Selective Photoreceptor Gene Knock-out Reveals a Regulatory Role for the Growth Behavior of Pseudomonas syringae.
The plant pathogen Pseudomonas syringae (Ps) is a well-established model organism for bacterial infection of plants. The genome sequences of two pathovars, pv. syringae and pv. tomato, revealed one gene encoding a blue and two genes encoding red/far red light-sensing photoreceptors. Continuing former molecular characterization of the photoreceptor proteins, we here report selective photoreceptor gene disruption for pv. tomato aiming at identification of potentially regulatory functions of these photoreceptors. Transformation of Ps cells with linear DNA constructs yielded interposon mutations of the corresponding genes. Cell growth studies of the generated photoreceptor knock-out mutants revealed their role in light-dependent regulation of cell growth and motility. Disruption of the blue-light (BL) receptor gene caused a growth deregulation, in line with an observed increased virulence of this mutant (Moriconi et al., Plant J., 2013, 76, 322). Bacterial phytochrome-1 (BphP1) deletion mutant caused unaltered cell growth, but a stronger swarming capacity. Inactivation of its ortholog, BphP2, however, caused reduced growth and remarkably altered dendritic swarming behavior. Combined knock-out of both bacteriophytochromes reproduced the swarming pattern observed for the BphP2 mutant alone. A triple knock-out mutant showed a growth rate between that of the BL (deregulation) and the phytochrome-2 mutant (growth reduction).
Max-Planck-Institute for Chemical Energy Conversion, Mülheim, Germany.
Rashmi
R
Shah
Max-Planck-Institute for Chemical Energy Conversion, Mülheim, Germany.
Gopal
G
Pathak
Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany.
Thomas
T
Drepper
Max-Planck-Institute for Chemical Energy Conversion, Mülheim, Germany.
Wolfgang
0000-0002-6898-7011
W
Gärtner
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D055786:Gene Knockout Techniques; D009068:Movement; D020283:Photoreceptors, Microbial / Q000235:genetics / Q000378:metabolism*; D044224:Pseudomonas syringae / Q000235:genetics* / Q000254:growth & development*
D001426:Bacterial Proteins; D020283:Photoreceptors, Microbial