scholarly journals Evaluation of Olive as a Host of Xylella fastidiosa and Associated Sharpshooter Vectors

Plant Disease ◽  
2014 ◽  
Vol 98 (9) ◽  
pp. 1186-1193 ◽  
Author(s):  
Rodrigo Krugner ◽  
Mark S. Sisterson ◽  
Jianchi Chen ◽  
Drake C. Stenger ◽  
Marshall W. Johnson
Keyword(s):  
Control Method ◽  
Xylella Fastidiosa ◽  
Primary Control ◽  
Homalodisca Vitripennis ◽  
Insecticide Treatment ◽  
Disease Symptoms ◽  
Leaf Scorch ◽  
Polymerase Chain ◽  
Low Efficiency ◽  
Branch Dieback

Olive (Olea europaea) trees exhibiting leaf scorch or branch dieback symptoms in California were surveyed for the xylem-limited, fastidious bacterium Xylella fastidiosa. Only approximately 17% of diseased trees tested positive for X. fastidiosa by polymerase chain reaction, and disease symptoms could not be attributed to X. fastidiosa infection of olive in greenhouse pathogenicity assays. Six strains of X. fastidiosa were isolated from olive in Southern California. Molecular assays identified strains recovered from olive as belonging to X. fastidiosa subsp. multiplex. Pathogenicity testing of olive strains on grapevine and almond confirmed that X. fastidiosa strains isolated from olive yield disease phenotypes on almond and grapevine typical of those expected for subsp. multiplex. Mechanical inoculation of X. fastidiosa olive strains to olive resulted in infection at low efficiency but infections remained asymptomatic and tended to be self-limiting. Vector transmission assays demonstrated that glassy-winged sharpshooter (Homalodisca vitripennis) could transmit strains of both subspp. multiplex and fastidiosa to olive at low efficiency. Insect trapping data indicated that two vectors of X. fastidiosa, glassy-winged sharpshooter and green sharpshooter (Draeculacephala minerva), were active in olive orchards. Collectively, the data indicate that X. fastidiosa did not cause olive leaf scorch or branch dieback but olive may contribute to the epidemiology of X. fastidiosa-elicited diseases in California. Olive may serve as an alternative, albeit suboptimal, host of X. fastidiosa. Olive also may be a refuge where sharpshooter vectors evade intensive areawide insecticide treatment of citrus, the primary control method used in California to limit glassy-winged sharpshooter populations and, indirectly, epidemics of Pierce's disease of grapevine.

scholarly journals Differential Susceptibility of Prunus Germplasm (Subgenus Amygdalus) to a California Isolate of Xylella fastidiosa

HortScience ◽  
2009 ◽  
Vol 44 (7) ◽  
pp. 1928-1931 ◽  
Author(s):  
Craig A. Ledbetter ◽  
Elizabeth E. Rogers
Keyword(s):  
First Generation ◽  
Prunus Persica ◽  
Xylella Fastidiosa ◽  
Differential Susceptibility ◽  
Inoculum Sources ◽  
Disease Symptoms ◽  
Leaf Scorch ◽  
Bacterial Titer ◽  
Almond Trees ◽  
Polymerase Chain

Seedling peach (Prunus persica Batsch) and clonal peach–almond hybrids are popular rootstock choices for commercial almond growers in California. In this study, clonal replicates of peach and almond [P. dulcis (Mill.) D.A. Webb] rootstock germplasm and a first-generation peach–almond hybrid created from them were challenged with Xylella fastidiosa isolate M23. Clonal replicates were needle-inoculated with M23 and maintained in a greenhouse environment for a growing season. Typical almond leaf scorch disease symptoms began to develop on M23-inoculated almonds 11 weeks after inoculation. No leaf scorch symptoms were observed on M23-inoculated peach or peach–almond hybrids. Quantitative real-time polymerase chain reaction revealed consistent levels of X. fastidiosa DNA among inoculated almond replicates, whereas X. fastidiosa DNA was undetectable in replicates of peach–almond hybrids. A trace level of X. fastidiosa DNA was detected in a single peach replicate, and statistical analysis demonstrated that this level differed significantly (P < 0.001) from that detected in almond replicates. Selected almonds were further sampled sequentially along their meristematic axes to examine bacterial titer throughout the trees. Selected almond trees differed significantly (P = 0.036) in bacterial titer, but no significant differences were noted in levels of X. fastidiosa from different vertical sections of the main growth axes. The results suggest that peach and peach–almond hybrid rootstock germplasm used by commercial almond tree nurseries in California are not primary inoculum sources for X. fastidiosa-induced diseases.

