Heterologous Biosynthesis of Crocin I in Solanum lycopersicum L.

Crocins are high-value apocarotenoid pigments with broad applications in pharmaceuticals, foods, and personal-care products, and they exhibit diverse bioactivities, including antioxidant, antidepressant, and antidementia effects. In this study, we achieved the heterologous biosynthesis of crocins in Solanum lycopersicum L. by introducing the GjCCD4a, GjALDH2C3, GjUGT74F8 and GjUGT94E13 of Gardenia jasminoides J.Ellis to the binary expression vector via in-fusion technology and self-cleaving 2A peptides. Following Agrobacterium-mediated transformation, the engineered tomato plants predominantly produced main active ingredient crocin I, which accounted for 97–99% of the total crocins. The transgenic fruits displayed mixed red-and-golden colouration. These results highlight S. lycopersicum as a promising chassis for crocin I biosynthesis, helping to address supply constraints and enabling colour-trait breeding through synthetic biology.