University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Papers in Plant Pathology Plant Pathology Department 1-1991 Comment on the Reinstatement of Xanthomonas citri (ex Hasse 1915) Gabriel et al. 1989 and X. phaseoli (ex Smith 1897) Gabriel et al. 1989: Indication of the Need for Minimal Standards for the Genus Xanthomonas J. M. Young Plant Protection, Department of Scientific and Industrial Research J. F. Bradbury CAB International Mycological Institute L. Gardan Institut National de la Recherche Agronomique R. I. Gvozdyak Ukrainian Academy of Sciences D. E. Stead ADAS Central Science Laboratory See next page for additional authors Follow this and additional works at: https://digitalcommons.unl.edu/plantpathpapers Part of the Plant Pathology Commons Young, J. M.; Bradbury, J. F.; Gardan, L.; Gvozdyak, R. I.; Stead, D. E.; Takikawa, Y.; and Vidaver, A. K., "Comment on the Reinstatement of Xanthomonas citri (ex Hasse 1915) Gabriel et al. 1989 and X. phaseoli (ex Smith 1897) Gabriel et al. 1989: Indication of the Need for Minimal Standards for the Genus Xanthomonas" (1991). Papers in Plant Pathology. 256. https://digitalcommons.unl.edu/plantpathpapers/256 This Article is brought to you for free and open access by the Plant Pathology Department at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Papers in Plant Pathology by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Authors J. M. Young, J. F. Bradbury, L. Gardan, R. I. Gvozdyak, D. E. Stead, Y. Takikawa, and A. K. Vidaver This article is available at DigitalCommons@University of Nebraska - Lincoln: https://digitalcommons.unl.edu/ plantpathpapers/256 Comment on the Reinstatement of Xanthomonas citri (ex Hasse 1915) Gabriel et al. 1989 and X. phaseoli (ex Smith 1897) Gabriel et al. 1989: Indication of the Need for Minimal Standards for the Genus Xanthomonas J. M. Young1, J. F. Bradbury2, L. Gardan3, R. I. Gvozdyak4, D. E. Stead5, Y. Takikawa6 and A. K. Vidaver7 1. Plant Protection, Department of Scientific and Industrial Research, Private Bag, Auckland, New Zealand 2. CAB International Mycological Institute, Ferry Lane, Kew, Surrey TW9 3AF, United Kingdom 3. Station de Pathologie Végétale-Phytobactériologie, Institut National de la Recherche Agronomique, Route de Saint-Clément, Beaucouzé, 49000 Angers, France 4. Institute of Microbiology and Virology, Ukrainian Academy of Sciences, 252143 Kiev, Ukraine, USSR 5. ADAS Central Science Laboratory, Ministry of Agriculture, Fisheries and Food, Hatching Green, Harpenden, Hertfordshire AL5 2BD, United Kingdom 6. Department of Plant Pathology, Shizuoka University, 836 Ohya, Shizuoka 422, Japan 7. Department of Plant Pathology, University of Nebraska—Lincoln, Lincoln, Nebraska 68583-0722 Corresponding author — J. M. Young Abstract The proposals to reinstate Xanthomonas citri (ex Hasse 1915) Gabriel et al. 1989 and X. phaseoli (Smith 1897) Gabriel et al. 1989 are examined in terms of conventional criteria for describing new species. We suggest that the descriptions presented are insufficient in terms of modern practice for the purposes of formal classification in the genus Xanthomonas. To create guidelines for future reinstatements, the Judicial Commission of the International Committee on Systematic Bacteriology is requested to arrange for the preparation and promulgation of minimal standards for Xanthomonas. The pathovars proposed, X. campestris pv. aurantifolii Gabriel et al. 1989 and X. campestris pv. citrumelo Gabriel et al. 1989, are considered to be defective in terms of the International Society for Plant Pathology's standards for naming pathovars. Int J Syst Bacteriol January 1991 41:172-177; doi:10.1099/00207713-41-1-172 Copyright 1991 International Union of Microbiological Societies INTERNATIONALJOURNAL OF SYSTEMATICBACTERIOLOGY, Jan. 1991, p. 172-177 Vol. 41, No. 1 0020-7713/91/010172-06$02.OO/O Copyright 0 1991, International Union of Microbiological Societies Comment on the Reinstatement of Xanthomonas citri (ex Hasse 1915) Gabriel et al. 1989 and X. phaseoli (ex Smith 1897) Gabriel et al. 1989: Indication of the Need for Minimal Standards for the Genus XanthomonasT J. M. YOUNG,’* J. F. BRADBURY,2 L. GARDAN,3 R. I. GVOZDYAK,4 D. E. STEAD,’ Y. TAKIKAWA,6 AND A. K. VIDAVER7 Plant Protection, Department of Scientijic and Industrial Research, Private Bag, Auckland, New Zealand‘; CAB International Mycological Institute, Ferry Lane, Kew, Surrey TW9 3AF, United Kingdom2; Station de Pathologie Vkgktale-Phytobactkriologie,Institut National de la Recherche Agronomique, Route de Saint-Cltment, Beaucouzk, 49000 Angers, France3;Institute of Microbiology and Virology, Ukrainian Academy of Sciences, 252143 Kiev, Ukraine, USSR4; ADAS Central Science