Live cell imaging was performed as described previously (Prusicki et al, 2019 (link)). In short, up to six flower buds of 0.2–0.6 mm were carefully positioned in a petri plate filled with half-strength MS medium, pH 5.8 and solidified with 0.8% (w/v) agar. Time lapse was performed using an upright Zeiss LSM 880 confocal microscope with ZEN 2.3 SP1 software (Carl Zeiss AG, Oberkochen, Germany) and a W-plan Apochromat 40X/1.0 DIC objective (Carl Zeiss AG, Oberkochen, Germany). GFP and TagRPF were excited at λ = 488 nm and 561 nm, respectively, and detected between 498 and 560 nm and 520 and 650 nm, respectively. Auto-fluorescence was detected between 680 and 750 nm. With a time interval of 10 min, a series of six Z-stacks with 50 µm distance was acquired under a thermally controlled environment (21°C/30°C/34°C [± 0.15%]) in an incubation chamber. Due to sample movement, the Z-planes were manually selected using the review multi-dimensional data function of the software Metamorph version 7.8 and the XY movement was corrected using the Stack Reg plugin of Fiji.