scholarly journals First Report of Pantoea agglomerans Causing a Leaf Blight and Bulb Rot of Onions in Georgia

Plant Disease ◽  
2006 ◽  
Vol 90 (12) ◽  
pp. 1551-1551 ◽  
Author(s):  
D. G. Edens ◽  
R. D. Gitaitis ◽  
F. H. Sanders ◽  
C. Nischwitz
Keyword(s):  
The United States ◽  
Field Trials ◽  
Positive Control ◽  
Universal Primers ◽  
Enzyme Linked Immunosorbent Assay ◽  
Bacterial Suspension ◽  
Water Control ◽  
First Report ◽  
Negative Results ◽  
Foliar Blight

In April 2006, sweet onions (Allium cepa) that were grown in Wayne County, GA displayed symptoms typical of either center rot caused by Pantoea ananatis or a foliar blight caused by Iris yellow spot virus (IYSV). After samples tested negative for IYSV by enzyme-linked immunosorbent assay and polymerase chain reaction, isolations were made from basal areas of leaves of infected plants where healthy and diseased tissues converged. All samples yielded yellow colonies on trypticase soy broth agar (TSBA) that were nonfluorescent when transferred to King's medium B. Four strains were characterized and tentatively identified as a Pantoea sp. by yellow pigmentation of colonies, oxidative and fermentative use of glucose, and lack of oxidase. However, the inability to produce indole from tryptophan, negative ice-nucleation activity, ability to reduce nitrate to nitrite, and the presence of phenylalanine deaminase were characteristics more typical of P. agglomerans than P. ananatis. Furthermore, all test strains utilized cellobiose, raffinose, lactose, gelatin, melibiose, and malonate. The identity of the bacterium was confirmed as P. agglomerans by BIOLOG (Hayward, CA). In addition, the 16S gene was amplified using universal primers (forward 5′-AGTTTGATCCTGGCTCAG-3′ and reverse 5′-TACCTTGTTACGACTTCGTCCCA-3′ (1) and sequenced. A BLAST search of the sequence against the NIH GenBank nucleotide library also confirmed the identity of the onion pathogen as P. agglomerans (97% identity) by having 8 of the top 10 bacteria providing significant alignments identified as P. agglomerans. The remaining two matches were uncultured bacteria from environmental samples. To confirm pathogenicity, two onion plants for each of the four test strains were inoculated with a turbid, aqueous bacterial suspension (~1 × 108 CFU ml-1) or sterile water in the lab (n = 8) and the field (n = 8). In addition, two plants each were inoculated with P. ananatis as a positive control and with a water blank and a nonpathogenic strain of P. agglomerans from peach (Png 86-2) as negative controls. All test strains of P. agglomerans produced severe blighting and withering of onion leaves in 4 days, while the water control and Png 86-2 were negative. Results were the same for both lab and field trials. Bacteria recovered from the plants infected with the test strains demonstrated the same characteristics of P. agglomerans as described above. Although P. agglomerans was originally reported as a pathogen of onion in South Africa (2), to the best of our knowledge, this is the first report of P. agglomerans causing a disease of onions in the United States. The long-term impact on the onion industry at this time is unknown. However, considering the close relationship of this organism with P. ananatis and the similarity of disease symptoms with those caused by center rot, there is potential that this bacterium could become established in the onion-growing area of Georgia and become part of a center rot ‘complex’. References: (1) T. De Baere et al. J. Clin. Microbiol. 42:4393, 2004. (2) M. J. Hattingh and D. F. Walters. Plant Dis. 65:615, 1981.

scholarly journals First Report of Xylella fastidiosa Associated with Leaf Scorch in Black Oak in Washington, D.C.

Plant Disease ◽  
2004 ◽  
Vol 88 (2) ◽  
pp. 224-224 ◽  
Author(s):  
Q. Huang
Keyword(s):  
Xylella Fastidiosa ◽  
The United States ◽  
Enzyme Linked Immunosorbent Assay ◽  
Bacterial Suspension ◽  
White Oak ◽  
First Report ◽  
Leaf Petiole ◽  
Leaf Scorch ◽  
Pcr Product ◽  
Black Oak

