Long-chain acyl-CoA synthetases (LACSs) are essential enzymes that activate free fatty acids to fatty acyl-CoA thioesters, playing key roles in fatty acid (FA) catabolism, lipid synthesis and storage, epidermal wax synthesis, and stress tolerance. Despite their importance, comprehensive information about LACS genes in maize, a primary food crop, remains scarce. In the present work, eleven maize LACS genes were identified and mapped across five chromosomes. Three pairs of segmentally duplicated genes were detected in the maize LACS gene family, which underwent significant purifying selection (Ka/Ks < 1). Subsequently, phylogenetic analysis indicated that ZmLACS genes were divided into four subclasses, as supported by highly conserved motifs and gene structures. On the basis of the PlantCARE database, analysis of the ZmLACS promoter regions revealed various cis-regulatory elements related to tissue-specific expression, hormonal regulation, and abiotic stress response. RT-qPCR analysis showed that ZmLACS genes exhibit tissue-specific expression patterns and respond to diverse abiotic stresses including drought and salt, as well as phytohormone abscisic acid. Furthermore, using the STRING database, several proteins involved in fatty acid and complex lipid synthesis were identified to be the potential interaction partners of ZmLACS proteins, which was also confirmed by the yeast two-hybrid (Y2H) assay, enhancing our understanding of wax biosynthesis and regulatory mechanisms in response to abiotic stresses in maize. These findings provide a comprehensive understanding of ZmLACS genes and offer a theoretical foundation for future research on the biological functions of LACS genes in maize environmental adaptability.

Expansins contribute to maize tolerance to salt stress, but the molecular mechanisms by which they function under high-salinity conditions remain poorly understood. In this research, the α-expansin gene ZmEXPA3 was characterized. We obtained overexpression transgenic lines in maize and determined physiological and biochemical indices to elucidate its molecular role in salt stress. Our results confirmed that ZmEXPA3 functioned as a positive salt tolerance regulator and was potentially regulated by abscisic acid (ABA) and methyl jasmonate (MeJA). ZmEXPA3 located to the cytoplasm and cell wall. Overexpression of ZmEXPA3 achieved thicker cell wall and bigger cell size and thereby promoted biomass accumulation. The ZmEXPA3-OE lines showed a marked reduction in malondialdehyde (MDA) and H₂O₂ accumulation compared to the WT under salt stress. Overexpression of ZmEXPA3 elevated the enzyme activity of peroxidase (POD) and superoxide dismutase (SOD) and proline accumulation and decreased the Na⁺/K⁺ ratio in roots. Transcriptome and Gene Ontology (GO) enrichment analysis of ZmEXPA3-OE lines and WT showed that many differentially expressed genes (DEGs) were enriched in cell-wall-related terms, plant hormone response, osmotic stress response, salt stress response, oxidoreductase activity, etc. Changes in these processes may be the primary reasons why ZmEXPA3 overexpression promotes growth and salt tolerance.

The cytokinin response factors (CRFs) are pivotal players in regulating plant growth, development, and responses to diverse stresses. Despite their significance, comprehensive information on CRF genes in the primary food crop, maize, remains scarce. In this study, a genome-wide analysis of CRF genes in maize was conducted, resulting in the identification of 12 members. Subsequently, we assessed the chromosomal locations, gene duplication events, evolutionary relationships, conserved motifs, and gene structures of all ZmCRF members. Analysis of ZmCRF promoter regions indicated the presence of cis-regulatory elements associated with plant growth regulation, hormone response, and various abiotic stress responses. The expression patterns of maize CRF genes, presented in heatmaps, exhibited distinctive patterns of tissue specificity and responsiveness to multiple abiotic stresses. qRT-PCR experiments were conducted on six selected genes and confirmed the involvement of ZmCRF genes in the plant’s adaptive responses to diverse environmental challenges. In addition, ZmCRF9 was demonstrated to positively regulate cold and salt tolerance. Ultimately, we explored the putative interaction partners of ZmCRF proteins. In summary, this systematic overview and deep investigation of ZmCRF9 provides a solid foundation for further exploration into how these genes contribute to the complex interplay of plant growth, development, and responses to stress.