scholarly journals Coffee Leaf Scorch Caused by a Strain of Xylella fastidiosa from Citrus

Plant Disease ◽  
2001 ◽  
Vol 85 (5) ◽  
pp. 501-505 ◽  
Author(s):  
W.-B. Li ◽  
W. D. Pria ◽  
D. C. Teixeira ◽  
V. S. Miranda ◽  
A. J. Ayres ◽  
...  
Keyword(s):  
Xylella Fastidiosa ◽  
Leaf Size ◽  
Coffea Canephora ◽  
Enzyme Linked Immunosorbent Assay ◽  
Lateral Shoot ◽  
Disease Symptoms ◽  
Citrus Variegated Chlorosis ◽  
Leaf Scorch ◽  
Coffee Plants ◽  
Polymerase Chain

Citrus variegated chlorosis (CVC) and coffee leaf scorch (CLS) are two economically important diseases in Brazil caused by the bacterium Xylella fastidiosa. Strains of the bacterium isolated from the two plant hosts are very closely related, and the two diseases share sharpshooter insect vectors. In order to determine if citrus strains of X. fastidiosa could infect coffee and induce CLS disease, plant inoculations were performed. Plants of coffee, Coffea arabica ‘Mundo Novo’, grafted on Coffea canephora var. robusta ‘Apuatão 2258’ were mechanically inoculated with triply cloned strains of X. fastidiosa isolated from diseased coffee and citrus. Three months postinoculation, 5 of the 10 plants inoculated with CLS-X. fastidiosa and 1 of the 10 plants inoculated with CVC-X. fastidiosa gave positive enzyme-linked immunosorbent assay (ELISA) and/or polymerase chain reaction (PCR). Eight months postinoculation, another six plants inoculated with CVC-X. fastidiosa gave positive PCR results. The two X. fastidiosa strains were isolated from the inoculated plants and showed the same characteristics as the original clones by microscopy, ELISA, and PCR. None of the plants inoculated with sterile periwinkle wilt (PW) medium as controls gave positive reactions in diagnostic tests, and none developed disease symptoms. Six months postinoculation, seven plants inoculated with CLS-X. fastidiosa and eight inoculated with CVC-X. fastidiosa began to develop characteristic CLS symptoms, including apical and marginal leaf scorch, defoliation, and reductions of internode length, leaf size, and plant height, terminal clusters of small chlorotic and deformed leaves, and lateral shoot dieback. We have demonstrated that X. fastidiosa from citrus plants is pathogenic for coffee plants. This has important consequences for the management of CLS disease and has implications for the origin of citrus variegated chlorosis disease.

scholarly journals Colonization and movement of GFP-labeled Clavibacter nebraskensis in maize

Plant Disease ◽  
2020 ◽  
Author(s):  
Alexander Mullens ◽  
Tiffany Jamann
Keyword(s):  
Crop Residue ◽  
Fluorescent Protein ◽  
Control Method ◽  
Leaf Surface ◽  
Leaf Tissue ◽  
Primary Control ◽  
Bacterial Strains ◽  
Natural Conditions ◽  
Disease Symptoms ◽  
Green Fluorescent

