scholarly journals First Report of Ageratum yellow vein virus Causing Tobacco Leaf Curl Disease in Fujian Province, China

Plant Disease ◽  
2008 ◽  
Vol 92 (1) ◽  
pp. 177-177 ◽  
Author(s):  
Z. Liu ◽  
C. X. Yang ◽  
S. P. Jia ◽  
P. C. Zhang ◽  
L. Y. Xie ◽  
...  
Keyword(s):  
Nucleotide Sequence ◽  
Nucleotide Sequence Identity ◽  
Yellow Vein ◽  
Tobacco Plants ◽  
Tobacco Leaf ◽  
Leaf Curling ◽  
Sequence Identity ◽  
Ageratum Yellow Vein Virus ◽  
Leaf Curl Disease ◽  
Leaf Curl

A leaf curling disease was observed on 7% of tobacco plants during December 2005 in research plots in the Cangshan District of Fuzhou, Fujian, China. Tobacco plants were infested with Bemisia tabaci, suggesting begomovirus etiology. To identify possible begomoviruses, total DNA was extracted from four symptomatic leaf samples (F1, F2, F3, and F4). The degenerate primers PA and PB were used to amplify part of the intergenic region and AV2 gene of DNA-A-like molecules (3). A 500-bp DNA fragment was amplified by PCR from all four samples. The PCR products were cloned and sequenced (GenBank Accession Nos. EF531601–EF531603 and EF527823). Alignment of the 500-bp sequences for the four isolates indicated that they shared 98.5 to 99.6% nt identity, suggesting that the plants were all infected by the same virus. Overlapping primers TV-Full-F (5′-GGATCCTCTTTTGAACGAGTTTCC-3′) and TV-Full-R (5′-GGATCCCACATGTTTAAAATAATAC-3′) were then designed to amplify the full-length DNA-A from sample F2. The sequence was 2,754 nucleotides long (GenBank Accession No. EF527823). A comparison with other begomoviruses indicated the F2 DNA-A had the highest nucleotide sequence identity (95.7%) with Ageratum yellow vein virus (AYVV; GenBank Accession No. X74516) from Singapore. To further test whether DNAβ was associated with the four viral isolates, a universal DNAβ primer pair (beta 01 and beta 02) was used (4). An amplicon of approximately 1.3 kb was obtained from all samples. The DNAβ molecule from F2 was then cloned and sequenced. F2 DNAβ was 1,345 nucleotides long (GenBank Accession No. EF527824), sharing the highest nucleotide sequence identity with the DNAβ of Tomato leaf curl virus (97.2%) from Taiwan (GenBank Accession No. AJ542495) and AYVV (88.8%) from Singapore (GenBank Accession No. AJ252072). The disease agent was transmitted to Nicotiana tabacum, N. glutinosa, Ageratum conyzoides, Oxalis corymbosa, and Phyllanthus urinaria plants by whiteflies (B. tabaci) when field infected virus isolate F2 was used as inoculum. In N. tabacum and N. glutinosa plants, yellow vein symptoms were initially observed in young leaves. However, these symptoms disappeared later during infection and vein swelling and downward leaf curling symptoms in N. tabacum and vein swelling and upward leaf curling in N. glutinosa were observed. In A. conyzoides, O. corymbosa, and P. urinaria plants, typical yellow vein symptoms were observed. The presence of the virus and DNAβ in symptomatic plants was verified by PCR with primer pairs TV-Full-F/TV-Full-R and beta 01/beta 02, respectively. The above sequence and whitefly transmission results confirmed that the tobacco samples were infected by AYVV. In China, Tobacco leaf curl Yunnan virus, Tobacco curly shoot virus, and Tomato yellow leaf curl China virus were reported to be associated with tobacco leaf curl disease (1,3). To our knowledge, this is the first report of AYVV infecting tobacco in China. A. conyzoides is a widely distributed weed in south China and AYVV was reported in A. conyzoides in Hainan Island, China (2). Therefore, this virus may pose a serious threat to tobacco production in south China. References: (1) Z. Li et al. Phytopathology 95:902, 2005. (2) Q. Xiong et al. Phytopathology 97:405, 2007. (3) X. Zhou et al. Arch. Virol. 146:1599, 2001. (4) X. Zhou et al. J. Gen. Virol. 84:237, 2003.

