title: A comparison of two strategies to modify the hydroxylation of condensed tannin polymers in Lotus corniculatus L.
abstract: A full-length sense Antirrhinum majus dihydroflavonol reductase (DFR) sequence was introduced into birdsfoot trefoil (Lotus corniculatus L.) in experiments aimed at modifying condensed tannin content and polymer hydroxylation in a predictable manner. Analysis of transgenic plants indicated lines that showed enhanced tannin content in leaf and stem tissues. In contrast to previous data from root cultures, levels of propelargonidin units were not markedly elevated in lines with enhanced tannin content. RT-PCR analysis of four selected lines indicated a correlation between enhanced tannin content and expression of the introduced DFR transgene. Using a contrasting approach we introduced a flavonoid 3'5' hydroxylase (F3'5'H) sequence derived from Eustoma grandiflorum into Lotus root cultures. Expression of the transgene was associated with increased levels of condensed tannins and in this case there was also no alteration in polymer hydroxylation. These results suggest that additional mechanisms may exist that control the hydroxylation state of condensed tannins in this model species.
authors.affiliation: Plant Cell Biology Team, Institute of Grassland and Environmental Research, Aberystwyth Research Centre, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, United Kingdom. mark.robbins@bbsrc.ac.uk
authors.forename: Mark P
authors.initials: MP
authors.lastname: Robbins
authors.forename: Adrian D
authors.initials: AD
authors.lastname: Bavage
authors.forename: Gordon
authors.initials: G
authors.lastname: Allison
authors.forename: Teri
authors.initials: T
authors.lastname: Davies
authors.forename: Barbara
authors.initials: B
authors.lastname: Hauck
authors.forename: Phillip
authors.initials: P
authors.lastname: Morris
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006900:Hydroxylation; D000070116:Lotus / Q000235:genetics* / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism; D018517:Plant Roots; D030821:Plants, Genetically Modified; D013634:Tannins / Q000378:metabolism*
chemical_list: D013634:Tannins; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D000429:Alcohol Oxidoreductases; C056570:dihydroflavanol 4-reductase; C084258:flavonoid 3',5'-hydroxylase