Imaging florigen distribution in vivo

抄録

Florigen is a mobile signal that initiates flowering, which is generated in leaves in response to various environmental stimuli and is transported to the shoot apical meristem (SAM) in plants. The molecular nature of florigen was found to be proteins encoded by the gene FLOWERING LOCUS T (FT) and its orthologs. Recent progress in the molecular biology of florigen revealed its receptors and a transcriptional complex composed of florigen, receptor and transcription factors. In vivo imaging of florigen distribution in the shoot apex and inside a cell contributed to elucidate the essential mechanisms for florigen function. In rice shoot apex, distribution of florigen is clearly visualized by expression of FT protein fused with green fluorescent protein (GFP), and the spatial patterns of downstream gene expression are also visualized by various techniques. At the cellular level, the distribution of florigen and its receptor complex is observed through bimolecular fluorescent complementation (BiFC), which revealed dynamic changes of subcellular localization for florigen and related proteins during the formation of florigen-receptor complex. Here the technique for dissecting SAM is presented to show how SAM samples are prepared for imaging florigen, and recent advances in the regulation of flowering in relation to the contributions from the application of imaging techniques are summarized.