Xiangwei Hu

Drought limits the stability of foxtail millet production and the efficient use of germplasm resources, yet whether drought-tolerant and drought-sensitive accessions engage fundamentally distinct pathways or a shared, quantitatively reprogrammed network remains unclear. We generated 36 leaf transcriptomes from three drought-sensitive (DSEN) and three drought-tolerant (DTOL) accessions under well-watered (WW) and drought-stress (DS) conditions, retaining 25,099 genes for downstream analyses. Principal component analysis confirmed water treatment as the primary driver of global expression variation. DS-versus-WW comparisons identified 10,635 and 6215 drought-responsive DEGs in the DSEN and DTOL groups, respectively, with 5195 shared and a genome-wide response correlation of 0.791. Crucially, accession-level tests revealed no significant DEGs between groups under WW, only 22 under DS, and none for the group × drought-response interaction, underscoring the absence of qualitative pathway shifts. Functional enrichment analyses jointly indicated suppression of photosynthesis and translation, accompanied by reprogramming of carbohydrate metabolism, membrane lipid remodeling, phenylpropanoid and secondary metabolism, protein homeostasis, and stress signaling. WGCNA partitioned 10,000 highly variable genes into 16 modules. The blue module, which showed the strongest drought response in DSEN, was enriched for cell-wall and carbohydrate metabolism, membrane lipid processes, and stress-protection pathways, whereas the brown module, which responded most robustly in DTOL, was enriched for calcium signaling, protein phosphorylation/dephosphorylation, transcriptional regulation, proline biosynthesis, and dehydration protection. The yellow and cyan modules exhibited the largest between-group effect sizes under drought but failed multiple-testing correction, remaining candidate networks. Collectively, our results support a model of shared core response with divergent regulatory intensity, where sensitive accessions undergo broader transcriptional perturbation, while tolerant ones deploy more concentrated and coordinated modules. This study provides modular targets for drought-tolerance breeding and highlights the necessity of accession-level replication and conservative statistical inference in comparative transcriptomics.

Abiotic stresses caused by climate change pose a significant challenge to global food security, making it necessary to develop stress-resistant crops. Foxtail millet (Setaria italica (L.) P. Beauv.) is a drought-tolerant C₄ cereal and serves as a model crop for elucidating stress adaptation mechanisms and promoting climate-resilient agricultural solutions. This paper reviews the tolerance mechanisms of foxtail millet to abiotic stresses. Physiologically, the species exhibits excellent water-use efficiency, requiring 75% less irrigation than traditional cereals, achieved through enhanced osmotic adjustment via soluble substance accumulation and the maintenance of ion homeostasis. Morphological adaptations include reduced leaf area, adjusted stomatal density, well-developed root systems, and specialized anatomical features that optimize water conservation. At the molecular level, stress tolerance involves complex transcriptional networks mediated by multiple transcription factor family members, including those (NF-Y, DREB, NAC, WRKY, MYB) that coordinate stress-responsive gene expression, antioxidant defense systems, and osmotic adjustment pathways. Furthermore, this review summarizes multi-omics characteristics, including genomics (such as QTL mapping and GWAS), proteomics, transcriptomics, metabolomics, and regulatory networks, for foxtail millet under abiotic stress tolerance. Additionally, reproductive resilience is maintained through efficient mobilization of stem reserves to panicles, phenological plasticity in flowering timing, and preserved gametic viability under thermal stress. Combining advanced molecular breeding with the inherent tolerance of foxtail millet positions this crop as both a solution to climate change and a genetic resource for enhancing the stress resistance of other cereals. These findings establish foxtail millet as a valuable model for developing sustainable agricultural technologies essential for food security under projected climate scenarios.

Foxtail millet ( Setaria italica L.), known for its climate resilience and dual‐purpose utility, is underutilized in breeding programs despite its agricultural potential. To address this, a comprehensive evaluation of 260 accessions from 19 countries was undertaken to assess phenotypic diversity and identify elite germplasms for breeding. Field‐based assessments were conducted using 22 traits (8 quantitative and 14 qualitative) measured at seedling and maturity stages. Data were analysed using genetic diversity indices, correlation analysis, principal component analysis (PCA) and hierarchical clustering. Seven traits showed high variability, with yield (CV: 25.92%), grain weight per panicle and single panicle weight being most diverse. Yield positively correlated with plant architecture, panicle structure and biomass traits. PCA revealed four principal components explaining 80.20% of the total variation. Cluster analysis grouped accessions into four phenotypically distinct clusters. The study identified four key groups of accessions: lodging‐resistant, dual‐purpose high‐yielding, early‐maturing and agronomically balanced types. This integrative phenotypic analysis enables efficient identification of superior accessions and supports targeted breeding and conservation strategies to improve foxtail millet adaptation and productivity across diverse agroecological zones.