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The Plant Pathogen Rhodococcus fascians Colonizes the Exterior and Interior of the Aerial Parts of Plants

¹Vakgroep Moleculaire Genetica & Departement Plantengenetica, Vlaams Interuniversitair Instituut voor Biotechnologie, Universiteit Gent, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium; ²Laboratoire de Biotechnologie Végétale, Université Libre de Bruxelles, Chaussée de Wavre 1850, B-1160 Brussels, Belgium; ³Laboratory of Experimental Plant Morphology and Cell Biology, Department of Plant Science, Wageningen University, Marijkeweg 22, NL-6709 PG Wageningen, The Netherlands

Rhodococcus fascians is a plant-pathogenic bacterium that causes malformations on aerial plant parts, whereby leafy galls occur at axillary meristems. The colonization behavior on Nicotiana tabacum and Arabidopsis thaliana plants was examined. Independent of the infection methods, R. fascians extensively colonized the plant surface where the bacteria were surrounded by a slime layer. R. fascians caused the collapse of epidermal cells and penetrated intercellularly into the plant tissues. The onset of symptom development preceded the extensive colonization of the interior. The meristematic regions induced by pathogenic strain D188 were surrounded by bacteria. The nonpathogenic strain, D188-5, colonized the exterior of the plant equally well, but the linear plasmid (pFiD188) seemed to be involved in the penetration efficiency and colonization of tobacco tissues.

Additional keywords: cytokinin , shoot induction.