Description and molecular phylogeny of <Emphasis Type="Italic">Ditylenchus gilanicus</Emphasis> n. sp. (Nematoda: Anguinidae) from northern forests of Iran

Commercial areas containing Eucalyptus plantations have expanded in recent years due to increased demands for pulp, paper and bioenergy. One of the threats that can reduce Eucalyptus production is the eucalyptus rust disease caused by Austropuccinia psidii, a biotrophic fungus that affects a broad range of Myrtaceae. An accurate diagnosis tool for the early detection of rust disease could be useful in breeding programs for selection of resistant plants against rust, in phytosanitary purposes or in rust epidemics studies. The aim of the present work was to develop a SYBR Green-based quantitative real-time PCR (qPCR) assay for the early detection and quantification of A. psidii in Eucalyptus grandis leaves. Three sets of primers based on the A. psidii ribosomal DNA intergenic space region (IGS), beta-tubulin and elongation factor genes were designed and evaluated. The assays using the IGS primer set resulted in the highest detection efficiency, detecting a lower limit of 0.5 pg of A. psidii DNA. Under artificial inoculation in plants, A. psidii was detected immediately after pathogen inoculation until 240 h post-inoculation using qPCR. In field validation of the method, A. psidii was detected using qPCR in naturally infected leaves with or without rust symptoms. This easy and fast method can be used for an efficient detection of A. psidii in E. grandis leaves. The implications of this tool for rust studies are discussed below.     

Molecular and morphological characterisation of <Emphasis Type="Italic">Aphelenchoides paraxui</Emphasis> n. sp. (Nematoda: Aphelenchoididae) isolated from <Emphasis Type="Italic">Quercus brantii</Emphasis> in western Iran

Aphelenchoides paraxui n. sp. is described and illustrated from bark samples of an oak tree (Quercus brantii L.) in Kermanshah province, western Iran. The new species is characterized by body length of 500–660 μm (females) and 630–665 μm (males), lip region set off from body contour, lateral fields with four lines, and total stylet 8–9 μm long with small basal swellings. The excretory pore is located ca one body diam. Posterior to metacorpus valve. The spicules are relatively large (29–33 μm in dorsal limb) with apex and rostrum rounded and well developed and the end of the dorsal limb clearly curved ventrad like a hook. The female tail is conical, the terminus having a complicated step-like projection, usually with many tiny nodular protuberances. Male tail bearing six (2 + 2 + 2) caudal papillae and a well-developed mucro. The new species belongs to the Group 2 category of Aphelenchoides species sensu Shahina (1996) in which eight known species among Group 2–4 sensu Shahina namely: A. arcticus, A. asteromucronatus, A. blastophthorus, A. lichenicola, A. saprophilus, A. seiachicus, A. silvester and A. xui, are the most closed species. Molecular analyses of the partial small subunit rDNA gene (SSU), D2/D3 expansion segments of the large subunit rDNA gene (LSU) and internal transcribed spacer (ITS) revealed this as a new species and supported the morphological results.     

<Emphasis Type="Italic">Aphelenchoides gorganensis</Emphasis> n. sp. (Nematoda: Aphelenchoididae)<Emphasis Type="Italic">,</Emphasis> a new species from Iran

Phytophthora capsici infection of chili pepper seedlings can cause substantial losses due to damping-off and collar rot diseases. Chemical control is no longer effective due to reported resistance development, on top of the related environmental concerns and the consumer demands for reduced use of fungicides. Biological control is a sustainable option, with several agents having been reported to be effective against this pathogen. This research focused on optimizing the application of strain THSW13 of Trichoderma hamatum and a bacterial isolate BJ10–86 with the objectives of improving chili pepper seed germination, reduce damping-off disease incidence, and improve the growth of the seedlings. Bacterial isolate BJ10–86 was subjected to molecular identification and found to be Pseudomonas aeruginosa. Chili pepper seeds treated with the biocontrol agents, individually or in combination, were seeded into commercial nursery media that had been pre-inoculated with P. capsici zoospores. Over a period of 35 days the chili pepper seed treatments significantly (P = 0.008) reduced the disease incidence of seedlings damping-off. Combined application of T. hamatum and P. aeruginosa was the best biocontrol treatment with an area under disease curve of only 36.61 units compared to 92.87 units for the control treatment. Similar results were observed in vitro where T. hamatum and P. aeruginosa synergistically inhibited P. capsici growth by 73.2 %. The inhibition activity of this treatment was similar to mefenoxam treatment, which implies that it is an effective and sustainable alternative for chili pepper seed treatment. The biocontrol seed treatment had no effect on seed germination and seedling growth.     

