and California CuLCrV isolates. Nucleic acid dot-blot hybridization assays of sap from homogenized leaves of the three December samples (from which the PCR product clones were obtained) with a digoxigenin-labeled CuLCrV cDNA probe also confirmed the presence of CuLCrV. Although CuLCrV has been reported to experimentally infect common bean and tobacco (2), to our knowledge, this is the first report of CuLCrV infecting any noncucurbit host in Florida. This finding suggests that CuLCrV may be more widely distributed than previously known in Florida (1) and that common bean (and potentially other legumes) are potential reservoirs for CuLCrV. References: (1) F. Akad et al. Plant Dis. 92:648, 2008. (2) J. K. Brown et al. Phytopathology 92:734, 2002. (3) M. R. Rojas et al. Plant Dis. 77:340, 1993. (4) S. D. Wyatt and J. K. Brown. Phytopathology 86:1288, 1996.
A new system for inoculation of plants with begomoviral DNA without cloning or the use insect vec... more A new system for inoculation of plants with begomoviral DNA without cloning or the use insect vectors is described. Total DNA extracted from begomovirus-infected plants was amplified by rolling circle amplification (RCA) using the bacteriophage phi29 DNA polymerase, and inoculated to plants by particle bombardment. Infection rates of up to 100% were obtained using this technique. This technique successfully inoculated all the begomoviruses evaluated: five bipartite (Bean golden yellow mosaic virus, Cabbage leaf curl virus, Squash leaf curl virus, Tomato mottle virus, Watermelon chlorotic stunt virus) as well as one monopartite (Tomato yellow leaf curl virus). The success of the technique was not dependent upon plant species. Four species from three plant families [Phaseolus vulgaris (bean), Solanum lycopersicum (tomato), Cucurbita pepo (squash), and Citrullus lanatus (watermelon)], could all be inoculated by this technique. The success of the method was not dependent upon either the type or the age of the source of virus. Infectious DNA was obtained successfully from fresh, freeze-dried or desiccated plant material, from squashes of plant leaves on FTA cards, as well as from the insect vector. Plant material collected and dried as long as 25 years ago yielded infectious DNA by this method. In summary, this method can be used to obtain infectious DNA of single-stranded circular DNA viruses that can be activated for purposes of completing Koch's postulates, for preservation of pure virus cultures, and for many other applications where infectious DNA is required.
A new geminivirus, tomato mottle virus (TMoV), affecting tomato production in Florida has been cl... more A new geminivirus, tomato mottle virus (TMoV), affecting tomato production in Florida has been cloned and sequenced. Sequence analysis of the cloned replicative forms of TMoV revealed four potential coding regions for the A component [2601 nucleotides (nt)] and two for the B component (2541 nt).
Los virus se propagan de planta a planta en varias formas. Algunas veces las malezas que existen ... more Los virus se propagan de planta a planta en varias formas. Algunas veces las malezas que existen en o cerca de los cultivos pueden estar afectadas, en otrso casos vienen a los cultivos en la semilla. La transmision y la fuente son muy importantes cuando se trata de controlar las enfermedades virosas. Se examinan los ciclos de patogenicidad de cuatro de los virus mas comunes de la soya : el virus del mosaico de la soya se transmite por varias especies de afidos y a traves de semilla de plantas infectadas. El virus del mosaico de la vaina del frijol, transmitido en el campo por tres especies de escarabajos que se nutren por leguminosas. Virus moteado del Mani, la migracion de insectos portadores del virus de un campo de mani hacia uno de soya. El virus de la mancha anular del tabaco, este se puede transmitir por nematodos, trips, y la semilla de soya. Se cuenta con diferentes metodos para identificar los virus fitopatogenicos, estos metodos se combinan para fortalecer el grado de confiabilidad de la identificacion. Los metodos mas comunes en uso son : pruebas serologicas, gama de hospederos, prueba de lesiones locales, microscopia electronica para determinar el tamano y la forma de las particulas virales. Una vez el virus haya sido identificado se obtiene informacion sobre la ecologia, lo que daria idea sobre como controlarlo
