Differential gene expression and metabolic pathways in <i>Toona sinensis</i> : Influence on colour and aroma

Toona sinensis, a plant species renowned for its culinary and medicinal properties, exhibits diverse colour variations that contribute to its aesthetic appeal and commercial value. Understanding the molecular mechanisms underlying colour and aroma traits in Toona sinensis is crucial for breeding programs and quality regulation in agriculture and the food industry. The present investigation included a comprehensive analysis of the transcriptomic and metabolomic profiles of Toona sinensis with different colours, including green, red, and red leaves with green stems. Metabolic analysis revealed that the flavonoid biosynthesis pathway governs the colour distinction between green and red Toona sinensis. The top 10 metabolites influenced by transcriptome include terpenoids (5), heterocyclic compounds (1), phenol (1), ketone (1), aldehyde (1), and alcohol (1). Fifteen highly expressed genes impacted by phenylpropanoid, sesquiterpenoid, and triterpenoid biosynthesis in coloured Toona sinensis. Functional annotation and pathway analysis revealed that terpene metabolites are predominantly synthesized via terpene metabolic pathway, involving eight key gene families. This study underscores the importance of multi-omics approaches in unravelling the genetic and metabolic basis of phenotypic traits in plant species aimed at improving colour, aroma, and nutritional quality in plants and derived products. HIGHLIGHTS: Flavonoid biosynthesis pathway governs the colour distinction between green and red Toona sinensis. The top 10 metabolites influenced by transcriptome include five terpenoids, one heterocyclic compound, one phenol, one ketone, one aldehyde, and one alcohol. Fifteen highly expressed genes impacted by phenylpropanoid, sesquiterpenoid, and triterpenoid biosynthesis in coloured Toona sinensis. Terpene metabolites are predominantly synthesized via the terpene metabolic pathway, involving eight key gene families. The net photosynthetic rate and intercellular CO₂ concentration are relatively high in the red Toon sinensis morph.