title: Examination of the auxin hypothesis of phytomelatonin action in classical auxin assay systems in maize.
abstract: Melatonin has been found in a wide range of plant groups. Its physiological roles have been suggested to be diverse in stress protection and plant growth regulation. An attractive hypothesis is that phytomelatonin acts as an auxin to regulate plant development. However, the auxin hypothesis is controversial, since both supporting and contradictory evidence has been reported. We systematically investigated whether melatonin fulfilled the definition for auxin in maize (Zea mays). Melatonin did not affect coleoptile elongation, root growth or ACC synthase gene expression, contrary to 10(-5)M IAA in our assay system. The auxin hypothesis of phytomelatonin action is not supported in maize, because melatonin appeared inactive in all of the auxin activity tests. On the other hand, melatonin was active in the protection of maize growth against salt stress, suggesting its importance in another context.
authors.affiliation: Department of Molecular Biology & Institute of Nanosensor and Biotechnology, Dankook University, Yongin-si 448-701, South Korea.
authors.forename: Minjae
authors.initials: M
authors.lastname: Kim
authors.affiliation: Department of Molecular Biology & Institute of Nanosensor and Biotechnology, Dankook University, Yongin-si 448-701, South Korea.
authors.forename: Hyesu
authors.initials: H
authors.lastname: Seo
authors.affiliation: Department of Molecular Biology & Institute of Nanosensor and Biotechnology, Dankook University, Yongin-si 448-701, South Korea.
authors.forename: Chanwoo
authors.initials: C
authors.lastname: Park
authors.affiliation: Department of Molecular Biology & Institute of Nanosensor and Biotechnology, Dankook University, Yongin-si 448-701, South Korea. Electronic address: parkwj@dku.edu.
authors.forename: Woong June
authors.initials: WJ
authors.lastname: Park
mesh_terms: D018548:Cotyledon / Q000254:growth & development / Q000378:metabolism; D015870:Gene Expression; D007210:Indoleacetic Acids / Q000378:metabolism; D008190:Lyases / Q000235:genetics / Q000378:metabolism; D008550:Melatonin / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D003313:Zea mays / Q000254:growth & development* / Q000378:metabolism
chemical_list: D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; D008190:Lyases; C021773:1-aminocyclopropanecarboxylate synthase; D008550:Melatonin
keywords: ACC synthase; Auxin; Coleoptiles elongation; Maize (Zea mays); Phytomelatonin; Root growth