scholarly journals Three Previously Unidentified Begomoviral Genotypes from Tomato Exhibiting Leaf Curl Disease Symptoms from Central Sudan

Plant Disease ◽  
2001 ◽  
Vol 85 (11) ◽  
pp. 1209-1209
Author(s):  
A. M. Idris ◽  
J. K. Brown
Keyword(s):  
Phylogenetic Analysis ◽  
Nucleotide Sequence ◽  
Nucleotide Sequence Identity ◽  
Degenerate Primers ◽  
Disease Symptoms ◽  
Old World ◽  
Sequence Identity ◽  
Central Sudan ◽  
Leaf Curl Disease ◽  
Leaf Curl

Field tomato plants exhibiting upward curling of leaflets, chlorosis, and stunting symptoms described for tomato leaf curl disease in Sudan (2) were collected in 1996 from Gezira (GZ) and Shambat (SH), Sudan. Disease symptoms were reproduced following experimental transmission of the causal agent(s) by the whitefly Bemisia tabaci from field tomato to virus-free tomato seedlings in a glasshouse at Gezira Research Station, Wad Medani, Sudan. Total nucleic acids were extracted from symptomatic tomato test plants. An ≈1.3-kbp fragment, diagnostic for begomovirus, was obtained from extracts by polymerase chain reaction using degenerate primers that amplify the coat protein gene (CP) and the respective flanking sequences for most begomoviuses (1). A second pair of degenerate primers was used to amplify a 2.3-kbp begomoviral fragment that overlaps both ends of the (CP) amplicon by >200 nt (1). At least 10 amplicons for each were cloned, and their sequences were determined, revealing three unique, tomato-infecting begomoviruses genotypes, two from GZ and one from SH. No B component was detected using degenerate primers that direct the amplification of a diagnostic fragment of the B component (1.4 kbp) for most bipartite begomoviruses. The organization of the three, apparently full-length viral genomes, was typical of other monopartite begomoviruses. A GenBank search revealed that the three viruses were previously undescribed. The GZ and SH tomato isolates are herein provisionally named ToLCV-GZ1 (GenBank Accession No. AY044137), ToLCV-GZ2 (GenBank Accession No. AY044138), and ToLCV-SH (GenBank Accession No. AY044139), respectively. All three tomato-infecting begomoviruses have identical stem-loop structures containing the conserved nonanucleotide motif characteristic of all members of the family Geminiviridae; however, the predicted Rep binding element located in the common region is unique for each virus. Phylogenetic analysis of the three viral sequences placed them in a large clade containing all other Old World begomoviruses. Distance comparisons among these and other well-studied begomoviruses indicated that ToLCV-GZ1 and ToLCV-SH shared an overall 90% nucleotide sequence identity, with ˜83% nucleotide sequence identity to ToLCV-GZ2. ToLCV-GZ1 and ToLCV-SH were 83% identical, with their closest relative, Tomato yellow leaf curl virus (TYLCV), while ToLCV-GZ2 shared 93% identity with TYLCV. The genomes of all three Sudan viruses contained regions of homologous nucleotide sequences, suggesting intermolecular exchange among these viruses. Exclusion of the homologous sequences (>800 nt) from the phylogenetic analysis indicated even lower shared nucleotide identities (<90%, the arbitrary cut-off for distinct species), which may warrant their classification as separate species. These three newly described begomoviruses are indigenous to central Sudan, and comprise a unique Old World lineage distinct from previously described begomoviruses associated with leaf curl disease of tomato in Africa and the Mediterranean Region. References: (1) A. M. Idris and J. K. Brown. Phytopathology 83:548, 1998. (2) A. M. Yassin. Trop. Pest Manage. 29:253, 1983.

scholarly journals First Report of Kudzu mosaic virus on Pueraria montana (Kudzu) in China

