ISHS Acta Horticulturae 381: International Symposium on Natural Phenols in Plant Resistance
CHARACTERISATION OF FLAVONOID O-GLYCOSYLTRANSFERASES FROM ALFALFA (MEDICAGO SATIVA) |
| Authors: | Andrew D. Parry, R. Edwards |
| Abstract:
At least three closely related flavonoid O-glycosyltransferases (OGTs) were identified in alfalfa, with activities towards; I flavonols (eg. quercetin), II isoflavones (eg. formononetin) and III coumestanspterocarpans (eg. coumestrolmedicarpin). Unlike OGT-II and OGT-III, OGT-I was unaffected by low molecular weight inhibitors present in crude extracts, showed higher specific activities in light-grown than etiolated leaves and was partially resolved by hydrophobic interaction chromatography from the other OGTs. OGT-II was selectively induced in the roots of mature field-grown and modulated plants, but the specific activities of all three OGTs remained constant during the growth of younger plants even though the levels of conjugated flavonoids increased markedly. In cell cultures OGT activities were reduced following treatment with a fungal elicitor, but only after maximal levels of medicarpin had been reached. Although possessing distinct substrate specificities the OGTs were all cytosolic, had native molecular weights of 47 ± 3 kDa, isoelectric points in the range of pH 4.6–4.7, were of low abundance, unstable and inhibited by a range of salts. | |
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