title: Improving flavour and quality of tomatoes by expression of synthetic gene encoding sweet protein monellin.
abstract: Monellin a sweet-tasting protein exists naturally as a heterodimer of two non-covalently linked subunits chain A and B, which loses its sweetness on denaturation. In this study, we validated the expression of a synthetic monellin gene encoding a single polypeptide chain covalently linking the two subunits under T7 and fruit-ripening-specific promoters in Escherichia coli and tomato fruits, respectively. Purified recombinant monellin protein retained its sweet flavour at 70 °C and pH 2. We developed 15 transgenic T0 tomato plants overexpressing monellin, which were devoid of any growth penalty or phenotypic abnormalities during greenhouse conditions. T-DNA integration and fruit-specific heterologous expression of monellin had occurred in these transgenic tomato lines. ELISA revealed that expression of monellin was 4.5% of the total soluble fruit protein. Functional analyses of transgenic tomatoes of T2-5 and T2-14 lines revealed distinctly strong sweetness compared with wild type. Monellin a potential non-carbohydrate sweetener, if expressed in high amounts in fruits and vegetables, would enhance their flavour and quality.
authors: Plant Molecular Biology Laboratory, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors: Chinreddy Subramanyam
authors: CS
authors: Reddy
authors: Muvva
authors: M
authors: Vijayalakshmi
authors: Tanushri
authors: T
authors: Kaul
authors: Tahmina
authors: T
authors: Islam
authors: Malireddy K
authors: MK
authors: Reddy
mesh_terms: D004926:Escherichia coli / Q000235:genetics; D005813:Genes, Synthetic; D018551:Solanum lycopersicum / Q000235:genetics / Q000502:physiology*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000502:physiology; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013549:Sweetening Agents
chemical_list: D010940:Plant Proteins; D011994:Recombinant Proteins; D013549:Sweetening Agents
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