Table III. Metabolomic analysis of rice and wheat coleoptiles in response to anoxia.
Rice plants were grown under (1) 4 d of aeration, (2) 6 d of anoxia, (3) 4 d of aeration and then 4 h of anoxia, or (4) 4 d of aeration and then 1 d of anoxia. Wheat plants were grown under all treatments except number 2. Coleoptile tissues were separated from leaves for analysis. Complex polar metabolite extracts were taken from all tissues and analyzed by GC-MS. Raw GC-MS data processing and statistical analyses were then carried out using MetabolomeExpress software (version 1.0; http://www.metabolome-express.org). Metabolite signal intensity ratios were calculated by dividing the mean tissue mass- and internal standard-normalized signal intensity for each metabolite in treated samples by its corresponding value in control samples (RV columns). The statistical significance of each ratio was tested by Welch’s t test (P < 0.05; n = 5). Values highlighted in boldface are significantly more abundant in anoxic coleoptiles, whereas negative boldface italic indicates a metabolite that is more abundant under aeration, with values that meet a threshold for significance of P < 0.05. N/D, No data; RV, response value.
| Sample | Metabolite | 6 d N2/4 d air |
4 d Air + 1 d N2/4 d Air |
4 d Air + 4 h N2/4 d Air |
|||||||
| Rice |
Rice |
Wheat |
Rice |
Wheat |
|||||||
| RV | P | RV | P | RV | P | RV | P | RV | P | ||
| Amino acids and polyamines | l-Pro | 98.6 | 5.8E-06 | 8.7 | 2.5E-02 | 2.6 | 1.7E-03 | 0.5 | 4.9E-01 | 0.5 | 1.4E-01 |
| l-Leu | 43.8 | 1.1E-05 | 11.6 | 1.7E-03 | 0.6 | 6.6E-02 | 0.6 | 4.6E-01 | 0.1 | 6.0E-01 | |
| β-Ala | 43.4 | 1.4E-08 | 0.7 | 2.6E-01 | 1.0 | 3.3E-03 | 0.9 | 4.4E-01 | 0.9 | 4.9E-04 | |
| l-Ala | 42.6 | 2.3E-06 | 43.2 | 8.1E-04 | 0.1 | 6.3E-01 | 6.9 | 1.5E-03 | 0.5 | 3.5E-01 | |
| l-Glu | 36.5 | 1.7E-06 | −11.7 | 6.9E-02 | −0.9 | 5.8E-02 | −39.2 | 7.7E-02 | −0.4 | 2.8E-01 | |
| l-Tyr | 22.5 | 4.4E-06 | −1.2 | 4.3E-03 | 0.4 | 2.7E-01 | −2.3 | 9.6E-02 | 0.2 | 3.0E-01 | |
| 2-Aminoadipic acid | 17.3 | 6.6E-07 | −1.0 | 8.1E-02 | −0.1 | 7.4E-01 | 0.1 | 7.4E-01 | −0.4 | 1.6E-01 | |
| l-Arg | 15.6 | 1.2E-05 | −0.7 | 2.7E-03 | 0.7 | 1.0E-01 | 0.0 | 9.6E-01 | 0.1 | 5.7E-01 | |
