title: Metabolomic, transcriptional, hormonal, and signaling cross-talk in superroot2.
abstract: Auxin homeostasis is pivotal for normal plant growth and development. The superroot2 (sur2) mutant was initially isolated in a forward genetic screen for auxin overproducers, and SUR2 was suggested to control auxin conjugation and thereby regulate auxin homeostasis. However, the phenotype was not uniform and could not be described as a pure high auxin phenotype, indicating that knockout of CYP83B1 has multiple effects. Subsequently, SUR2 was identified as CYP83B1, a cytochrome P450 positioned at the metabolic branch point between auxin and indole glucosinolate metabolism. To investigate concomitant global alterations triggered by knockout of CYP83B1 and the countermeasures chosen by the mutant to cope with hormonal and metabolic imbalances, 10-day-old mutant seedlings were characterized with respect to their transcriptome and metabolome profiles. Here, we report a global analysis of the sur2 mutant by the use of a combined transcriptomic and metabolomic approach revealing pronounced effects on several metabolic grids including the intersection between secondary metabolism, cell wall turnover, hormone metabolism, and stress responses. Metabolic and transcriptional cross-talks in sur2 were found to be regulated by complex interactions between both positively and negatively acting transcription factors. The complex phenotype of sur2 may thus not only be assigned to elevated levels of auxin, but also to ethylene and abscisic acid responses as well as drought responses in the absence of a water deficiency. The delicate balance between these signals explains why minute changes in growth conditions may result in the non-uniform phenotype. The large phenotypic variation observed between and within the different surveys may be reconciled by the complex and intricate hormonal balances in sur2 seedlings decoded in this study.
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant Biology and Biotechnology, University of Copenhagen, 40 Thorvaldsensvej, Frederiksberg C, Copenhagen, Denmark.
authors.forename: Marc
authors.initials: M
authors.lastname: Morant
authors.forename: Claus
authors.initials: C
authors.lastname: Ekstrøm
authors.forename: Peter
authors.initials: P
authors.lastname: Ulvskov
authors.forename: Charlotte
authors.initials: C
authors.lastname: Kristensen
authors.forename: Mats
authors.initials: M
authors.lastname: Rudemo
authors.forename: Carl Erik
authors.initials: CE
authors.lastname: Olsen
authors.forename: Jørgen
authors.initials: J
authors.lastname: Hansen
authors.forename: Kirsten
authors.initials: K
authors.lastname: Jørgensen
authors.forename: Bodil
authors.initials: B
authors.lastname: Jørgensen
authors.forename: Birger Lindberg
authors.initials: BL
authors.lastname: Møller
authors.forename: Søren
authors.initials: S
authors.lastname: Bak
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D005030:Ethylenes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D007210:Indoleacetic Acids / Q000378:metabolism; D008954:Models, Biological; D010641:Phenotype; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D005030:Ethylenes; D007210:Indoleacetic Acids; D014157:Transcription Factors; C036216:ethylene