Laboratory, Ministry of Agriculture, Fisheries and Food, Hatching Green, Harpenden, Hertfordshire AL5 2BD, United Kingdom’; Department of Plant Pathology, Shizuoka University, 836 Ohya, Shizuoka 422, Japan6; and Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, Nebraska 68583-07227 The proposals to reinstate Xanthomonas citri (ex Hasse 1915) Gabriel et al. 1989 and X. phased (Smith 1897) Gabriel et al. 1989 are examined in terms of conventional criteria for describing new species. We suggest that the descriptions presented are insufficient in terms of modern practice for the purposes of formal classification in the genus Xanthomonas. To create guidelines for future reinstatements, the Judicial Commission of the International Committee on Systematic Bacteriology is requested to arrange for the preparation and promulgation of minimal standards for Xanthomonas. The pathovars proposed, X. campestris pv. aurantifolii Gabriel et al. 1989 and X. campestris pv. citrumelo Gabriel et al. 1989, are considered to be defective in terms of the International Society for Plant Pathology’s standards for naming pathovars. Xanthomonas citri (Hasse 1915) Dowson 1939 and X. taxa should be as complete as possible and are expected to phaseoli (Smith 1897) Dowson 1939 were originally de- include such information as morphological descriptions, scribed as the pathogens that cause bacterial canker of citrus physiological behavior, biochemical reactions, chemical (Citrus spp.) and common blight of bean (Phaseolus spp.), composition, and nucleic acid comparisons. The general respectively. These organisms were listed by Dye and Lel- proposals of Triiper and Kramer (28) and Murray et al. (21) liott (5) as species whose descriptions did not allow them to and the methodologies described by Johnson (14), Jones be distinguished from X. campestris (Pammel 1895) Dowson (15), Jones and Krieg (16), and Sneath (24) give clear 1939 or from each other except by host reactions. These indications of what is intended in a modern description. The species and most of the other Xanthomonas spp. accepted at modern description is an independent reference for a taxon. the time did not fulfill the criteria established for validation in The International Code calls for the preparation of minimal the Approved Lists of Bacterial Names (23). However, the standards (Recommendation 30b) to which species descrip- names were retained (4) at the infrasubspecific level as tions should conform in the future, which should “include pathovars of X. campestris. Recently, Gabriel et al. (8) tests for generic identity, and tests which would distinguish proposed reinstatement of X. phaseoli from X. campestris the species from others.” The description of a given taxon pv. phaseoli (Smith 1897) Dye 1978 as the name for the can expand and become more detailed as closely related taxa pathogen of common blight of beans and reinstatement of X. are distinguished and as new methods are applied. citri as the name for the group A strains of X. campestris pv. As an assessment of modern practices for naming new citri (Hasse 1915) Dye 1978 which cause Oriental or Asian species, we examined a representative sample of 35 reports citrus canker. Gabriel et al. (8) also proposed the pathovar published in the International Journal of Systematic Bacte- name X. campestris pv. aurantifolii for group B, C, and D riology in the years from 1980 to 1988. This examination strains and the pathovar name X. campestris pv. citrumelo for group E strains of X. campestris pv. citri. showed that, on average, for each species proposed approx- imately 16 strains were examined by using about 60 bio- chemical tests. An examination of all plant-pathogenic spe- CLASSIFICATION cies named in the same period gave a similar result. Our The naming of a taxon according to the International Code examinations did not include polyphasic or multicharacter of Nomenclature of Bacteria (19) presupposes that the taxon tests, such as electrophoresis of proteins, guanine-plus- has been characterized by a range of methods which are cytosine ratios, or DNA-DNA hybridization studies. Com- sufficient to classify it as a distinct entity in terms of its monly found in these descriptions was a list of procedures by overall characteristics and to distinguish it from all other which strains of the species could be distinguished from named taxa (18, 21, 25, 26, 28). Published descriptions of related species by using biochemical determinative tests. One intention of the authors of the International Code in requiring adequate differentiation of species by modern * Corresponding author. descriptions was to provide independent references which t Position of the International Society for Plant Pathology Sub-