Table 2.
Results of linear combination fitting (LCF) of Se K-edge XANES data for roots of rice (Oryza sativa L.) and wheat (Triticum aestivum L.) exposed to 1 μM of either Se(IV) or Se(VI) for 1 week
These analyses are based upon two-dimensional analyses of three-dimensional roots (for an example, see Fig. 1C, D) and do not take into account their concentric structure (Table 3).
| Rice | Wheat | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Exposed to Se(IV) | Exposed to Se(VI) | Exposed to Se(IV) | Exposed to Se(VI) | ||||||||
| Outer | Inner | Lateral root primordia | Outer | Middle | Inner | Outer | Inner | Outer | Middle | Inner | |
| C-Se-C compoundsa (%) | 94 (1.4) | 99 (0.7) | 99 (3.3) | 69 (0.8) | 77 (0.5) | 84 (0.4) | 96 (1.4) | 100 (0) | 88 (0.9) | 90 (0.7) | 92 (0.4) |
| Se(IV) (%) | 6.3 (1.4) | 1.1 (0.7) | 1.5 (3.3) | 3.6 (1.4) | |||||||
| Se(VI) (%) | 31 (0.8) | 23 (0.5) | 16 (0.4) | 12 (0.9) | 10 (0.7) | 7.9 (0.4) | |||||
| R-factor | 0.0025 | 0.0012 | 0.0104 | 0.0033 | 0.0016 | 0.0006 | 0.0027 | 0.0021 | 0.0050 | 0.0027 | 0.0010 |
Data are presented for the ‘outer’, ‘middle’, and ‘inner’ tissues (see Figs 1, 2, 4, 5) and the lateral root primordia (Fig. 3).
Data are rounded to two significant figures, means (SE). The spatial distribution of three pixel populations (outer, middle, and inner) identified by comparing energy intensities (see Fig. 1 and Supplementary Fig. S1 at JXB online for an example).
The R-factor is the residual factor generated by the LCF tool in Athena and indicates the goodness of fit, with R-factor=∑i(data–fit)2/∑i(data)2.
a C-Se-C compounds refer to selenomethionine (SeMet) or methylselenocysteine (MeSeCys).