title: Multilocus Sequence Typing of Strains of Bacterial Spot of Lettuce Collected in the United States.
abstract: Studies on genetic diversity and recombination in bacterial pathogens are providing a better understanding of the mechanisms shaping bacterial diversity, which can affect disease control. Xanthomonas campestris pv. vitians, causal agent of bacterial leaf spot of lettuce, is a threat to the worldwide lettuce industry. We examined the genetic variation within a sample of 83 strains from California, Florida, and Ohio using multilocus sequence typing of six housekeeping genes, totaling 2.7 kb. Additionally, polymorphism in two virulence-related genes, hrpB2 and a putative glycosyl hydrolase, were examined. Based on housekeeping genes, we found three genetic groups of strains that were all able to induce the disease. These included strains collected from weeds and irrigation water that had haplotypes identical to strains from diseased lettuce. High linkage disequilibrium across the sequenced loci indicates that the pathogen is predominantly clonal but recombination has contributed to the observed sequence variation. Although there was significant genetic variation in X. campestris pv. vitians within and among sampled states, identical haplotypes were observed across all three states. This finding suggests that seedborne inoculum may contribute to the diversity of X. campestris pv. vitians in the United States. Knowledge of the genetic structure of the pathogen may be used for developing resistant lettuce varieties.
authors.affiliation: First, second, and fifth authors: Everglades Research and Education Center, University of Florida Institute of Food and Agricultural Sciences (IFAS), Belle Glade; third author: Southwest Florida Research and Education Center, University of Florida/IFAS, Immokalee; first, second, third, fourth, fifth, and seventh authors: Department of Plant Pathology, University of Florida, Gainesville; sixth author: United States Department of Agriculture-Agricultural Research Service, Pacific West Area, 1636 E. Alisal St., Salinas, CA; and seventh author: Emerging Pathogens Institute, University of Florida, Gainesville.
authors.forename: Joubert
authors.initials: J
authors.lastname: Fayette
authors.affiliation: First, second, and fifth authors: Everglades Research and Education Center, University of Florida Institute of Food and Agricultural Sciences (IFAS), Belle Glade; third author: Southwest Florida Research and Education Center, University of Florida/IFAS, Immokalee; first, second, third, fourth, fifth, and seventh authors: Department of Plant Pathology, University of Florida, Gainesville; sixth author: United States Department of Agriculture-Agricultural Research Service, Pacific West Area, 1636 E. Alisal St., Salinas, CA; and seventh author: Emerging Pathogens Institute, University of Florida, Gainesville.
authors.forename: Richard
authors.initials: R
authors.lastname: Raid
authors.affiliation: First, second, and fifth authors: Everglades Research and Education Center, University of Florida Institute of Food and Agricultural Sciences (IFAS), Belle Glade; third author: Southwest Florida Research and Education Center, University of Florida/IFAS, Immokalee; first, second, third, fourth, fifth, and seventh authors: Department of Plant Pathology, University of Florida, Gainesville; sixth author: United States Department of Agriculture-Agricultural Research Service, Pacific West Area, 1636 E. Alisal St., Salinas, CA; and seventh author: Emerging Pathogens Institute, University of Florida, Gainesville.
authors.forename: Pamela D
authors.initials: PD
authors.lastname: Roberts
authors.affiliation: First, second, and fifth authors: Everglades Research and Education Center, University of Florida Institute of Food and Agricultural Sciences (IFAS), Belle Glade; third author: Southwest Florida Research and Education Center, University of Florida/IFAS, Immokalee; first, second, third, fourth, fifth, and seventh authors: Department of Plant Pathology, University of Florida, Gainesville; sixth author: United States Department of Agriculture-Agricultural Research Service, Pacific West Area, 1636 E. Alisal St., Salinas, CA; and seventh author: Emerging Pathogens Institute, University of Florida, Gainesville.
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Jones
authors.affiliation: First, second, and fifth authors: Everglades Research and Education Center, University of Florida Institute of Food and Agricultural Sciences (IFAS), Belle Glade; third author: Southwest Florida Research and Education Center, University of Florida/IFAS, Immokalee; first, second, third, fourth, fifth, and seventh authors: Department of Plant Pathology, University of Florida, Gainesville; sixth author: United States Department of Agriculture-Agricultural Research Service, Pacific West Area, 1636 E. Alisal St., Salinas, CA; and seventh author: Emerging Pathogens Institute, University of Florida, Gainesville.
authors.forename: Ken
authors.initials: K
authors.lastname: Pernezny
authors.affiliation: First, second, and fifth authors: Everglades Research and Education Center, University of Florida Institute of Food and Agricultural Sciences (IFAS), Belle Glade; third author: Southwest Florida Research and Education Center, University of Florida/IFAS, Immokalee; first, second, third, fourth, fifth, and seventh authors: Department of Plant Pathology, University of Florida, Gainesville; sixth author: United States Department of Agriculture-Agricultural Research Service, Pacific West Area, 1636 E. Alisal St., Salinas, CA; and seventh author: Emerging Pathogens Institute, University of Florida, Gainesville.
authors.forename: Carolee T
authors.initials: CT
authors.lastname: Bull
authors.affiliation: First, second, and fifth authors: Everglades Research and Education Center, University of Florida Institute of Food and Agricultural Sciences (IFAS), Belle Glade; third author: Southwest Florida Research and Education Center, University of Florida/IFAS, Immokalee; first, second, third, fourth, fifth, and seventh authors: Department of Plant Pathology, University of Florida, Gainesville; sixth author: United States Department of Agriculture-Agricultural Research Service, Pacific West Area, 1636 E. Alisal St., Salinas, CA; and seventh author: Emerging Pathogens Institute, University of Florida, Gainesville.
authors.forename: Erica M
authors.initials: EM
authors.lastname: Goss
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D002140:California; D005431:Florida; D014644:Genetic Variation; D005838:Genotype; D006239:Haplotypes; D018545:Lactuca / Q000382:microbiology*; D058885:Multilocus Sequence Typing; D009820:Ohio; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D014774:Virulence; D016959:Xanthomonas campestris / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity
chemical_list: D001426:Bacterial Proteins