First Identification of Xanthomonas nasturtii as the Cause of Black Rot of Watercress in Hawaii

HomePlant DiseaseVol. 107, No. 8First Identification of Xanthomonas nasturtii as the Cause of Black Rot of Watercress in Hawaii PreviousNext DISEASE NOTE OPENOpen Access licenseFirst Identification of Xanthomonas nasturtii as the Cause of Black Rot of Watercress in HawaiiJoana G. Vicente, John McHugh, Adam Bryning, Sarah Carroll, James Harrison, and David J. StudholmeJoana G. Vicente†Corresponding author: J. G. Vicente; E-mail Address: [email protected]https://orcid.org/0000-0001-8442-5935Fera Science Ltd., York Biotech Campus, York YO41 1LZ, U.K.School of Life Sciences, Wellesbourne Campus, The University of Warwick, Warwick CV35 9EF, U.K.Search for more papers by this author, John McHughPlant Industry Division, Hawaii Department of Agriculture, Honolulu, HI 96814-2512, U.S.A.Search for more papers by this author, Adam Bryninghttps://orcid.org/0000-0001-7628-3615Fera Science Ltd., York Biotech Campus, York YO41 1LZ, U.K.Search for more papers by this author, Sarah Carrollhttps://orcid.org/0000-0002-2761-0744Fera Science Ltd., York Biotech Campus, York YO41 1LZ, U.K.Search for more papers by this author, James Harrisonhttps://orcid.org/0000-0002-8314-9411College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, U.K.Search for more papers by this author, and David J. Studholmehttps://orcid.org/0000-0002-3010-6637College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, U.K.Search for more papers by this authorAffiliationsAuthors and Affiliations Joana G. Vicente1 2 † John McHugh3 Adam Bryning1 Sarah Carroll1 James Harrison4 David J. Studholme4 1Fera Science Ltd., York Biotech Campus, York YO41 1LZ, U.K. 2School of Life Sciences, Wellesbourne Campus, The University of Warwick, Warwick CV35 9EF, U.K. 3Plant Industry Division, Hawaii Department of Agriculture, Honolulu, HI 96814-2512, U.S.A. 4College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, U.K. Published Online:16 Aug 2023https://doi.org/10.1094/PDIS-05-22-1043-PDNAboutSectionsView articlePDFSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat View articleWatercress (Nasturtium officinale) has been in continuous production in Hawaii for over a century and is part of the local diet. Black rot of watercress was first identified as caused by Xanthomonas nasturtii in Florida (Vicente et al. 2017), but symptoms of this disease have also been regularly observed in Hawaii’s production in all islands, mostly during the rainy season from December to April in areas with poor air circulation (McHugh and Constantinides 2004). Initially, this disease was attributed to X. campestris due to similar symptoms to black rot of brassicas. Samples of watercress with symptoms that could be attributed to a bacterial disease including yellow spots and lesions on leaves and stunting and deformation of plants in more advanced stages were collected from a farm in Aiea in the island of Oahu, Hawaii, in October 2017. Isolations were performed at the University of Warwick. Fluid from macerated leaves was streaked into plates of King’s B (KB) medium and yeast dextrose calcium carbonate agar. After 48 to 72 h of incubation at 28°C, the plates showed a range of mixed colonies. Single cream-yellow mucoid colonies were subcultured several times, and pure isolates including WHRI 8984 were stored at −76°C as previously described (Vicente et al. 2017). Colony morphology was observed in KB plates and, in contrast to the type strain from Florida (WHRI 8853 = NCPPB 4600), isolate WHRI 8984 did not cause browning of the medium. Pathogenicity was tested on 4-week-old watercress and Savoy cabbage cv. Wirosa F1 plants by inoculation on leaves as previously described (Vicente et al. 2017). WHRI 8984 did not produce symptoms when inoculated on cabbage but produced typical symptoms on watercress. A reisolation from a leaf showing a V-shaped lesion produced isolates with the same morphology, including isolate WHRI 10007A, which was also shown to be pathogenic to watercress, therefore completing Koch’s postulates. Fatty acid profiling was performed on WHRI 8984 and 10007A and controls grown on Trypticase soy broth agar (TSBA) plates at 28°C for 48 h as described by Weller et al. (2000). Profiles were compared with the RTSBA6 v6.21 library; as the database does