The Role of Two Glycoalkaloid Metabolism Genes in α-Tomatine Biosynthesis and Basal Defence in Tomato.
You Y, Balaji A, Herrera Valderrama AL, Denarié ME, Suraj HM
Crispr
The gray mold that collapses your tomato plants by August has evolved its own molecular toolkit to crack the very chemical shield tomatoes spent millions of years perfecting — and now we can see exactly how that arms race plays out gene by gene.
Tomato plants naturally produce a bitter chemical called tomatine in their green leaves and unripe fruit that helps ward off fungal invaders. When scientists switched off the gene responsible, the plant didn't give up — it redirected its chemistry to make a different defense compound, one normally found in wild black nightshade. The gray mold fungus, however, proved craftier than both plants: it carries enzymes that can break down either compound, letting it infect the tomatine-free tomatoes just as readily.
Key Findings
Knocking out the GAME4 gene eliminated tomatine production entirely and redirected the plant toward making uttroside B, a saponin defense compound characteristic of black nightshade
The GAME2 gene, previously published as essential for tomatine biosynthesis, turned out to have no role in tomatine production — a direct correction of prior scientific literature
Gray mold (Botrytis cinerea) was slightly but measurably more virulent on tomatine-deficient plants, and the fungus uses glycosyl hydrolase and glycosyltransferase enzymes to detoxify both tomatine and uttroside B
chevron_right Technical Summary
Researchers used CRISPR gene-editing to switch off two tomato defense genes one at a time, finding that α-tomatine (the bitter compound in green tomatoes) provides real but modest protection against gray mold fungus — and that when the tomatine pathway is blocked, the plant reroutes its chemistry toward a related compound from black nightshade that the same fungus has independently learned to neutralize.
Abstract Preview
Steroidal glycoalkaloids and saponins are plant cholesterol-based steroid metabolites with antimicrobial activities and potential pharmacological value. The saponin uttroside B from black nightshad...
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The tomato is a plant whose fruit is an edible berry that is eaten as a vegetable. The tomato is a member of the nightshade family that includes tobacco, potato, and chili peppers. It originated from western South America, and may have been domesticated there, in Mexico, or in Central America. Th...