Multi-omics analysis of the metabolic and transcriptional regulatory mechanisms underlying strontium-induced anthocyanin accumulation in fresh purple maize

Fresh purple corn ( Zea mays L.) is rich in anthocyanins, and enhancing its anthocyanin content is crucial for improving its nutritional profile and commercial appeal. Strontium (Sr), an essential human micronutrient involved in physiological processes such as bone formation, exhibits low dietary bioavailability, making the consumption of Sr-enriched agricultural products a critical route for Sr supplementation. Given the biphasic effect of strontium on plant growth, characterized by low-dose stimulation and high-dose inhibition, elucidating its regulatory mechanism in fresh purple corn anthocyanin biosynthesis and breeding cultivars with dual high strontium and anthocyanin traits represents a biofortification strategy with considerable application potential. In this study, a pot experiment was conducted with fresh purple corn, and the anthocyanin and strontium contents in the kernels were quantified. To characterize the dynamic expression profiles of anthocyanin-related genes and metabolite accumulation under strontium treatment, an integrated transcriptomic and metabolomic approach was employed. Key differentially expressed genes were further validated by qRT-PCR. The results demonstrated that strontium treatment significantly increased the anthocyanin content in purple corn kernels relative to the control. Integrated multi-omics analysis revealed that strontium promotes anthocyanin synthesis by activating genes such as Zm00001d003015 , Zm00001d015513 and Zm00001d016471 , enhances the accumulation of pivotal hub metabolites (such as naringin chalcone, 4-coumaric acid), and optimizes the allocation of glycosylation donors by suppressing competing metabolic pathways such as coumarin biosynthesis. Collectively, this study provides the first systematic elucidation of how strontium, as a novel inducer, promotes anthocyanin synthesis in purple corn through a multi-level, temporally regulated network, providing a theoretical foundation and a practical biofortification strategy for developing Sr-enriched, high-anthocyanin maize.