Multilocus Sequence Analysis of Xanthomonads Causing Bacterial Spot of Tomato and Pepper Plants Reveals Strains Generated by Recombination among Species and Recent Global Spread of Xanthomonas gardneri

Sujan Timilsina; Mustafa O. Jibrin; Neha Potnis; Gerald V. Minsavage; Misrak Kebede; Allison Schwartz; Rebecca Bart; Brian Staskawicz; Claudine Boyer; Gary E. Vallad; Olivier Pruvost; Jeffrey B. Jones; Erica M. Goss

doi:10.1128/AEM.03000-14

Multilocus Sequence Analysis of Xanthomonads Causing Bacterial Spot of Tomato and Pepper Plants Reveals Strains Generated by Recombination among Species and Recent Global Spread of Xanthomonas gardneri

^aDepartment of Plant Pathology, University of Florida, Gainesville, Florida, USA
^bGulf Coast Research and Education Center, University of Florida, Wimauma, Florida, USA
^cDepartment of Crop Protection, Ahmadu Bello University, Zaria, Nigeria
^dPlant Pathology Department, School of Plant Science, Haramaya University, Dire Dawa, Ethiopia
^eDepartment of Plant and Microbial Biology, University of California—Berkeley, California, USA
^fDanforth Center, St. Louis, Missouri, USA
^gCIRAD, UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical CIRAD-Université de la Réunion, Pôle de Protection des Plantes, Saint Pierre, La Réunion, France
^hEmerging Pathogens Institute, University of Florida, Gainesville, Florida, USA

H. Goodrich-Blair, Editor

ABSTRACT

Four Xanthomonas species are known to cause bacterial spot of tomato and pepper, but the global distribution and genetic diversity of these species are not well understood. A collection of bacterial spot-causing strains from the Americas, Africa, Southeast Asia, and New Zealand were characterized for genetic diversity and phylogenetic relationships using multilocus sequence analysis of six housekeeping genes. By examining strains from different continents, we found unexpected phylogeographic patterns, including the global distribution of a single multilocus haplotype of X. gardneri, possible regional differentiation in X. vesicatoria, and high species diversity on tomato in Africa. In addition, we found evidence of multiple recombination events between X. euvesicatoria and X. perforans. Our results indicate that there have been shifts in the species composition of bacterial spot pathogen populations due to the global spread of dominant genotypes and that recombination between species has generated genetic diversity in these populations.

FOOTNOTES

Received 15 September 2014.
Accepted 14 December 2014.
Accepted manuscript posted online 19 December 2014.

Address correspondence to Jeffrey B. Jones, jbjones{at}ufl.edu.
G.E.V., O.P., J.B.J., and E.M.G. are joint last authors.
Citation Timilsina S, Jibrin MO, Potnis N, Minsavage GV, Kebede M, Schwartz A, Bart R, Staskawicz B, Boyer C, Vallad GE, Pruvost O, Jones JB, Goss EM. 2015. Multilocus sequence analysis of xanthomonads causing bacterial spot of tomato and pepper plants reveals strains generated by recombination among species and recent global spread of Xanthomonas gardneri. Appl Environ Microbiol 81:1520–1529. doi:10.1128/AEM.03000-14.
Supplemental material for this article may be found at http://dx.doi.org/10.1128/AEM.03000-14.