Figure 4.
Spatially resolved x-ray absorption near-edge spectra recorded by using a 100 × 100 μm2 beam from selected portions of mature (Top), intermediate (Middle), and young (Bottom) leaves. The spectra of selenate and selenomethionine (org. Se) are also included. The Insets show maps of the percentage of total Se as organoselenium (balance selenate) and indicate the spatial location for the spectra. The percentages of selenate in each leaf specimen as determined by near-edge fitting for a (stem), b (petiole), c (mid-vein), and d (leaf blade) respectively are: mature 36, 0, 69, 88; intermediate 3, 0, 7, 28; young 3, 0, 1, 1. Spectra from two locations on the root (main part of the root, and a high-concentration spot, data not shown) both yielded 0% selenate.