A viral metagenomics-based study of the viromes of Saccharum species from Florida, Reunion, Guade... more A viral metagenomics-based study of the viromes of Saccharum species from Florida, Reunion, Guadeloupe, and Cirad's sugarcane quarantine in Montpellier, France, was carried out using the virion-associated nucleic acid (VANA) approach. The goal of this study was to identify known and potentially new sugarcane viruses. This study revealed the presence of a potential new Mastrevirus species infecting Saccharum species in Florida, Guadeloupe and Reunion. Seventeen full genome sequences (2738-2749 nt long) were obtained using either rolling circle amplification followed by enzymatic restriction, or PCR using back-to-back primers, followed by cloning of full length restricted fragment or full length amplicon and Sanger sequencing. Three full genome sequences were obtained from S. barberi (Florida), five from S. officinarum (Florida and Guadeloupe), four from S. spontaneum (Florida) and five from sugarcane hybrids (Guadeloupe). BLASTn and BLASTx comparisons between these 17 genome sequences and all sequences in GenBank resulted in the highest identity score with a recently deposited geminivirus genome isolated from sugarcane in China (KR150789, highest percentage identity = 89%, e-value = 0.0). Based on the distribution of pairwise identity scores yielded by the species demarcation tool (SDTv1.2), and using Mastrevirus species demarcation threshold of >78 %, we propose that all 18 genomic sequences (17 from our study and KR150789 from China) belong to the same species of Mastrevirus. ,Because this novel Mastrevirus species has never been tested in routine quarantine detection assays, it most likely occurs in several countries of Africa, America, Asia and the Caribbean Islands. In order to develop a new molecular diagnostic assay, we designed specific detection primers using the alignment of the 18 full available genomes. This assay will be used to screen the 2016 variety collection of Cirad's sugarcane quarantine for the presence of the new Mastrevirus species. Results of this screening and analysis of the genetic diversity of the produced amplicons will be presented. (Resume d'auteur)
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution author... more The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations.
A tospovirus was identified in tomato plants from two counties in Florida by reverse transcriptio... more A tospovirus was identified in tomato plants from two counties in Florida by reverse transcription-PCR and sequencing of portions of the S, M and L genomic segments. The predicted amino-acid sequences of the N protein of PCR products from four plant samples were >96% identical to those of TCSV. Partial nucleic acid sequences of the L and M RNA were >97% identical to those reported for TCSV isolates. Extracts from field samples infected test plants and produced symptoms similar to those reported for TCSV. This is the first report of an isolate of TCSV in Florida and in the USA.
In October 1998, symptoms characteristic of tomato yellow leaf curl virus (TYLCV) were observed o... more In October 1998, symptoms characteristic of tomato yellow leaf curl virus (TYLCV) were observed on fresh market tomato (Lycopersicon esculentum Mill.) in four production fields, two in Decatur County, Georgia, and two in Gadsden County, Florida. Symptoms observed were plant stunting, reduced leaf size, yellow leaf margins, and mottling. The incidence of symptomatic plants was less than 1% in all fields examined. In most cases, symptoms were observed only on the upper portion of plants, suggesting these plants had been infected by secondary spread from an unknown source. Nuclear inclusions characteristic of geminiviruses were observed by light microscopy in leaf tissue from symptomatic plants (1). To identify the geminivirus, total DNA from infected plants was extracted from six symptomatic tomato plants (two from Georgia and four from Florida) for polymerase chain reaction (PCR; J. E. Polston, personal communication). DNA was amplified with geminivirus DNA A degenerate primer set PAL1v1978 and PAR1c496 (2) from these extracts in addition to extracts from a known TYLCV-infected, a tomato mottle virus (ToMoV)-infected, and a healthy tomato plant. A PCR product of 1.4 kb was obtained from plants with TYLCV-like symptoms, while a 1.4-kb product and a 1.1-kb product were obtained from extracts of the known TYLCV-infected and ToMoV-infected tomato plants, respectively. No PCR product was obtained from extracts of healthy tomato plants. The 1.4-kb PCR products from one Georgia sample and one Florida sample were compared with those of TYLCV and ToMoV by restriction enzyme (RE) digestion with EcoRI and ClaI. The RE pattern of the 1.4-kb fragment from both samples was identical to the RE pattern of TYLCV and different from that of ToMoV. Adult and immature whiteflies collected from the fields where TYLCV was found were identified as Bemisia tabaci, the vector of TYLCV, but the biotype was not established. This report of TYLCV in south Georgia and north Florida extends the geographic range of TYLCV in the U.S. northward approximately 100 km. Georgia is the second state in which TYLCV was found since its initial detection in south Florida in July 1997 (J. E. Polston, personal communication). Monitoring of silverleaf whitefly populations and detection of TYLCV on alternate hosts will continue in order to estimate the potential impact of this virus on south Georgia and north Florida agriculture. References: (1) R. G. Christie and J. R. Edwardson. Plant Dis. 70:273, 1986, (2) M. R. Rojas et al. Plant Dis. 77:340, 1993.