Genetic structure of <Emphasis Type="Italic">Pyrenophora teres</Emphasis> f. <Emphasis Type="Italic">teres</Emphasis> and <Emphasis Type="Italic">P. teres</Emphasis> f. <Emphasis Type="Italic">maculata</Emphasis> populations from western Canada

Infection by Pyrenophora teres f. teres (Ptt) or P. teres f. maculata (Ptm), the causal agents of the net and spot forms of net blotch of barley, respectively, can result in significant yield losses. The genetic structure of a collection of 128 Ptt and 92 Ptm isolates from the western Canadian provinces of Alberta (55 Ptt, 27 Ptm), Saskatchewan (58 Ptt, 46 Ptm) and Manitoba (15 Ptt, 19 Ptm) were analyzed by simple sequence repeat (SSR) marker analysis. Thirteen SSR loci were examined and found to be polymorphic within both Ptt and Ptm populations. In total, 110 distinct alleles were identified, with 19 of these shared between Ptt and Ptm, 75 specific to Ptt, and 16 specific to Ptm. Genotypic diversity was relatively high, with a clonal fraction of approximately 10 % within Ptt and Ptm populations. Significant genetic differentiation (PhiPT = 0.230, P = 0.001) was found among all populations; 77 % of genetic variation occurred within populations and 23 % between populations. Lower, but still significant genetic differentiation (PhiPT = 0.038, P = 0.001) was detected in Ptt, with 96 % of genetic variation occurring within populations. No significant genetic differentiation (PhiPT = 0.010, P = 0.177) was observed among Ptm populations. Isolates clustered in two distinct groups conforming to Ptt or Ptm, with no intermediate cluster. The high number of haplotypes observed, combined with an equal mating type ratio for both forms of the fungus, suggests that P. teres goes through regular cycles of sexual recombination in western Canada.     

Partial characterisation of a novel <Emphasis Type="Italic">Tobamovirus</Emphasis> infecting <Emphasis Type="Italic">Actinidia chinensis</Emphasis> and <Emphasis Type="Italic">A. deliciosa</Emphasis> (Actinidiaceae) from China

Actinidia chinensis and A. deliciosa plants from China, showing a range of symptoms, including vein clearing, interveinal mottling, mosaics and chlorotic ring spots, were found to contain ~300 nm rod-shaped virus particles. The virus was mechanically transmitted to several herbaceous indicators causing systemic infections in Nicotiana benthamiana, N. clevelandii, and N. occidentalis, and local lesions in Chenopodium quinoa. Systemically- infected leaves reacted with a Tobacco mosaic virus polyclonal antibody in indirect ELISA. PCR using generic and specific Tobamovirus primers produced a 1,526 bp sequence spanning the coat protein (CP), movement protein (MP), and partial RNA replicase genes which showed a maximum nucleotide identity (88%) with Turnip vein clearing virus and Penstemon ringspot virus. However, when the CP sequence alone was considered the highest CP sequence identity (96% nt and 98% aa) was to Ribgrass mosaic virus strain Kons 1105. The morphological, transmission, serological and molecular properties indicate that the virus is a member of subgroup 3 of the genus Tobamovirus.     

Isolation and characterisation of fusaricidin-type compound-producing strain of <Emphasis Type="Italic">Paenibacillus polymyxa</Emphasis> SQR-21 active against <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> f.sp. <Emphasis Type="Italic">nevium</Emphasis>

A bacterial strain was isolated from the rhizosphere of healthy watermelon plants in a heavily wilt-diseased field. This isolate was tentatively identified as Paenibacillus polymyxa (SQR-21) based on biochemical tests and partial 16S rRNA sequence similarity. The purified antifungal compounds were members of the fusaricidin group of cyclic depsipeptides having molecular masses of 883, 897, 947, and 961 Da with an unusual 15-guanidino-3-hydroxypentadecanoic acid moiety, bound to a free amino group. The strain SQR-21 was not able to produce antifungal volatile compounds but was able to produce cellulase, mannase, pectinase, protease, β-1,3-glucanase and lipase enzymes. However, the strain did not show any chitinase activity. Biocontrol potential of this strain was evaluated against Fusarium oxysporum cause of Fusarium wilt disease of watermelon in a greenhouse experiment. This strain combined with organic fertiliser decreased the disease incidence by 70% and increased the dry plant weight by 113% over the control.     