Plant Disease ◽  
2013 ◽  
Vol 97 (1) ◽  
pp. 148-148 ◽  
Author(s):  
J. Zhang ◽  
Z. J. Wu
Keyword(s):  
Sequence Analysis ◽  
Nucleotide Sequence ◽  
Mosaic Virus ◽  
Nucleotide Sequence Identity ◽  
Southern China ◽  
Full Length ◽  
Yellow Vein ◽  
Mosaic Symptom ◽  
First Report ◽  
Sequence Identity

Kudzu (Pueraria montana), a weed widely distributed in southern China, is common in the Fuzhou region of Fujian Province, where many plants show yellow vein mosaic disease. In September 2008, four leaf samples from different plants exhibiting yellow vein mosaic symptom were collected in suburban district of Fuzhou (25°15′ N, 118°08′ E). Whitefly (Bemisia tabaci) infestation was also observed in this region. Total DNA was extracted from all samples using a CTAB method (4). Universal primers (PA/PB) were used to amplify part of the intergenic region and coat protein gene of DNA-A of begomoviruses (1). An amplicon of approximately 500 bp was obtained from all four samples and then sequenced. Comparison of 500-bp fragments (GenBank Accession Nos. FJ539016-18 and FJ539014) revealed the presence of the same virus (98.8 to 99.4%). A pair of back-to-back primers (Yg3FL-F: 5′-GGATCCTTTGTTGAACGCCTTTCC-3′/Yg3FL-R: 5′-GGATCCCACATGTTTAAAGTAAAGC-3′) were designed to amplify the full-length DNA-A from the Chinese isolate identified as Yg3. Sequence analysis showed that full-length DNA-A of Yg3 isolate comprised 2,729 nucleotides (GenBank Accession No. FJ539014) and shared the highest nucleotide sequence identity (91.9%) with Kudzu mosaic virus (KuMV, GenBank Accession No. DQ641690) from Vietnam. To further test the association of DNA-B fragments with the four samples from southern China, rolling circle amplification (RCA) was performed (3). When RCA products were digested with Sph I, approximately 2.7 kb was obtained from all samples. Yg3 isolate was chosen to be sequenced. Sequence analysis showed that full-length DNA-B of Yg3 isolate comprised 2,677 nucleotides (GenBank Accession No. FJ539015) and shared the highest nucleotide sequence identity (76.8%) with KuMV DNA-B (GenBank Accession No. DQ641691) from Vietnam. Based on the current convention of begomovirus species demarcation of <89% sequence identity cut-off criterion (2), Yg3 was identified as an isolate of KuMV. To our knowledge, this is the first report of association of KuMV with yellow vein mosaic symptom of kudzu in China. References: (1). D. Deng et al. Annals Appl. Biol. 125:327, 1994. (2). C. M. Fauquet et al. Arch. Virol. 148:405, 2003. (3). D. Haible et al. J. Virol. Methods 135:9, 2006. (4). Y. Xie et al. Chinese Sci. Bull. 47:197, 2002.

scholarly journals First Report of Squash leaf curl Philippines virus Infecting Chayote (Sechium edule) in Taiwan

Plant Disease ◽  
2011 ◽  
Vol 95 (9) ◽  
pp. 1197-1197 ◽  
Author(s):  
W. S. Tsai ◽  
C. J. Hu ◽  
D. P. Shung ◽  
L. M. Lee ◽  
J. T. Wang ◽  
...  
Keyword(s):  
Nucleotide Sequence ◽  
Mosaic Virus ◽  
Nucleotide Sequence Identity ◽  
Zucchini Yellow Mosaic Virus ◽  
Yellow Mosaic Virus ◽  
First Report ◽  
Sequence Identity ◽  
Sechium Edule ◽  
Complementary Sense ◽  
Leaf Curl