Clavibacter nebraskensis (Cn) causes Goss’s bacterial wilt and leaf blight, a major disease of maize. Infected crop residue is the primary inoculum source and infection can occur via wounds or natural openings, such as stomata or hydathodes. The use of resistant hybrids is the primary control method for Goss’s wilt. In this study, colonization and movement patterns of Cn during infection were examined using green fluorescent protein (GFP)-labeled bacterial strains. We successfully introduced a plasmid to Cn via electroporation, which resulted in GFP accumulation. Fluorescence microscopy revealed that in the absence of wounding, bacteria colonize leaf tissue via entry through the hydathodes when guttation droplets are present. Stomatal penetration was not observed under natural conditions. Bacteria initially colonize the xylem and subsequently the mesophyll, which creates the freckles that are characteristic of the disease. Bacteria infiltrated into the mesophyll did not cause disease symptoms, could not enter the vasculature, and did not spread from the initial inoculation point. Bacteria were observed exuding through stomata onto the leaf surface, resulting in the characteristic sheen of diseased leaves. Resistant maize lines exhibited decreased bacterial spread in the vasculature and the mesophyll. These tools to examine Cn movement offer opportunities and new insights into the pathogenesis process and can form the basis for improved Goss’s wilt management through host resistance.

scholarly journals Coffee Leaf Scorch Bacterium: Axenic Culture, Pathogenicity, and Comparison with Xylella fastidiosa of Citrus

Plant Disease ◽  
1998 ◽  
Vol 82 (1) ◽  
pp. 94-97 ◽  
Author(s):  
J. E. O. de Lima ◽  
V. S. Miranda ◽  
J. S. Hartung ◽  
R. H. Brlansky ◽  
A. Coutinho ◽  
...  
Keyword(s):  
Shoot Growth ◽  
Xylella Fastidiosa ◽  
Polymerase Chain Reaction Amplification ◽  
Axenic Culture ◽  
Enzyme Linked Immunosorbent Assay ◽  
Leaf Scorch ◽  
Mature Leaves ◽  
Reaction Amplification ◽  
Polymerase Chain ◽  
Cultured Bacteria

Symptoms of coffee leaf scorch (CLS) appear on young flushes of field plants as large marginal and apical scorched areas on recently mature leaves. Affected leaves drop, shoot growth is stunted, and apical leaves are small and chlorotic. Symptoms may progress to shoot dieback. Only scorched leaves which could not be related to other known agents consistently contained bacteria and bacterial agglomerates when observed with light microscopy. Only plants with these symptoms were positive in enzyme-linked immunosorbent assay (ELISA) tests using antiserum to Xylella fastidiosa Wells et al. The bacterium Xylella fastidiosa Wells et al. was isolated in November 1995 from coffee (Coffea arabica) leaves with scorch symptoms on supplemented periwinkle wilt medium. Colonies were circular, dome-shaped, white, and 0.5 to 1.5 mm in diameter. Two of 10 young coffee seedlings stem-inoculated with a suspension of the isolated X. fastidiosa in January 1996 showed leaf scorch symptoms 3 to 5 months later, contained bacteria in xylem extracts, and reacted positively in ELISA using antiserum to the citrus variegated chlorosis (CVC) strain of X. fastidiosa. ELISA-positive bacteria were reisolated from this plant. None of the symptomless plants, including controls, revealed bacteria on microscopic examinations, ELISA, or isolation attempts. Antisera developed against cultured bacteria from both CLS and CVC plants reacted positively against plant extracts of both diseases in dot immunobinding assays (DIBA). The level of detection was about 5 × 105 bacteria ml-1 for both homologous and heterologous reactions. The polymerase chain reaction amplification products produced by CLS and CVC strains of X. fastidiosa were indistinguishable. Geographical distribution of these strains is not the same. CLS is widespread and usually occurs if coffee is adjacent to CVC-affected citrus. However, CVC does not always occur when citrus is grown adjacent to CLS-affected coffee. The bacteria are closely related, if not identical.

