Generation of high purity capsanthin and capsorubin through synthetic metabolic engineering in carrot germplasm.

This article focuses on engineering carrot (Daucus carota L.) taproots to produce high-purity capsanthin and capsorubin, red κ-xanthophyll carotenoids typically found in red pepper (Capsicum annuum L.) and tiger lily (Lilium lancifolium Thunb.). By introducing capsanthin-capsorubin synthase genes (CaCCS from pepper and LiCCS from tiger lily) and co-expressing a carrot non-heme carotene beta-hydroxylase gene (DcBCH1), the study achieved the highest reported yield and purity of these pigments in a heterologous plant system, with up to 150.09 μg/g dry weight and 91.10% purity of total carotenoids. The engineered carrots accumulated capsanthin and capsorubin in esterified forms stored within globular chromoplasts, and the resulting germplasms offer potential for sustainable industrial extraction and breeding of novel colorful carrot cultivars. This work demonstrates carrot taproot as a promising green bioreactor alternative to red pepper for capsanthin and capsorubin production.