Panicle traits are important factors affecting yield, and their improvement has long been a critical goal in foxtail millet breeding. In order to understand the genetic basis of panicle formation, a large-scale genome-wide association study (GWAS) was performed in this study for six panicle-related traits based on 706,646 high-polymorphism SNP loci in 407 accessions. As a result, 87 quantitative trait loci (QTL) regions with a physical distance of less than 100 kb were detected to be associated with these traits in three environments. Among them, 27 core regions were stably detected in at least two environments. Based on rice–foxtail millet homologous comparison, expression, and haplotype analysis, 27 high-confidence candidate genes in the QTL regions, such as Si3g11200 (OsDER1), Si1g27910 (OsMADS6), Si7g27560 (GS5), etc., affected panicle-related traits by involving multiple plant growth regulator pathways, a photoperiod response, as well as panicle and grain development. Most of these genes showed multiple effects on different panicle-related traits, such as Si3g11200 affecting all six traits. In summary, this study clarified a strategy based on the integration of GWAS, a homologous comparison, and haplotype analysis to discover the genomic regions and candidate genes for important traits in foxtail millet. The detected QTL regions and candidate genes could be further used for gene clone and marker-assisted selection in foxtail millet breeding.

A water-soluble polysaccharide from foxtail millet (FM-D1) was isolated and purified through gradient ethanol precipitation and column chromatography. Size-Exclusion Chromatography–Multi-Angle Light Scattering–Refractive Index (SEC-MALLS-RI) and high-performance anion-exchange chromatography (HPAEC) analyses revealed that FM-D1 constitutes a highly purified neutral polysaccharide exclusively composed of glucose as the sugar unit, with a molecular weight of 14.823 kDa. The structural characterization results obtained from gas chromatography–mass spectrometer (GC–MS) and nuclear magnetic resonance spectroscopy (NMR) spectra suggest that FM-D1 primarily consists of a main chain linked by →4)-α-D-Glcp-(1→ and minor quantities of →4,6)-α-D-Glcp-(1→ to form the main chain, with branching mainly composed of α-D-Glcp-(1→ attached to the O-6 position of →4,6)-α-D-Glcp-(1→ sugar residues. Based on these findings, the antioxidant and immunomodulatory activities of FM-D1 were evaluated in vitro. The results indicated that FM-D1 exhibited moderate 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) radical scavenging capacity and total antioxidant capacity (TAOC). Furthermore, FM-D1 stimulated macrophage proliferation and inhibited the production of nitric oxide (NO) and inflammatory factors (TNF-α, IL-1β, and IL-6) in lipopolysaccharide (LPS)-stimulated RAW 246.7 cells. Overall, the findings of this study suggest that foxtail millet holds promise as a potential antioxidant agent and immunologic substance in functional foods.

Foxtail millet is a plant that is highly drought-resistant and rich in nutrients. Its grain structure traits are linked with water uptake during grain germination, which is closely related to plant density for high yield under rain fed regions; however, there is no related research. Using Micro-CT technology, we investigated a total of 15 internal structure traits of foxtail millet grains, such as the volume and surface area of the embryo, endosperm, cavity, hull, and whole grain, and mapped relevant quantitative trait loci (QTLs) using recombination inbred lines (RILs). With phenotypic variations in these traits and genome sequences of 100 foxtail millet RILs, four QTLs were identified. In combination with transcriptome profiling during grain development, we identified seven candidate genes that may play a role in the regulation of grain structure in foxtail millet.