scholarly journals Distribution of Xylella fastidiosa in Citrus Rootstocks and Transmission of Citrus Variegated Chlorosis Between Sweet Orange Plants Through Natural Root Grafts

Plant Disease ◽  
2000 ◽  
Vol 84 (6) ◽  
pp. 622-626 ◽  
Author(s):  
C. X. He ◽  
W. B. Li ◽  
A. J. Ayres ◽  
J. S. Hartung ◽  
V. S. Miranda ◽  
...  
Keyword(s):  
Bacterial Translocation ◽  
Sweet Orange ◽  
Xylella Fastidiosa ◽  
Disease Symptoms ◽  
Citrus Variegated Chlorosis ◽  
Plant Parts ◽  
Aerial Parts ◽  
Leaf Symptom ◽  
Polymerase Chain ◽  
Root Grafts

To study translocation of Xylella fastidiosa to citrus rootstocks, budsticks from citrus variegated chlorosis (CVC)-affected cv. Pera sweet orange (Citrus sinenesis (L.) Osb.) were top grafted on 15 citrus rootstocks. Disease symptoms were conspicuous 3 months later on all 15 rootstocks tested. The presence of X. fastidiosa was confirmed by light microscopy, double-antibody sandwich enzyme-linked immunosorbent assays, and polymerase chain reaction in rootlets and main roots of CVC-symptomatic Pera sweet orange in 11 of the 15 rootstocks tested. These results suggest that bacterial translocation from the aerial plant parts to the root system occurs but is not essential for X. fastidiosa to induce symptoms in the aerial parts. Bacterial translocation to the roots was not correlated with CVC leaf-symptom severity in the Pera scion. To determine if CVC disease could be transmitted by natural root grafts, two matched seedlings of each of four sweet orange cultivars (Pera, Natal, Valencia, and Caipira) were transplanted into single pots. One seedling rootstock of each pair was inoculated by top grafting with a CVC-contaminated budstick while the other seedling rootstock was cut but not graft inoculated. Transmission of X. fastidiosa from an inoculated plant to a noninoculated plant sharing the same pot was observed in all four sweet orange cultivars tested. Transmission was confirmed by observation of natural roots grafts between the two plants, presence of X. fastidiosa in the root grafts, and disease development in the uninoculated plants. This is the first report of transmission of CVC disease through natural root grafts.

scholarly journals Phylogenetic Relationships of Xylella fastidiosa Strains Isolated from Landscape Ornamentals in Southern California

2007 ◽  
Vol 97 (7) ◽  
pp. 857-864 ◽  
Author(s):  
Rufina Hernandez-Martinez ◽  
Karla A. de la Cerda ◽  
Heather S. Costa ◽  
Donald A. Cooksey ◽  
Francis P. Wong
Keyword(s):  
Southern California ◽  
Genetic Characterization ◽  
Xylella Fastidiosa ◽  
Random Amplified Polymorphic Dna ◽  
Intergenic Spacer ◽  
Disease Symptoms ◽  
Intergenic Spacer Region ◽  
Rapd Pcr ◽  
Polymerase Chain ◽  
Maidenhair Tree

Xylella fastidiosa is an insect-borne, xylem-limited pathogenic bacterium that has been associated with a rise in incidence of diseased landscape ornamentals in southern California. The objective of this study was to genetically characterize strains isolated from ornamental hosts to understand their distribution and identity. Strains of X. fastidiosa isolated from ornamentals were characterized using a multiprimer polymerase chain reaction (PCR) system, random amplified polymorphic DNA (RAPD)-PCR, and sequence analysis of the 16S-23S rDNA intergenic spacer region (ISR). Based on RAPD-PCR and 16S-23S rDNA ISR, strains isolated from daylily, jacaranda, and magnolia clustered with members of X. fastidiosa subsp. sandyi and caused oleander leaf scorch but not Pierce's disease symptoms in glasshouse assays on oleander and grape, respectively. This demonstrated both that our groupings based on genetic characterization were valid and that strains of X. fastidiosa subsp. sandyi are present in hosts other than oleander. Strains isolated from Spanish broom, cherry, and one strain isolated from western redbud clustered with X. fastidiosa subsp. fastidiosa members. Strains isolated from purple-leafed plum, olive, peach, plum, sweetgum, maidenhair tree, crape myrtle, and another western redbud strain clustered with members of X. fastidiosa subsp. multiplex. All strains isolated from mulberry and one from heavenly bamboo formed a separate cluster that has not yet been defined as a subspecies.

