Figure 3.

Noninvasive in vivo MRM analyses of water uptake and distribution during wild-type tobacco seed germination. The spatial distribution of protons within the seed tissues is visualized by false colors (relative scales from zero [0, black] to maximum signal strength [max, white]). A scale bar is given as a size marker. The NMR microimages were obtained with approximately 30 μm resolution. A, Serial sections through three dry seeds, the proton signal is indicative for the water plus lipid signal. B to E, The proton signal during imbibition and germination is indicative for water signal. Each of the sections shows the water distribution in phase II and III tobacco seeds and each section corresponds to a time window presented in Figure 2A as gray box. The time window, medium (Control or ABA, see Fig. 2), and seed stage are indicated for each section. Each of the sections shows 2D slices from the full 3D NMR microimages as serial sections through three single seeds (one per row) at the given stage. Top two rows of each section, The serial microimages correspond to longitudinal sections with the orientation; radicle at the bottom, shoot at the top (as in drawing I). Bottom row of each section, The serial microimages correspond more or less to transverse sections (as in drawing H). Small white arrows in D indicate the emerged root tip. F and G, Enlarged view of selected NMR microimages in the testa rupture stage (F) and the endosperm rupture stage (G) corresponding to slices presented in C and D, respectively. The small numbers designate the corresponding slices. Left side of each section, Microphotographs of seeds in the testa rupture (F) and endosperm rupture (G) stage. H and I, Drawings of a transverse (H) and a longitudinal (I) section through a germinating tobacco seed are from from Avery (1933).