Cloning of the pathogenicity-related gene <Emphasis Type="Italic">FPD1</Emphasis> in <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> f. sp. <Emphasis Type="Italic">lycopersici</Emphasis>

We selected a reduced-pathogenicity mutant of Fusarium oxysporum f. sp. lycopersici, a tomato wilt pathogen, from the transformants generated by restriction enzyme-mediated integration (REMI) transformation. The gene tagged with the plasmid in the mutant was predicted to encode a protein of 321 amino acids and was designated FPD1. Homology search showed its partial similarity to a chloride conductance regulatory protein of Xenopus, suggesting that FPD1 is a transmembrane protein. Although the function of FPD1 has not been identified, it does participate in the pathogenicity of F. oxysporum f. sp. lycopersici because FPD1-deficient mutants reproduced the reduced pathogenicity on tomato.The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under the accession number AB110097     

<Emphasis Type="Italic">Fusarium ershadii</Emphasis> sp. nov., a Pathogen on <Emphasis Type="Italic">Asparagus officinalis</Emphasis> and <Emphasis Type="Italic">Musa acuminata</Emphasis>

Two Fusarium strains, isolated from Asparagus in Italy and Musa in Vietnam respectively, proved to be members of an undescribed clade within the Fusarium solani species complex based on phylogenetic species recognition on ITS, partial RPB2 and EF-1α gene fragments. Macro- and micro-morphological investigations followed with physiological studies done on this new species: Fusarium ershadii sp. nov can be distinguished by its conidial morphology. Both isolates of Fusarium ershadii were shown to be pathogenic to the monocot Asparagus officinalis when inoculated on roots and induced hollow root symptoms within two weeks in Asparagus officinalis seedlings. In comparison mild disease symptoms were observed by the same strains on Musa acuminata seedlings.     

Morphological and molecular characterization of <Emphasis Type="Italic">Diaporthe (</Emphasis>anamorph <Emphasis Type="Italic">Phomopsis)</Emphasis> complex and pathogenicity of <Emphasis Type="Italic">Diaporthe aspalathi</Emphasis> isolates causing stem canker in soybean

The complex of Diaporthe (asexual morph) species occurring on soybean constitutes an important pathogenic group associated with diseases such as pod and stem blight, seed decay and stem canker. Stem canker, caused by Diaporthe aspalathi, has been reported as the most aggressive form of canker and its occurrence has limited soybean crop productivity in the southern United States. The main form of pathogen control is the use of stem canker resistant soybean varieties. In this study, strains of Diaporthe and Phomopsis were isolated from stem and seeds of soybean in different locations in South America during the years 1989–2014. Genomic DNA from 26 isolates were analyzed by PCR-restriction fragment length polymorphism (RFLP) and Amplified Fragment Length Polymorphism (AFLP) techniques, and sequencing of internal transcribed spacer (ITS) regions of ribosomal DNA. The molecular analysis of ITS sequences by alignment with those of ex-type strains deposited in GenBank and morphological characteristics allowed the identification of Phomopsis longicolla, D. phaseolorum var. sojae, D. caulivora and D. aspalathi. An analysis of the pathogenicity of 13 isolates of D. aspalathi inoculated in soybean genotypes carrying different resistance genes to stem canker (Rdm1, Rdm2, Rdm3, Rdm4, Rdm5 and Rdm?) enabled us to identify the occurrence of at least three races of D. aspalathi occurring in Brazil. Among the isolates identified as D. aspalathi, both molecular and phenotypic analyses showed clustering depending on the date of collection and pathogenicity, which revealed the existence of variability of the pathogen.     

