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Sample Set Information

ID TSE1333
Title A flavonoid 3-O-glucoside:2"-O-glucosyltransferase responsible for terminal modification of pollen-specific flavonols in Arabidopsis thaliana.
Description Flavonol 3-O-diglucosides with a 1→2 inter-glycosidic linkage are representative pollen-specific flavonols that are widely distributed in plants, but their biosynthetic genes and physiological roles are not well understood. Flavonoid analysis of four Arabidopsis floral organs (pistils, stamens, petals and calyxes) and flowers of wild-type and male sterility 1 (ms1) mutants, which are defective in normal development of pollen and tapetum, showed that kaempferol/quercetin 3-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranosides accumulated in Arabidopsis pollen. Microarray data using wild-type and ms1 mutants, gene expression patterns in various organs, and phylogenetic analysis of UDP-glycosyltransferases (UGTs) suggest that UGT79B6 (At5g54010) is a key modification enzyme for determining pollen-specific flavonol structure. Kaempferol and quercetin 3-O-glucosyl-(1→2)-glucosides were absent from two independent ugt79b6 knockout mutants. Transgenic ugt79b6 mutant lines transformed with the genomic UGT79B6 gene had the same flavonoid profile as wild-type plants. Recombinant UGT79B6 protein converted kaempferol 3-O-glucoside to kaempferol 3-O-glucosyl-(1→2)-glucoside. UGT79B6 recognized 3-O-glucosylated/galactosylated anthocyanins/flavonols but not 3,5- or 3,7-diglycosylated flavonoids, and prefers UDP-glucose, indicating that UGT79B6 encodes flavonoid 3-O-glucoside:2″-O-glucosyltransferase. A UGT79B6-GUS fusion showed that UGT79B6 was localized in tapetum cells and microspores of developing anthers.
Authors Yonekura-Sakakibara, K., Nakabayashi, R., Sugawara, S., Tohge, T., Ito, T., Koyanagi, M., Kitajima, M., Takayama, H. and Saito, K.
Reference Plant J. 2014 Sep;79(5):769-82. doi: 10.1111/tpj.12580.

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Analytical Method Details Information

Instrument LC, Waters Acquity UPLC system; MS, Q-ToF Premier mass spectrometer
Instrument Type UPLC-QTOF-MS
Ionization ESI
Ion Mode Positive
Description Frozen tissues were homogenized in 5 μl extraction solvent (1:1 methanol/H2O) per mg fresh weight of tissue in a mixer mill (MM300; Retsch, for 5 min at 30 Hz. Supernatants were immediately used for analysis after centrifugation at 12 000 g. Flavonol analyses were performed essentially as described previously (Yonekura-Sakakibara et al., 2008). Untargeted metabolome analyses of wild-type (Ler) and ms1 mutants were also performed as described previously (Yonekura-Sakakibara et al., 2008).

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