uch of the American subtropics and tropics have a climate that is condu- cive to the year-round p... more uch of the American subtropics and tropics have a climate that is condu- cive to the year-round production of to- mato, Lycopersicon esculentum Mill. The tomato has been grown for centuries in the Americas, with the center of origin be- lieved to be in northern South America. Processing tomatoes are produced through- out the tropics for local consumption and for
Whiteflies are a key pest of crops in open-field production throughout the tropics and subtropics... more Whiteflies are a key pest of crops in open-field production throughout the tropics and subtropics. This is due in large part to the long and diverse list of devastating plant viruses transmitted by these vectors. Open-field production provides many challenges to manage these viruses and in many cases adequate management has not been possible. Diseases caused by whitefly-transmitted viruses have become limiting factors in open-field production of a wide range of crops, i.e., bean golden mosaic disease in beans, tomato yellow leaf curl disease in tomato, cassava mosaic disease and cassava brown streak disease in cassava, and cotton leaf crumple disease in cotton. While host resistance has proven to be the most cost-effective management solution, few examples of host resistance have been developed to date. The main strategy to limit the incidence of virus-infected plants has been the application of insecticides to reduce vector populations aided to some extent by the use of selected cultural practices. However, due to concerns about the effect of insecticides on pollinators, consumer demand for reduced pesticide use, and the ability of the whitefly vectors to develop insecticide-resistance, there is a growing need to develop and deploy strategies that do not rely on insecticides. The reduction in pesticide use will greatly increase the need for genetic resistance to more viruses in more crop plants. Resistance combined with selected IPM strategies could become a viable means to increase yields in crops produced in open fields despite the presence of whitefly-transmitted viruses.
Five Capsicum species were tested for susceptibility to Tomato yellow leaf curl virus (TYLCV) and... more 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. Whiteflies 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.
and 8 Dec. The sprayer was operated at 60 psi and delivered 100 gpa using a single nozzle fitted ... more and 8 Dec. The sprayer was operated at 60 psi and delivered 100 gpa using a single nozzle fitted with a D-5 disk and #45 core. Fruit were harvested on 15, 28 Nov and 12 Dec. The number and weight of undamaged fruit and the number of fruit damaged by armyworm larvae were determined. The southern armyworm population was low throughout the trial. No treatment resulted in fewer or more fruit yielded per plot compared to the check. Fewer fruit damaged by armyworm larvae were harvested from all sprayed plots, except those sprayed with the lowest rate of CM-006, relative to plots sprayed with water. No foliar symptoms of phytotoxicity were observed with any treatment. This is Florida Agricultural Experiment Station Journal Series No. N-01289.
Current knowledge of plant virus diversity is biased towards agents of visible and economically i... more Current knowledge of plant virus diversity is biased towards agents of visible and economically important diseases. Less is known about viruses that have not caused major diseases in crops, or viruses from native vegetation, which are a reservoir of biodiversity that can contribute to viral emergence. Discovery of these plant viruses is hindered by the traditional approach of sampling individual symptomatic plants. Since many damaging plant viruses are transmitted by insect vectors, we have developed ''vector-enabled metagenomics'' (VEM) to investigate the diversity of plant viruses. VEM involves sampling of insect vectors (in this case, whiteflies) from plants, followed by purification of viral particles and metagenomic sequencing. The VEM approach exploits the natural ability of highly mobile adult whiteflies to integrate viruses from many plants over time and space, and leverages the capability of metagenomics for discovering novel viruses. This study utilized VEM to describe the DNA viral community from whiteflies (Bemisia tabaci) collected from two important agricultural regions in Florida, USA. VEM successfully characterized the active and abundant viruses that produce disease symptoms in crops, as well as the less abundant viruses infecting adjacent native vegetation. PCR assays designed from the metagenomic sequences enabled the complete sequencing of four novel begomovirus genome components, as well as the first discovery of plant virus satellites in North America. One of the novel begomoviruses was subsequently identified in symptomatic Chenopodium ambrosiodes from the same field site, validating VEM as an effective method for proactive monitoring of plant viruses without a priori knowledge of the pathogens. This study demonstrates the power of VEM for describing the circulating viral community in a given region, which will enhance our understanding of plant viral diversity, and facilitate emerging plant virus surveillance and management of viral diseases.