Seed transmission of<Emphasis Type="Italic">Fusarium oxysporum</Emphasis> f.sp.<Emphasis Type="Italic">lactucae</Emphasis>

Twenty-seven seed samples belonging to the lettuce cultivars most frequently grown in Lombardy (northwestern Italy), in an area severely affected by Fusarium wilt of lettuce, were assayed for the presence ofFusarium oxysporum on a Fusarium-selective medium. Isolations were carried out on subsamples of seeds (500 to 1500) belonging to the same seed lots used for sowing, and either unwashed or disinfected in 1% sodium hypochloride. The pathogenicity of the isolates ofF. oxysporum obtained was tested in four trials carried out on lettuce cultivars of the butterhead type, very susceptible to Fusarium wilt. Nine of the 27 samples of seeds obtained from commercial seed lots used for sowing in fields affected by Fusarium wilt were contaminated byF. oxysporum. Among the 16 isolates ofF. oxysporum obtained, only one was isolated from disinfected seeds. Three of the isolates were pathogenic on the tested cultivars of lettuce, exhibiting a level of pathogenicity similar to that of the isolates ofF. oxysporum f.sp.lactucae obtained from infected wilted plants in Italy, USA and Taiwan, used as comparison. The results obtained indicate that lettuce seeds are a potential source of inoculum for Fusarium wilt of lettuce. The possibility of isolatingF. oxysporum f.sp.lactucae, although from a low percent of seeds, supports the hypothesis that the rapid spread of Fusarium wilt of lettuce observed recently in Italy is due to the use of infected propagation material. Measures for prevention and control of the disease are discussed. http://www.phytoparasitica.org posting Dec. 16, 2003.     

Morphological and molecular characterisation of Longidorus sabalanicus n. sp. (Nematoda: Longidoridae) from Iran

European Journal of Plant Pathology - The effects of three biological control agents (BCAs) including Funneliformis mosseae BEG12 (FM) as arbuscular mycorrhizal fungi (AMF), Bacillus velezensis...     

Fusarium rot of hyacinth caused by <Emphasis Type="Italic">Gibberella zeae</Emphasis> (anamorph: <Emphasis Type="Italic">Fusarium</Emphasis><Emphasis Type="Italic"> graminearum</Emphasis>)

Severe rot of leaves, peduncles and flowers caused by Gibberella zeae (anamorph: Fusarium graminearum) was found on potted plants of hyacinth (Hyacinthus orientalis), a liliaceous ornamental, in greenhouses in Kagawa Prefecture, Japan, in January 2001. This disease was named “Fusarium rot of hyacinth” as a new disease because only the anamorph, F. graminearum, was identified on the diseased host plant. The authors contributed equally to this work. The fungal isolate and its nucleotide sequence data obtained in this study were deposited in the Genebank, National Institute of Agrobiological Sciences and the DDBJ/EMBL/GenBank databases under the accession numbers MAFF239499 and AB366161, respectively.     

Description of a new species of seed-gall nematode, <Emphasis Type="Italic">Anguina obesa</Emphasis> n. sp. (Nematoda: Anguinidae) from northern Iran,and its phylogenetic relations with other species and genera

Anguina obesa n. sp., a new species of the genus, causing small seed galls inside the ovaries of foxtail weed plants (Alopecurus mysuroides Huds.) is described and illustrated based on its morphological and molecular characters. The new species is characterized by its 1516–2564 μm long obese females irregularly ventrally curved after fixation, having six lines in lateral fields, 6–9 μm long stylet with well-developed rounded knobs, constriction at junction of isthmus with the pharyngeal bulb, monodelphic-prodelphic female reproductive system, and conical, 60–80 μm long tail. Males of the new species are characterized with their slender 936–1420 μm long body, 25–30 μm long tylenchoid spicules, and bursa not reaching tail tip. Second stage juveniles of the new species were also common inside the galls and also recovered from soil in type locality. The new species is morphologically close to Anguina agropyronifloris, A. amsinckiae, A. paludicola and A. tumefaciens, but is more closely related to A. paludicola, from which it can be separated based on differences in morphological characters and internal transcribed spacer sequence. In Bayesian inference using sequences of the aforementioned genomic fragment, the new species formed a clade with A. agrostis, A. funesta, A. graminis, A. phalaridis and some unidentified isolates, with robust Bayesian posterior probability (BPP). The morphologically closest species, A. paludicola, occupied a separate position, outside of the clade containing the new species. The sequences of two other genomic fragments, 18S and 28S rDNA (D2/D3 region) were also made available for the new species. Morphological comparisons of the new species with the related species are discussed.     