Bacterial leaf scorch caused by Xylella fastidiosa has been reported in 17 species of oak including bur, pin, red, scarlet, shingle, and white oaks (3). In September 2002, a leaf scorch symptom characterized by marginal necrosis of leaves bordered by a darker brown band was observed in a mature black oak (Quercus velutina Lam.) at the U.S. National Arboretum in Washington, D.C. The leaf petiole of the black oak was processed in general extraction buffer (Agdia, Inc., Elkhart, IN) contained in a FastDNA lysing matrix tube using the FastPrep FP120 instrument (Qbiogene, Inc., Carlsbad, CA) (1). The leaf petiole extract reacted with an antiserum specific for X. fastidiosa (Agadia, Inc.) in an enzyme-linked immunosorbent assay (ELISA). A slow-growing bacterium was cultured from leaf petioles of the affected black oak tree by soaking the surface-sterilized, finely cut leaf petioles in sterile water for 30 min, followed by spreading the bacterial suspension on periwinkle wilt plates (1). When the cultured bacterium was subjected to polymerase chain reaction (PCR) with primers specific for X. fastidiosa (2), a 472-bp PCR product was detected. The PCR product was confirmed to be the predicted X. fastidiosa product by sequencing and sequence comparison with the reported genomic sequence of X. fastidiosa. ELISA and bacterial isolation from leaf petioles of a nearby symptomless white oak (Q. alba L.) tree were negative. To our knowledge, this is the first report of X. fastidiosa associated with leaf scorch in black oak in the United States, expanding the host range of the bacterium in economically important landscape tree species. References: (1) Q. Huang and J. L. Sherald. Curr. Microbiol. 48:73, 2004. (2) M. R. Pooler and J. S. Hartung. Curr. Microbiol. 31:377, 1995. (3) J. L. Sherald. Xylella fastidiosa, A bacterial pathogen of landscape trees. Page 191 in: Shade Tree Wilt Diseases, C. L. Ash, ed. The American Phytopathological Society, 2001.

scholarly journals First Report of Pseudomonas savastanoi Causing Bacterial Leaf Spot of Mandevilla sanderi in Slovenia

Plant Disease ◽  
2015 ◽  
Vol 99 (3) ◽  
pp. 415-415 ◽  
Author(s):  
M. Pirc ◽  
M. Ravnikar ◽  
T. Dreo
Keyword(s):  
Uv Light ◽  
Geographical Area ◽  
The United States ◽  
Positive Control ◽  
Hypersensitive Reaction ◽  
Negative Control ◽  
Bacterial Suspension ◽  
First Report ◽  
Systemic Spread ◽  
Necrotic Spots

Foliar necrotic spots with narrow chlorotic halos were observed on different cultivars of Brazilian Jasmine (Mandevilla sanderi) during spring 2010 in several commercial greenhouses in Slovenia. Up to 70% were symptomatic and were unmarketable. No galls were observed on the stems of symptomatic plants. Circular, flat, granulated colonies with entire margins were isolated from symptomatic leaves of two plants from different greenhouses on King's B medium (KB). The isolates were negative for levan, oxidase, pectinolytic and arginine dihydrolase activity. They caused a hypersensitive reaction on tomato but not on tobacco cv. White Burley. Isolates were weakly fluorescent on KB under UV light. One isolate per sample (NIB Z 1413 and 1415) was further characterized. Partial sequences of 16S rDNA (1; GenBank KM603318 of 722 bp, KM603319 of 686 bp) grouped the isolates within genomospecies 2 of Pseudomonas. Repetitive polymerase chain reaction (PCR) assay using the BOXA1R primer (5) resulted in highly similar DNA fragment banding patterns of the two NIB Z isolates and other reference strains of genomospecies 2 (minimum 95.1% identity with Pearson's correlation). Partial sequences of rpoD (3) of the two Slovenian isolates (600 bp; GenBank KJ744202, KJ744201) were identical to the P. savastanoi isolate from Mandevilla B200 (W. Wohanka, Germany; GenBank KJ744203) and P. s. pv. nerii strain NCPPB 3334 (GenBank AB039513). The sequences differed in two nucleotides relative to the sequence of the pathotype strain of pv. nerii NCPPB 3278 (positions 487 and 510 relative to GenBank FN433279) and had an insertion of six nucleotides compared to available P. savastanoi pv. savastanoi rpoD sequences (NZ_JOJV01000073, CM001834). Pathogenicity of isolated bacteria (two isolates) was determined on M. sanderi cv. Pretty Rose inoculated by two different methods, spraying foliage and pricking stems. The abaxial and adaxial surfaces of leaves were sprayed with a 30-ml bacterial suspension (5 × 106 CFU/ml). Three plants were inoculated with each isolate: NIB Z 1413 and 1415 and the reference strain NCPPB 3278. Necrotic spots developed on leaves after 14 days of incubation, under >80% high relative humidity, with 16 h of daylight at 25°C and 8 h of dark at 21°C. One month after inoculation, necrosis also developed on stems and new growth. Inoculation of bacteria by pricking nodes of healthy M. sanderi cv. Pretty Rose with a needle dipped in the isolates grown on KB for 24 h (each of NIB Z 1413, 1415, and NCPPB 3278 for positive control) led to development of galls in 14 days at the inoculation points. The re-isolation was performed separately from necrotic spots on leaves, stems, new growth above the inoculation points, and galls. The BOX-PCR profiles of the bacteria isolated from symptomatic tissues were identical to the original profiles, thus confirming the systemic spread of the bacteria. None of the three negative control plants sprayed with 0.01M MgSO4 or pricked with a sterile needle developed symptoms. This is the first report of P. savastanoi on Mandevilla sanderi plants in greenhouse production in Slovenia. The galls caused by P. savastanoi have previously been reported from the United States (4) and Germany (2). This report broadens the geographical area where P. savastanoi, causing both galls on stems and necrotic spots on leaves, can be found in commercial production of Mandevilla spp. References: (1) U. Edwards et al. Nucleic Acids Res. 17:7843, 1989. (2) N. Eltlbany et al. Appl. Environ. Microbiol. 78:8492, 2012. (3) N. Parkinson et al. Plant Pathol. 60:338, 2011. (4) M. L. Putnam et al. Phytopathology 100:S104, 2010. (5) J. Versalovic et al. Methods Mol. Cell Biol. 5:25, 1994.

