Cover illustration: MADS box transcription factors are important regulators of plant development and are active in a combinatorial manner. To get an insight into the molecular mechanisms behind their functioning it is essential to analyse these proteins in planta. MADS box protein–protein interactions can be analysed in vivo by Fluorescence Resonance Energy Transfer (FRET)–Fluorescence Lifetime Imaging Microscopy (FLIM). In case of dimerization between two fluorescently labelled MADS box proteins, FRET occurs, which results in a decrease in the fluorescent lifetime of the donor fluorescent molecule. The distribution of fluorescent lifetimes within a plant cell or specific plant cell organelle can be depicted by a false colour code. Blue and green colours indicate relatively high fluorescence lifetimes and no interaction, whereas yellow and red colours indicate low fluorescence lifetime values and, hence, places where protein–protein interactions occur. The upper nucleus is from a plant cell expressing the non-interacting MADS box proteins FBP2 and Petunia Flowering Gene (PFG). The nucleus in the middle is an example of a stable interaction between FBP2 and FBP24, and the lower nucleus is an example of interaction between FBP24 and FBP11 in sub-nuclear spots, exclusively. (See Nougalli Tonaco et al., pp. 33–42.)
[Table of Contents]