This week’s leaf is inspired by recent publications about research from UC Riverside related to potato toxicity. Most of us know that eating green potatoes can make us ill. The problem is not the green(chlorophyll), but toxic alkaloids, e.g. solanine, that appear as potatoes turn green. The same toxins appear in other members of the Solanaceae family such as tomatoes and peppers.
In the published research (Jozwiak et al, 2024), the scientists silenced the GAME15 gene that usually controls conversion of cholesterol to steroidal glycoalkaloids. Eliminating the toxins means that stored potatoes stay safe even if exposed to light.
Normally, toxic alkaloids are actively synthesized in potato leaves but disappear in the tubers we eat. When potatoes turn green when exposed to light, they are getting ready to sprout new shoots and leaves. Tomatoes also have toxic leaves, and the cultivated varieties have been selected because the toxins are depleted in the fruit. By silencing GAME15, even the leaves of potatoes and tomatoes plants become edible.
This brings me to repeat things already stated in early leaves of this series – the plants don’t produce phytochemicals, toxic or otherwise, for man’s benefit. It turns out that solanine and other toxic glycoalkaloids help potato and tomato plants to repel pests. Thus, insect infestations quickly appeared in the genetically-engineered, GAME15-suppressed tomato plants. This is a case where the science is interesting but the practical outcome questionable.
There are plenty of toxic plants in nature and when used appropriately these plants and their phytochemicals can be used as biomedicines. This does not mean we should eat them as food! As for potatoes, it seems a lot easier just to store them properly and destroy them if they accidentally turn green.
Sources
🥔 University of California - Riverside. (2024,December 20). Growing safer spuds: Removing toxins from potatoes. ScienceDaily. Retrieved January 9, 2025 from www.sciencedaily.com/releases/2024/12/241220132905.htm
🥔 A et al (2024). A Jozwiak cellulose synthase-like protein governs the biosynthesis of Solanum alkaloids. Science 386(6728),eadq5721. https://doi.org/10.1126/science.adq5721
