The status of Erwinia amylovora in the former Yugoslav Republics over the past two decades (original) (raw)
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Acta horticulturae, 2011
In the present study the correlation of visual fire blight symptoms and the migration of a virulent E. amylovora strain within the tissue of susceptible and tolerant apple and pear cultivars was investigated. Flowers and shoots of commercial apple cultivars were artificially inoculated. Three cultivars diverged in terms of symptom expression after flower and shoot inoculation, respectively: 'Fuji KIKU 8' ® and 'Topaz' ® developed severe symptoms on shoots but only a relatively low number of flowers were infected. Conversely, 'Golden Delicious Kl. B Laimburg' ® displayed severe necrosis on shoots but was the least susceptible of all the cultivars after flower inoculation. Apple and pear cultivars that have a regional importance for large trees in extensive orchard management were tested for their susceptibility to artificial shoot inoculation. In our experiments the susceptibility (i.e., expression of shoot necrosis) of investigated apple cultivars for commercial and traditional orchards was compared and ranged from 17 to 50%. A lesion length of more than 60% was observed for only one apple cultivar ('Brentewinar'). The opposite situation arose in the tested traditional pear cultivars where 61% showed 60% lesion length. In this study the visual symptoms did not correspond with the spatial distribution patterns and the quantities of E. amylovora within the plant tissue. In apple cultivars most bacteria remained near the site of inoculation. However, in two tested apple cultivars, and in all tested pear cultivars, the pathogen could be detected even in the rootstocks. Also in pear trees, large numbers of the pathogen could be detected in non-inoculated shoots and further downwards. Even the pear cultivar 'Harrow Sweet' and the apple cultivars 'Schmiedberger Renette', and 'Rewena', which had been considered less susceptible, showed an extended endophytic bacterial dissemination. These findings may have an impact on both the evaluation of new cultivars and on sanitary measures regarding fire blight control.
Journal of Plant Pathology, 2016
Fire blight is a bacterial disease caused by Erwinia amylovora. It is one of the most destructive diseases of pome fruit trees, particularly affecting apple and pear trees. In the present study, 15 bacterial isolates were isolated from apple orchards displaying fire blight disease symptoms in the summer of 2015. They were identified as E. amylovora based on morphological, pathological and biochemical (BIOLOG) analyses, including PCR assays. The molecular characterisation of these isolates using PCR were performed with specific primers for conventional (single) PCR, as well as from PCR amplification of the 16S rRNA gene using universal primers. The PCR products were positive and had the expected length of 1.1 kb. There is little information about the presence of E. amylovora on apple trees in Macedonia. To the best of our knowledge, this is the first report of fire blight in apples caused by E. amylovora in the Republic of Macedonia.
Erwinia amylovora strains from outbreaks of fire blight in Spain: phenotypic characteristics
Annals of applied …, 2005
One hundred and thirty strains of Erwinia amylovora recovered from Spanish foci of fire blight from 1995 to 2000 were characterised and compared to reference strains from different sources and origins. Their rapid identification was performed by double antibody sandwich indirect (DASI) ELISA, using specific monoclonal antibodies against E. amylovora, and molecular confirmation by PCR using primers specific to the native plasmid pEA29. The Spanish strains of E. amylovora grew on different general and selective media producing typical colonies, except one of them that was deficient in levan production, whereas none of them grew on minimal agar medium with copper sulphate and low content of asparagine. All of them were susceptible to tetracycline, streptomycin, kasugamycin and oxolinic acid. Biochemical characterisation of selected strains by API 20E system revealed a great homogeneity, with 80% of the Spanish strains showing one of the two majority API 20E profiles described for E. amylovora, and the remaining strains showing minor differences. Pathogenicity on pear fruits and hypersensitivity reaction was confirmed, but a delayed reaction was observed for two Spanish strains. This is the first characterisation of a large collection of Spanish strains of E. amylovora.
2008
From among 151 bacterial isolates obtained from apple leaves and soil environment 47 were able to protect pear fruitlets against fire blight to various extent. 21 isolates appeared highly effective and after their application the disease hardly developed on the fruitlets. Study on biotic relationship between these isolates and Erwinia amylovora on nutrient agar with sucrose and King B media indicate that only six isolates from this group and almost all from groups with low and very low efficacy inhibited pathogen growth on at least one of these media. This indicates that mechanisms other than antibiosis could be responsible for protective activity of bacteria and that medium composition influences production of secondary metabolites active against E. amylovora by the bacteria under study. Evaluation of selected isolates for ability to protect apple blossoms showed that results obtained from screening on pear fruitlets generally corresponded to that from blossom test.
Advances in Microbiology, 2016
Erwinia amylovora species were isolated from the blossoms, exudates, infected fruits, leaves and bent branches of diseased apple, pear and hawthorn trees, selected in the Chy, Osh and Jalal Abad regions. Biochemical and pathogenicity tests, alongside PCR analyses, were conducted to identify the local isolates of Erwinia amylovora. The alternative antagonistic microorganisms which combat bacterium E. amylovora were tested within in vitro and in vivo conditions. The results revealed the ability of Streptomyces antagonistic bacteria to decrease fire blight severity on pear and apple trees during the first stage of the fire blight disease in leaf tissues. Streptomyces strain C1-4 suppressed E. amylovora disease symptoms in the leaf tissues and excised apple and pear shoots. The incidence of fire blight on leaves was reduced by about 70% with two applications of bacterial antagonists. Further studies at different locations in Kyrgyzstan, using large scale application, would allow for stronger recommendations to be made, including studies and recommendations on their ability to prevent disease and to use them as main components in an integrated pest management program.