scholarly journals First Report of Stem and Foliage Blight of Chrysanthemum Caused by Phytophthora drechsleri in the United States

Plant Disease ◽  
2021 ◽  
Author(s):  
Charles Krasnow ◽  
Nancy Rechcigl ◽  
Jennifer Olson ◽  
Linus Schmitz ◽  
Steven N. Jeffers
Keyword(s):  
United States ◽  
South Carolina ◽  
Sequence Similarity ◽  
Morphological Characteristics ◽  
The United States ◽  
Universal Primers ◽  
Broad Host Range ◽  
Pathogenicity Test ◽  
First Report ◽  
Foliage Blight

Chrysanthemum (Chrysanthemum × morifolium) plants exhibiting stem and foliage blight were observed in a commercial nursery in eastern Oklahoma in June 2019. Disease symptoms were observed on ~10% of plants during a period of frequent rain and high temperatures (26-36°C). Dark brown lesions girdled the stems of symptomatic plants and leaves were wilted and necrotic. The crown and roots were asymptomatic and not discolored. A species of Phytophthora was consistently isolated from the stems of diseased plants on selective V8 agar (Lamour and Hausbeck 2000). The Phytophthora sp. produced ellipsoid to obpyriform sporangia that were non-papillate and persistent on V8 agar plugs submerged in distilled water for 8 h. Sporangia formed on long sporangiophores and measured 50.5 (45-60) × 29.8 (25-35) µm. Oospores and chlamydospores were not formed by individual isolates. Mycelium growth was present at 35°C. Isolates were tentatively identified as P. drechsleri using morphological characteristics and growth at 35°C (Erwin and Ribeiro 1996). DNA was extracted from mycelium of four isolates, and the internal transcribed spacer (ITS) region was amplified using universal primers ITS 4 and ITS 6. The PCR product was sequenced and a BLASTn search showed 100% sequence similarity to P. drechsleri (GenBank Accession Nos. KJ755118 and GU111625), a common species of Phytophthora that has been observed on ornamental and vegetable crops in the U.S. (Erwin and Ribeiro 1996). The gene sequences for each isolate were deposited in GenBank (accession Nos. MW315961, MW315962, MW315963, and MW315964). These four isolates were paired with known A1 and A2 isolates on super clarified V8 agar (Jeffers 2015), and all four were mating type A1. They also were sensitive to the fungicide mefenoxam at 100 ppm (Olson et al. 2013). To confirm pathogenicity, 4-week-old ‘Brandi Burgundy’ chrysanthemum plants were grown in 10-cm pots containing a peat potting medium. Plants (n = 7) were atomized with 1 ml of zoospore suspension containing 5 × 103 zoospores of each isolate. Control plants received sterile water. Plants were maintained at 100% RH for 24 h and then placed in a protected shade-structure where temperatures ranged from 19-32°C. All plants displayed symptoms of stem and foliage blight in 2-3 days. Symptoms that developed on infected plants were similar to those observed in the nursery. Several inoculated plants died, but stem blight, dieback, and foliar wilt were primarily observed. Disease severity averaged 50-60% on inoculated plants 15 days after inoculation. Control plants did not develop symptoms. The pathogen was consistently isolated from stems of symptomatic plants and verified as P. drechsleri based on morphology. The pathogenicity test was repeated with similar results. P. drechsleri has a broad host range (Erwin and Ribeiro 1996; Farr et al. 2021), including green beans (Phaseolus vulgaris), which are susceptible to seedling blight and pod rot in eastern Oklahoma. Previously, P. drechsleri has been reported on chrysanthemums in Argentina (Frezzi 1950), Pennsylvania (Molnar et al. 2020), and South Carolina (Camacho 2009). Chrysanthemums are widely grown in nurseries in the Midwest and other regions of the USA for local and national markets. This is the first report of P. drechsleri causing stem and foliage blight on chrysanthemum species in the United States. Identifying sources of primary inoculum may be necessary to limit economic loss from P. drechsleri.

