Construction and preliminary characterization of an early generation multi-parent sorghum bicolor population for climate-adaptive breeding

Abstract Multi-parent populations can broaden allelic diversity and recombination available for genetic analysis and crop improvement. In this study, we developed and preliminary characterized an early generation partially developed multi-parent advanced generation intercross (pMAGIC) population for sorghum ( Sorghum bicolor (L.) Moench) derived from eleven genetically diverse founder lines selected for complementary agronomic traits, including drought tolerance, stay-green, early maturity, and high yield. The population, comprised 176 S₂-derived lines and the eleven founders, with Gadam included as a local check. Genotyping using DArTseq technology identified 5,512 high-quality SNP markers, with moderate polymorphic information content (PIC) across the population. Population structure analyses revealed residual genetic differentiation among nine sub-groups (F st = 0.16) and admixture among progenies, consistent with contribution of multiple founders. Days to flowering (DTF), used as a proof-of-concept trait, was evaluated across multiple environments for and substantial phenotypic variation among the S 2 -derived lines, including transgressive segregation beyond parental ranges, demonstrating the enhanced recombination and allelic diversity captured in the pMAGIC population. Genome-wide linkage disequilibrium declined to half of its maximum value at approximately 339.34 kb. Exploratory genome-wide association analysis (GWAS) identified nine significant SNPs associated with DTF across multiple chromosomes, with several associated intervals containing candidate genes with reported roles in flowering time regulation, including photoreceptor signaling and transcriptional regulation. These finding demonstrate that the population has retained substantial genetic and phenotypic diversity during early-generation development and provides a useful foundation for further population advancement and genetic analysis. Continued selfing, population expansion, and higher-density genotyping are expected to enhance its resolution and utility for dissecting complex agronomic traits in sorghum.