The phytopathogen Rhodococcus fascians breaks apical dominance and activates axillary meristems by inducing plant genes involved in hormone metabolism.
SUMMARY Rhodococcus fascians is a Gram-positive bacterium that interacts with many plant species and induces multiple shoots through a combination of activation of dormant axillary meristems and de novo meristem formation. Although phenotypic analysis of the symptoms of infected plants clearly demonstrates a disturbance of the phytohormonal balance and an activation of the cell cycle, the actual mechanism of symptom development and the targets of the bacterial signals are unknown. To elucidate the molecular pathways that are responsive to R. fascians infection, differential display was performed on Nicotiana tabacum as a host. Four differentially expressed genes could be identified that putatively encode a senescence-associated protein, a gibberellin 2-oxidase, a P450 monooxygenase and a proline dehydrogenase. The differential expression of the three latter genes was confirmed on infected Arabidopsis thaliana plants by quantitative reverse transcription polymerase chain reactions, supporting their general function in R. fascians-induced symptom development. The role of these genes in hormone metabolism, especially of gibberellin and abscisic acid, in breaking apical dominance and in activating axillary meristems, which are processes associated with symptom development, is discussed.
Simón-Mateo
Carmen
C
Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology (VIB), Ghent University, Technologiepark 927, B-9052 Gent, Belgium.
Depuydt
Stephen
S
DE Oliveira Manes
Carmem Lara
CL
Cnudde
Filip
F
Holsters
Marcelle
M
Goethals
Koen
K
Vereecke
Danny
D