Could we turn poisonous plants into edible crops? Well we actually already eat several plants that are poisonous. Kidney beans, for example, contain the toxin phytohemagglutinin and just five beans are enough to give you vomiting and diarrhoea – unless you cook them first.


Cooking is a human innovation that has added lots of new plant species to our diet by destroying the toxins in them. Plants have evolved to synthesise these toxic chemicals in order to discourage animals and insects from eating them, but farmers are constantly looking for ways to produce tastier crops by lowering the concentrations of these chemicals.

Thanks to this, modern varieties of grapefruit, Brussels sprouts and aubergine are now much less bitter than they were 50 years ago. But there is a balance to strike between their taste on the plate and how attractive they are to agricultural pests in the field. The ideal would be a plant that keeps the pests away until harvest time and then ripens into something more appetising.

Tomatoes already do this – the toxic alkaloid in green tomatoes naturally breaks down as the fruit ripens – but modern gene-editing techniques are taking this a step further.

Canola or rapeseed is grown commercially for its oil but the seed husks were previously discarded due to the toxins produced by the plant. However, in 2012 scientists at the Norwegian University of Science and Technology used genetic editing to reprogramme canola plants so that the toxin levels faded away as the seeds matured. The pressed seeds can now be turned into a protein-rich flour that is used in cereal bars and vegan meat substitutes.

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luis villazon
Luis VillazonQ&A expert

Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.