This study highlights the changes in umami-related nucleotide and glutamate levels when the AMP deaminase gene was elevated in transgenic tomato.
Taste is perceived as one of a combination of five sensations, sweet, sour, bitter, salty, and umami. The umami taste is best known as a savoury sensation and plays a central role in food flavour, palatability, and eating satisfaction. Umami flavour can be imparted by the presence of glutamate and is greatly enhanced by the addition of ribonucleotides, such as inosine monophosphate (IMP) and guanosine monophosphate (GMP). The production of IMP is regulated by the enzyme adenosine monophosphate (AMP) deaminase which functions to convert AMP into IMP. We have generated transgenic tomato (Solanum lycopersicum) lines over expressing AMP deaminase under the control of a fruit-specific promoter. The transgenic lines showed substantially enhanced levels of AMP deaminase expression in comparison to the wild-type control. Elevated AMP deaminase levels resulted in the reduced accumulation of glutamate and increased levels of the umami nucleotide GMP. AMP concentrations were unchanged. The effects on the levels of glutamate and GMP were unexpected and are discussed in relation to the metabolite flux within this pathway.
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The first author would like to acknowledge The University of Nottingham, United Kingdom, and Universiti Sains Malaysia (1001/PBIOLOGI/811258) for funding the project and other related expenses. Some of the methods utilised were developed under BBSRC BB/F017014/1.
Conflict of interest
The authors declare that they have no conflict of interest.
Communicated by R. Wells.
Electronic supplementary material
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Supplementary Fig. 1: Southern blot analysis of T1 progeny (1-8) from three independent T0 lines (P4, P44 and P55) of transgenic Micro Tom DNA. Wild-type (WT) and transgene bands in each line are shown. Homozygous lines indicated by red boxes (PDF 242 kb)
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Chew, B.L., Fisk, I.D., Fray, R. et al. The effect of adenosine monophosphate deaminase overexpression on the accumulation of umami-related metabolites in tomatoes. Plant Cell Rep 36, 81–87 (2017). https://doi.org/10.1007/s00299-016-2058-z
- Transgenic tomato
- Inosine monophosphate and guanosine monophosphate