title: An auxin maximum in the middle layer controls stamen development and pollen maturation in Arabidopsis.
abstract: Here, we investigated the role of auxin distribution in controlling Arabidopsis thaliana late stamen development. We analysed auxin distribution in anthers by monitoring DR5 activity: at different flower developmental stages; inhibiting auxin transport; in the rpk2-3 and ems1 mutants devoid of middle layer (ML) or tapetum, respectively; and in the auxin biosynthesis yuc6 and perception afb1-3 mutants. We ran a phenotypic, DR5::GUS and gene expression analysis of yuc6rpk2 and afb1rpk2 double mutants, and of 1-N-naphthylphthalamic acid (NPA)-treated flower buds. We show that an auxin maximum, caused by transport from the tapetum, is established in the ML at the inception of late stamen development. rpk2-3 mutant stamens lacking the ML have an altered auxin distribution with excessive accumulation in adjacent tissues, causing non-functional pollen grains, indehiscent anthers and reduced filament length; the expression of genes controlling stamen development is also altered in rpk2-3 as well as in NPA-treated flower buds. By decreasing auxin biosynthesis or perception in the rpk2-3 background, we eliminated these developmental and gene expression anomalies. We propose that the auxin maximum in the ML plays a key role in late stamen development, as it ensures correct and coordinated pollen maturation, anther dehiscence and filament elongation.
authors.affiliation: Istituto di Biologia e Patologia Molecolari (IBPM), Consiglio Nazionale delle Ricerche (CNR), Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185, Rome, Italy.|Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185, Rome, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Cecchetti
authors.affiliation: Istituto di Biologia e Patologia Molecolari (IBPM), Consiglio Nazionale delle Ricerche (CNR), Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185, Rome, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Celebrin
authors.affiliation: Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185, Rome, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Napoli
authors.affiliation: Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185, Rome, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Ghelli
authors.affiliation: Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185, Rome, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Brunetti
authors.affiliation: Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185, Rome, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Costantino
authors.affiliation: Istituto di Biologia e Patologia Molecolari (IBPM), Consiglio Nazionale delle Ricerche (CNR), Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185, Rome, Italy.
authors.forename: Maura
authors.initials: M
authors.lastname: Cardarelli
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D017930:Genes, Reporter; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008954:Models, Biological; D009928:Organ Specificity / Q000235:genetics; D011058:Pollen / Q000187:drug effects / Q000254:growth & development*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D012333:RNA, Messenger; D014157:Transcription Factors
keywords: 
  Arabidopsis thaliana
  ; anther dehiscence; auxin maximum; auxin transport; filament elongation; middle layer; pollen maturation; stamen-specific genes