{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,1,15]],"date-time":"2026-01-15T12:52:03Z","timestamp":1768481523667,"version":"3.49.0"},"posted":{"date-parts":[[2018,8,22]]},"group-title":"Microbiology","reference-count":42,"publisher":"openRxiv","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2018,8,22]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                <jats:p>\n                  <jats:italic>Xanthomonas arboricola<\/jats:italic>\n                  pv.\n                  <jats:italic>juglandis<\/jats:italic>\n                  (\n                  <jats:italic>Xaj<\/jats:italic>\n                  ) is the etiological agent of walnut diseases affecting leaves, fruits, branches and trunks. Although this phytopathogen is widely spread in walnut producing regions and has a considerable genetic diversity, there is still a poor understanding of its epidemic behaviour. To shed some light on the epidemiology of these bacteria, 131\n                  <jats:italic>Xanthomonas<\/jats:italic>\n                  isolates obtained from 64 walnut trees were included in this study considering epidemiological metadata such as year of isolation, bioclimatic regions, walnut cultivars, production regimes, host walnut specimen and plant organs. Genetic diversity was assessed by multilocus sequence analysis (MLSA) and dot blot hybridization patterns obtained with nine\n                  <jats:italic>Xaj<\/jats:italic>\n                  -specific DNA markers (XAJ1 \u2013 XAJ9). The results showed that\n                  <jats:italic>Xanthomonas<\/jats:italic>\n                  isolates grouped in ten distinct MLSA clusters and in 18 hybridization patterns (HP). The majority of isolates (112 out of 131) were closely related with\n                  <jats:italic>X. arboricola<\/jats:italic>\n                  strains of pathovar\n                  <jats:italic>juglandis<\/jats:italic>\n                  as revealed by MLSA (clusters I to VI) and hybridize with more than five\n                  <jats:italic>Xaj<\/jats:italic>\n                  -specific markers. Nineteen isolates clustered in four MLSA groups (clusters VII to X) which do not include\n                  <jats:italic>Xaj<\/jats:italic>\n                  strains, and hybridize to less than five markers. Taking this data together, was possible to distinguish 17 lineages of\n                  <jats:italic>Xaj<\/jats:italic>\n                  , three lineages of\n                  <jats:italic>X. arboricola<\/jats:italic>\n                  and 11 lineages of\n                  <jats:italic>Xanthomonas<\/jats:italic>\n                  sp. Some\n                  <jats:italic>Xaj<\/jats:italic>\n                  lineages appeared to be widely distributed and prevalent across the different bioclimatic regions and apparently not constrained by the other features considered. Assessment of type III effector genes and pathogenicity tests revealed that representative lineages of MLSA clusters VII to X were nonpathogenic on walnut, with exception for strain CPBF 424, making this bacterium particularly appealing to address\n                  <jats:italic>Xanthomonas<\/jats:italic>\n                  pathoadaptations to walnut.\n                <\/jats:p>\n                <jats:sec>\n                  <jats:title>IMPORTANCE<\/jats:title>\n                  <jats:p>\n                    <jats:italic>Xanthomonas arboricola<\/jats:italic>\n                    pv.\n                    <jats:italic>juglandis<\/jats:italic>\n                    is one of the most serious threats of walnut trees. New disease epidemics caused by this phytopathogen has been a big concern causing high economic losses on walnut production worldwide. Using a comprehensive sampling methodology to disclose the diversity of walnut infective\n                    <jats:italic>Xanthomonas<\/jats:italic>\n                    , we were able to identify a genetic diversity higher than previously reported and generally independent of bioclimatic regions and the other epidemiological features studied. Furthermore, co-colonization of the same plant sample by distinct\n                    <jats:italic>Xanthomonas<\/jats:italic>\n                    strains were frequent and suggested a sympatric lifestyle. The extensive sampling carried out resulted in a set of non-\n                    <jats:italic>arboricola Xanthomonas<\/jats:italic>\n                    sp. strains, including a pathogenic strain, therefore diverging from the nonpathogenic phenotype that have been associated to these atypical strains, generally considered to be commensal. This new strain might be particularly informative to elucidate novel pathogenicity traits and unveil pathogenesis evolution within walnut infective xanthomonads. Beyond extending the present knowledge about walnut infective xanthomonads, this study might contribute to provide a methodological framework for phytopathogen epidemiological studies, still largely disregarded.