scholarly journals Homalodisca coagulata (Hemiptera, Cicadellidae) Transmission of Xylella fastidiosa to Almond

Plant Disease ◽  
2003 ◽  
Vol 87 (10) ◽  
pp. 1255-1259 ◽  
Author(s):  
R. P. P. Almeida ◽  
A. H. Purcell
Keyword(s):  
Xylella Fastidiosa ◽  
Stone Fruit ◽  
Bacterial Populations ◽  
Leaf Scorch ◽  
Laboratory Conditions ◽  
Fruit Species ◽  
Homalodisca Coagulata ◽  
Woody Tissues ◽  
Low Efficiency ◽  
Almond Leaf Scorch

Almond leaf scorch (ALS) is caused by the bacterium Xylella fastidiosa, transmitted by sharpshooter leafhoppers and spittlebugs. The recent invasion of a X. fastidiosa vector, Homalodisca coagulata (Hemiptera, Cicadellidae), into California may have major consequences to the spread of ALS because this insect feeds readily on trees, including stone fruit species. We found that, under laboratory conditions, H. coagulata acquired X. fastidiosa from symptomatic almond plants with low efficiency relative to grape (3.3 to 10% per individual per day). Inoculation efficiency also was low, approximately 4% per insect per day. H. coagulata inoculated 1-year-old woody tissues of almond plants at similar rates as green shoots. H. coagulata transmitted two X. fastidiosa grape strains from grape source plants to grape and almond. We also observed X. fastidiosa transmission to dormant almond plants. X. fastidiosa populations in the petioles of field-collected symptomatic almond leaves were not higher than 107 CFU/g of tissue, suggesting that low bacterial populations within almond are partially responsible for the lower acquisition rates observed from diseased almond compared with diseased grape, which are usually within the range of 108 to 109 CFU/g. The relevance of our findings to ALS epidemiology, considering H. coagulata as a vector, is discussed.

scholarly journals An Experimental Inoculation System to Study Citrus-Xylella fastidiosa Interactions

Plant Disease ◽  
2005 ◽  
Vol 89 (3) ◽  
pp. 250-254 ◽  
Author(s):  
S. A. Lopes ◽  
D. C. Teixeira ◽  
N. G. Fernandes ◽  
A. J. Ayres ◽  
S. C. Z. Torres ◽  
...  
Keyword(s):  
Xylella Fastidiosa ◽  
Polymerase Chain Reaction Analysis ◽  
Extensive Study ◽  
Experimental Conditions ◽  
Disease Symptoms ◽  
Polymerase Chain ◽  
Reduced Space ◽  
Phosphate Buffered Saline ◽  
Strain 9A5c ◽  
Important Disease

Difficulties in reproducing the citrus variegated chlorosis (CVC) disease symptoms in experimental plants have delayed implementation of studies to better understand the essential aspects of this important disease. In an extensive study, cultivars of sweet orange (Citrus sinensis) were inoculated with Xylella fastidiosa using procedures that included root immersion, and stem absorption, pricking, or infiltration of the inoculum into plants of different ages. Inoculum consisted of 5-day-old cultures or cell suspensions of CVC strain 9a5c diluted in phosphate-buffered saline. Inoculated plants and controls were grown, or transferred just after inoculation, to 5-liter pots or 72-cell foam trays. Approximately 4, 5, 9, and 12 months after inoculation, leaves were collected and processed for polymerase chain reaction analysis or X. fastidiosa isolation on BCYE agar medium. Root immersion and stem inoculation of 4- and 6-month-old plants resulted in low percentages of symptomatic (0 to 7%) and plants positive by isolation (0 to 9%). Pinpricked or injected stems of 1-month-old seedlings resulted in high percentages of plants symptomatic (29 and 90% in Pera Rio, 75, 59, and 83% in Valencia, and 77% in Natal) or positive by isolation (26 and 93% in Pera Rio, 98, 96, and 83% in Valencia, and 77% in Natal). In foam trays, the seedlings grew less, the incubation period was shorter, and disease severity was higher than in pots. This system allows testing of higher numbers of plants in a reduced space with a more precise reproduction of the experimental conditions.