scholarly journals Severe Outbreak of Bacterial Blight Caused by Xanthomonas arboricola pv. corylina on Hazelnut cv. Tonda di Giffoni in Central Italy

Plant Disease ◽  
2012 ◽  
Vol 96 (10) ◽  
pp. 1577-1577 ◽  
Author(s):  
J. R. Lamichhane ◽  
A. Fabi ◽  
L. Varvaro
Keyword(s):  
16S Rdna ◽  
Bacterial Blight ◽  
Central Italy ◽  
Positive Control ◽  
Negative Control ◽  
Early Summer ◽  
Nutrient Broth ◽  
Universal Primers ◽  
Bacterial Suspension ◽  
Xanthomonas Arboricola

Hazelnut (Corylus avellana L.) is one of the most economically important tree crops in Italy. Xanthomonas arboricola pv. corylina (Xac) causes bacterial blight of hazelnut (4). During early summer 2010, a survey of three orchards (5 ha total) containing 4-year-old hazelnut trees (cv. Tonda di Giffoni) in Viterbo Province, Latium region, Italy, showed an 80 to 100% incidence of bacterial blight. Initially, water-soaked, necrotic spots were visible on leaves, fruit involucres, and shells, followed by lateral shoot dieback and development of cankers as longitudinal bark cracks on twigs, branches, and main trunks. Brown necrosis of the cambium was observed when bark tissue was removed. By late summer, necrosis had extended down main branches to the trunk, causing complete girdling of branches. Symptomatic tissues were collected from leaves, branches, and trunks, sections were surface-sterilized in 1% NaOCl for 1 min followed by two rinses in sterile distilled water (SDW, each for 1 min), and each section was then crushed in SDW. A loopful of the suspension was streaked onto yeast extract-dextrose-calcium carbonate agar medium (YDCA). Thirty six (12 from each type of tissue) yellow-mucoid, shiny, round bacterial colonies, each approximately 2 mm in diameter, were subcultured on YDCA. All strains were gram-negative and aerobic; negative for indole, lecithinase, urease, tyrosinase, and nitrate reduction; and positive for catalase, growth in 2% NaCl in nutrient broth, and growth at 35°C. All strains produced dark green pigment on succinate-quinate (SQ) medium. Inoculum of each of 15 isolates was prepared in nutrient broth, and washed cells from late log-phase cultures used to prepare a bacterial suspension of each isolate for inoculation of 2-year-old potted hazelnut plants cv. Tonda di Giffoni. A suspension of 106 CFU/ml for each isolate was sprayed onto leaves (10 ml/plant), and drops of inoculum were placed on wounds made on twigs with a sterile scalpel (0.10 μl/wound). For each isolate, three plants were inoculated per inoculation method. Inoculations with two reference strains of Xac (Xaco 1 from central Italy (3) and NCPPB 2896 from England) and SDW were performed on the same number of plants for positive and negative control treatments, respectively. Inoculated plants were maintained at 26 ± 1°C in a greenhouse. After 21 days, all inoculated plants had developed symptoms on leaves, while cankers developed on twigs after 40 days. Positive control plants developed the same symptoms, while negative control plants remained asymptomatic. Bacteria recovered from lesions on plants inoculated with the test strains or positive control strains had the same morphological and physiological characteristics as the original strains. No bacteria were recovered from negative control plants. Total DNA was extracted from bacterial suspensions and 16S rDNA amplified using universal primers (2). Sequences (GenBank Accession Nos. JQ861273, JQ861274, and JQ861275 for strains Xaco VT3 to VT5) had 99 to 100% identity with 16S rDNA sequences of Xac strains in GenBank. In Italy, Xac was reported by Petri in 1932 in Latium, and later in other regions on several hazelnut cultivars (1). However, to our knowledge, this is the first report of the disease causing severe damage in Italy. References: (1) M. Fiori et al. Petria 16:71, 2006. (2) J. R. Lamichhane et al. Plant Dis. 95:221, 2011. (3) J. R. Lamichhane et al. Acta Horticol.:In press. 2012. (4) OEPP/EPPO Bull. 179:179, 2004.

