title: Transcription factors of Lotus: regulation of isoflavonoid biosynthesis requires coordinated changes in transcription factor activity.
abstract: Isoflavonoids are a class of phenylpropanoids made by legumes, and consumption of dietary isoflavonoids confers benefits to human health. Our aim is to understand the regulation of isoflavonoid biosynthesis. Many studies have shown the importance of transcription factors in regulating the transcription of one or more genes encoding enzymes in phenylpropanoid metabolism. In this study, we coupled bioinformatics and coexpression analysis to identify candidate genes encoding transcription factors involved in regulating isoflavonoid biosynthesis in Lotus (Lotus japonicus). Genes encoding proteins belonging to 39 of the main transcription factor families were examined by microarray analysis of RNA from leaf tissue that had been elicited with glutathione. Phylogenetic analyses of each transcription factor family were used to identify subgroups of proteins that were specific to L. japonicus or closely related to known regulators of the phenylpropanoid pathway in other species. R2R3MYB subgroup 2 genes showed increased expression after treatment with glutathione. One member of this subgroup, LjMYB14, was constitutively overexpressed in L. japonicus and induced the expression of at least 12 genes that encoded enzymes in the general phenylpropanoid and isoflavonoid pathways. A distinct set of six R2R3MYB subgroup 2-like genes was identified. We suggest that these subgroup 2 sister group proteins and those belonging to the main subgroup 2 have roles in inducing isoflavonoid biosynthesis. The induction of isoflavonoid production in L. japonicus also involves the coordinated down-regulation of competing biosynthetic pathways by changing the expression of other transcription factors.
authors.affiliation: Department of Plant Biology and Biotechnology, University of Copenhagen, 1871 Frederiksberg, Denmark.
authors.forename: Dale
authors.initials: D
authors.lastname: Shelton
authors.forename: Maria
authors.initials: M
authors.lastname: Stranne
authors.forename: Lisbeth
authors.initials: L
authors.lastname: Mikkelsen
authors.forename: Nima
authors.initials: N
authors.lastname: Pakseresht
authors.forename: Tracey
authors.initials: T
authors.lastname: Welham
authors.forename: Hideki
authors.initials: H
authors.lastname: Hiraka
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tabata
authors.forename: Shusei
authors.initials: S
authors.lastname: Sato
authors.forename: Suzanne
authors.initials: S
authors.lastname: Paquette
authors.forename: Trevor L
authors.initials: TL
authors.lastname: Wang
authors.forename: Cathie
authors.initials: C
authors.lastname: Martin
authors.forename: Paul
authors.initials: P
authors.lastname: Bailey
mesh_terms: D003001:Cloning, Molecular; D019295:Computational Biology; D057225:Data Mining; D005419:Flavonoids / Q000096:biosynthesis* / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005978:Glutathione / Q000494:pharmacology; D000070116:Lotus / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D017423:Sequence Analysis, RNA; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D019076:Transgenes
chemical_list: D005419:Flavonoids; D010940:Plant Proteins; D018749:RNA, Plant; D014157:Transcription Factors; D005978:Glutathione