Young shoots and leaves of chayote (Sechium edule (Jacq.) Sw.) are commonly consumed as a vegetable in Taiwan. In Hualien County, the major chayote-production area of Taiwan, as much as 15% of chayote plants were not marketable between September and October 2010 because of mosaic symptoms on the leaves. Three symptomatic leaves were collected from each of three fields in Hualien. All nine samples tested positive for a begomovirus by PCR using general primer pair PAL1v1978B/PAR1c715H (3) and negative for Zucchini yellow mosaic virus, Cucumber mosaic virus, Cucumber green mottle mosaic virus, Melon yellow spot virus, Papaya ringspot virus - type W, Watermelon mosaic virus, and Watermelon silver mottle virus by ELISA (2). On the basis of the high nucleotide sequence identity (97.7 to 99.6%) of the 1.5-kb begomoviral DNA-A fragments, all nine samples were considered infected by the same begomovirus species. The 1.5-kb sequences had greatest nucleotide sequence identity (96.6 to 97.8%) with Squash leaf curl Philippines virus (SLCPHV) pumpkin isolate from Taiwan (1) (GenBank Accession No. DQ866135; SLCPHV-TW[TW:Pum:05]). One sample was selected to complete viral genomic DNA analysis. Abutting primer pairs PKA-V/C (PKA-V: 5′-AACGGATCCACTTATGCACGATTTCCCT-3′; PKA-C: 5′-TAAGGATCCCACATGTTGTGGAGCA-3′) and PKB-V/C (PKB-V: 5′-TGTCCATGGATTGATGCGTTATCGGA-3′; PKB-C: 5′-TGACCATGGCATTTCCGAGATCTCCCA-3′') were used to amplify the complete DNA-A and DNA-B, respectively. The sequences of DNA-A (GenBank Accession No. JF146795) and DNA-B (GenBank Accession No. JF146796) contain 2,734 and 2,715 nucleotides, respectively. The geminivirus conserved sequence TAATATTAC was found in both DNA-A and -B. The DNA-A has two open reading frames (ORFs) in the virus sense (V1 and V2) and four in the complementary sense (C1 to C4). The DNA-B also had one ORF each in the virus sense (BV1) and the complementary sense (BC1). When compared by BLASTn in GenBank and analyzed by MEGALIGN software (DNASTAR, Madison, WI), they were found to have greatest nucleotide identity (98.0 to 99.0% of DNA-A and 96.7% of DNA-B) with SLCPHV isolates from Taiwan. In addition, SLCPHV caused similar symptoms on leaves when transmitted to healthy chayote by viruliferous whitefly. In Taiwan, SLCPHV has been detected and sequenced from naturally infected melon (GenBank Accession No. EU479710), pumpkin (GenBank Accession No. DQ866135), and wax gourd (GenBank Accession No. EU310406). To our knowledge, this is the first report of SLCPHV infecting chayote plants in Taiwan. The prevalence of SLCPHV infection on different cucurbit crops should be taken into consideration for managing viral diseases in Taiwan. References: (1) W. S. Tsai et al. Plant Dis. 91:907, 2007. (2) W. S. Tsai et al. Plant Dis. 94:923, 2010. (3) W. S. Tsai et al. Online publication. doi: 10.1111/j.1365-3059.2011.02424.x. Plant Pathol., 2011.

scholarly journals First Report of Pepper yellow leaf curl Indonesia virus in Ageratum conyzoides in Indonesia

Plant Disease ◽  
2007 ◽  
Vol 91 (9) ◽  
pp. 1198-1198 ◽  
Author(s):  
Y. Shibuya ◽  
J. Sakata ◽  
N. Sukamto ◽  
T. Kon ◽  
P. Sharma ◽  
...  
Keyword(s):  
Nucleotide Sequence ◽  
Nucleotide Sequence Identity ◽  
Restriction Site ◽  
Full Length ◽  
Yellow Vein ◽  
Yellow Leaf ◽  
Ageratum Conyzoides ◽  
Sequence Identity ◽  
Vein Disease ◽  
Sense Primer

