title: Brassinosteroid control of sex determination in maize.
abstract: Brassinosteroids (BRs) are plant hormones that regulate growth and development. They share structural similarities with animal steroids, which are decisive factors of sex determination. BRs are known to regulate morphogenesis and environmental stress responses, but their involvement in sex determination in plants has been only speculative. We show that BRs control sex determination in maize revealed through characterization of the classical dwarf mutant nana plant1 (na1), which also feminizes male flowers. na1 plants carry a loss-of-function mutation in a DET2 homolog--a gene in the BR biosynthetic pathway. The mutant accumulates the DET2-specific substrate (24R)-24-methylcholest-4-en-3-one with a concomitant decrease of downstream BR metabolites. Treatment of wild-type maize plants with BR biosynthesis inhibitors completely mimicked both dwarf and tasselseed phenotypes of na1 mutants. Tissue-specific na1 expression in anthers throughout their development supports the hypothesis that BRs promote masculinity of the male inflorescence. These findings suggest that, in the monoecious plant maize, BRs have been coopted to perform a sex determination function not found in plants with bisexual flowers.
authors: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA.
authors: Thomas
authors: T
authors: Hartwig
authors: George S
authors: GS
authors: Chuck
authors: Shozo
authors: S
authors: Fujioka
authors: Antje
authors: A
authors: Klempien
authors: Renate
authors: R
authors: Weizbauer
authors: Devi Prasad V
authors: DP
authors: Potluri
authors: Sunghwa
authors: S
authors: Choe
authors: Gurmukh S
authors: GS
authors: Johal
authors: Burkhard
authors: B
authors: Schulz
mesh_terms: D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D060406:Brassinosteroids / Q000096:biosynthesis*; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017403:In Situ Hybridization; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010802:Phylogeny; D010840:Phytosterols / Q000378:metabolism; D019441:Plant Epidermis / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D003313:Zea mays / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D060406:Brassinosteroids; D010840:Phytosterols; D010940:Plant Proteins; D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase