Table I. Levels of sulfite, sulfate, Cys, glutathione, and other sulfur compounds detected in Arabidopsis 3 h after injection with sulfite solutions of different strengths.
ND, Not determined. Different uppercase letters indicate significant differences (P < 0.05) between the treatments within one line, while different lowercase letters show significant differences between the lines within one treatment, as calculated using Tukey’s HSD (JMP 8.0 software; http://www.jmp.com/).
| Genotypea | Sulfite (Increment)b | Detected Sulfitec | Detected Sulfated | Expected Sulfatee | Detected Cysf | Detected Glutathioneg | Other Sulfur Compoundsh | Total Sulfuri |
|---|---|---|---|---|---|---|---|---|
| mm (µmol g−1 fresh wt) | µmol g−1 fresh wt | |||||||
| Col | 0 (0) | 0.119 ± 0.044 B, b | 7.36 ± 0.54 B, ab | 7.36 ± 0.54 | 0.011 ± 0.002 C, a | 0.451 ± 0.011 A, a | 9.06 ± 0.37 A, b | 17.03 ± 0.43 B, b |
| SIR KD | 0.188 ± 0.026 B, b | 9.44 ± 0.69 A, a | 9.44 ± 0.69 | 0.008 ± 0.001 C, a | 0.414 ± 0.009 A, b | 11.99 ± 0.49 A, a | 22.07 ± 1.02 B, a | |
| SIR OE | 0.100 ± 0.023 B, b | 7.18 ± 0.27 A, b | 7.84 ± 0.76 | 0.009 ± 0.002 B, a | 0.268 ± 0.011 B, c | 10.73 ± 0.66 B, ab | 18.26 ± 1.02 A, b | |
| SO Ri5 | 0.342 ± 0.029 B, a | 7.68 ± 0.43 A, ab | 7.68 ± 0.43 | 0.009 ± 0.003 C, a | 0.378 ± 0.006 A, b | 9.83 ± 0.77 A, ab | 18.24 ± 0.78 A, b | |
| Col | 0.5 (0.079) | 0.129 ± 0.035 B, ab (87 ± 44%) | 7.23 ± 0.99 B, ab | 7.44 ± 0.54 | 0.008 ± 0.002 C, a | 0.327 ± 0.010 B, ab | ND | ND |
| SIR KD | 0.189 ± 0.039 B, ab (97 ± 50%) | 10.95 ± 1.11 A, a | 9.52 ± 0.69 | 0.011 ± 0.001 C, a | 0.371 ± 0.027 AB, a | ND | ND | |
| SIR OE | 0.064 ± 0.019 B, b (146 ± 24%) | 7.04 ± 0.55 A, b | 7.92 ± 0.76 | 0.012 ± 0.002 B, a | 0.302 ± 0.012 B, ab | ND | ND | |
| SO Ri5 | 0.315 ± 0.044 B, a (135 ± 56%) | ND | 7.76 ± 0.43 | 0.011 ± 0.001 C, a | 0.230 ± 0.006 C, b | ND | ND | |
| Col | 4 (0.632) | 0.160 ± 0.025 B, b (94 ± 4%) | 7.95 ± 0.31 B, ab | 7.99 ± 0.54 | 0.063 ± 0.008 B, ab | 0.359 ± 0.009 B, ab | ND | ND |
| SIR KD | 0.237 ± 0.030 B, b (92 ± 5%) | 10.51 ± 0.74 A, a | 10.07 ± 0.69 | 0.068 ± 0.009 B, a | 0.337 ± 0.022 BC, b | ND | ND | |
| SIR OE | 0.155 ± 0.025 AB, b (91 ± 4%) | 7.18 ± 0.79 A, b | 8.47 ± 0.76 | 0.033 ± 0.006 B, b | 0.417 ± 0.013 A, a | ND | ND | |
| SO Ri5 | 0.512 ± 0.086 B, a (73 ± 14%) | 6.73 ± 0.43 A, b | 8.31 ± 0.43* | 0.075 ± 0.004 B, a | 0.220 ± 0.011 C, c | ND | ND | |
| Col | 8 (1.264) | 0.505 ± 0.038 A, c (70 ± 3%) | 12.10 ± 0.02 A, ab | 8.62 ± 0.54* | 0.199 ± 0.003 A, a | 0.340 ± 0.008 B, b | 8.76 ± 0.94 A, b | 21.91 ± 1.48 A, b |
| SIR KD | 0.956 ± 0.071 A, b (39 ± 6%) | 12.72 ± 1.29 A, a | 10.71 ± 0.69 | 0.150 ± 0.010 A, b | 0.289 ± 0.006 C, c | 13.23 ± 0.89 A, a | 27.33 ± 1.24 A, a | |
| SIR OE | 0.252 ± 0.051 A, c (88 ± 4%) | 6.93 ± 0.37 A, b | 9.11 ± 0.76* | 0.088 ± 0.015 A, c | 0.403 ± 0.009 A, a | 12.90 ± 0.30 A, a | 20.59 ± 0.10 A, b | |
| SO Ri5 | 1.422 ± 0.122 A, a (15 ± 10%) | 7.61 ± 0.64 A, ab | 8.94 ± 0.43 | 0.167 ± 0.004 A, ab | 0.315 ± 0.005 B, bc | 10.95 ± 1.11 A, ab | 20.47 ± 1.24 A, b | |
Data on detected metabolite concentrations are means ± se for Col, SIR KD (SALK075776, SAIL867D09, and SAIL1223C03 lines), and SIR OE (SIR OE7 and SIR OE12) 4-week-old plants (n = 3 or 4). The values were normalized by dry weight content in the mock- and sulfite-injected plants, as described in “Materials and Methods.”
Freshly prepared sulfite solutions (pH 5.7). The increased concentration of sulfite was calculated based on weight increase after injection.
Sulfite was detected by the SO detection method (Brychkova et al., 2012a). The percentage of consumed exogenous sulfite is shown in parentheses.
Sulfate was detected in a formaldehyde-stabilized solution to prevent sulfite oxidation, as described (Brychkova et al., 2012a).
Expected sulfate was calculated by adding to the basal sulfate level the value of the injected sulfite at zero time, assuming that 100% of the converted sulfite is expected to be oxidized to sulfate. Asterisks show significant differences from the experimental data by two-tailed Student’s t test (P < 0.05).
Cys was determined as described (Brychkova et al., 2012a).
Glutathione was determined as described (Brychkova et al., 2012a).
Other sulfur compounds were calculated by subtracting sulfite, sulfate, Cys, and glutathione from total sulfur.
Total sulfur was measured in dried samples and calculated according to fresh weight content.