Ageratum conyzoides L. plants affected with yellow vein disease were collected from Magelang, Bandung, and Purwokerto locations in Indonesia during 2001. A. conyzoides is a naturally occurring weed that is found in and around fields of cultivated pepper (Capsicum annuum L.) and tomato (Lycopersicon esculentum L.). It is frequently found with symptoms of yellow vein disease and the abundance of whiteflies on the affected plants suggested the possible involvement of a geminivirus. Total nucleic acids were extracted from nine samples collected from these locations of A. conyzoides-affected plants exhibiting yellow vein disease and amplified using PCR with geminivirus DNA-A-specific designed primers (virion-sense primer 5′-GAGCTCTTAGCCGCCTGAATGTTC-3′; complementary-sense primer 5′-GAGCTCGTCAGATGTTAAGACCTAC-3′) (1). A PCR-amplified product of approximately 2.7 kbp was obtained from each sample. Five independent sequences were cloned and sequenced from each sample. Sequence analysis showed that five of nine samples were Ageratum yellow vein virus (one each from Bandung and Purwokerto and three from Magelang) and the remaining four samples (two samples each from Bandung and Purwokerto) were a strain of Pepper yellow leaf curl Indonesia virus (PepYLCIDV). Full-length DNA-A of PepYLCIDV from systemic A. coniziodes was amplified using PCR with additional primers designed at only one restriction site (BamHI) (5′-GGATCCGCTTGTTCATCCTTTTCCAG-3′/5′-GGATCCCACATCTTTGGTTAGTGGAGGGTG-3′) and cloned. Three independent clones obtained were sequenced and analyzed. The sequence of a full-length DNA-A component was determined (2,760 bases, GenBank Accession No. AB267838). PCR using degenerate primers (DNABLC1: 5′-GTVAATGGRGTDCACTTCTG-3′; DNABLC2: 5′-RGTDCACTTCTGYARGATGC-3′, DNABLV2: 5′-GAGTAGTAGTGBAKGTTGCA-3′) of begomovirus DNA-B component (2), five independent clones were obtained and sequenced. Primers designed to amplify a full-length B component were constructed around a unique restriction site (BamHI) (5′-GGATCCCCTCATTCCTTTTGCGGAG-3′/5′-GGATCCACAGAGGAAAACTCGCAAGGC-3′). A PCR product was obtained from A. conyzoides samples and three independent clones were sequenced and analyzed. A full-length sequence of a begomovirus B component was determined (2,746 bases, GenBank Accession No. AB267839). Five open reading frames (ORF) were found in DNA-A and two in DNA-B. The DNA-A and DNA-B had a common region (CR) (74% nucleotide sequence identity) that comprised approximately 160 nucleotides. The DNA-A and DNA-B had an identical 31-base stem loop region in the CR. In addition, DNA-A and DNA-B had the highest nucleotide sequence identity (93%) with those of PepYLCIDV (GenBank Accession Nos. AB267834 and AB267835), suggesting it is a strain of PepYLCIDV, which is widely prevalent in Indonesia. To our knowledge, this is the first report of PepYLCIDV isolated from A. conyzoides plants affected with yellow vein disease. References: (1) R. W. Briddon and P. G. Markham. Mol. Biotechnol. 1:202, 1994. (2) S. K. Green et al. Plant Dis. 85:1286, 2001.

scholarly journals A New Begomovirus Inducing Yellow Mottle in Okra Crops in Mexico is Related to Sida yellow vein virus

Plant Disease ◽  
2006 ◽  
Vol 90 (3) ◽  
pp. 378-378 ◽  
Author(s):  
R. De La Torre-Almaraz ◽  
A. Monsalvo-Reyes ◽  
A. Romero-Rodriguez ◽  
G. R. Argüello-Astorga ◽  
S. Ambriz-Granados
Keyword(s):  
Nucleotide Sequence ◽  
Nucleotide Sequence Identity ◽  
Blot Hybridization ◽  
Pcr Amplification ◽  
Yellow Vein ◽  
Universal Primers ◽  
Degenerate Primers ◽  
Sequence Identity ◽  
Pcr Products ◽  
Yellow Mottle

