In plants, transcription factors often act as cell-to-cell trafficking mobile proteins and specify cell fate. Thus, to visualize spatiotemporal expression pattern and localization of transcription factors are essential to understand their functions during development. Several protocols have been developed to observe fluorescent protein. However, plant-specific autofluorescent compounds and various tissue components with different refractive indexes interfere with detection of fluorescent signals of your interest. Furthermore, cell fate specification often occurs in a limited number of cells covered by lateral/layers of organs. To overcome those issues, the plant clearing method, ClearSee, was recently developed for high-resolution imaging inside tissues by making background transparent. In this chapter, we provide three-dimensional imaging of fluorescent-protein-fused transcription factors by two-photon excitation microscopy in Arabidopsis and rice. Complex cell patterning with gene expression could be observed from any direction three-dimensionally. This method could be applicable to visualize any protein of your interest or it can readily be adapted in various other plants.
Keywords: Arabidopsis thaliana; ClearSee; Deep imaging; Fluorescent proteins; Oryza sativa; Pistil; Shoot meristem; Two-photon excitation microscopy.