Project description:Three bacteriophages, f20-Xaj, f29-Xaj, and f30-Xaj, with lytic activity against Xanthomonas arboricola pv. juglandis were isolated from walnut trees (VIII Bío Bío Region, Chile). These lytic bacteriophages have double-stranded DNA (dsDNA) genomes of 43,851 bp, 41,865 bp, and 44,262 bp, respectively. These are the first described bacteriophages with lytic activity against X. arboricola pv. juglandis that can be utilized as biocontrol agents.
Project description:Here, we report the draft genome sequence of Xanthomonas arboricola pv. juglandis J303, isolated from infected walnut trees in southern Chile. The size of the genome is 5,066,424 bp with a G+C content of 65.4%. X. arboricola pv. juglandis J303 has several genes related to virulence, antibiotic resistance, and copper resistance.
Project description:The recent report of distinct <i>Xanthomonas</i> lineages of <i>Xanthomonas arboricola</i> pv. <i>juglandis</i> and <i>Xanthomonas euroxanthea</i> within the same walnut tree revealed that this consortium of walnut-associated <i>Xanthomonas</i> includes both pathogenic and nonpathogenic strains. As the implications of this co-colonization are still poorly understood, in order to unveil niche-specific adaptations, the genomes of three <i>X. euroxanthea</i> strains (CPBF 367, CPBF 424<sup>T</sup>, and CPBF 426) and of an <i>X. arboricola</i> pv. <i>juglandis</i> strain (CPBF 427) isolated from a single walnut tree in Loures (Portugal) were sequenced with two different technologies, Illumina and Nanopore, to provide consistent single scaffold chromosomal sequences. General genomic features showed that CPBF 427 has a genome similar to other <i>X. arboricola</i> pv. <i>juglandis</i> strains, regarding its size, number, and content of CDSs, while <i>X. euroxanthea</i> strains show a reduction regarding these features comparatively to <i>X. arboricola</i> pv. <i>juglandis</i> strains. Whole genome comparisons revealed remarkable genomic differences between <i>X. arboricola</i> pv. <i>juglandis</i> and <i>X. euroxanthea</i> strains, which translates into different pathogenicity and virulence features, namely regarding type 3 secretion system and its effectors and other secretory systems, chemotaxis-related proteins, and extracellular enzymes. Altogether, the distinct genomic repertoire of <i>X. euroxanthea</i> may be particularly useful to address pathogenicity emergence and evolution in walnut-associated <i>Xanthomonas</i>.
Project description:Here, we report the complete genome sequence of Xanthomonas arboricola pv. juglandis 417, a copper-resistant strain isolated from a blighted walnut fruit (Juglans regia L. cv. Chandler). The genome consists of a single chromosome (5,218 kb).
Project description:<h4>Background</h4>The species Xanthomonas arboricola comprises up to nine pathovars, two of which affect nut crops: pv. juglandis, the causal agent of walnut bacterial blight, brown apical necrosis, and the vertical oozing canker of Persian (English) walnut; and pv. corylina, the causal agent of the bacterial blight of hazelnut. Both pathovars share a complex population structure, represented by different clusters and several clades. Here we describe our current understanding of symptomatology, population dynamics, epidemiology, and disease control.<h4>Taxonomic status</h4>Bacteria; Phylum Proteobacteria; Class Gammaproteobacteria; Order Lysobacterales (earlier synonym of Xanthomonadales); Family Lysobacteraceae (earlier synonym of Xanthomonadaceae); Genus Xanthomonas; Species X. arboricola; Pathovars: pv. juglandis and pv. corylina.<h4>Host range and symptoms</h4>The host range of each pathovar is not limited to a single species, but each infects mainly one plant species: Juglans regia (X. arboricola pv. juglandis) and Corylus avellana (X. arboricola. pv. corylina). Walnut bacterial blight is characterized by lesions on leaves and fruits, and cankers on twigs, branches, and trunks; brown apical necrosis symptoms consist of apical necrosis originating at the stigmatic end of the fruit. A peculiar symptom, the vertical oozing canker developing along the trunk, is elicited by a particular genetic lineage of the bacterium. Symptoms of hazelnut bacterial blight are visible on leaves and fruits as necrotic lesions, and on woody parts as cankers. A remarkable difference is that affected walnuts drop abundantly, whereas hazelnuts with symptoms do not.<h4>Distribution</h4>Bacterial blight of walnut has a worldwide distribution, wherever Persian (English) walnut is cultivated; the bacterial blight of hazelnut has a more limited distribution, although disease outbreaks are currently more frequently reported. X. arboricola pv. juglandis is regulated almost nowhere, whereas X. arboricola pv. corylina is regulated in most European and Mediterranean Plant Protection Organization (EPPO) countries.<h4>Epidemiology and control</h4>For both pathogens infected nursery material is the main pathway for their introduction and spread into newly cultivated areas; additionally, infected nursery material is the source of primary inoculum. X. arboricola pv. juglandis is also disseminated through pollen. Disease control is achieved through the phytosanitary certification of nursery material (hazelnut), although approved certification schemes are not currently available. Once the disease is present in walnut/hazelnut groves, copper compounds are widely used, mostly in association with dithiocarbamates; where allowed, antibiotics (preferably kasugamycin) are sprayed. The emergence of strains highly resistant to copper currently represents the major threat for effective management of the bacterial blight of walnut. USEFUL WEBSITES: https://gd.eppo.int/taxon/XANTJU, https://gd.eppo.int/taxon/XANTCY, https://www.euroxanth.eu, http://www.xanthomonas.org.
Project description:Here, we report the complete genome sequence of Xanthomonas arboricola pv. juglandis DW3F3, a strong pathogenic strain isolated from blighted walnut immature fruit (Juglans regia L. cv. Qingxiang). The genome consists of a single chromosome (5,144?kb).
Project description:Xanthomonas arboricola pv. juglandis (hereafter X. juglandis) is the etiological agent of walnut blight, the most important bacterial disease affecting walnut production worldwide. Currently, the disease is treated mainly with copper-derived compounds (e.g., CuSO4) despite the evidence of genetic resistance in these strains. Regarding the effectiveness and sustainability, the use of a bacteriophage appears to be a biocontrol alternative to reduce X. juglandis load and symptomatology of walnut blight. Here, the phages f20-Xaj, f29-Xaj, and f30-Xaj were characterized, and their effectiveness in walnut orchards against walnut blight was determined. These bacteriophages showed a specific lytic infection in X. juglandis strains isolated from Chile and France. Phylogenetic analysis of the complete genome of f20-Xaj and f30-Xaj indicates that these phages belong to the Pradovirus genus. In the field, the cocktail of these bacteriophages showed similar effectivity to CuSO4 in the reduction of incidence and severity in walnut tissue. Moreover, the bacterial load of X. juglandis was significantly reduced in the presence of bacteriophages in contrast to a CuSO4 treatment. These results show that the use of bacteriophages can be an alternative to combat the symptoms of walnut blight caused by X. juglandis.
Project description:We report the genome sequence of <i>Xanthomonas arboricola</i> pv. juglandis strain CPBF 427, which was isolated from early-season buds of a diseased walnut tree, suggesting overwinter potential. This study provides a consistent genomic reference for this pathovar and may contribute to addressing the overwinter survival of these walnut pathogens.
Project description:Here, we report the draft genome sequence of Xanthomonas arboricola pv. juglandis CPBF 1521, isolated from symptomatic leaves of an ornamental walnut in a public site in Portugal without any record of phytosanitary treatment. This isolate may constitute a genomic reference of a wild-type strain in comparative genomics studies.