scholarly journals First Report of Grapevine leafroll associated virus-3 in American Vitis spp. Grapevines in Washington State

Plant Disease ◽  
2006 ◽  
Vol 90 (11) ◽  
pp. 1461-1461 ◽  
Author(s):  
M. J. Soule ◽  
K. C. Eastwell ◽  
R. A. Naidu
Keyword(s):  
New York ◽  
Economic Impact ◽  
Virus Disease ◽  
The United States ◽  
Washington State ◽  
The State ◽  
Enzyme Linked Immunosorbent Assay ◽  
Rt Pcr ◽  
First Report ◽  
Table Grapes

Washington State is the largest producer of juice grapes (Vitis labruscana ‘Concord’ and Vitis labrusca ‘Niagara’) and ranks second in wine grape production in the United States. Grapevine leafroll disease (GLD) is the most wide spread and economically significant virus disease in wine grapes in the state. Previous studies (2) have shown that Grapevine leafroll associated virus-3 (GLRaV-3) is the predominant virus associated with GLD. However, little is known about the incidence and economic impact of GLD on juice and table grapes. Because typical GLD symptoms may not be obvious among these cultivars, the prevalence and economic impact of GLD in Concord and Niagara, the most widely planted cultivars in Washington State, has received little attention from the grape and nursery industries. During the 2005 growing season, 32 samples from three vineyards and one nursery of ‘Concord’ and three samples from one nursery of ‘Niagara’ were collected randomly. Petiole extracts were tested by single-tube reverse transcription-polymerase chain reaction (RT-PCR; 3) with primers LC 1 (5′-CGC TAG GGC TGT GGA AGT ATT-3′) and LC 2 (5′-GTT GTC CCG GGT ACC AGA TAT-3′), specific for the heat shock protein 70 homologue (Hsp70h gene) of GLRaV-3 (GenBank Accession No. AF037268). One ‘Niagara’ nursery sample and eleven ‘Concord’ samples from the three vineyards tested positive for GLRaV-3, producing a single band of the expected size of 546 bp. The ‘Niagara’ and six of the ‘Concord’ RT-PCR products were cloned in pCR2.1 (Invitrogen Corp, Carlsbad, CA) and the sequences (GenBank Accession Nos. DQ780885, DQ780886, DQ780887, DQ780888, DQ780889, DQ780890, and DQ780891) compared with the respective sequence of a New York isolate of GLRaV-3 (GenBank Accession No. AF037268). The analysis revealed that GLRaV-3 isolates from ‘Concord’ and ‘Niagara’ share nucleotide identities of 94 to 98% and amino acid identities and similarities of 97 to 98% with the Hsp70h gene homologue of the New York isolate of GLRaV-3. Additional testing by double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) using antibodies specific to GLRaV-3 (BIOREBA AG, Reinach, Switzerland) further confirmed these results in the ‘Niagara’ and two of the ‘Concord’ isolates. GLRaV-3 has previously been reported in labrusca cvs. Concord and Niagara in western New York (4) and Canada (1), but to our knowledge, this is the first report of GLRaV-3 in American grapevine species in the Pacific Northwest. Because wine and juice grapes are widely grown in proximity to each other in Washington State and grape mealybug (Pseudococcus maritimus), the putative vector of GLRaV-3, is present in the state vineyards, further studies will focus on the role of American grapevine species in the epidemiology of GLD. References: (1) D. J. MacKenzie et al. Plant Dis. 80:955, 1996. (2) R. R. Martin et al. Plant Dis. 89:763, 2005. (3) A. Rowhani et al. ICGV, Extended Abstracts, 13:148, 2000. (4) W. F. Wilcox et al. Plant Dis. 82:1062, 1998.

scholarly journals First report of Coleus blumei viroid 1 in commercial Coleus blumei in the United States

Plant Disease ◽  
2021 ◽  
Author(s):  
Gardenia Orellana ◽  
Alexander V Karasev
Keyword(s):  
United States ◽  
Leaf Tissue ◽  
The United States ◽  
Universal Primers ◽  
Rt Pcr ◽  
Universal Primer ◽  
Tissue Samples ◽  
First Report ◽  
Specific Pcr ◽  
Coleus Blumei

