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 <i>Solanum lycopersicum</i> L. by introducing the <i>GjCCD4a</i>, <i>GjALDH2C3</i>, <i>GjUGT74F8</i> and <i>GjUGT94E13</i> of <i>Gardenia jasminoides</i> J.Ellis to the binary expression vector via in-fusion technology and self-cleaving 2A peptides. Following <i>Agrobacterium</i>-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 <i>S. lycopersicum</i> as a promising chassis for crocin I biosynthesis, helping to address supply constraints and enabling colour-trait breeding through synthetic biology.