scholarly journals First Report of Bacterial Leaf Scorch Caused by Xylella fastidiosa on Southern Highbush Blueberry in Florida

Plant Disease ◽  
2009 ◽  
Vol 93 (11) ◽  
pp. 1220-1220 ◽  
Author(s):  
P. F. Harmon ◽  
D. L. Hopkins
Keyword(s):  
Xylella Fastidiosa ◽  
Vaccinium Corymbosum ◽  
Pathogen Transmission ◽  
Highbush Blueberry ◽  
Disease Symptoms ◽  
Leaf Scorch ◽  
Three Samples ◽  
Southern Highbush ◽  
Das Elisa ◽  
Bacterial Leaf Scorch

In May of 2008, samples of southern highbush blueberry (interspecific Vaccinium corymbosum hybrids) exhibiting marginal leaf necrosis were collected at a farm in Interlachen, FL. The cv. Star showed severe leaf scorch, partial defoliation, and a generally unthrifty growth structure of many thin twigs as has been observed in Georgia (1). The block of Star plants was approximately 10 years old and incidence of the disease was 100%. The grower reported the planting had become increasingly unproductive in the most recent 4 to 5 years. Plants of the cv. Windsor also showed scorch symptoms and yellow-to-red discoloration of leaves. Proportionally fewer Windsor plants showed disease symptoms than Star plants and the disease was not as severe on this cultivar on the basis of visual estimates at the time. Each sample consisted of 5 to 10 cuttings of spring wood with attached leaves showing marginal necrosis taken from a single plant. Three samples, two from Star plants and one from a Windsor plant, were divided into two subsamples each. One subsample was submitted to Agdia for Xylella fastidiosa double-antibody sandwich (DAS)-ELISA assay (TSE XF; Agdia Inc., Elkhart IN). All three samples were reported as positive for X. fastidiosa by DAS-ELISA. A number of asymptomatic plants from this farm and other additional farms were tested in the same manner and results were negative. The other subsample was used for isolation of the causal bacterium. Petioles and main veins from symptomatic leaves were surface disinfested in 1% sodium hypochlorite, cut into segments (0.5 cm), and squeezed with forceps or pliers. Sap that exuded from the segment was blotted directly onto periwinkle wilt medium (2). Bacterial colonies consistent in morphology with X. fastidiosa that were DAS-ELISA positive were obtained from all three samples. One isolate from each sample was inoculated into four Star plants each with the pin-pricking method (3). Leaf scorch symptoms were first observed 8 weeks after inoculation. By 12 weeks after inoculation, all plants inoculated with the three isolates had developed symptoms, including defoliation. Plants inoculated without bacteria showed no symptoms. X. fastidiosa was reisolated from symptomatic plants. Bacterial leaf scorch is an important emerging disease that threatens the southern highbush blueberry industry in the south. On certain cultivars like Star, the potential to reduce yield appears to be great. Differences between cultivars are likely, but have not yet been explored. Additional research is needed into the epidemiology of the disease and potential vectors of pathogen transmission. References: (1) C. Chang et al. HortScience 44:413, 2009. (2) M. Davis et al. Curr. Microbiol. 6:309, 1981. (3) D. L. Hopkins et al. Phytopathology 75:713, 1985.

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