Understanding Plant Metabolic Networks for Better Tasting Food

Lee Sweetlove’s research group studies the regulation and engineering of plant metabolic networks, which could lead to improvements in food crops, such as increased yields or enhanced flavour.

The group’s research is in two strands: computational modelling and experimental metabolic engineering.

Computational Modelling

The group are developing genome-scale computational models of metabolic networks for a number of plants including thale cress, Arabidopsis thaliana, the first plant to have its genome sequenced. The computational models help understand the behaviour of complex metabolic systems that are hard to assess in detail experimentally. They also give a better understanding of the limits and trade-offs inherent within the metabolic system and can be used to predict how to metabolically engineer actual plants to optimise crop performance.

Experimental Metabolic Engineering

Lee Sweetlove’s experimental work involves targeted genetic manipulation of plants, such as the tomato, to alter the amounts of specific enzymes and transporters. The general aim is to tweak the metabolic system of the plant to produce more of a specific target compound.

The aim of the experiment was to improve the taste of the tomato, since flavour is a product of metabolism: in the case of tomatoes, flavour develops during the ripening process due to accumulation of sugars and acidic compounds, in particular the amino acids aspartate and glutamate.


After extensive work, they concluded that it was a particular transporter protein that controls the accumulation of these amino acids. They then identified the gene responsible for encoding the transporter and developed transgenic fruit with that particular gene over-expressed. They found that levels of both aspartate and glutamate were significantly increased, demonstrating that this transporter has substantial control over the accumulation of the compounds that determine flavour.

Wider Interest

The work on improving the taste of tomatoes has so far been carried out on a lab-variety of tomato. Lee Sweetlove’s team are working with an industrial partner, Syngenta, who part-funded the research, to make similar genetic changes to commercial tomato varieties using advanced molecular breeding techniques.

Further work into the functioning of transporter proteins could improve nitrogen use efficiency in plants. His group have established that some amino acid transporters perform an additional role of signalling the plant’s nitrogen status. A better understanding of this mechanism could allow for genetic manipulation of the plant to take up and utilise more of the available soil nitrogen, which in turn could lead to faster growth and a reduced input of nitrogen fertiliser.


This research has been funded by the BBSRC and Syngenta.

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For further information, please read the following publication in Plant Journal: Snowden, C. J., Thomas, B., Baxter, C. J., Smith, J. A. C. & Sweetlove, L. J. (2015) A tonoplast Glu/Asp/GABA exchanger that affects tomato fruit amino acid composition. Plant J. doi:10.1111/tpj.12766

Photo of cherry tomatoes from Pixabay

Photo of Tomato experiment in lab by Syngenta