Coleus scutellarioides (syn. Coleus blumei) is a widely grown evergreen ornamental plant valued for its highly decorative variegated leaves. Six viroids, named Coleus blumei viroid 1 to 6 (CbVd-1 to -6) have been identified in coleus plants in many countries of the world (Nie and Singh 2017), including Canada (Smith et al. 2018). However there have been no reports of Coleus blumei viroids occurring in the U.S.A. (Nie and Singh 2017). In April 2021, leaf tissue samples from 27 cultivars of C. blumei, one plant of each, were submitted to the University of Idaho laboratory from a commercial nursery located in Oregon to screen for the presence of viroids. The sampled plants were selected randomly and no symptoms were apparent in any of the samples. Total nucleic acids were extracted from each sample (Dellaporta et al. 1983) and used in reverse-transcription (RT)-PCR tests (Jiang et al. 2011) for the CbVd-1 and CbVd-5 with the universal primer pair CbVds-P1/P2, which amplifies the complete genome of all members in the genus Coleviroid (Jiang et al. 2011), and two additional primer pairs, CbVd1-F1/R1 and CbVd5-F1/R1, specific for CbVd-1 and CbVd-5, respectively (Smith et al. 2018). Five C. blumei plants (cvs Fire Mountain, Lovebird, Smokey Rose, Marrakesh, and Nutmeg) were positive for a coleviroid based on the observation of the single 250-nt band in the RT-PCR test with CbVds-P1/P2 primers. Two of these CbVd-1 positive plants (cvs Lovebird and Nutmeg) were also positive for CbVd-1 based on the presence of a single 150-nt band in the RT-PCR assay with CbVd1-F1/R1 primers. One plant (cv Jigsaw) was positive for CbVd-1, i.e. showing the 150-nt band in RT-PCR with CbVd1-F1/R1 primers, but did not show the ca. 250-bp band in RT-PCR with primers CbVds-P1/P2. None of the tested plants were positive for CbVd-5, either with the specific, or universal primers. All coleviroid- and CbVd-1-specific PCR products were sequenced directly using the Sanger methodology, and revealed whole genomes for five isolates of CbVd-1 from Oregon, U.S.A. The genomes of the five CbVd-1 isolates displayed 96.9-100% identity among each other and 96.0-100% identity to the CbVd-1 sequences available in GenBank. Because the sequences from cvs Lovebird, Marrakesh, and Nutmeg, were found 100% identical, one sequence was deposited in GenBank (MZ326145). Two other sequences, from cvs Fire Mountain and Smokey Rose, were deposited in the GenBank under accession numbers MZ326144 and MZ326146, respectively. To the best of our knowledge, this is the first report of CbVd-1 in the United States.

scholarly journals First Report of Plum pox virus (Sharka Disease) in Prunus persica in the United States

Plant Disease ◽  
2000 ◽  
Vol 84 (2) ◽  
pp. 202-202 ◽  
Author(s):  
L. Levy ◽  
V. Damsteegt ◽  
R. Welliver
Keyword(s):  
Prunus Persica ◽  
Virus Disease ◽  
Sandwich Elisa ◽  
Pcr Amplification ◽  
The United States ◽  
Enzyme Linked Immunosorbent Assay ◽  
Plum Pox Virus ◽  
Rt Pcr ◽  
Peach Fruit ◽  
First Report

Plum pox (Sharka) is the most important virus disease of Prunus in Europe and the Mediterranean region and is caused by Plum pox potyvirus (PPV). In September 1999, PPV-like symptoms were observed in peach fruit culls in a packinghouse in Pennsylvania. All symptomatic fruit originated from a single block of peach (P. persica cv. Encore) in Adams County. Trees in the block exhibited ring pattern symptoms on their leaves. A potyvirus was detected in symptomatic fruit using the Poty-Group enzyme-linked immunosorbent assay (ELISA) test from Agdia (Elkhart, IN). Reactions for symptomatic peach fruit and leaves also were positive using triple-antibody sandwich ELISA with the PPV polyclonal antibody from Bioreba (Carrboro, NC) for coating, the Poty-Group monoclonal antibody (MAb; Agdia) as the intermediate antibody, and double-antibody sandwich ELISA with PPV detection kits from Sanofi (Sanofi Diagnostics Pasteur, Marnes-La-Coquette, France) and Agdia and the REAL PPV kit (Durviz, Valencia, Spain) containing universal (5B) and strain typing (4DG5 and AL) PPV MAbs (1). PPV also was identified by immunocapture-reverse transcription-polymerase chain reaction (IC-RT-PCR) amplification and subsequent sequencing of the 220-bp 3′ noncoding region (2) (>99% sequence homology to PPV) and by IC-RT-PCR amplification of a 243-bp product in the coat protein (CP) gene (1). The virus was identified as PPV strain D based on serological typing with strainspecific MAbs and on PCR-restriction fragment length polymorphism of the CP IC-RT-PCR product with Rsa1 and Alu1 (1). This is the first report of PPV in North America. References: (1) T. Candresse et al. Phytopathology 88:198, 1998. (2) L. Levy and A. Hadidi. EPPO Bull. 24:595, 1994.