The Abstracts that follow are arranged in numerical sequence by the abstract number. For Poster S... more The Abstracts that follow are arranged in numerical sequence by the abstract number. For Poster Sessions, the number preceded by PB (i.e., PB XXX) indicates the poster board number on which the poster will be mounted. Abstracts for Oral Sessions, Colloquia,and Workshops are grouped by sessions. To determine when a paper is to be presented, check the session number in the Program Schedule or the Conference at a Glance charts. The author presenting the paper is indicated by an asterisk.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Virus-like symptoms of leaf deformation and rugosity, especially of younger leaves, and a mild mo... more Virus-like symptoms of leaf deformation and rugosity, especially of younger leaves, and a mild mosaic were observed on fresh market common (green) bean (Phaseolus vulgaris L.) plants in Hendry County in southwest Florida in December of 2007 and again in February of 2008. All bean fields were adjacent to watermelon fields in which Cucurbit leaf crumple virus (CuLCrV), Squash vein yellowing virus (SqVYV), and Papaya ringspot virus type W (PRSV-W) infections had previously been confirmed (fall of 2007) by PCR, reverse transcription (RT)-PCR, and/or ELISA. Whiteflies, Bemisia tabaci, were observed on both bean and watermelon plants in December and February. Fifteen samples (eleven with symptoms) were collected in December and two (both with symptoms) in February. Initial ELISA assays using commercially available antisera for potyviruses or Cucumber mosaic virus (Agdia, Elkhart, IN) were negative. Total nucleic acids were extracted and used for PCR testing. All samples tested negative by RT-PCR using specific primers for SqVYV, PRSV-W, and Cucurbit yellow stunting disorder virus, and degenerate primers for potyviruses. Ten of fifteen December samples (ten of eleven symptomatic samples) and both February samples yielded PCR products of the expected size with the degenerate begomovirus primers, PAR1c496/PAL1v1978, which amplify a portion of the begomovirus A component (3). PCR products from three December and both February samples were cloned and sequenced. The 1,159-nt PCR products shared 99% identity with each other and 96% identity with the corresponding region of A component sequences of Arizona and California CuLCrV isolates (GenBank Accession Nos. AF256200 and AF224760, respectively). Additional degenerate begomovirus primers PBL1v2040/PCRc154, which amplify a 381-nt portion of the hypervariable region of the begomovirus B component (3), and AC1048/AV494, which amplify a 533-nt portion of a conserved region of the coat protein gene (4), were used to confirm the identity of CuLCrV in the three December samples. The PBL1v2040/PCRc154 PCR products shared 98 to 99% identity with each other and 94 to 95% identity with the corresponding region of B component sequences of Arizona and California CuLCrV isolates (GenBank Accession Nos. AF327559 and AF224761, respectively), whereas the AC1048/AV494 PCR products shared 99% identity with each other and 97% identity with the corresponding region of A component sequences of Arizona and California CuLCrV isolates. Nucleic acid dot-blot hybridization assays of sap from homogenized leaves of the three December samples (from which the PCR product clones were obtained) with a digoxigenin-labeled CuLCrV cDNA probe also confirmed the presence of CuLCrV. Although CuLCrV has been reported to experimentally infect common bean and tobacco (2), to our knowledge, this is the first report of CuLCrV infecting any noncucurbit host in Florida. This finding suggests that CuLCrV may be more widely distributed than previously known in Florida (1) and that common bean (and potentially other legumes) are potential reservoirs for CuLCrV. References: (1) F. Akad et al. Plant Dis. 92:648, 2008. (2) J. K. Brown et al. Phytopathology 92:734, 2002. (3) M. R. Rojas et al. Plant Dis. 77:340, 1993. (4) S. D. Wyatt and J. K. Brown. Phytopathology 86:1288, 1996.