not include X. nasturtii, the results were only interpreted at the genus level, and both isolates were shown to be Xanthomonas sp. For molecular analysis, DNA was extracted, and the partial gyrB gene was amplified and sequenced as described by Parkinson et al. (2007). Comparisons with sequences available in the National Center for Biotechnology Information (NCBI) databases using the Basic Local Alignment Search Tool showed that partial gyrB gene sequences of WHRI 8984 and 10007A were identical to the type strain from Florida, therefore confirming that they belong to X. nasturtii. For whole genome sequencing, genomic libraries for WHRI 8984 were prepared using Illumina’s Nextera XT v2 kit and sequenced on a HiSeq Rapid Run flow cell. The sequences were processed as previously described (Vicente et al. 2017), and the whole genome assembly has been deposited in GenBank (accession QUZM00000000.1); the phylogenetic tree shows that WHRI 8984 is close, but not identical to the type strain. This is the first identification of X. nasturtii in watercress crops in Hawaii. Control of this disease generally involves the use of copper bactericides and minimizing moisture on leaves by reducing overhead irrigation and increasing air circulation (Mchugh and Constantinides 2004); seed testing might help to select batches that are disease-free and, in longer term, breeding for disease resistance might produce cultivars that can be part of management strategies.The author(s) declare no conflict of interest.References:McHugh, J. J., and Constantinides, L. N. 2004. Pest Management Strategic Plan for Watercress Production in Hawaii. Workshop summary. University of Hawaii at Manoa, Honolulu, HI. https://ipmdata.ipmcenters.org/documents/pmsps/HiWatercress.pdf Google ScholarParkinson, N., et al. 2007. Int. J. Syst. Evol. Microbiol. 57:2881. https://doi.org/10.1099/ijs.0.65220-0 Crossref, ISI, Google ScholarVicente, J. G., et al. 2017. Int. J. Syst. Evol. Microbiol. 67:3645. https://doi.org/10.1099/ijsem.0.002189 Crossref, ISI, Google ScholarWeller, S. A., et al. 2000. EPPO Bull. 30:375. https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2338.2000.tb00914.x Crossref, Google ScholarFunding: J. G. Vicente, J. Harrison, and D. J. Studholme were supported by the project “Xanthomonas plant diseases: mitigating existing, emerging and future threats to UK agriculture” funded by UK Research and Innovation (UKRI) through the Strategic Priorities Fund (SPF), by grants (BB/T01924/1, BB/T010908/1, and BB/T010916/1) from the Biotechnology and Biological Sciences Research Council (BBSRC) with support from the Department for Environment, Food and Rural Affairs (Defra) and the Scottish Government. The work was carried out under UK plant health licenses 10035/199069 and 33173/199261 at the University of Warwick and Fera Science Ltd., respectively. The DNA sequencing at the University of Exeter utilized equipment funded by the Wellcome Trust Institutional Strategic Support Fund (grant no. WT097835MF), Wellcome Trust Multi-User Equipment Award (grant no. WT101650MA), and BBSRC LOLA award (grant no. BB/K003240/1). This disease note is also based on work developed during the COST Action CA16107 EuroXanth, supported by the European Cooperation in Science and Technology (COST).The author(s) declare no conflict of interest.DetailsFiguresLiterature CitedRelated Vol. 107, No. 8 August 2023SubscribeISSN:0191-2917e-ISSN:1943-7692 Download Metrics Article History Issue Date: 29 Aug 2023Published: 16 Aug 2023First Look: 3 Mar 2023Accepted: 16 Feb 2023 Page: 2511 Information© 2023 The American Phytopathological SocietyFundingUK Research and Innovation (UKRI)Grant/Award Number: BB/T01924/1Grant/Award Number: BB/T010908/1Grant/Award Number: BB/T010916/1Biotechnology and Biological Sciences Research CouncilDepartment for Environment, Food and Rural Affairs (Defra)Scottish GovernmentUniversity of WarwickFera Science Ltd.Wellcome Trust Institutional Strategic Support FundGrant/Award Number: WT097835MFWellcome Trust Multi-User Equipment AwardGrant/Award Number: WT101650MABBSRCGrant/Award Number: BB/K003240/1European Cooperation in Science and Technology (COST)Keywordsblack rotfatty acid profilinggyrBidentificationNasturtium officinalesequencingwatercressXanthomonas nasturtiiThe author(s) declare no conflict of interest.PDF download