Okra (Abelmoschus esculentus L. Moench), an annual vegetable of African origin, has been cultivated in Mexico for 3 decades. Since 2000, the most important okra-producing areas in the states of Guerrero and Morelos have been affected by a disease causing yellow streak and severe distortion of fruits, a bright yellow mottle, and curling and distortion of leaves. These symptoms and the presence of whiteflies (Bemisia tabaci Gennadius) suggest a viral etiology. Samples of symptomatic plants from three localities, Iguala (Guerrero), Mazatepec, and Xochitepec (Morelos) were collected in November 2004 and tested for the presence of viruses. Single whitefly transmissions, grafting experiments, and experimental inoculation of healthy plants by biolistic delivery of DNA extracts from symptomatic plants consistently induced yellow mottle in okra plants and suggest the presence of a DNA virus. Total DNA extracts from symptomatic plants from field and greenhouse conditions were analyzed by Southern blot hybridization using the coat protein gene of Pepper yellow vein huasteco virus as a probe at low stringency. More than 20 positive samples were subsequently used as templates for polymerase chain reaction (PCR) amplification with the degenerate primers pRepMot and pCPMot (1). PCR products of approximately 600 bp were obtained and directly sequenced. Eight isolates from the three localities (GenBank Accession Nos. AY624016 to AY624023) shared 97 to 100% nucleotide identity but were significantly different from other known begomoviruses. The complete genome A sequence of one isolate from Mazatepec (Ok-M3) was determined using PCR amplification of viral DNA with the degenerate primers PAL1v1978 and PAL1c1960 (3) and four new universal primers, pRepQGR (5′-TCCCTGWATGTTYGGATGGAAATG-3′), pRepQGR-rev (5′-CATTTCCATCCRAACATWCAGGGA-3′), pCp70-MAC (5′-GTC TAGACCTTRCANGGNCCTTCACA-3′), and pCp70-MAC-rev (5′-GAA GGSCCNTGYAAGGTNCAGTC-3′). Partially overlapping PCR products of 0.9, 1.3, and 1.7 kb were cloned into pGEM-T easy vector (Promega, Madison, WI) and sequenced. The 2612-bp DNA-A sequence of Ok-M3 (GenBank Accession No. DQ022611) was compared with sequences available from GenBank using the Clustal alignment method (MegAlign, DNASTAR software, London). The highest sequence identity was obtained with Sida yellow vein virus (SiYVV; Accession No. Y11099), Sida golden mosaic Honduras virus (SiGMHV; Accession No. Y11097), and Chino del tomate virus (CdTV; Accession No. AF101478) that had 85.4, 85.4, and 84.4% nucleotide sequence identity with the Ok-M3 isolate, respectively. Comparative analysis of the intergenic region of the Ok-M3 isolate and its closest relatives revealed that these viruses display different putative Rep-binding sites (iterons): Ok-M3 (GGTACACA), SiYVV (GGAGTA), and SiGMHV (GGKGTA). Current taxonomic criteria for the classification of begomoviruses establishes that less than 89% DNA-A nucleotide sequence identity with the closest relative of a virus is indicative of a separate species (2). Our results indicate that the okra-infecting virus identified in this study is a new begomovirus species, and the provisional name of Okra yellow mottle Mexico virus is proposed. References: (1) J. T. Ascencio-Ibañez et al. Plant Dis. 86:692, 2002. (2) C. Fauquet et al. Arch. Virol. 148:405, 2003. (3) M. Rojas et al. Plant Dis. 77:340, 1993.

scholarly journals Complete Genome Sequences of Tomato Leaf Curl Guam Virus, a Novel Tomato-Infecting Begomovirus from Guam, USA

2021 ◽  
Vol 10 (49) ◽  
Author(s):  
Robert L. Schlub ◽  
Rugang Li ◽  
Jesse P. Bamba ◽  
Mari Marutani ◽  
Kai-Shu Ling
Keyword(s):  
Nucleotide Sequence ◽  
Complete Genome ◽  
Nucleotide Sequence Identity ◽  
Tomato Leaf ◽  
Genome Sequences ◽  
Sequence Identity ◽  
Tomato Leaf Curl ◽  
Leaf Curl