A new system for inoculation of plants with begomoviral DNA without cloning or the use insect vec... more A new system for inoculation of plants with begomoviral DNA without cloning or the use insect vectors is described. Total DNA extracted from begomovirus-infected plants was amplified by rolling circle amplification (RCA) using the bacteriophage phi29 DNA polymerase, and inoculated to plants by particle bombardment. Infection rates of up to 100% were obtained using this technique. This technique successfully inoculated all the begomoviruses evaluated: five bipartite (Bean golden yellow mosaic virus, Cabbage leaf curl virus, Squash leaf curl virus, Tomato mottle virus, Watermelon chlorotic stunt virus) as well as one monopartite (Tomato yellow leaf curl virus). The success of the technique was not dependent upon plant species. Four species from three plant families [Phaseolus vulgaris (bean), Solanum lycopersicum (tomato), Cucurbita pepo (squash), and Citrullus lanatus (watermelon)], could all be inoculated by this technique. The success of the method was not dependent upon either the type or the age of the source of virus. Infectious DNA was obtained successfully from fresh, freeze-dried or desiccated plant material, from squashes of plant leaves on FTA cards, as well as from the insect vector. Plant material collected and dried as long as 25 years ago yielded infectious DNA by this method. In summary, this method can be used to obtain infectious DNA of single-stranded circular DNA viruses that can be activated for purposes of completing Koch's postulates, for preservation of pure virus cultures, and for many other applications where infectious DNA is required.
A new geminivirus, tomato mottle virus (TMoV), affecting tomato production in Florida has been cl... more A new geminivirus, tomato mottle virus (TMoV), affecting tomato production in Florida has been cloned and sequenced. Sequence analysis of the cloned replicative forms of TMoV revealed four potential coding regions for the A component [2601 nucleotides (nt)] and two for the B component (2541 nt).
Los virus se propagan de planta a planta en varias formas. Algunas veces las malezas que existen ... more Los virus se propagan de planta a planta en varias formas. Algunas veces las malezas que existen en o cerca de los cultivos pueden estar afectadas, en otrso casos vienen a los cultivos en la semilla. La transmision y la fuente son muy importantes cuando se trata de controlar las enfermedades virosas. Se examinan los ciclos de patogenicidad de cuatro de los virus mas comunes de la soya : el virus del mosaico de la soya se transmite por varias especies de afidos y a traves de semilla de plantas infectadas. El virus del mosaico de la vaina del frijol, transmitido en el campo por tres especies de escarabajos que se nutren por leguminosas. Virus moteado del Mani, la migracion de insectos portadores del virus de un campo de mani hacia uno de soya. El virus de la mancha anular del tabaco, este se puede transmitir por nematodos, trips, y la semilla de soya. Se cuenta con diferentes metodos para identificar los virus fitopatogenicos, estos metodos se combinan para fortalecer el grado de confiabilidad de la identificacion. Los metodos mas comunes en uso son : pruebas serologicas, gama de hospederos, prueba de lesiones locales, microscopia electronica para determinar el tamano y la forma de las particulas virales. Una vez el virus haya sido identificado se obtiene informacion sobre la ecologia, lo que daria idea sobre como controlarlo
A viral metagenomics-based study of the viromes of Saccharum species from Florida, Reunion, Guade... more A viral metagenomics-based study of the viromes of Saccharum species from Florida, Reunion, Guadeloupe, and Cirad's sugarcane quarantine in Montpellier, France, was carried out using the virion-associated nucleic acid (VANA) approach. The goal of this study was to identify known and potentially new sugarcane viruses. This study revealed the presence of a potential new Mastrevirus species infecting Saccharum species in Florida, Guadeloupe and Reunion. Seventeen full genome sequences (2738-2749 nt long) were obtained using either rolling circle amplification followed by enzymatic restriction, or PCR using back-to-back primers, followed by cloning of full length restricted fragment or full length amplicon and Sanger sequencing. Three full genome sequences were obtained from S. barberi (Florida), five from S. officinarum (Florida and Guadeloupe), four from S. spontaneum (Florida) and five from sugarcane hybrids (Guadeloupe). BLASTn and BLASTx comparisons between these 17 genome sequences and all sequences in GenBank resulted in the highest identity score with a recently deposited geminivirus genome isolated from sugarcane in China (KR150789, highest percentage identity = 89%, e-value = 0.0). Based on the distribution of pairwise identity scores yielded by the species demarcation tool (SDTv1.2), and using Mastrevirus species demarcation threshold of >78 %, we propose that all 18 genomic sequences (17 from our study and KR150789 from China) belong to the same species of Mastrevirus. ,Because this novel Mastrevirus species has never been tested in routine quarantine detection assays, it most likely occurs in several countries of Africa, America, Asia and the Caribbean Islands. In order to develop a new molecular diagnostic assay, we designed specific detection primers using the alignment of the 18 full available genomes. This assay will be used to screen the 2016 variety collection of Cirad's sugarcane quarantine for the presence of the new Mastrevirus species. Results of this screening and analysis of the genetic diversity of the produced amplicons will be presented. (Resume d'auteur)
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution author... more The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations.
