SE159:/MS1
Sample Set Information
| ID | TSE1316 |
|---|---|
| Title | Comprehensive flavonol profiling and transcriptome coexpression analysis leading to decoding gene-metabolite correlations in Arabidopsis. |
| Description | To complete the metabolic map for an entire class of compounds, it is essential to identify gene-metabolite correlations of a metabolic pathway. We used liquid chromatography-mass spectrometry (LC-MS) to identify the flavonoids produced by Arabidopsis thaliana wild-type and flavonoid biosynthetic mutant lines. The structures of 15 newly identified and eight known flavonols were deduced by LC-MS profiling of these mutants. Candidate genes presumably involved in the flavonoid pathway were delimited by transcriptome coexpression network analysis using public databases, leading to the detailed analysis of two flavonoid pathway genes, UGT78D3 (At5g17030) and RHM1 (At1g78570). The levels of flavonol 3-O-arabinosides were reduced in ugt78d3 knockdown mutants, suggesting that UGT78D3 is a flavonol arabinosyltransferase. Recombinant UGT78D3 protein could convert quercetin to quercetin 3-O-arabinoside. The strict substrate specificity of UGT78D3 for flavonol aglycones and UDP-arabinose indicate that UGT78D3 is a flavonol arabinosyltransferase. A comparison of flavonol profile in RHM knockout mutants indicated that RHM1 plays a major role in supplying UDP-rhamnose for flavonol modification. The rate of flavonol 3-O-glycosylation is more affected than those of 7-O-glycosylation by the supply of UDP-rhamnose. The precise identification of flavonoids in conjunction with transcriptomics thus led to the identification of a gene function and a more complete understanding of a plant metabolic network. |
| Authors | Yonekura-Sakakibara K, Tohge T, Matsuda F, Nakabayashi R, Takayama H, Niida R, Watanabe-Takahashi A, Inoue E, Saito K. |
| Reference | Plant Cell. 2008 Aug;20(8):2160-76. doi: 10.1105/tpc.108.058040. Epub 2008 Aug 29. |
| Comment |
Analytical Method Details Information
| ID | MS1 |
|---|---|
| Title | UPLC-PDA-ESI/Q-TOF/MS |
| Instrument | LC, Waters Acquity UPLC system; MS, Q-ToF Premier mass spectrometer |
| Instrument Type | UPLC-QTOF-MS |
| Ionization | ESI |
| Ion Mode | Positive |
| Description | Flavonol analyses were performed in quintuplicate. Frozen leaves were homogenized in 5 μL of extraction solvent (methanol: CH3COOH:H2O = 9:1:10, 0.02 mM naringenin-7-O-glucoside) per milligram of fresh weight of tissue in a mixer mill (MM300; Retsch) for 5 min at 30 Hz. After centrifugation at 12,000g, the supernatants were immediately used for flavonoid analysis.
For flavonol profiling, a Waters Acquity UPLC system (Waters) fitted with a Q-TOF Premier mass spectrometer (Micromass MS Technologies) was used. UPLC was performed on a UPLC phenyl C18 column (Φ2.1 mm × 100 mm; Waters) at a flow rate of 0.5 mL/min at 35°C. Compounds were separated with a linear elution gradient with solvent A (0.1% formic acid in water) and solvent B (0.1% formic acid in acetonitrile) from 0 min, 100% A to 10 min, 40% B. PDA was used for the detection of UV-visible absorption in the range of 210 to 500 nm. The TOF mass analyzer was used for the detection of flavonol glycosides [M + H]+ and the peak of fragment ions in a positive ion scanning mode with the following setting: desolvation temperature, 400°C with a nitrogen gas flow of 600 L/h; capillary spray, 3.0 kV; source temperature, 150°C; and cone voltage of 10 V for flavonoid glycosides [M + H]+ or 30 V for fragment ions. |
| Comment_of_details |
