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De novo Cortical Cell Division Triggered by the Phytopathogen Rhodococcus fascians in Tobacco

February 2001 , Volume 14 , Number  2
Pages  189 - 195

Carmem-Lara de O. Manes , 1 Marc Van Montagu , 1 Els Prinsen , 2 Koen Goethals , 1 and Marcelle Holsters 1

1Vakgroep Moleculaire Genetica & Departement Plantengenetica, Vlaams Interuniversitair Instituut voor Biotechnologie (VIB), Universiteit Gent, B-9000 Gent, Belgium; 2Departement Biologie, Universitaire Instelling Antwerpen, B-2610 Antwerpen, Belgium

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Accepted 18 October 2000.

Plant growth, development, and morphology can be affected by several environmental stimuli and by specific interactions with phytopathogens. In many cases, plants respond to pathogenic stimuli by adapting their hormone levels. Here, the interaction between the phytopathogen Rhodococcus fascians and one of its host plants, tobacco, was analyzed phenotypically and molecularly. To elucidate the basis of the cell division modulation and shoot primordia initiation caused by R. fascians, tobacco plants were infected at leaf axils and shoot apices. Adventitious meristems that gave rise to multiple-shoot primordia (leafy galls) were formed. The use of a transgenic line carrying the mitotic CycB1 promoter fused to the reporter gene coding for β-glucuronidase from Escherichia coli (uidA), revealed that stem cortical cells were stimulated to divide in an initial phase of the leafy gall ontogenesis. Local cytokinin and auxin levels throughout the infection process as well as modulation of expression of the cell cycle regulator gene Nicta;CycD3;2 are discussed.

Additional keywords: cyclinD3 ; epiphylly ; phytohormones.

© 2001 The American Phytopathological Society