The carotenoids metabolism during tomato fruit ripening: insights into multi-level regulatory network

Carotenoids play an indispensable positive role in human nutrition and health. Understanding the biosynthesis and catabolism pathways of carotenoids in tomato fruits has practical value and fundamental importance. Carotenoid biosynthesis and catabolism are developmental program regulated at multiple levels. In recent years, numerous studies have explored the dynamic interactions between phytohormones, transcription factors, and epigenetic modifications to establish a regulatory network for carotenoid accumulation. However, understanding the regulation of the diversity and complexity of carotenoid accumulation remains incomplete. In this review, we summarize the molecular mechanisms of plastid storage capacity, phytohormones, epigenetic modifications, and transcription factors in regulating carotenoid biosynthesis and metabolism in tomato fruit. These insights offer foundational research and considerations for metabolic engineering aimed at altering carotenoid composition and content in tomatoes. We have also identified several unresolved issues for future research, which will help to better understand the factors regulating carotenoid accumulation in tomato fruits.