Transcriptome and targeted metabolome analysis reveals sugar metabolism regulation in maize stalks at different...

The objective of this study is to investigate the regulatory mechanisms of sugar metabolism in maize stalks at varying planting densities. Targeted metabolomics and transcriptomics analyses were performed on stem samples of two varieties (M1 B12 and M2 J1590) at two planting densities (105,000 plants ha^-1 and 135,000 plants ha^-1) during the tasselling stage and grain filling stage. Combined with bioinformatics methods, these analyses elucidated sugar metabolism-related metabolites, gene expression patterns, and regulatory networks. Results showed that three structural components of the stalk accumulated significantly, sucrose content increased significantly, sucrose synthase activity decreased significantly, and sucrose phosphate synthase activity exhibited genotypic differences with increasing planting density and advancing growth stage. In targeted metabolomics, glucose was identified as the primary sugar metabolite. In transcriptome analysis, 39,757 differentially expressed genes were detected, whose expression was influenced by variety, density, and growth stage, and enriched in pathways such as hormone signal transduction, starch metabolism, and sucrose metabolism. In weighted gene co-expression network analysis, modules associated with monosaccharide metabolites were revealed, 12 sugar metabolism-related differentially expressed genes were identified, and a sugar metabolism regulatory network was constructed. These findings provide a theoretical basis for elucidating how maize stalk sugar metabolism responds to planting density. The screened candidate transcription factors offer indirect genetic resources for studying maize stalk lodging resistance mechanisms and references for improving lodging resistance in high-density maize planting.