Leafy gall formation by Rhodococcus fascians

• Published in: Annual review of phytopathology Vol. 39; pp. 27 - 52
• Main Authors: GOETHALS, Koen, VEREECKE, Danny, JAZIRI, Mondher, VAN MONTAGU, Marc, HOLSTERS, Marcelle
• Format: Journal Article
• Language: English
• Published: Palo Alto, CA Annual Reviews 01.01.2001; Annual Reviews, Inc
• Subjects: Bacterial plant pathogens; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; leafy gall; Magnoliopsida - metabolism; Magnoliopsida - microbiology; Pathology. Damages, economic importance; Phytopathology. Animal pests. Plant and forest protection; Plant Diseases - genetics; Plant Diseases - microbiology; Plant Growth Regulators - metabolism; Plant Leaves - metabolism; Plant Leaves - microbiology; Plant Tumors - genetics; Plant Tumors - microbiology; Rhodococcus - genetics; Rhodococcus - metabolism; Rhodococcus - pathogenicity; Rhodococcus fascians; Virulence - genetics; Pathogenesis; Epiphyte; Host agent relation; Rhodococcus fascians; Plant leaf; Review; Cytokinin; Meristem; Infection; Cecidiogen; Bacteriosis; Plant gall; Bacteria; Endophyte; Plant growth substance; Actinomycetes; Fasciation; Spermatophyta; Phytohormone; Formation mechanism; Colonization
• ISSN: 0066-4286; 1545-2107
• DOI: 10.1146/annurev.phyto.39.1.27

Rhodococcus fascians infects a wide range of plants, initiating the formation of leafy galls that consist of centers of shoot amplification and shoot growth inhibition. R. fascians is an epiphyte but it also can establish endophytic populations. Bacterial signals involved in symptom development initiate de novo cell division and shoot meristem formation in differentiated tissues. The R. fascians signals exert activities that are distinct from mere cytokinin effects, and the evidence points to a process that adopted cytokinin biosynthetic enzymes to form derivatives with unique activity. Genes implicated in leafy gall formation are located on a linear plasmid and are subject to a highly controlling, complex regulatory network, integrating autoregulatory compounds and environmental signals. Leafy galls are considered as centers with specific metabolic features, a niche where populations of R. fascians experience a selective advantage. Such "metabolic habitat modification" might be universal for gall-inducing bacteria.