title: A regulatory network for coordinated flower maturation.
abstract: For self-pollinating plants to reproduce, male and female organ development must be coordinated as flowers mature. The Arabidopsis transcription factors AUXIN RESPONSE FACTOR 6 (ARF6) and ARF8 regulate this complex process by promoting petal expansion, stamen filament elongation, anther dehiscence, and gynoecium maturation, thereby ensuring that pollen released from the anthers is deposited on the stigma of a receptive gynoecium. ARF6 and ARF8 induce jasmonate production, which in turn triggers expression of MYB21 and MYB24, encoding R2R3 MYB transcription factors that promote petal and stamen growth. To understand the dynamics of this flower maturation regulatory network, we have characterized morphological, chemical, and global gene expression phenotypes of arf, myb, and jasmonate pathway mutant flowers. We found that MYB21 and MYB24 promoted not only petal and stamen development but also gynoecium growth. As well as regulating reproductive competence, both the ARF and MYB factors promoted nectary development or function and volatile sesquiterpene production, which may attract insect pollinators and/or repel pathogens. Mutants lacking jasmonate synthesis or response had decreased MYB21 expression and stamen and petal growth at the stage when flowers normally open, but had increased MYB21 expression in petals of older flowers, resulting in renewed and persistent petal expansion at later stages. Both auxin response and jasmonate synthesis promoted positive feedbacks that may ensure rapid petal and stamen growth as flowers open. MYB21 also fed back negatively on expression of jasmonate biosynthesis pathway genes to decrease flower jasmonate level, which correlated with termination of growth after flowers have opened. These dynamic feedbacks may promote timely, coordinated, and transient growth of flower organs.
authors.affiliation: Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: Paul H
authors.initials: PH
authors.lastname: Reeves
authors.forename: Christine M
authors.initials: CM
authors.lastname: Ellis
authors.forename: Sara E
authors.initials: SE
authors.lastname: Ploense
authors.forename: Miin-Feng
authors.initials: MF
authors.lastname: Wu
authors.forename: Vandana
authors.initials: V
authors.lastname: Yadav
authors.forename: Dorothea
authors.initials: D
authors.lastname: Tholl
authors.forename: Aurore
authors.initials: A
authors.lastname: Chételat
authors.forename: Ina
authors.initials: I
authors.lastname: Haupt
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Kennerley
authors.forename: Charles
authors.initials: C
authors.lastname: Hodgens
authors.forename: Edward E
authors.initials: EE
authors.lastname: Farmer
authors.forename: Punita
authors.initials: P
authors.lastname: Nagpal
authors.forename: Jason W
authors.initials: JW
authors.lastname: Reed
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D003517:Cyclopentanes / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D035264:Flowers / Q000235:genetics* / Q000254:growth & development*; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks / Q000235:genetics*; D009154:Mutation; D054883:Oxylipins / Q000378:metabolism; D010641:Phenotype; D057048:Plant Nectar / Q000235:genetics; D030821:Plants, Genetically Modified / Q000235:genetics; D011058:Pollen / Q000235:genetics / Q000254:growth & development; D012717:Sesquiterpenes / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D004268:DNA-Binding Proteins; C512797:MYB21 protein, Arabidopsis; C512798:MYB24 protein, Arabidopsis; D054883:Oxylipins; D057048:Plant Nectar; D012717:Sesquiterpenes; D014157:Transcription Factors; C517136:auxin response factor 6, Arabidopsis; C495666:auxin response factor 8, Arabidopsis; C011006:jasmonic acid