scholarly journals First Report of Anthracnose Caused by Colletotrichum gloeosporioides in Pumpkin in Trinidad

Plant Disease ◽  
2010 ◽  
Vol 94 (8) ◽  
pp. 1062-1062
Author(s):  
S. N. Rampersad
Keyword(s):  
Colletotrichum Gloeosporioides ◽  
Phylogenetic Analyses ◽  
Pcr Amplification ◽  
Positive Control ◽  
Universal Primers ◽  
Conidial Suspension ◽  
Specific Primers ◽  
First Report ◽  
Main Production ◽  
Species Specific

In Trinidad, pumpkin (Cucurbita pepo L. and C. moschata L.) is extensively grown for local and international export markets. In November 2008, symptoms of foliar chlorosis and necrosis were observed in 15 commercial pumpkin fields located in the main production areas of St. George East, Caroni, Victoria, and St. Patrick counties. Severely infected plants were unable to support fruit maturation, which resulted in yield loss. The pathogen was isolated from surface-sterilized tissues of symptomatic plants. Colonies on potato dextrose agar (PDA) were white to cream with gray spore masses in the center. Conidia were hyaline, cylindrical with rounded ends, aseptate, and measured 12.5 to 16.5 μm × 3.5 to 5.0 μm. PCR amplification was carried out with ITS4/5 universal primers (4) and species-specific primers, CgInt/ITS4 (1), using a positive control of Colletotrichum gloeosporioides (courtesy of D. Perez-Brito). Species-specific primers generated a single amplicon, ~450 bp long, which corresponded with the positive control. The ITS1 region (1) of pumpkin isolates (GenBank No. GU320190) was 100% identical to cognate sequences of C. gloeosporioides isolates (GenBank Nos. AY841136 and FJ624257). Phylogenetic analyses (MEGA 4 – Molecular Evolutionary Genetic Analysis Software version 4 for Windows) using the neighbor-joining (NJ) algorithm placed the pumpkin isolates in a well-supported cluster (>90% bootstrap value based on 1,000 replicates) with other C. gloeosporioides isolates. The tree was rooted with C. crassipes (GenBank No. AJ536230). The pathogen was similar to C. gloeosporioides (Penz.) Penz. & Sacc. (3). In pathogenicity tests, six plants (cv. Jamaican squash) for each of five isolates were spray inoculated to runoff with a conidial suspension (1.0 × 106 conidia/ml). Negative controls were sprayed with sterile distilled water. In repeated tests, plants were symptomatic of infection 7 days postinoculation. There were no symptoms on control plants. Koch's postulates were fulfilled with the reisolation of the pathogen from symptomatic leaf tissues. Anthracnose is a serious threat to cucurbit production; however, infection is not common in pumpkin and squash (2). To my knowledge, this is the first report of C. gloeosporioides causing widespread anthracnose infection in pumpkin in Trinidad. References: (1) A. E. Brown et al. Phytopathology 86:523, 1996. (2) G. Kelly. Acta Hortic. (ISHS) 731:479, 2007. (3) B. C. Sutton. Page 1 in: Colletotrichum: Biology, Pathology and Control. CAB International. Wallingford, UK, 1992. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

scholarly journals First Report of Alfalfa mosaic virus in Viburnum lucidum in Spain

Plant Disease ◽  
2008 ◽  
Vol 92 (7) ◽  
pp. 1132-1132 ◽  
Author(s):  
M. C. Cebrián ◽  
M. C. Córdoba-Sellés ◽  
A. Alfaro-Fernández ◽  
J. A. Herrera-Vásquez ◽  
C. Jordá
Keyword(s):  
Mosaic Virus ◽  
Natural Infection ◽  
Alfalfa Mosaic Virus ◽  
The United States ◽  
Rt Pcr ◽  
Water Control ◽  
First Report ◽  
Pcr Product ◽  
Pcr Assays ◽  
The Mediterranean

