title: Genetic diversity and population structure of Clavibacter michiganensis subsp. nebraskensis.
abstract: Clavibacter michiganensis subsp. nebraskensis (CMN) is a gram-positive bacterium and an incitant of Goss's bacterial wilt and leaf blight or "leaf freckles" in corn. A population structure of a wide temporal and geographic collection of CMN strains (n = 131), originating between 1969 and 2009, was determined using amplified fragment length polymorphism (AFLP) analysis and repetitive DNA sequence-based BOX-PCR. Analysis of the composite data set of AFLP and BOX-PCR fingerprints revealed two groups with a 60% cutoff similarity: a major group A (n = 118 strains) and a minor group B (n = 13 strains). The clustering in both groups was not correlated with strain pathogenicity. Group A contained two clusters, A1 (n = 78) and A2 (n = 40), with a linkage of 75%. Group A strains did not show any correlation with historical, geographical, morphological, or physiological properties of the strains. Group B was very heterogeneous and eight out of nine clusters were represented by a single strain. The mean similarity between clusters in group B varied from 13% to 63%. All strains in group B were isolated after 1999. The percentage of group B strains among all strains isolated after 1999 (n = 69) was 18.8%. Implications of the findings are discussed.
authors.affiliation: Plant Pathology Department, University of Nebraska-Lincoln, NE 68583-0900, USA.
authors.forename: I V
authors.initials: IV
authors.lastname: Agarkova
authors.forename: P A
authors.initials: PA
authors.lastname: Lambrecht
authors.forename: A K
authors.initials: AK
authors.lastname: Vidaver
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D014644:Genetic Variation; D060005:Genotyping Techniques; D008835:Micrococcaceae / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D010935:Plant Diseases / Q000382:microbiology; D016133:Polymerase Chain Reaction; D012091:Repetitive Sequences, Nucleic Acid; D003313:Zea mays / Q000382:microbiology
chemical_list: D004269:DNA, Bacterial