A tospovirus was identified in tomato plants from two counties in Florida by reverse transcriptio... more A tospovirus was identified in tomato plants from two counties in Florida by reverse transcription-PCR and sequencing of portions of the S, M and L genomic segments. The predicted amino-acid sequences of the N protein of PCR products from four plant samples were >96% identical to those of TCSV. Partial nucleic acid sequences of the L and M RNA were >97% identical to those reported for TCSV isolates. Extracts from field samples infected test plants and produced symptoms similar to those reported for TCSV. This is the first report of an isolate of TCSV in Florida and in the USA.
In October 1998, symptoms characteristic of tomato yellow leaf curl virus (TYLCV) were observed o... more In October 1998, symptoms characteristic of tomato yellow leaf curl virus (TYLCV) were observed on fresh market tomato (Lycopersicon esculentum Mill.) in four production fields, two in Decatur County, Georgia, and two in Gadsden County, Florida. Symptoms observed were plant stunting, reduced leaf size, yellow leaf margins, and mottling. The incidence of symptomatic plants was less than 1% in all fields examined. In most cases, symptoms were observed only on the upper portion of plants, suggesting these plants had been infected by secondary spread from an unknown source. Nuclear inclusions characteristic of geminiviruses were observed by light microscopy in leaf tissue from symptomatic plants (1). To identify the geminivirus, total DNA from infected plants was extracted from six symptomatic tomato plants (two from Georgia and four from Florida) for polymerase chain reaction (PCR; J. E. Polston, personal communication). DNA was amplified with geminivirus DNA A degenerate primer set PAL1v1978 and PAR1c496 (2) from these extracts in addition to extracts from a known TYLCV-infected, a tomato mottle virus (ToMoV)-infected, and a healthy tomato plant. A PCR product of 1.4 kb was obtained from plants with TYLCV-like symptoms, while a 1.4-kb product and a 1.1-kb product were obtained from extracts of the known TYLCV-infected and ToMoV-infected tomato plants, respectively. No PCR product was obtained from extracts of healthy tomato plants. The 1.4-kb PCR products from one Georgia sample and one Florida sample were compared with those of TYLCV and ToMoV by restriction enzyme (RE) digestion with EcoRI and ClaI. The RE pattern of the 1.4-kb fragment from both samples was identical to the RE pattern of TYLCV and different from that of ToMoV. Adult and immature whiteflies collected from the fields where TYLCV was found were identified as Bemisia tabaci, the vector of TYLCV, but the biotype was not established. This report of TYLCV in south Georgia and north Florida extends the geographic range of TYLCV in the U.S. northward approximately 100 km. Georgia is the second state in which TYLCV was found since its initial detection in south Florida in July 1997 (J. E. Polston, personal communication). Monitoring of silverleaf whitefly populations and detection of TYLCV on alternate hosts will continue in order to estimate the potential impact of this virus on south Georgia and north Florida agriculture. References: (1) R. G. Christie and J. R. Edwardson. Plant Dis. 70:273, 1986, (2) M. R. Rojas et al. Plant Dis. 77:340, 1993.
uch of the American subtropics and tropics have a climate that is condu- cive to the year-round p... more uch of the American subtropics and tropics have a climate that is condu- cive to the year-round production of to- mato, Lycopersicon esculentum Mill. The tomato has been grown for centuries in the Americas, with the center of origin be- lieved to be in northern South America. Processing tomatoes are produced through- out the tropics for local consumption and for
Uploads
Papers by Jane Polston