Genome sequences of a novel begomovirus infecting tomato on Guam were obtained using primer-walking and sequencing. The complete genome sequences are 2,750 nucleotides long with a typical monopartite organization and display less than 91% nucleotide sequence identity to other begomoviruses. A provisional name, tomato leaf curl Guam virus (ToLCGuV), is proposed.

scholarly journals Emergence of a New Cucurbit-Infecting Begomovirus Species Capable of Forming Viable Reassortants with Related Viruses in the Squash leaf curl virus Cluster

2002 ◽  
Vol 92 (7) ◽  
pp. 734-742 ◽  
Author(s):  
J. K. Brown ◽  
A. M. Idris ◽  
C. Alteri ◽  
Drake C. Stenger
Keyword(s):  
Nucleotide Sequence ◽  
Host Range ◽  
Nucleotide Sequence Identity ◽  
Begomovirus Species ◽  
Progeny Virus ◽  
Bipartite Begomovirus ◽  
Sequence Identity ◽  
Squash Leaf Curl Virus ◽  
Leaf Curl Virus ◽  
Leaf Curl

Cucurbit leaf curl virus (CuLCV), a whitefly-transmitted geminivirus previously partially characterized from the southwestern United States and northern Mexico, was identified as a distinct bipartite begomovirus species. This virus has near sequence identity with the previously partially characterized Cucurbit leaf crumple virus from California. Experimental and natural host range studies indicated that CuLCV has a relatively broad host range within the family Cucurbitaceae and also infects bean and tobacco. The genome of an Arizona isolate, designated CuLCV-AZ, was cloned and completely sequenced. Cloned CuLCV-AZ DNA A and B components were infectious by biolistic inoculation to pumpkin and progeny virus was transmissible by the whitefly vector, Bemisia tabaci, thereby completing Koch's postulates. CuLCV-AZ DNA A shared highest nucleotide sequence identity with Squash leaf curl virus-R (SLCV-R), SLCV-E, and Bean calico mosaic virus (BCaMV) at 84, 83, and 80%, respectively. The CuLCV DNA B component shared highest nucleotide sequence identity with BCaMV, SLCV-R, and SLCV-E at 71, 70, and 68%, respectively. The cis-acting begomovirus replication specificity element, GGTGTCCTGGTG, in the CuLCV-AZ origin of replication is identical to that of SLCV-R, SLCV-E, and BCaMV, suggesting that reassortants among components of CuLCV-AZ and these begomoviruses may be possible. Reassortment experiments in pumpkin demonstrated that both reassortants of CuLCV-AZ and SLCV-E A and B components were viable. However, for CuLCV-AZ and SLCV-R, only one reassortant (SLCV-R DNA A/CuLCV-AZ DNA B) was viable on pumpkin, even though the cognate component pairs of both viruses infect pumpkin. These results demonstrate that reassortment among sympatric begomovirus species infecting cucurbits are possible, and that, if generated in nature, could result in begomoviruses bearing distinct biological properties.

scholarly journals Sequence identity in an early chorion multigene family is the result of localized gene conversion.

Genetics ◽  
1991 ◽  
Vol 128 (3) ◽  
pp. 595-606
Author(s):  
B L Hibner ◽  
W D Burke ◽  
T H Eickbush
Keyword(s):  
Nucleotide Sequence ◽  
Gene Conversion ◽  
Nucleotide Sequence Identity ◽  
Early Period ◽  
Gene Families ◽  
Multigene Families ◽  
Coding Regions ◽  
Sequence Identity ◽  
Isolation And Characterization ◽  
Sequence Exchange

