Three-Dimensional Analysis of Lotus japonicus Seeds Using X-Ray Computed Tomography

Abstract

It is not easy to inspect structural changes inside seeds, because seed coats intercept optical conditions, and fixation and cutting seed coats are necessary to examine at microscope level. Here we introduce X-ray computed tomography (CT) to test whether structural changes during seed germination can be traced. The present work used the Beamline BL20B2 of SPring-8. A seed of Lotus japonicus was placed on a rotating stage and the successive images with 2.3μm or 4.9μm pixel size were obtained using an X-ray beam at 10keV. Tomograms were constructed and analyzed using SP-μCT and IMOD software. Using this method, not only vascular bundles in cotyledons, but also borders between seed coats and the endosperm, outlines of the embryo, and void spaces in the seed were clearly seen. Scanning electron microscope observation supported our observation. Three-dimensional structure of Arabidopsis and onion seeds using X-rayCT were also reported.