Pieretti I. auteur aut IRD Royer M. auteur aut IRD Barbe V. auteur aut IRD Carrere S. auteur aut IRD Koebnik Ralf auteur aut IRD Cociancich S. auteur aut IRD Couloux A. auteur aut IRD Darrasse A. auteur aut IRD Gouzy J. auteur aut IRD Jacques M. A. auteur aut IRD Lauber E. auteur aut IRD Manceau C. auteur aut IRD Mangenot S. auteur aut IRD Poussier S. auteur aut IRD Segurens B. auteur aut IRD Szurek Boris auteur aut IRD Verdier Valérie auteur aut IRD Arlat M. auteur aut IRD Rott P. auteur aut IRD text journalArticle eng text/pdf reformatted digital access Background: The Xanthomonadaceae family contains two xylem-limited plant pathogenic bacterial species, Xanthomonas albilineans and Xylella fastidiosa. X. fastidiosa was the first completely sequenced plant pathogen. It is insect-vectored, has a reduced genome and does not possess hrp genes which encode a Type III secretion system found in most plant pathogenic bacteria. X. fastidiosa was excluded from the Xanthomonas group based on phylogenetic analyses with rRNA sequences. Results: The complete genome of X. albilineans was sequenced and annotated. X. albilineans, which is not known to be insect-vectored, also has a reduced genome and does not possess hrp genes. Phylogenetic analysis using X. albilineans genomic sequences showed that X. fastidiosa belongs to the Xanthomonas group. Order of divergence of the Xanthomonadaceae revealed that X. albilineans and X. fastidiosa experienced a convergent reductive genome evolution during their descent from the progenitor of the Xanthomonas genus. Reductive genome evolutions of the two xylem-limited Xanthomonadaceae were compared in light of their genome characteristics and those of obligate animal symbionts and pathogens. Conclusion: The two xylem-limited Xanthomonadaceae, during their descent from a common ancestral parent, experienced a convergent reductive genome evolution. Adaptation to the nutrient-poor xylem elements and to the cloistered environmental niche of xylem vessels probably favoured this convergent evolution. However, genome characteristics of X. albilineans differ from those of X. fastidiosa and obligate animal symbionts and pathogens, indicating that a distinctive process was responsible for the reductive genome evolution in this pathogen. The possible role in genome reduction of the unique toxin albicidin, produced by X. albilineans, is discussed. specialized 076 10 616 2009 1471-2164 https://www.documentation.ird.fr/hor/fdi:010049222 10.1186/1471-2164-10-616 1471-2164 [F B010049222] https://www.documentation.ird.fr/hor/fdi:010049222 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers17-09/010049222.pdf IRD - Base Horizon / Pleins textes 2010-03-10 2017-10-03 fdi:010049222 fre