title: Changes in melatonin levels in transgenic 'Micro-Tom' tomato overexpressing ovine AANAT and ovine HIOMT genes.
abstract: In animals, the melatonin biosynthesis pathway has been well defined after the isolation and identification of the four key genes that are involved in the conversion of tryptophan to melatonin. In plants, there are special alternative catalyzing steps, and plant genes share very low homology with the animal genes. It was of interest to examine the phenotype of transgenic Micro-Tom tomato plants overexpressing the homologous sheep oAANAT and oHIOMT genes responsible for the last two steps of melatonin synthesis. The oAANAT transgenic plants have higher melatonin levels and lower indoleacetic acid (IAA) contents than control due to the competition for tryptophan, the same precursor for both melatonin and IAA. Therefore, the oAANAT lines lose the 'apical dominance' inferring that melatonin likely lacks auxin activity. The significantly higher melatonin content in oHIOMT lines than oAANAT lines provides new proof for the important role of ASMT in plant melatonin synthesis. In addition, the enhanced drought tolerance of oHIOMT lines will also be an important contribution for plant engineering.
authors.affiliation: Institute for Horticultural Plants, China Agricultural University, Beijing, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhao
authors.forename: Russel J
authors.initials: RJ
authors.lastname: Reiter
authors.forename: Changjiu
authors.initials: C
authors.lastname: He
authors.forename: Guoshi
authors.initials: G
authors.lastname: Liu
authors.forename: Qiong
authors.initials: Q
authors.lastname: Lei
authors.forename: Bixiao
authors.initials: B
authors.lastname: Zuo
authors.forename: Xiao Dong
authors.initials: XD
authors.lastname: Zheng
authors.forename: Qingtian
authors.initials: Q
authors.lastname: Li
authors.forename: Jin
authors.initials: J
authors.lastname: Kong
mesh_terms: D000121:Acetylserotonin O-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D047068:Arylalkylamine N-Acetyltransferase / Q000235:genetics / Q000378:metabolism*; D055864:Droughts; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D008550:Melatonin / Q000032:analysis / Q000378:metabolism*; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism* / Q000502:physiology
chemical_list: D010940:Plant Proteins; D000121:Acetylserotonin O-Methyltransferase; D047068:Arylalkylamine N-Acetyltransferase; D008550:Melatonin
keywords: Micro-Tom; genetic transformation; melatonin; oAANAT; oHIOMT