| l-Homo-Ser | 15.5 | 1.9E-02 | −0.9 | 1.0E-02 | 0.6 | 3.2E-01 | −0.9 | 9.6E-02 | −0.2 | 3.2E-01 | |
| l-Ile | 12.0 | 3.2E-05 | 5.2 | 6.6E-04 | 0.7 | 1.1E-01 | 0.3 | 4.7E-01 | 0.3 | 3.3E-01 | |
| l-Lys | 10.9 | 3.6E-05 | −2.0 | 3.1E-03 | 1.5 | 3.5E-02 | −1.8 | 1.1E-01 | 0.5 | 1.0E-01 | |
| l-Val | 10.2 | 5.8E-07 | 5.5 | 3.4E-07 | −0.1 | 6.6E-01 | −0.1 | 8.8E-01 | 0.3 | 4.2E-01 | |
| l-Ser | 9.0 | 5.9E-12 | 2.0 | 2.3E-03 | −0.8 | 4.4E-03 | 0.1 | 8.3E-01 | −0.4 | 4.2E-01 | |
| γ-Aminobutyric acid | 8.9 | 1.5E-08 | 8.1 | 1.2E-03 | 0.4 | 3.5E-03 | 2.3 | 1.4E-01 | 0.6 | 8.6E-04 | |
| l-Met | 6.0 | 2.8E-02 | −1.9 | 3.9E-02 | 0.6 | 1.4E-01 | −123.6 | 5.4E-02 | −0.2 | 4.4E-01 | |
| l-Trp | 5.2 | 1.8E-05 | 4.6 | 1.7E-02 | 0.6 | 1.9E-01 | −0.4 | 3.5E-01 | 0.5 | 8.8E-02 | |
| l-Thr | 2.4 | 1.1E-06 | 2.1 | 6.4E-06 | 0.1 | 4.3E-01 | 0.6 | 1.4E-01 | 0.5 | 1.2E-01 | |
| Gly | 1.9 | 2.5E-03 | 3.7 | 1.2E-03 | 1.4 | 4.4E-03 | 0.6 | 1.9E-01 | 0.4 | 2.0E-01 | |
| l-Gln | 1.8 | 4.6E-04 | −0.5 | 4.4E-03 | −1.4 | 9.0E-02 | −0.2 | 2.3E-01 | −1.5 | 2.0E-03 | |
| 4-Hyp | 1.4 | 1.1E-06 | −0.1 | 4.9E-01 | −0.1 | 4.9E-01 | 0.1 | 5.0E-01 | −0.9 | 2.2E-02 | |
| Orn | 0.6 | 3.5E-03 | −1.3 | 2.8E-04 | 0.4 | 1.8E-01 | −10.0 | 4.3E-02 | −0.9 | 1.2E-01 | |
| l-Asn | −0.6 | 4.5E-01 | 0.0 | 9.7E-01 | −0.2 | 5.9E-01 | −40.0 | 4.7E-02 | 0.1 | 6.1E-01 | |
| l-Asp | −1.5 | 1.5E-01 | −16.6 | 2.2E-01 | −1.7 | 3.7E-02 | −448.4 | 4.7E-02 | −3.2 | 1.2E-03 | |
| l-Phe | N/D | N/D | −2.1 | 1.5E-01 | 0.9 | 5.3E-03 | −0.2 | 2.1E-01 | 0.4 | 6.6E-02 | |
| l-α-Aminobutyric acid | N/D | N/D | 2.5 | 1.5E-04 | −2.7 | 2.7E-01 | 0.2 | 4.6E-01 | −1.2 | 2.4E-03 | |
| Putrescine | 52.4 | 6.9E-08 | 7.9 | 1.1E-04 | 1.7 | 4.2E-03 | 0.2 | 5.9E-01 | −0.2 | 1.5E-01 | |
| Sugars and glycolytic substrates | 6-Phosphogluconate | 9.7 | 1.0E-03 | −0.8 | 3.6E-01 | −1.6 | 1.1E-01 | −1.4 | 3.9E-02 | −1.0 | 1.0E-02 |
| d-Rib | −0.8 | 9.2E-05 | −1.2 | 9.2E-04 | −1.3 | 3.1E-03 | −0.5 | 2.9E-04 | −0.6 | 1.3E-02 | |
| Trehalose | −1.0 | 2.3E-02 | −2.1 | 3.1E-02 | −1.6 | 3.3E-04 | −0.3 | 1.8E-01 | −0.9 | 1.9E-03 | |
| d-Xyl | −2.7 | 5.8E-06 | −0.5 | 1.4E-01 | 0.1 | 6.4E-01 | 0.1 | 2.2E-01 | 0.1 | 4.0E-01 | |
| 3-Phosphoglyceric acid | 18.0 | 1.3E-04 | −0.5 | 5.5E-01 | −0.2 | 7.6E-01 | −0.3 | 5.6E-01 | −0.2 | 1.2E-01 | |
