Plant Molecular Biology

, Volume 78, Issue 6, pp 525–543

Serotonin accumulation in transgenic rice by over-expressing tryptophan decarboxlyase results in a dark brown phenotype and stunted growth

  • Parawee Kanjanaphachoat
  • Bi-Yin Wei
  • Shuen-Fang Lo
  • I-Wen Wang
  • Chang-Sheng Wang
  • Su-May Yu
  • Ming-Liang Yen
  • Sheng-Hsien Chiu
  • Chien-Chen Lai
  • Liang-Jwu Chen
Article

DOI: 10.1007/s11103-012-9882-5

Cite this article as:
Kanjanaphachoat, P., Wei, BY., Lo, SF. et al. Plant Mol Biol (2012) 78: 525. doi:10.1007/s11103-012-9882-5

Abstract

A mutant M47286 with a stunted growth, low fertility and dark-brown phenotype was identified from a T-DNA-tagged rice mutant library. This mutant contained a copy of the T-DNA tag inserted at the location where the expression of two putative tryptophan decarboxlyase genes, TDC-1 and TDC-3, were activated. Enzymatic assays of both recombinant proteins showed tryptophan decarboxlyase activities that converted tryptophan to tryptamine, which could be converted to serotonin by a constitutively expressed tryptamine 5′ hydroxylase (T5H) in rice plants. Over-expression of TDC-1 and TDC-3 in transgenic rice recapitulated the stunted growth, dark-brown phenotype and resulted in a low fertility similar to M47286. The degree of stunted growth and dark-brown color was proportional to the expression levels of TDC-1 and TDC-3. The levels of tryptamine and serotonin accumulation in these transgenic rice lines were also directly correlated with the expression levels of TDC-1 and TDC-3. A mass spectrometry assay demonstrated that the dark-brown leaves and hulls in the TDC-overexpressing transgenic rice were caused by the accumulation of serotonin dimer and that the stunted growth and low fertility were also caused by the accumulation of serotonin and serotonin dimer, but not tryptamine. These results represent the first evidence that over-expression of TDC results in stunted growth, low fertility and the accumulation of serotonin, which when converted to serotonin dimer, leads to a dark brown plant color.

Keywords

Tryptophan decarboxylaseTryptophanTryptamineSerotonin dimerBrown pigmentationT-DNA taggingTransgenic rice

Abbreviations

DAI

Days after imbibition

GUS

β-Glucuronidase

LC/MS/MS

Liquid chromatography tandem mass spectrometry

NMR

Nuclear magnetic resonance

RT-PCR

Reverse transcription-PCR

TDC

Tryptophan decarboxylase

TYDC

Tyrosine decarboxylase

TT

Homozygous genotype

TW

Heterozygous genotype

WW

Wild type genotype

Supplementary material

11103_2012_9882_MOESM1_ESM.doc (78 kb)
Supplementary material 1 (DOC 78 kb)
11103_2012_9882_MOESM2_ESM.pdf (504 kb)
Supplementary material 2 (PDF 504 kb)
11103_2012_9882_MOESM3_ESM.doc (37 kb)
Supplementary material 3 (DOC 37 kb)

Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Parawee Kanjanaphachoat
    • 1
  • Bi-Yin Wei
    • 1
  • Shuen-Fang Lo
    • 1
    • 3
  • I-Wen Wang
    • 1
  • Chang-Sheng Wang
    • 2
  • Su-May Yu
    • 3
  • Ming-Liang Yen
    • 4
  • Sheng-Hsien Chiu
    • 4
  • Chien-Chen Lai
    • 1
  • Liang-Jwu Chen
    • 1
  1. 1.Institute of Molecular BiologyNational Chung Hsing UniversityTaichungTaiwan
  2. 2.Department of AgronomyNational Chung Hsing UniversityTaichungTaiwan
  3. 3.Institute of Molecular BiologyAcademia SinicaTaipeiTaiwan
  4. 4.Department of ChemistryNational Taiwan UniversityTaipeiTaiwan