Figure 4.

Effects of exogenous BR on cell cytosolic cGMP in Arabidopsis seedlings expressing the fluorescent reporter protein FlincG. After application of BR (or water as a control) to one end of the seedling chamber mounted on the stage of a confocal microscope, fluorescence images of the root tip were taken over time. A to C, Images of the root tip at 0, 5, and 10 min after application of BR. Corresponding images of control-treated roots were dark to the eye at all time points. D, Quantitative analysis of change in fluorescence over time is shown for BR- and control (water with 0.001% [v/v] DMSO)-treated roots. Signals are shown as means (biological replication numbers, recorded from different seedlings, are in parentheses) ± se. For each replicate recording, a series of fluorescence ratios at specific times after treatment were generated. The fluorescence ratios were signals recorded at a specific times relative to the signal at time 0 (F/F₀; for comparison, see Isner and Maathuis [2011]). The difference in fluorescence change between seedlings treated with BR and water was not due to differences in the initial fluorescence (F₀) of the seedlings, which was 374 ± 35 and 397 ± 59 for water- and BR-treated seedlings, respectively.