Mensi I. auteur aut IRD Vernerey M. S. auteur aut IRD Gargani D. auteur aut IRD Nicole Michel auteur aut IRD Rott P. auteur aut IRD text journalArticle eng text/pdf born digital access Xanthomonas albilineans, the causal agent of sugarcane leaf scald, is missing the Hrp type III secretion system that is used by many Gram-negative bacteria to colonize their host. Until now, this pathogen was considered as strictly limited to the xylem of sugarcane. We used confocal laser scanning microscopy, immunocytochemistry and transmission electron microscopy (TEM) to investigate the localization of X. albilineans in diseased sugarcane. Sugarcane plants were inoculated with strains of the pathogen labelled with a green fluorescent protein. Confocal microscopy observations of symptomatic leaves confirmed the presence of the pathogen in the protoxylem and metaxylem; however, X. albilineans was also observed in phloem, parenchyma and bulliform cells of the infected leaves. Similarly, vascular bundles of infected sugarcane stalks were invaded by X. albilineans. Surprisingly, the pathogen was also observed in apparently intact storage cells of the stalk and in intercellular spaces between these cells. Most of these observations made by confocal microscopy were confirmed by TEM. The pathogen exits the xylem following cell wall and middle lamellae degradation, thus creating openings to reach parenchyma cells. This is the first description of a plant pathogenic vascular bacterium invading apparently intact non-vascular plant tissues and multiplying in parenchyma cells. specialized Xanthomonas albilineans confocal laser scanning microscopy cytochemistry transmission electron microscopy non-vascular plant tissue 076 020 4 art. 130116 [13 ] 2014 2046-2441 https://www.documentation.ird.fr/hor/fdi:010061830 10.1098/rsob.130116 2046-2441 [F B010061830] https://www.documentation.ird.fr/hor/fdi:010061830 https://www.documentation.ird.fr/intranet/publi/2014/04/010061830.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2014-04-29 2017-08-23 fdi:010061830 fre