title: Auxin controls Arabidopsis anther dehiscence by regulating endothecium lignification and jasmonic acid biosynthesis.
abstract: It has been suggested that, in Arabidopsis, auxin controls the timing of anther dehiscence, possibly by preventing premature endothecium lignification. We show here that auxin content in anthers peaks before the beginning of dehiscence and decreases when endothecium lignification occurs. We show that, in the auxin-perception mutants afb1-3 and tir1 afb2 afb3, endothecium lignification and anther dehiscence occur earlier than wild-type, and the gene encoding the transcription factor MYB26, which is required for endothecium lignification, is over-expressed specifically at early stages; in agreement, MYB26 expression is reduced in naphthalene acetic acid-treated anthers, and afb1 myb26 double mutants show no endothecial lignification, suggesting that auxin acts through MYB26. As jasmonic acid (JA) controls anther dehiscence, we analysed how auxin and JA interact. In the JA-defective opr3 mutant, indehiscent anthers show normal timing of endothecium lignification, suggesting that JA does not control this event. We show that expression of the OPR3 and DAD1 JA biosynthetic genes is enhanced in afb1-3 and tir1 afb2 afb3 flower buds, but is reduced in naphthalene acetic acid-treated flower buds, suggesting that auxin negatively regulates JA biosynthesis. The double mutant afb1 opr3 shows premature endothecium lignification, as in afb1-3, and indehiscent anthers due to lack of JA, which is required for stomium opening. By treating afb1 opr3 and opr3 inflorescences with JA, we show that a high JA content and precocious endothecium lignification both contribute to induction of early anther dehiscence. We propose that auxin controls anther dehiscence timing by negatively regulating two key events: endothecium lignification via MYB26, and stomium opening via the control of JA biosynthesis.
authors: Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185 Rome, Italy.
authors: Valentina
authors: V
authors: Cecchetti
authors: Maria Maddalena
authors: MM
authors: Altamura
authors: Patrizia
authors: P
authors: Brunetti
authors: Valentina
authors: V
authors: Petrocelli
authors: Giuseppina
authors: G
authors: Falasca
authors: Karin
authors: K
authors: Ljung
authors: Paolo
authors: P
authors: Costantino
authors: Maura
authors: M
authors: Cardarelli
mesh_terms: D017360:Arabidopsis / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003517:Cyclopentanes / Q000378:metabolism*; D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism; D035264:Flowers / Q000378:metabolism / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007210:Indoleacetic Acids / Q000378:metabolism*; D008031:Lignin / Q000378:metabolism*; D009280:Naphthaleneacetic Acids / Q000494:pharmacology; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D054883:Oxylipins / Q000378:metabolism*; D054466:Phospholipases A1 / Q000235:genetics / Q000378:metabolism; D059828:Plant Cells / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D044783:F-Box Proteins; D007210:Indoleacetic Acids; C517159:MYB26 protein, Arabidopsis; D009280:Naphthaleneacetic Acids; D054883:Oxylipins; D011956:Receptors, Cell Surface; C501405:TIR1 protein, Arabidopsis; D014157:Transcription Factors; C011006:jasmonic acid; D008031:Lignin; C416525:OPR3 protein, Arabidopsis; D010088:Oxidoreductases; C445094:DAD1 protein, Arabidopsis; D054466:Phospholipases A1