title: Stress-responsive hydroxycinnamate glycosyltransferase modulates phenylpropanoid metabolism in Populus.
abstract: The diversity of phenylpropanoids offers a rich inventory of bioactive chemicals that can be exploited for plant improvement and human health. Recent evidence suggests that glycosylation may play a role in the partitioning of phenylpropanoid precursors for a variety of downstream uses. This work reports the functional characterization of a stress-responsive glycosyltransferase, GT1-316 in Populus. GT1-316 belongs to the UGT84A subfamily of plant glycosyltransferase family 1 and is designated UGT84A17. Recombinant protein analysis showed that UGT84A17 is a hydroxycinnamate glycosyltransferase and able to accept a range of unsubstituted and substituted cinnamic and benzoic acids as substrates in vitro. Overexpression of GT1-316 in transgenic Populus led to plant-wide increases of hydroxycinnamoyl-glucose esters, which were further elevated under N-limiting conditions. Levels of the two most abundant flavonoid glycosides, rutin and kaempferol-3-O-rutinoside, decreased, while levels of other less abundant flavonoid and phenylpropanoid conjugates increased in leaves of the GT1-316-overexpressing plants. Transcript levels of representative phenylpropanoid pathway genes were unchanged in transgenic plants, supporting a glycosylation-mediated redirection of phenylpropanoid carbon flow as opposed to enhanced phenylpropanoid pathway flux. The metabolic response of N-replete transgenic plants overlapped with that of N-stressed wild types, as the majority of phenylpropanoid derivatives significantly affected by GT1-316 overexpression were also significantly changed by N stress in the wild types. These results suggest that UGT84A17 plays an important role in phenylpropanoid metabolism by modulating biosynthesis of hydroxycinnamoyl-glucose esters and their derivatives in response to developmental and environmental cues.
authors.affiliation: Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Babst
authors.affiliation: Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA.
authors.forename: Han-Yi
authors.initials: HY
authors.lastname: Chen
authors.affiliation: Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Hong-Qiang
authors.initials: HQ
authors.lastname: Wang
authors.affiliation: Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA.
authors.forename: Raja S
authors.initials: RS
authors.lastname: Payyavula
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA.
authors.forename: Tina P
authors.initials: TP
authors.lastname: Thomas
authors.affiliation: Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Harding
authors.affiliation: Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA Department of Genetics, University of Georgia, Athens, GA 30602, USA cjtsai@uga.edu.
authors.forename: Chung-Jui
authors.initials: CJ
authors.lastname: Tsai
mesh_terms: D003373:Coumaric Acids / Q000378:metabolism*; D016695:Glycosyltransferases / Q000378:metabolism*; D062385:Hydroxybenzoates / Q000378:metabolism*; D005810:Multigene Family; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D032107:Populus / Q000201:enzymology* / Q000235:genetics; D013312:Stress, Physiological
chemical_list: D003373:Coumaric Acids; D062385:Hydroxybenzoates; D010940:Plant Proteins; D016695:Glycosyltransferases
keywords: Glycosylation; Populus; UGT84A.; hydroxycinnamate glucose ester; metabolite profiling; phenylpropanoid; stress