\n                  <\/jats:p>\n                <\/jats:sec>","DOI":"10.1101\/397703","type":"posted-content","created":{"date-parts":[[2018,8,22]],"date-time":"2018-08-22T09:45:25Z","timestamp":1534931125000},"source":"Crossref","is-referenced-by-count":7,"title":["Genotyping and epidemiological metadata provides new insights into population structure of\n                  <i>Xanthomonas<\/i>\n                  isolated from walnut trees"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7566-1255","authenticated-orcid":false,"given":"Camila","family":"Fernandes","sequence":"first","affiliation":[]},{"given":"Pedro","family":"Albuquerque","sequence":"additional","affiliation":[]},{"given":"Leonor","family":"Cruz","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9913-1155","authenticated-orcid":false,"given":"Fernando","family":"Tavares","sequence":"additional","affiliation":[]}],"member":"54368","reference":[{"key":"2019072204305398000_397703v1.1","doi-asserted-by":"publisher","DOI":"10.1094\/PHYTO-95-1098"},{"key":"2019072204305398000_397703v1.2","doi-asserted-by":"publisher","DOI":"10.1099\/00207713-45-3-472"},{"key":"2019072204305398000_397703v1.3","doi-asserted-by":"publisher","DOI":"10.1086\/328100"},{"key":"2019072204305398000_397703v1.4","first-page":"119","article-title":"Walnut culture in California and walnut blight","volume":"231","year":"1912","journal-title":"California Agricultural Experiments Station Bulletin"},{"key":"2019072204305398000_397703v1.5","doi-asserted-by":"crossref","first-page":"1014","DOI":"10.1111\/j.1365-3059.2010.02362.x","article-title":"Identification of a genetic lineage within Xanthomonas arboricola pv. juglandis as the causal agent of vertical oozing canker of Persian (English) walnut in France","volume":"59","year":"2010","journal-title":"Plant Pathol"},{"key":"2019072204305398000_397703v1.6","doi-asserted-by":"crossref","first-page":"1565","DOI":"10.1094\/PDIS-03-11-0259","article-title":"Apical necrosis and premature drop of Persian (English) walnut fruit caused by Xanthomonas arboricola pv. juglandis","volume":"95","year":"2011","journal-title":"Plant Dis"},{"key":"2019072204305398000_397703v1.7","doi-asserted-by":"publisher","DOI":"10.1094\/Phyto-72-434"},{"key":"2019072204305398000_397703v1.8","first-page":"1163","article-title":"Colonization of dormant walnut buds by Xanthomonas arboricola pv","volume":"104","year":"2014","journal-title":"juglandis is predictive of subsequent disease. Phytopathology"},{"key":"2019072204305398000_397703v1.9","first-page":"1","article-title":"Morphological and genotypic features of Xanthomonas arboricola pv. juglandis populations from walnut groves in Romagna region, Italy","volume":"145","year":"2015","journal-title":"Eur J Plant Pathol"},{"key":"2019072204305398000_397703v1.10","first-page":"S79","article-title":"Bacterial diseases of walnut and hazelnut and genetic resources","volume":"92","year":"2010","journal-title":"J Plant Pathol"},{"key":"2019072204305398000_397703v1.11","doi-asserted-by":"publisher","DOI":"10.1094\/PDIS-08-14-0831-FE"},{"key":"2019072204305398000_397703v1.12","doi-asserted-by":"crossref","first-page":"583","DOI":"10.1023\/A:1017951406237","article-title":"Investigation of genomic variability of Xanthomonas arboricola pv. juglandis by AFLP analysis","volume":"107","year":"2001","journal-title":"Eur J Plant Pathol"},{"key":"2019072204305398000_397703v1.13","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1111\/j.1574-6968.2008.01315.x","article-title":"Integron variability in Xanthomonas arboricola pv. juglandis and Xanthomonas arboricola pv. pruni strains","volume":"288","year":"2008","journal-title":"FEMS - Microbiol Lett"},{"key":"2019072204305398000_397703v1.14","doi-asserted-by":"publisher","DOI":"10.1128\/AEM.00050-15"},{"key":"2019072204305398000_397703v1.15","doi-asserted-by":"publisher","DOI":"10.1128\/AEM.06119-11"},{"key":"2019072204305398000_397703v1.16","doi-asserted-by":"publisher","DOI":"10.1111\/1758-2229.12397."},{"key":"2019072204305398000_397703v1.17","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1080\/00221589.1982.11515025","article-title":"Potential sources of inoculum of Xanthomonas juglandis in walnut blight outbreaks","volume":"57","year":"1982","journal-title":"Journal of Horticultural Science"},{"key":"2019072204305398000_397703v1.18","doi-asserted-by":"crossref","first-page":"925","DOI":"10.1051\/agro:19881012","article-title":"Dynamics of epiphytic survival of Xanthomonas campestris pathovar corylina, Xanthomonas campestris pathovar juglandis, Erwinia herbicola and Pseudomonas paucimobilis on hazelnut leaves","volume":"8","year":"1988","journal-title":"Agronomie"},{"key":"2019072204305398000_397703v1.19","doi-asserted-by":"crossref","unstructured":"Rudolpht R. 1993. Infection of the plant by Xanthomonas, p 193-264. In Swings JG , Civerolo EL (ed), Xanthomonas, 1st ed, Chapman & Hall, London.","DOI":"10.1007\/978-94-011-1526-1_4"},{"key":"2019072204305398000_397703v1.20","doi-asserted-by":"publisher","DOI":"10.1128\/AEM.00835-15"},{"key":"2019072204305398000_397703v1.21","first-page":"133","article-title":"Molecular assessment of genetic diversity of Xanthomonas arboricola pv","volume":"141","year":"2014","journal-title":"juglandis strains from Serbia by various DNA fingerprinting techniques. Eur J Plant Pathol"},{"key":"2019072204305398000_397703v1.22","doi-asserted-by":"publisher","DOI":"10.1046\/j.1439-0434.2001.00628.x"},{"key":"2019072204305398000_397703v1.23","first-page":"1404","article-title":"The genetic characterization of Xanthomonas arboricola pv","volume":"63","year":"2014","journal-title":"juglandis, the causal agent of walnut blight in Poland. 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International rules for seed testing rules 1999. Seed Science & Technology 27 supplement."},{"key":"2019072204305398000_397703v1.42","unstructured":"Lelliott RA , Stead DE . 1987. Methods for the diagnosis of bacterial diseases of plants. In Methods in Plant Pathology, vol 2, Preece Series, British Society of Plant Pathology, Blackwell Scientific Publications, Oxford, UK."}],"container-title":[],"original-title":[],"link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1101\/397703","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,14]],"date-time":"2026-01-14T22:52:23Z","timestamp":1768431143000},"score":1,"resource":{"primary":{"URL":"http:\/\/biorxiv.org\/lookup\/doi\/10.1101\/397703"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,8,22]]},"references-count":42,"URL":"https:\/\/doi.org\/10.1101\/397703","relation":{},"subject":[],"published":{"date-parts":[[2018,8,22]]},"subtype":"preprint"}}