Lowering phytoene synthase adjusts a plant pigment signal that controls key light response regulators and chloroplast development

Four genetic variants of the phytoene synthase enzyme were identified, impacting carotenoid composition and plastid development in plants.

• The identified variants were linked to rescued leaf virescence phenotypes and plastid abnormalities in a mutant plant under shorter photoperiod conditions.
• These mutations affected processes such as alternative splicing and enzyme interactions without changing the enzyme's location within the plant cells.
• Specific acyclic linear cis-carotenes associated with an unidentified apocarotenoid signal were reduced, which may influence plastid biogenesis and chlorophyll synthesis.
• The variants modulated the ratio of two proteins involved in light response, suggesting a regulatory role in seedling development.
• Normal prolamellar body formation and chlorophyll accumulation during seedling growth were observed, indicating functional plastid development despite reduced phytoene synthase activity.

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