European Journal of Plant Pathology
This study included eight bacterial isolates originating from the apple phyllosphere or soil environment that were previously selected using the pear fruitlet test (Mikiciński 2017). Identification of these isolates based on phenotypic assays and DNA analysis showed that five of them belonged to species for which an antagonistic activity against Erwinia amylovora and the protective capacity of apple and pear against fire blight were not previously demonstrated. These were L16 identified as Pseudomonas vancouverensis, 3 M as Pseudomonas chlororaphis subsp. aureofaciens, 35 M – Pseudomonas congelans, 43 M – Enterobacter ludwigii, and 59 M – Pseudomonas protegens. Investigation of the biotic relationships between the tested strains and E. amylovora showed that 3 M, 35 M and 59 M inhibited the growth of the pathogen on five out of six media used (NAS, KB, LB, R2A, NAG), but 43 M did not do so on any of these media. Strain L16 did not inhibit the growth of the pathogen on LB or R2A mediu...
INFECTION OF ERWINIA AMYLOVORA ON DIFFERENT APPLE VARIETIES AND THE IMPACT ON FRUITS QUALITY
Fire Blight (FB) caused by Erwinia amylovora is the most feared bacterial disease in the genus Malus and other genera belonging to Rosaceae family, causing severe losses in orchards in favourable years, unmarketable fruits quality and even completely trees dieback, especially in highly susceptible genotypes. Currently E. amylovora is of quarantine concern in many countries all over the world and continue to conquer new territories. During 2018-year, six apple genotypes ('Golden Delicious', 'Idared', 'Gala', 'Jonagold', 'Fuji' and 'Jonathan'), within an orchard located in the proximity of Craiova city, Romania, have been assessed for their response to the infection to Erwinia amylovora and the impact of the pathogen attack on fruits yield and quality. The response of apple genotypes to the Fire Blight (FB) attack ranged from moderately resistant/susceptible ('Golden Delicious' and 'Fuji') to highly susceptible ('Idared', 'Gala', 'Jonagold' and 'Jonathan') depending on genetic background and environmental conditions. Fruits chemical parameters Total Soluble Solids (TSS), Total acidity (TA), Total Sugar (TS) were significantly affected by the pathogen attack in all apple varieties.
Scientific Opinion on the pest categorisation of Erwinia amylovora (Burr.) Winsl. et al
EFSA Journal
The European Commission requested the EFSA Panel on Plant Health to perform the pest categorisation for Erwinia amylovora, which is the causal agent of fire blight. E. amylovora is a plant pathogenic bacterium regulated by the Directive 2000/29/EC (Annexes II-A-II). E. amylovora is a single taxonomic entity. This organism can be accurately identified, based on a range of discriminative methods. Detection methods are available for symptomatic and asymptomatic plant material. E. amylovora is present in all EU Member States except Estonia, Finland and Malta, where host plants are not widely distributed or are rare. The host plants (mainly pear and apple) are cultivated throughout Europe where environmental conditions are conducive to disease development. Although no recent data are available on losses caused by E. amylovora in the EU, fire blight is considered to be the most destructive disease on pear and apple owing to the loss of trees. The analysis of past disease outbreaks previously reported in the EU highlights their considerable potential to have a severe impact on commercial horticulture, especially on apple, pear and quince, as well as on ornamentals and on nursery trade. The disease causes a range of symptoms on the aerial parts of plants, including the fruits, and E. amylovora often kills the trees and causes destructive outbreaks. Contaminated rootstocks, cuttings and grafted trees for transplanting, beehive transportation, rain and wind, are responsible for medium-and longdistance dissemination of the pathogen. Existing control is mainly based on prevention and exclusion. The use of chemical or biological products can prevent infection, and sanitation methods applied to infected plants can control the disease to a certain extent. No curative chemical control agents are available that eradicate E. amylovora in infected orchards.
Isolation and genetic characterization of Erwinia amylovora bacteria from Kyrgyzstan
European Journal of Plant Pathology, 2019
Fire Blight is a devastating disease of Rosaceae plants and is of economic relevance in the cultivation of apple, pear, and quince (Thompson 2000; Acimovic et al. 2015). The disease is caused by the bacterium Erwinia amylovora (Enterobacterales; Erwiniaceae) (Adeolu et al. 2016) that infects the host through natural openings or wounds in above-ground parts of fruit trees including blossoms, fruits, shoots, and branches (Agrios 2005 and references therein). Infected tissues typically produce a viscous bacteria-carrying exudate (termed "ooze") from that the pathogen is efficiently spread by insects, birds, wind, and rain (Slack et al. 2017). Originating from North America, Fire Blight has in the 1950s been introduced to Great Britain and in the 1970s to Northern and Central Europe (Van der Zwet and Beer 1995). The disease has subsequently continued to spread towards Southern and Eastern Europe and further to Central Asia. In 2008, Fire Blight was first reported in Kyrgyzstan and registered a