The phytopathogenic actinomycete Rhodococcus fascians strain D188 relies on the linear plasmid-encoded fas operon for its virulence. The bacteria secrete six cytokinin bases that synergistically redirect the developmental program of the plant to stimulate proliferation of young shoot tissue, thus establishing a niche. A yeast-based cytokinin bioassay combined with cytokinin profiling of bacterial mutants, revealed that the fas operon is essential for the enhanced production of iP, cZ, tZ, 2MeScZ, and 2MeStZ. The cytokinin metabolite data and the demonstration of the enzymatic activities of FasD (isopentenyltransferase), FasE (cytokinin oxidase/dehydrogenase), and FasF (phosphoribohydrolase), allowed us to propose a pathway for the production of the cytokinin spectrum. Further evaluation of the pathogenicity of different fas mutants, in planta fas gene expression, and cytokinin signal transduction upon infection implied that the secretion of the cytokinin mix is a highly dynamic process with the production of symptom initiation and maintenance waves.

Rhodococcus fascians impacts plant development through the dynamic Fas-mediated production of a cytokinin mix

BIONDI, STEFANIA;
2010

Abstract

The phytopathogenic actinomycete Rhodococcus fascians strain D188 relies on the linear plasmid-encoded fas operon for its virulence. The bacteria secrete six cytokinin bases that synergistically redirect the developmental program of the plant to stimulate proliferation of young shoot tissue, thus establishing a niche. A yeast-based cytokinin bioassay combined with cytokinin profiling of bacterial mutants, revealed that the fas operon is essential for the enhanced production of iP, cZ, tZ, 2MeScZ, and 2MeStZ. The cytokinin metabolite data and the demonstration of the enzymatic activities of FasD (isopentenyltransferase), FasE (cytokinin oxidase/dehydrogenase), and FasF (phosphoribohydrolase), allowed us to propose a pathway for the production of the cytokinin spectrum. Further evaluation of the pathogenicity of different fas mutants, in planta fas gene expression, and cytokinin signal transduction upon infection implied that the secretion of the cytokinin mix is a highly dynamic process with the production of symptom initiation and maintenance waves.
PERTRY I.; VÁCLAVÍKOVÁ K.; GEMROTOVÁ M.; SPÍCHAL L.; GALUSZKA P.; DEPUYDT S.; TEMMERMAN W.; STES E.; DEKEYSER A.; RIEFLER M.; BIONDI S.; NOVÁK O.; SCHMÜLLING T.; STRNAD M.; TARKOWSKI P.; HOLSTERS M.; VEREECKE D.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/101785
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