The Biosynthesis of Non-Endogenous Apocarotenoids in Transgenic Nicotiana glauca

Crocins are high-value compounds with industrial and food applications. Saffron is currently the main source of these soluble pigments, but its high market price hinders its use by sectors, such as pharmaceutics. Enzymes involved in the production of these compounds have been identified in saffron, Buddleja, and gardenia. In this study, the enzyme from Buddleja, BdCCD4.1, was constitutively expressed in Nicotiana glauca, a tobacco species with carotenoid-pigmented petals. The transgenic lines produced significant levels of crocins in their leaves and petals. However, the accumulation of crocins was, in general, higher in the leaves than in the petals, reaching almost 302 mu g/g DW. The production of crocins was associated with decreased levels of endogenous carotenoids, mainly beta-carotene. The stability of crocins in leaf and petal tissues was evaluated after three years of storage, showing an average reduction of 58.06 +/- 2.20% in the petals, and 78.37 +/- 5.08% in the leaves. This study illustrates the use of BdCCD4.1 as an effective tool for crocin production in N. glauca and how the tissue has an important impact on the stability of produced high-value metabolites during storage.

Automated summary

This study demonstrates the production of crocins in tobacco plants using BdCCD4.1 enzyme and highlights the higher accumulation of crocins in leaves compared to petals. The production of crocins is associated with decreased levels of beta-carotene and the stability of crocins decreases during long-term storage.