Morphological and molecular analysis of <Emphasis Type="Italic">Paratrichodorus teres</Emphasis> (Hooper 1962) (Nematoda: Trichodoridae): a groundwork for discussion on the phylogeny and pathogenicity of <Emphasis Type="Italic">Paratrichodorus</Emphasis> species

Due to its ability to transmit plant viruses, Paratrichodorus teres (Hooper in Nematologica, 7, 273–280, 1962) is recognized as an economically important trichodorid species. Morphological and molecular analyses (18S and 28S rDNA) were performed, and 10 new plant hosts are reported for Polish P. teres populations. Major morphological features and the measurements obtained for the investigated specimens were within the wide ranges indicated for this species. However, a more detailed comparative analysis of Polish and Iranian P. teres showed significant morphological differences, particularly, in the shape and the structure of the walls of pars proximalis vaginae and the shape of the rectum.Phylogenetic study based on the 18S rDNA data suggests positioning of the Polish P. teres sequences within a cluster of sequences originating from the Netherlands. A comparison of the 28S rDNA fragment from Polish populations with the only P. teres 28S rDNA sequence available (from Iran) in GenBank revealed a sequence variability of 9.3%. The variation across these two representatives was higher than in the case of many other pairs of Trichodoridae species. The results obtained on the Polish P. teres specimens are discussed in the framework of the species taxonomy and phylogenetic relationships.     

Potential inhibitors against <Emphasis Type="Italic">Sclerotinia sclerotiorum</Emphasis>, produced by the fungus <Emphasis Type="Italic">Myrothecium</Emphasis> sp. associated with the marine sponge <Emphasis Type="Italic">Axinella</Emphasis> sp.

Sclerotinia sclerotiorum is a worldwide ascomycete fungal plant pathogen, which causes enormous yield losses on major economic crops such as crucifers, grain legumes and several other plant families. The objective of this research was to isolate and characterise some bioactive products from cultures of fungi associated with the marine sponge Axinella sp. In total, nine fungal isolates were obtained from the marine sponge Axinella sp. collected from the South China Sea. A group of test strains, including two G⁺ strains (Bacillus subtilis and Staphylococcus aureus), two G⁻ strains (Escherichia coli and Pseudomonas aeruginosa) and three fungi including two plant pathogenic fungi Sclerotinia sclerotiorum and Magnaporthe grisea and Saccharomyces cerevisiae, were employed as the indicator organisms for bioactivity screening. Using antagonistic tests and bioactive screening of the ethyl acetate (EtOAc) extracts of the corresponding cultures, fungal isolate JS9 showed the stronger efficacy against the test indicator strains, especially the indicator fungal pathogens. Isolate JS9 was further identified as Myrothecium sp. by a combination of morphological features and 18S rDNA BLAST on GenBank. Two macrocyclic trichothecenes, roridin A (compound 1) and roridin D (compound 2) were purified by tracking the activity of the EtOAc extract fractions and characterised with spectral analyses including MS, ¹H-NMR, ¹³C-NMR and disortionless enhancement by polarization transfer (DEPT). In vitro antifungal tests showed that the two macrocyclic trichothecenes were bioactive against S. cerevisiae, M. grisea and S. sclerotiorum with minimal inhibitory concentrations of 31.25, 125 and 31.25 μg ml⁻¹ for roridin A, and 62.5, 250 and 31.25 μg ml⁻¹ for roridin D, respectively. The present investigation demonstrated that two antifungal trichothecenes including roridin A and roridin D produced by the fungus Myrothecium sp. isolated from the marine sponge Axinella sp. could be potential inhibitors against the plant pathogen S. sclerotiorum. Lian Wu Xie and Shu Mei Jiang contributed equally to this work.     

First report of blueberry red ringspot disease caused by <Emphasis Type="Italic">Blueberry</Emphasis><Emphasis Type="Italic">red</Emphasis><Emphasis Type="Italic">ringspot</Emphasis><Emphasis Type="Italic">virus</Emphasis> in Japan

Virus-like symptoms—red ringspots on stems and leaves, circular blotches or pale spots on fruit—were found on commercial highbush blueberry (Vaccinium corymbosum) cultivars Blueray, Weymouth, Duke and Sierra in Japan. In PCR testing, single DNA fragments were amplified from total nucleic acid samples of the diseased blueberry bushes using primers specific to Blueberry red ringspot virus (BRRV). Sequencing analysis of the amplified products revealed 95.7–97.7% nucleotide sequence identity with the BRRV genome. This paper is the first report of blueberry red ringspot disease caused by BRRV in Japan. The nucleotide sequence data reported in this paper are available in the GenBank/EMBL/DDBJ database as accessions AB469884 to AB469893 for BRRV isolates from Japan.     

