title: Isolation of HAG1 and its regulation by plant hormones during in vitro floral organogenesis in Hyacinthus orientalis L.
abstract: Floral organs have been successfully induced from the regenerated floral buds of Hyacinthus orientalis L. by precisely controlling exogenous hormones in the medium. Under high concentrations of cytokinin and auxin, the regenerated floral bud produces only tepals. However, at reduced levels of the hormones, the regenerated floral bud can produce stamens and/or carpels with ovules. To understand the molecular mechanism of hormone-regulated flower development, a MADS-box gene, HAG1, which is homologous to AGAMOUS (AG) in Arabidopsis, was isolated from the floral tissues of Hyacinthus. Overexpression of HAG1 in Arabidopsis created flower phenotypes resembling those of the apetala2 mutant and AG transgenic Arabidopsis plants. Furthermore, the HAG1 expression pattern was similar to that of AG, confirming that HAG1 is the ortholog of AG in Hyacinthus. HAG1 mRNA was first detected in cultured explants at day 5 in the medium containing high levels of cytokinin and auxin, which could induce floral regeneration in vitro. However, no HAG1 mRNA was detected in the cultured explants until day 10 in media with low or no hormones. Further, HAG1 mRNA was detected in the stamens and carpels of regenerated floral buds, but not in the tepals. Our data support the hypothesis that hormone-regulated HAG1 activity is required for the induction of floral buds and the determination of floral organ types during the regeneration of floral buds.
authors.affiliation: College of Life Sciences, Shandong Agricultural University, Taian, Shandong, 271018, China.
authors.forename: Quan Zi
authors.initials: QZ
authors.lastname: Li
authors.forename: Xing Guo
authors.initials: XG
authors.lastname: Li
authors.forename: Shu Nong
authors.initials: SN
authors.lastname: Bai
authors.forename: Wen Liang
authors.initials: WL
authors.lastname: Lu
authors.forename: Xian Sheng
authors.initials: XS
authors.lastname: Zhang
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D026342:AGAMOUS Protein, Arabidopsis / Q000235:genetics; D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins; D001593:Benzyl Compounds; D002454:Cell Differentiation / Q000187:drug effects; D003583:Cytokinins / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018398:Homeodomain Proteins / Q000235:genetics; D007210:Indoleacetic Acids / Q000494:pharmacology; D007701:Kinetin; D019668:Liliaceae / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D026161:MADS Domain Proteins / Q000235:genetics* / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics; D010937:Plant Growth Regulators / Q000494:pharmacology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018547:Plant Stems / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D011687:Purines; D017386:Sequence Homology, Amino Acid
chemical_list: D026342:AGAMOUS Protein, Arabidopsis; C499534:APETALA2 protein, Arabidopsis; D029681:Arabidopsis Proteins; D001593:Benzyl Compounds; D003583:Cytokinins; D018398:Homeodomain Proteins; D007210:Indoleacetic Acids; D026161:MADS Domain Proteins; D009687:Nuclear Proteins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D011687:Purines; D015084:2,4-Dichlorophenoxyacetic Acid; D000225:Adenine; C480551:benzylaminopurine; D007701:Kinetin