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Xanthomonas axonopodis pv. eucalyptorum pv. nov. Causing Bacterial Leaf Blight on Eucalypt in Brazil
Plant Pathol. J. 2018;34:269-285
Published online August 1, 2018
© 2018 The Korean Society of Plant Pathology.

Hélvio Gledson Maciel Ferraz1, Jorge Luis Badel1, Lúcio Mauro da Silva Guimarães1, Bruna Paolinelli Reis1, Marcos Rogério Tótola2, Rivadalve Coelho Gonçalves3, and Acelino Couto Alfenas1*

1Department of Phytopathology, Universidade Federal de Viçosa, Viçosa, MG 36570-900, Brazil
2Department of Microbiology, Universidade Federal de Viçosa, Viçosa, MG 36570-900, Brazil
3EMBRAPA Acre, BR 364, Km 14, Zona Rural, CEP 69.908.970, Caixa Postal 321, Rio Branco, AC, Brazil
Correspondence to: Phone) +55-31-3899-2937, FAX) +55-31-3899-2240
E-mail) aalfenas@ufv.br
Received January 30, 2018; Revised April 2, 2018; Accepted April 17, 2018.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Bacterial leaf blight is a major disease of eucalypt, especially under nursery conditions. Different bacterial species have been associated with the disease in several countries, and despite its importance worldwide, it is not clear to date whether similar disease symptoms are caused by the same or by different etiological agents. In this study, 43 bacterial strains were isolated from blighted eucalypt leaves collected in different geographic areas of Brazil and inoculated onto a susceptible eucalypt clone. Polyphasic taxonomy, including morphological, physiological, biochemical, molecular, and pathogenicity tests showed that only certain strains of Xanthomonas axonopodis caused symptoms of the disease. Strains varied in their aggressiveness, but no correlation with geographic origin was observed. MLSA-based phylogenetic analysis using concatenated dnaK, fyuA, gyrB and rpoD gene sequences allocated the strains in a well-defined clade, corresponding to Rademarker’s group RG 9.6. Inoculation of nineteen plant species belonging to seven botanical families with representative strain LPF 602 showed it to be pathogenic only on Eucalyptusspp, and Corymbia spp. Based on distinct biochemical and pathogenic characteristics that differentiate the eucalypt strains from other pathovars of the X. axonopodis species, here we propose their allocation into the new pathovar X. axonopodis pv. eucalyptorum pv. nov.
Keywords : Eucalyptus spp., fatty acid profile, metabolism fingerprinting, multilocus sequence analysis, Xanthomonas axonopodis


August 2018, 34 (4)
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