Integrated multi-omics revealed that the RsNF-YA6-RsSUS2 pathway regulates sucrose content in fleshy taproot of...

Soluble sugar content is a key determinant of taste and flavor in radish taproots, particularly differences in sucrose content. To elucidate the regulatory mechanisms underlying sucrose accumulation in radish taproots, targeted sugar metabolomics and transcriptome analyses were performed using 'QX' (high soluble sugar and high sucrose content) and 'HG' (low soluble sugar and low sucrose content) at the mature taproot stage (90 days after sowing). Targeted metabolomics analysis identified a total of eight differentially expressed metabolites (DEMs), including five upregulated and three downregulated metabolites. Transcriptome analysis revealed 5265 upregulated genes and 5539 downregulated genes. RT-qPCR analysis displayed that there were multiple differentially expressed pivotal genes and transcription factors of sucrose metabolism. Integrated multi-omics analysis indicated that differentially expressed genes (DEGs) were predominantly enriched in fructose and mannose metabolism, galactose metabolism, and starch and sucrose metabolism pathways. Further yeast one-hybrid screening demonstrated that the RsNF-YA6 specifically binds to RsSUS2. Dual-luciferase reporter assays indicated that RsNF-YA6 significantly suppressed RsSUS2 expression, confirming its role as a negative regulatory transcription factor localized in the nucleus. The overexpression of RsNF-YA6 in Arabidopsis and radish led to a remarkable elevation in sucrose content. Collectively, these results reveal the regulatory function of the RsNF-YA6-RsSUS2 module in radish sucrose metabolism, offer novel insights into the molecular mechanisms underlying sucrose accumulation in radish taproots, and provide important genetic resources and a theoretical basis for breeding high-sucrose radish varieties.