The organizational trends of the grain metabolome in the sorghum association panel

Despite the rich metabolic profile of sorghum [Sorghum bicolor (L.) Moench], containing unique bioactive compounds and high antioxidant potential, its full exploitation as a breeding resource remains underexplored. This study shifts the understanding of sorghum grain biochemical profiles from discrete compound catalogues to network topology, utilizing non-targeted metabolomics to reveal systems-level insights into metabolomic architecture. Liquid chromatography-mass spectrometry (LC-MS) generated metabolomic profiles of an expanded Sorghum Association Panel (SAP) containing 407 accessions. Across the SAP, anthocyanin biosynthesis, flavonoid biosynthesis, cysteine and methionine metabolism, and aminoacyl-tRNA biosynthesis demonstrated consistent enrichment in multiple subpopulations, though levels varied substantially between races, panicle structures, and grain colors. Compact and semi-compact panicle morphologies showed the most widespread metabolic pathway enrichment, while white grain demonstrated the lowest pathway diversity despite exhibiting the highest anthocyanin biosynthesis enrichment. Building on these baseline metabolomic patterns, sorghum grain mold (SGM) tolerant (Tx2911) and susceptible (P850029) check lines underwent Fusarium inoculation and fumonisin quantification to examine how metabolomic variation correlates with environmental stress responses. SGM involves a multi-species fungal complex dominated by Fusarium, causing 30-100 % yield losses in susceptible genotypes and inducing extensive biochemical reprogramming, making it an ideal system for studying metabolic plasticity in the host. Metabolomic profiling revealed that grain mold-tolerant Tx2911 accumulated higher fumonisin levels despite elevated defensive metabolites, namely flavonoids. Collectively, these findings underpin the development of a pathway-resolved, phenotype-correlated metabolomic atlas, enriching an established community resource with a novel and accessible 'omics layer to empower metabolomics-assisted breeding for the creation of improved, resilient sorghum varieties.