Nightowl camera

NightOWL camera (Berthold Technologies) was used for imaging fluorescence of bacteria grown on agar plates or plant roots. Each CCD image consisted of an array 1,024 by 1,024 pixels, and after acquisition, images were postprocessed for cosmic suppression and background correction. Fluorescence CCD images were acquired with a Ring-light epi illumination accessory exposed for 1 s and special filters have to be used. Filter used for GFP quantification at excitation wavelength 475/20 and emission wavelength 520/10 nm. Filter used for mCherry quantification at excitation wavelength 550/10 and emission wavelength 620/10 nm. Images were analyzed with the imaging software IndiGO (Berthold Technologies).
The author responsible for distribution of materials integral to the findings presented in this article is: Philip S. Poole (philip.poole@plants.ox.ac.uk).

Approximately 100 seeds from each bulk were grown on a 100 mm × 100 mm × 15 mm square Petri dish vertically for 3 days in the dark, exposed to white light for 15 min, and then Luciferin solution (1 mM Luciferin + 0.01% Triton X-100) were sprayed on the seedlings. The plates remained in the dark for another 5 min before being imaged by the NightOWL camera (Berthold Technologies GmbH & Co. KG, Germany). The luminescent signal picture and the regular picture taken under white light have been combined together by the software Photoshop. The pseudo colors, red for the luminescent signal and green for the brightfield picture, were added by the same software for visualization.

Plates were photographed using a NightOWL camera (Berthold Technologies) as previously described (Pini et al. 2017 ). Briefly, CCD images (1,024 by 1,024 pixels) of light output were exposed for 120 s and analysed with the imaging software IndiGO (Berthold Technologies). Data are expressed as counts per second (cps) or as the ratio of luminescence to surface (cps mm^− 2).