Diversity 2010, 2(11), 1205-1222; doi:10.3390/d2111205
Article

Multilocus Sequence Typing Reveals Relevant Genetic Variation and Different Evolutionary Dynamics among Strains of Xanthomonas arboricola pv. juglandis

email, email and * email
Received: 14 October 2010; in revised form: 11 November 2010 / Accepted: 16 November 2010 / Published: 22 November 2010
(This article belongs to the Special Issue Genetic and Functional Diversity of Microorganisms)
Download PDF [1569 KB, uploaded 22 November 2010]
Abstract: Forty-five Xanthomonas arboricola pv. juglandis (Xaj) strains originating from Juglans regia cultivation in different countries were molecularly typed by means of MultiLocus Sequence Typing (MLST), using acnB, gapA, gyrB and rpoD gene fragments. A total of 2.5 kilobases was used to infer the phylogenetic relationship among the strains and possible recombination events. Haplotype diversity, linkage disequilibrium analysis, selection tests, gene flow estimates and codon adaptation index were also assessed. The dendrograms built by maximum likelihood with concatenated nucleotide and amino acid sequences revealed two major and two minor phylotypes. The same haplotype was found in strains originating from different continents, and different haplotypes were found in strains isolated in the same year from the same location. A recombination breakpoint was detected within the rpoD gene fragment. At the pathovar level, the Xaj populations studied here are clonal and under neutral selection. However, four Xaj strains isolated from walnut fruits with apical necrosis are under diversifying selection, suggesting a possible new adaptation. Gene flow estimates do not support the hypothesis of geographic isolation of the strains, even though the genetic diversity between the strains increases as the geographic distance between them increases. A triplet deletion, causing the absence of valine, was found in the rpoD fragment of all 45 Xaj strains when compared with X. axonopodis pv. citri strain 306. The codon adaptation index was high in all four genes studied, indicating a relevant metabolic activity.
Keywords: MLST; Juglans regia; haplotype; walnut apical necrosis; rpoD; valine; CAI
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Export to BibTeX |
EndNote


MDPI and ACS Style

Marcelletti, S.; Ferrante, P.; Scortichini, M. Multilocus Sequence Typing Reveals Relevant Genetic Variation and Different Evolutionary Dynamics among Strains of Xanthomonas arboricola pv. juglandis. Diversity 2010, 2, 1205-1222.

AMA Style

Marcelletti S, Ferrante P, Scortichini M. Multilocus Sequence Typing Reveals Relevant Genetic Variation and Different Evolutionary Dynamics among Strains of Xanthomonas arboricola pv. juglandis. Diversity. 2010; 2(11):1205-1222.

Chicago/Turabian Style

Marcelletti, Simone; Ferrante, Patrizia; Scortichini, Marco. 2010. "Multilocus Sequence Typing Reveals Relevant Genetic Variation and Different Evolutionary Dynamics among Strains of Xanthomonas arboricola pv. juglandis." Diversity 2, no. 11: 1205-1222.

Diversity EISSN 1424-2818 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert