Maize is an essential staple food, and its genetic diversity plays a central role in breeding programs aimed at developing climate-adapted cultivars. Constructing a representative core germplasm set is necessary for the efficient conservation and utilization of maize genetic resources. In this study, we analyzed 588 cultivated maize accessions using agronomic traits such as plant morphology and yield traits such as ear characteristics and single-nucleotide polymorphisms (SNPs) to assess molecular diversity and population structure and to construct a core collection. Nineteen phenotypic traits were evaluated, revealing high genetic diversity and significant correlations among most quantitative traits. The optimal sampling strategy was identified as “Mahalanobis distance + 20% + deviation sampling + flexible method.” Whole-genome genotyping was conducted using the Maize6H-60K liquid phase chip. Population structure analysis, principal component analysis, and cluster analysis divided the 588 accessions into six subgroups. A core collection of 172 accessions was selected based on both phenotypic and genotypic data. These were further evaluated for salt–alkali tolerance during germination, and cluster analysis classified them into five groups. Sixty-five accessions demonstrated salt–alkali tolerance, including 18 with high resistance. This core collection serves as a valuable foundation for germplasm conservation and utilization strategies.

MYB transcription factors constitute a diverse and functionally versatile family, playing central roles in regulating plant responses to a range of abiotic stressors. Based on previous research, we identified and characterized a maize MYB transcription factor gene, ZmMYBR24, which is involved in responses to salt, alkali, and low-temperature stress. This study aimed to investigate the function and mechanism of ZmMYBR24 in response to salt, alkali, and low-temperature stresses. We hypothesized that ZmMYBR24 regulates biosynthetic pathways to influence maize resistance to multiple abiotic stresses. The results indicate that ZmMYBR24 expression was markedly upregulated (p < 0.01) and the fold-change in gene expression ranged from 1.54 to 25.69 when plants were exposed to these combined stresses. Phenotypically, the zmmybr24 mutant line exhibited more pronounced inhibition of seedling and root growth under stress compared to the wild-type B73 line. Based on a correlation expression pattern analysis and mutant line evaluation, ZmMYBR24 was confirmed to be a positive regulatory transcription factor for multiple types of abiotic stress resistance. An RNA-seq analysis of both lines revealed differentially expressed genes (DEGs), with gene ontology (GO) and KEGG enrichment analyses indicating that ZmMYBR24 may mediate stress responses by modulating the expression of genes involved in flavonoid biosynthesis. Notable differences were observed in the expression of pathway-associated genes between the mutant and wild-type plants. A haplotype analysis across 80 inbred maize lines revealed 16 ZmMYBR24 coding region haplotypes—comprising 25 SNPs and 17 InDels—with HAP12 emerging as a superior haplotype. These results demonstrate that ZmMYBR24 enhances maize yields by regulating the flavonoid biosynthesis pathway in response to adverse climatic conditions including salt, alkaline conditions, and low temperatures. Collectively, these findings offer novel insights into the molecular mechanisms underlying maize adaptation to combined abiotic stresses and lay the groundwork for breeding programs targeting multi-stress resistance.

Maize is one of the most widely cultivated crops worldwide and is extensively used for animal feed and industrial applications. Plant height (PH) and ear height (EH) are critical determinants of lodging resistance and tolerance to high planting density, and coordinated regulation of these traits is essential for yield improvement. In this study, 479 maize inbred lines from Northeast and North China were genotyped using 7861 single-nucleotide polymorphism (SNP) markers to perform a genome-wide association study (GWAS). After controlling for population structure and relatedness, the mixed linear model (MLM) identified 20 loci significantly associated with PH on chromosomes 2, 4, 5, 6, 7, and 8, and 8 loci associated with EH on chromosomes 2, 3, 4, and 7. A total of 23 candidate genes were identified, including PLATZ8, pectin methylesterase 36, and leucine-rich repeat extensin 14. Gene Ontology (GO) enrichment analysis revealed significant enrichment in biological and molecular functions such as DNA binding, pectinesterase activity, zinc ion binding, ATP binding, and uniporter activity. Bioinformatic characterization of the two most likely candidate genes, Zm00001d002726 and Zm00001d015394, showed that both possess a typical compact four-exon structure. Functional prediction indicated that Zm00001d002726 encodes a pectinesterase/pectinase, potentially regulating cell elongation through pectin degradation and remodeling of the cell wall. Pectinesterase activity may influence PH and EH by mediating pectin demethylation within the cell wall. In contrast, Zm00001d015394 encodes a PLATZ family transcription factor that may regulate downstream gene expression through DNA-binding activity. These findings provide insight into the genetic architecture and potential molecular mechanisms underlying PH and EH in maize and offer a foundation for future breeding efforts.