| Suc | 4.8 | 3.4E-04 | 0.7 | 9.3E-02 | −5.6 | 3.6E-05 | −0.3 | 1.3E-01 | −11.5 | 1.5E-03 | |
| Fru-6-P | 2.9 | 2.9E-04 | 0.1 | 8.7E-01 | −0.3 | 2.8E-01 | −0.2 | 3.4E-01 | −1.2 | 8.8E-03 | |
| Glc-6-P | 2.8 | 4.4E-05 | −0.2 | 6.9E-01 | −0.5 | 1.0E-01 | −0.1 | 1.7E-01 | −1.4 | 2.2E-03 | |
| d-Fru | −2.4 | 9.9E-07 | −0.3 | 1.7E-05 | −0.4 | 3.9E-01 | 0.0 | 8.1E-01 | −0.4 | 3.8E-02 | |
| d-Glc | −4.2 | 2.1E-05 | −0.4 | 8.8E-05 | −0.3 | 6.3E-03 | −0.1 | 2.0E-01 | 0.1 | 4.9E-01 | |
| TCA cycle substrates and other acids | Succinate | 116.5 | 1.8E-08 | 3.5 | 4.2E-03 | 1.0 | 1.1E-03 | 6.5 | 1.5E-03 | −1.1 | 2.7E-03 |
| Fumarate | 7.0 | 2.9E-07 | −0.7 | 2.7E-01 | −0.2 | 1.6E-01 | 1.1 | 5.1E-02 | −0.4 | 1.7E-01 | |
| Aconitate | 4.3 | 5.3E-04 | −2.8 | 3.2E-02 | −0.5 | 1.5E-01 | −1.6 | 1.1E-02 | −0.2 | 2.4E-01 | |
| Citrate | 2.5 | 4.0E-05 | −11.7 | 5.5E-02 | −1.5 | 8.3E-03 | −3.2 | 1.3E-02 | −0.7 | 1.4E-04 | |
| Malate | 0.0 | 1.5E-01 | −2.2 | 8.8E-05 | −1.0 | 3.1E-05 | −0.1 | 9.2E-02 | 0.0 | 7.5E-01 | |
| Isocitrate | −0.1 | 1.9E-01 | −2.1 | 8.7E-02 | −0.5 | 3.7E-02 | −5.3 | 6.0E-03 | −0.5 | 1.1E-03 | |
| 2-Oxoglutarate | −2.2 | 1.3E-03 | −3.8 | 2.6E-02 | −0.3 | 1.8E-01 | −24.5 | 6.4E-04 | −0.8 | 2.8E-03 | |
| Glycerate | −1.8 | 1.3E-04 | −1.5 | 2.6E-06 | −0.9 | 7.3E-03 | −0.5 | 1.6E-02 | −0.2 | 8.9E-03 | |
| Threonate | −118.6 | 1.0E-05 | −1.1 | 7.0E-04 | −0.2 | 4.3E-03 | 0.3 | 8.7E-03 | −0.2 | 2.0E-01 | |
| Ascorbate | N/D | N/D | −1.8 | 3.8E-04 | 1.2 | 2.2E-01 | −0.1 | 2.0E-01 | −0.1 | 2.7E-01 | |
| Glucarate | 0.9 | 1.1E-04 | −0.3 | 3.0E-02 | −0.4 | 3.9E-03 | −0.2 | 1.9E-01 | −0.2 | 2.1E-01 | |
| Citramalate | −0.5 | 5.7E-02 | −0.8 | 1.9E-02 | −0.2 | 6.8E-02 | 0.2 | 6.1E-02 | −1.4 | 4.9E-03 | |
| 4-Hydroxycinnamate | N/D | N/D | −0.1 | 3.0E-01 | 0.5 | 1.2E-03 | 0.2 | 2.2E-02 | 0.8 | 8.0E-04 | |
| Urate | 561 | 2.1E-06 | 0.2 | 5.8E-01 | 15.2 | 2.9E-03 | −1.4 | 3.3E-01 | 15.4 | 3.4E-04 | |
| Other | Shikimic acid | −0.7 | 1.0E-03 | −0.1 | 4.1E-01 | 4.5 | 6.2E-02 | 0.0 | 9.3E-01 | 3.4 | 1.5E-01 |
| Phosphate | 1.6 | 5.5E-08 | 0.3 | 2.9E-02 | −0.1 | 6.0E-01 | −0.1 | 6.2E-01 | −0.2 | 2.4E-01 | |
| Cytosine | N/D | N/D | −1.6 | 2.0E-04 | −0.6 | 1.5E-05 | −0.2 | 4.0E-01 | −0.3 | 3.0E-01 | |