Abstract The multigene families that encode the chorion (eggshell) of the silk moth, Bombyx mori, are closely linked on one chromosome. We report here the isolation and characterization of two segments, totaling 102 kb of genomic DNA, containing the genes expressed during the early period of choriogenesis. Most of these early genes can be divided into two multigene families, ErA and ErB, organized into five divergently transcribed ErA/ErB gene pairs. Nucleotide sequence identity in the major coding regions of the ErA genes was 96%, while nucleotide sequence identity for the ErB major coding regions was only 63%. Selection pressure on the encoded proteins cannot explain this difference in the level of sequence conservation between the ErA and ErB gene families, since when only fourfold redundant codon positions are considered, the divergence within the ErA genes is 8%, while the divergence within the ErB genes (corrected for multiple substitutions at the same site) is 110%. The high sequence identity of the ErA major exons can be explained by sequence exchange events similar to gene conversion localized to the major exon of the ErA genes. These gene conversions are correlated with the presence of clustered copies of the nucleotide sequence GGXGGX, encoding paired glycine residues. This sequence has previously been correlated with gradients of gene conversion that extend throughout the coding and noncoding regions of the High-cysteine (Hc) chorion genes of B. mori. We suggest that the difference in the extent of the conversion tracts in these gene families reflects a tendency for these recombination events to become localized over time to the protein encoding regions of the major exons.

scholarly journals First Report of Cucurbit aphid-borne yellows virus in Spain

Plant Disease ◽  
2004 ◽  
Vol 88 (8) ◽  
pp. 907-907 ◽  
Author(s):  
M. Juarez ◽  
V. Truniger ◽  
M. A. Aranda
Keyword(s):  
Nucleotide Sequence ◽  
Nucleotide Sequence Identity ◽  
Rt Pcr ◽  
Sequence Comparisons ◽  
E Coli ◽  
Sequence Identity ◽  
Tissue Print ◽  
Sigma Chemical ◽  
Beet Pseudo Yellows Virus ◽  
Cucumis Melo L

In late spring 2003, field-grown melon plants (Cucumis melo L.) showing bright yellowing of older leaves were observed near Valladolises in Campo de Cartagena, Murcia, Spain. Symptoms resembled those caused by viruses of the genus Crinivirus (family Closteroviridae), but absence or very low populations of whiteflies were observed. However, diseased foci showed clear indications of heavy aphid infestations. Later, during the fall of 2003, squash plants (Cucurbita pepo L.) grown in open fields in the same area showed similar symptoms. Tissue print hybridizations to detect Cucurbit yellow stunting disorder virus (CYSDV) and Beet pseudo yellows virus (BPYV) in symptomatic samples were negative. CYSDV and BPYV are two yellowing-inducing criniviruses previously described in Spain. In contrast, standard double-antibody sandwich enzyme-linked immunosorbent assays (DAS-ELISA) with antiserum against Cucurbit aphid-borne yellows virus (CABYV; genus Polerovirus, family Luteoviridae) that was kindly provided by H. Lecoq (INRA-Montfavet Cedex, France) were consistently positive. Definitive confirmation of CABYV associated with symptomatic samples was obtained by performing reverse-transcription polymerase chain reaction (RT-PCR) analyses for the CABYV coat protein gene. Total RNA extracts (TRI reagent; Sigma Chemical, St. Louis, MO) were obtained from symptomatic and asymptomatic leaf samples and RT-PCR reactions were carried out using the primers 5′-GAATACGGTCGCGGCTAGAAATC-3′ (CE9) and 5′-CTATTTCGGGTTCTGGACCTGGC-3′ (CE10) based on the CABYV sequence published by Guilley et al. (2). A single DNA product of approximately 600 bp was obtained only from symptomatic samples. Amplified DNA fragments from two independent samples (samples 36-2 and 37-5) were cloned in E. coli and sequenced (GenBank Accession Nos. AY529653 and AY529654). Sequence comparisons showed a 95% nucleotide sequence identity between the two sequences. A 97% and 94% nucleotide sequence identity was found among 36-2 and 37-5, respectively and the CABYV sequence published by Guilley et al. (2). CABYV seems to be widespread throughout the Mediterranean Basin (1,3) but to our knowledge, it has not previously been described in Spain. Additionally, our data suggest that significant genetic variability might be present in the Spanish CABYV populations. References: (1) Y. Abou-Jawdah et al. Crop Prot. 19:217, 2000. (2) H. Guilley et al. Virology 202:1012, 1994. (3) H. Lecoq et al. Plant Pathol. 41:749, 1992.

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