Single-Cell C4 Photosynthesis in Chenopodiaceae Species

Accurate three-dimensional imaging of plant structures and gene activity will facilitate a deeper understanding of the mechanisms that underlie plant growth and development. Lee et al. (pages 2145–2156) used optical projection tomography (OPT) to capture three-dimensional data from plant specimens. OPT has the advantages of other optical methods but with greater penetration and the ability to generate three-dimensional images of nonfluorescent signals. Although most specimens must be prepared in an organic solvent for high-quality optical imaging, live imaging using OPT is also possible for naturally semitransparent structures, such as Arabidopsis roots. The authors demonstrate the use of OPT with a variety of tissue types at different developmental stages in Arabidopsis and Antirrhinum and describe tools and software that allow OPT data to be quantified and visualized. They show that OPT provides a convenient means of examining 3D morphology and gene expression patterns for a variety of plant structures, including large, thick specimens. At the highest resolution, large individual cells can be seen in the context of the surrounding plant structure. Three-dimensional domains of gene expression can be visualized using marker genes or more directly by wholemount in situ hybridization.