Regulation of apocarotenoids for quality improvement and biofortification of horticultural crops

Agro-food production and consumption impact climate change and human health. Bioactive secondary metabolites in horticulture crops make them an indispensable part of environmentally sustainable and healthy diet. Among them, apocarotenoids from carotenoid degradation are promising in promoting a preference for plant-based foods over other metabolites.

In horticulture crops, carotenoids are vital for photosynthesis and antioxidant defense, but their enzymatic or oxidative metabolites, apocarotenoids, offer greater structural diversity and biological functions. They serve as pigments, scents, signaling molecules, and growth regulators in crop growth and development and provide antioxidant, nutraceutical, and pharmaceutical benefits to human health. The carotenoids as bioactive compounds are well understood. By contrast, much less is explored and reviewed about apocarotenoids.

Recently identified metabolic pathways and components of apocarotenoids are reviewed. Their significance for quality formation in horticulture crops, including the regulation of pigmentation, aroma, flavor, architecture, nutrition value, and broader ecological interactions is discussed. Additionally, this review specifically highlights two representative apocarotenoids, retinal and abscisic acid (ABA), that exhibit conserved yet distinct regulatory functions across plant and animal kingdoms. Comprehensive dissection of apocarotenoid metabolism and their regulatory mechanisms will enhance apocarotenoid biofortification and subsequent biotechnological exploitation in horticultural commodities. We put forward the perspective that apocarotenoids could enhance horticultural crop quality and then promote sensory- and health-driven dietary choices which will in turn increase consumption and production of horticultural plants and promote both human and ecosystem health.