A functional genomics approach to (iso)flavonoid glycosylation in the model legume Medicago truncatula.
Analysis of over 200,000 expressed sequence tags from a range of Medicago truncatula cDNA libraries resulted in the identification of over 150 different family 1 glycosyltransferase (UGT) genes. Of these, 63 were represented by full length clones in an EST library collection. Among these, 19 gave soluble proteins when expressed in E. coli, and these were screened for catalytic activity against a range of flavonoid and isoflavonoid substrates using a high-throughput HPLC assay method. Eight UGTs were identified with activity against isoflavones, flavones, flavonols or anthocyanidins, and several showed high catalytic specificity for more than one class of (iso)flavonoid substrate. All tested UGTs preferred UDP-glucose as sugar donor. Phylogenetic analysis indicated that the Medicago (iso)flavonoid glycosyltransferase gene sequences fell into a number of different clades, and several clustered with UGTs annotated as glycosylating non-flavonoid substrates. Quantitative RT-PCR and DNA microarray analysis revealed unique transcript expression patterns for each of the eight UGTs in Medicago organs and cell suspension cultures, and comparison of these patterns with known phytochemical profiles suggested in vivo functions for several of the enzymes.
Modolo
Luzia V
LV
Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA.
Blount
Jack W
JW
Achnine
Lahoucine
L
Naoumkina
Marina A
MA
Wang
Xiaoqiang
X
Dixon
Richard A
RA
D018744:DNA, Plant / Q000235:genetics; D020224:Expressed Sequence Tags; D005419:Flavonoids / Q000235:genetics*; D018745:Genome, Plant; D023281:Genomics; D016695:Glycosyltransferases / Q000235:genetics*; D007529:Isoflavones / Q000235:genetics; D046913:Medicago truncatula / Q000145:classification / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018744:DNA, Plant; D005419:Flavonoids; D007529:Isoflavones; D010940:Plant Proteins; D018749:RNA, Plant; D016695:Glycosyltransferases