Viburnum sp. is an ornamental shrub widely used in private and public gardens. It is common in natural wooded areas in the Mediterranean Region. The genus includes more than 150 species distributed widely in climatically mild and subtropical regions of Asia, Europe, North Africa, and the Americas. In January 2007, yellow leaf spotting in young plants of Viburnun lucidum was observed in two ornamental nurseries in the Mediterranean area of Spain. Symptoms appeared sporadically depending on environmental conditions but normally in cooler conditions. Leaf tissue from 24 asymptomatic and five symptomatic plants was sampled and analyzed by double-antibody sandwich (DAS)-ELISA with specific polyclonal antibodies against Tomato spotted wilt virus (TSWV) (Loewe Biochemica, Sauerlach, Germany) and Alfalfa mosaic virus (AMV) (SEDIAG S.A.S, Longvic, France). All symptomatic plants of V. lucidum were positive for Alfalfa mosaic virus (AMV). The presence of AMV was tested in the 29 samples by one-step reverse transcription (RT)-PCR with the platinum Taq kit (Invitrogen Life Technologies, Barcelona, Spain) using primers derived from a partial fragment of the coat protein gene of AMV (2). The RT-PCR assays produced an expected amplicon of 700 bp in the five symptomatic seropositive samples. No amplification product was observed when healthy plants or a water control were used as a template in the RT-PCR assays. One PCR product was purified (High Pure PCR Product Purification Kit; Roche Diagnostics, Mannheim, Germany) and directly sequenced (GenBank Accession No. EF427449). BLAST analysis showed 96% nucleotide sequence identity to an AMV isolate described from Phlox paniculata in the United States (GenBank Accession No. DQ124429). This virosis has been described as affecting Viburnum tinus L. in France (1). To our knowledge, this is the first report of natural infection of Viburnum lucidum with AMV in Spain, which might have important epidemiological consequences since V. lucidum is a vegetatively propagated ornamental plant. References: (1) L. Cardin et al. Plant Dis. 90:1115, 2006. (2) Ll. Martínez-Priego et al. Plant Dis. 88:908, 2004.

scholarly journals First Report of Strawberry Crown Rot Caused by Xanthomonas fragariae in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Zhiwei Song ◽  
Chen Yang ◽  
Rong Zeng ◽  
Shi-gang Gao ◽  
Wei Cheng ◽  
...  
Keyword(s):  
16S Rrna ◽  
Crown Rot ◽  
Universal Primers ◽  
Bacterial Suspension ◽  
Rrna Gene ◽  
Species Identity ◽  
Specific Primers ◽  
16S Rrna Sequence ◽  
First Report ◽  
Xanthomonas Fragariae

Strawberry (Fragaria × ananassa Duch.) is a kind of fruit with great economic importance and widely cultivated in the world. From 2019 to 2020, a serious crown rot disease was sporadically observed in several strawberry cultivars including ‘Zhang Ji’, ‘Hong Yan’ and ‘Yue Xiu’ in Shanghai, China. Initially, water-soaked rot appeared in inner tissue of strawberry crown, then progressed into browning and hollowing symptoms accompanied with yellow discolorations of young leaves. To isolate and identify the causal agent, small pieces of tissue taken from ten diseased crowns were sterilized by 70% alcohol. The cut-up pieces were macerated and serially diluted. The dilutions were placed on nutrient agar (NA) medium. After incubation at 25°C for 4-5 days, the yellow bacterial colonies were tiny and were streaked on NA plate for purification. The colonies were yellow, mucoid, smooth-margined, and five independent representative colonies were used for further confirmation. To confirm the species identity of the bacterial, genomic DNA was extracted from the five representative isolates, and 16S rRNA gene was amplified and sequenced using universal primers 27F/1492R. The 16S rRNA sequence was deposited in GenBank (MW725235) and showed 99% nucleotide similarity with Xanthomonas fragariae strain LMG 708 (NR_026318). The isolate’s identity was further confirmed by X. fragariae-specific primers XF9/XF12 (Roberts et al. 1996). All five isolates could be detected by XF9/XF12 primer. To confirm Koch’s postulates, five healthy strawberry plants were placed in 1000 ml glass beakers by submerging the cutting wound in 50 ml the bacterial suspension of 108 CFU/ml. Five additional strawberry plants treated with sterilized water served as a control. The beakers containing inoculated plants were sealed with plastic film at 25°C. Water-soaked rot appeared on internal tissue of crown similar to those observed in the field within 10-12 days after inoculation, while the control samples remained healthy. The bacteria were re-isolated from rot of inoculated crowns, and confirmed by X. fragariae-specific primers XF9/XF12. X. fragariae has been reported to cause angular leaf spot on strawberry in China (Wang et al. 2017; Wu et al., 2020). It’s also found that X. fragariae could systematically infect crown tissue (Milholland et al. 1996; Mahuku and Goodwin, 1997). To our knowledge, this is the first report of X. fragariae causing strawberry crown rot in China. This report increased our understanding of X. fragariae, and showed that the spread of this disease might seriously threaten the development of strawberry industry in the future

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