AUTHOR=Ahrazem Oussama , Zhu Changfu , Huang Xin , Rubio-Moraga Angela , Capell Teresa , Christou Paul , Gómez-Gómez Lourdes 

TITLE=Metabolic Engineering of Crocin Biosynthesis in Nicotiana Species

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.861140

DOI=10.3389/fpls.2022.861140

ISSN=1664-462X

ABSTRACT=<p>Crocins are high-value soluble pigments that are used as colorants and supplements, their presence in nature is extremely limited and, consequently, the high cost of these metabolites hinders their use by other sectors, such as the pharmaceutical and cosmetic industries. The carotenoid cleavage dioxygenase 2L (<italic>CsCCD2L</italic>) is the key enzyme in the biosynthetic pathway of crocins in <italic>Crocus sativus</italic>. In this study, <italic>CsCCD2L</italic> was introduced into <italic>Nicotiana tabacum</italic> and <italic>Nicotiana glauca</italic> for the production of crocins. In addition, a chimeric construct containing the <italic>Brevundimonas</italic> sp. β-carotene hydroxylase (<italic>BrCrtZ</italic>), the <italic>Arabidopsis thaliana ORANGE</italic> mutant gene (<italic>AtOrMut</italic>), and <italic>CsCCD2L</italic> was also introduced into <italic>N. tabacum</italic>. Quantitative and qualitative studies on carotenoids and apocarotenoids in the transgenic plants expressing <italic>CsCCD2L</italic> alone showed higher crocin level accumulation in <italic>N. glauca</italic> transgenic plants, reaching almost 400 μg/g DW in leaves, while in <italic>N. tabacum</italic> 36 μg/g DW was obtained. In contrast, <italic>N. tabacum</italic> plants coexpressing <italic>CsCCD2L</italic>, <italic>BrCrtZ</italic>, and <italic>AtOrMut</italic> accumulated, 3.5-fold compared to <italic>N. tabacum</italic> plants only expressing <italic>CsCCD2L</italic>. Crocins with three and four sugar molecules were the main molecular species in both host systems. Our results demonstrate that the production of saffron apocarotenoids is feasible in engineered <italic>Nicotiana</italic> species and establishes a basis for the development of strategies that may ultimately lead to the commercial exploitation of these valuable pigments for multiple applications.</p>