FRET-FLIM measurements showing that RRS1-R and RRS1-S proteins interact with PopP2 in the nucleus of plant cells.

*Mean lifetime, τ, in ns. (a) for each nucleus, average fluorescence decay profiles were plotted and fitted with exponential function using a non linear square estimation procedure and the mean lifetime was calculated according to τ = Σ αiτi2/Σ αiτi with I(t)  = Σ αi e−t/τi , standard error of the mean, (b) Δt = τD - τDA (in ps), (c) total number of measured nuclei , and (d) % FRET efficiency: E = 1 – (τDA/τD). p-value of the difference between the donor lifetimes in the presence and in the absence of acceptor (Student's t test).