<Emphasis Type="Italic">Cucumber mosaic virus</Emphasis> isolated from Amazon lily (<Emphasis Type="Italic">Eucharis grandiflora</Emphasis>)

Cucumber mosaic virus (CMV) was isolated from a mosaic diseased plant of Eucharis grandiflora. The virus caused mosaic symptoms on leaves and slight distortion of flower petals in E. grandiflora by either mechanical or aphid inoculation. The virus was identified as a strain of CMV subgroup I from its biological and serological characteristics.     

<Emphasis Type="Italic">Erwinia aphidicola</Emphasis> isolated from commercial bean seeds (<Emphasis Type="Italic">Phaseolus vulgaris)</Emphasis>

In late 2003, a new disease appeared in protected bean crops in southeastern Spain, causing a decrease of over 50% in production. Several samples of affected plants were collected and analyzed and the agent of this disease was identified as the bacterium Erwinia aphidicola, which had never been described as a pathogen previously. We attempted to determine the possible bacterium transmission through seeds, using 120 commercial bean seeds from the same batch as that used in an affected farm, and 120 seeds from the fruiting plants of the same farm. Seed coats, cotyledons and leaves of plants originating from them, were taken and analyzed. Several of the developed symptoms on plants from commercial and fruiting plant seeds were internervial chlorosis, necrotic pits and rough roots and they coincided with those observed on affected crops. Bacteria present in commercial seed cotyledons were isolated and analyzed by biochemical and molecular tests. Results confirmed the presence of Erwinia aphidicola in four analyzed seeds; moreover, Bacillus simplex/Bacillus muralis, Pseudomonas mendocina, Pseudomonas putida and Paenibacillus polymyxa were also identified.     

<Emphasis Type="Italic">Eremothecium coryli</Emphasis> and <Emphasis Type="Italic">E.</Emphasis><Emphasis Type="Italic">ashbyi</Emphasis> cause yeast spot of azuki bean

Yeast-like fungi were isolated from lesions on azuki bean (cv. Shin-Kyotodainagon) seeds that had been sucked by bean bugs in Kyoto Prefecture, Japan. On the basis of morphological and physiological characteristics and sequence data of the internal transcribed spacer (ITS) regions including the 5.8S rDNA, these yeasts were identified as Eremothecium coryli and E. ashbyi. Pathogenicity of those yeasts was confirmed by a reinoculation test. To our knowledge, this is the first report of the occurrence of yeast spot in azuki bean in Japan. The nucleotide sequence data reported are available in the GeneBank/EMBL/DDBJ database as accessions AB478291–AB478309 for E. coryli AZC1–19 and AB478310–AB478317 for E. ashbyi AZA1–8.     

Population features of <Emphasis Type="Italic">Xanthomonas arboricola</Emphasis> pv. <Emphasis Type="Italic">pruni</Emphasis> from <Emphasis Type="Italic">Prunus spp.</Emphasis> orchards in northern Italy

Bacterial leaf/fruit spot and canker of stone fruits, caused by Xanthomonas arboricola pv. pruni, is a recurrent disease in Italy. A set of 23 strains has been isolated in peach and plum orchards in an intensively stone fruit cultivated area located in north-eastern Italy. They were all identified as X. arboricola pv. pruni by means of phytopathological and serological features: hypersensitive reaction on bean pods, pathogenicity test on immature peach or plum fruitlets, identification by immunofluorescence assay and conventional PCR. Phylogenetic analysis based on sequencing of the gyrB housekeeping gene of the isolates showed that they formed a unique clade, well characterised and separated from other xanthomonads. An insight into the genetic population features was attempted by rep-PCR analysis, using the ERIC, REP and BOX primers. The combined rep-PCR fingerprints showed a slight intra-pathovar variation within our isolates, which grouped in five close clusters. Copper resistance has been assessed in vitro for our whole X. arboricola pv. pruni collection, highlighting that two isolates show a level of resistance in vitro up to 200 ppm of copper. Nonetheless, the copLAB gene cluster, present in many other species of Xanthomonads, was not detected in any isolate, confirming the presence of a still unknown mechanism of copper detoxification in our Xanthomonads arboricola pv. pruni tolerant/resistant strains.