The ethylene response factor (ERF) plays a crucial role in plant innate immunity. However, the molecular function of ERF in response to Exserohilum turcicum (E. turcicum) remains unknown in maize. In this study, a novel ERF gene, designated as ZmERF105, was firstly isolated and characterized. The ZmERF105 protein contains an APETALA2/ETHYLENE RESPONSIVE FACTOR (AP2/ERF) domain and a conserved LSPLSPHP motif in its C-terminal region. ZmERF105 protein was exclusively localized to the nucleus. ZmERF105 expression responded to E. turcicum treatment. Yeast one-hybrid and transcription activity assays revealed that ZmERF105 is an activator of transcription and binds to GCC-box elements. Over-expression of ZmERF105 was shown to increase maize resistance against E. turcicum, and erf105 mutant lines displayed opposite phenotype. Moreover, the activities of superoxide dismutase (SOD) and peroxidase (POD) in the ZmERF105 over-expression lines were markedly higher than in the wild-type maize lines (WT) after infection with E. turcicum, and were compromised in the erf105 mutant lines. Simultaneously, ZmERF105 over-expression lines enhanced the expression of several pathogenesis-related (PR) genes, including ZmPR1a, ZmPR2, ZmPR5, ZmPR10.1, and ZmPR10.2 after infection with E. turcicum. In contrast, the expression of PR genes was reduced in erf105 mutant lines. Our work reveals that ZmERF105 as a novel player of the ERF network and positively regulates the maize resistance response to E. turcicum.

Plants have evolved a series of sophisticated defense mechanisms to help them from harm. Ethylene Response Factor (ERF) plays pivotal roles in plant immune reactions, however, its underlying mechanism in maize with a defensive function to Exserohilum turcicum (E. turcicum) remains poorly understood. Here, we isolated and characterized a novel ERF transcription factor, designated ZmERF061, from maize. Phylogenetic analysis revealed that ZmERF061 is a member of B3 group in the ERF family. qRT-PCR assays showed that the expression of ZmERF061 is significantly induced by E. turcicum inoculation and hormone treatments with salicylic acid (SA) and methyl jasmonate (MeJA). ZmERF061 was proved to function as a nucleus-localized transcription activator and specifically bind to the GCC-box element. zmerf061 mutant lines resulted in enhanced susceptibility to E. turcicum via decreasing the expression of ZmPR10.1 and ZmPR10.2 and the activity of antioxidant defense system. zmerf061 mutant lines increased the expression of the SA signaling-related gene ZmPR1a and decreased the expression of the jasmonic acid (JA) signaling-related gene ZmLox1 after infection with E. turcicum. In addition, ZmERF061 could interact with ZmMPK6-1. These results suggested that ZmERF061 plays an important role in response to E. turcicum and may be useful in genetic engineering breeding.

Calmodulin (CaM) and Calmodulin-like (CML) genes are the primary families of Calcium (Ca²⁺) sensors which are found to be involved in response to various stresses. Some genes involved in Ca²⁺ signal transduction have been genome-wide characterized in various species. However, the detailed identification, characterization, and expression profilings of ZmCaM and ZmCML genes in maize remain poorly understood, especially in the response to drought stress. In this study, a total of 7 ZmCaMs and 46 ZmCMLs are identified in maize and unevenly located on 10 chromosomes. ZmCaM and ZmCML proteins are divided into 9 groups. Protein structures analysis shows that the EF-hand motif number of ZmCaMs/ZmCMLs ranges from 3 to 4 and 2 to 4, respectively. A large number of cis-regulatory elements are found in the promoter regions of ZmCaM and ZmCML genes. ZmCaM and ZmCML genes display highly diversified tissue-specific expression patterns. Furthermore, ZmCaM2, ZmCML3, ZmCML6, ZmCML8, ZmCML19, ZmCML24, ZmCML27, ZmCML28, ZmCML36, ZmCML39, and ZmCML40 are induced significantly under drought stress through RNA-seq data and RT-qPCR. Taken together, these results will help to understand the critical roles of ZmCaM and ZmCML genes played in drought resistance and provide valuable candidate genes that could be used to develop drought-resistant maize.

Low temperature during early spring severely impairs maize germination, leading to significant yield losses. To elucidate the mechanisms underlying cold tolerance at the germination stage, we compared two cold-tolerant maize inbred lines (AM and CM) with a cold-sensitive line (BM) under control (25 °C) and chilling (6 °C) conditions. Phenotypic observations showed that AM and CM maintained high germination rates and exhibited enhanced coleoptile elongation under cold stress, whereas BM displayed substantial growth inhibition. Cold-tolerant lines accumulated less malondialdehyde and showed markedly higher SOD and POD activities, indicating a stronger antioxidant defense. Transcriptome profiling revealed that cold tolerance is associated with a more robust transcriptional response in AM and CM, characterized by significant activation of the phenylpropanoid and flavonoid biosynthesis pathways. Among the differentially expressed genes, the class III peroxidase gene ZmPER5 was strongly upregulated in AM and CM but only weakly induced in BM, suggesting its central role in reinforcing the cell wall structure and enhancing ROS-scavenging capacity under chilling conditions. Other lignin- and flavonoid-related genes, including ZmHCT4 and ZmCYP75, also exhibited genotype-specific induction patterns consistent with cold tolerance. qRT-PCR validation confirmed the RNA-seq expression trends. These results demonstrate that maize cold tolerance during germination relies on the coordinated enhancement of antioxidant enzyme activity, activation of phenylpropanoid-derived lignin biosynthesis, and accumulation of protective flavonoids. The identified candidate genes, especially ZmPER5, provide valuable targets for improving cold tolerance in maize breeding.

Drought stress is one of the important abiotic stresses that affects maize production. As an important Ca²⁺ sensor, calmodulin-like proteins (CMLs) play key roles in plant growth, development, and stress response, but there are a limited number of studies regarding CMLs in response to drought stress. In this study, a Calmodulin-like gene, namely ZmCML3, was isolated from maize (Zea mays L.). The coding sequence (CDS) of ZmCML3 was 474 bp and a protein of 158 aa which contains three EF-hand motifs. ZmCML3 was localized within the nucleus and plasma membrane. The expression of ZmCML3 was induced by polyethylene glycol (PEG) 6000, NaCl, methyl jasmonate (MeJA), and abscisic acid (ABA). Overexpression of ZmCML3 resulted in enhanced drought tolerance in maize through increasing proline (Pro) content and the activity of peroxide (POD) and superoxide dismutase (SOD). Meanwhile, ZmCML3 also positively regulated the expression of drought stress-responsive genes in maize under drought stress treatment. Taken together, ZmCML3 acts as a positive regulator in maize response to drought stress. These results will provide theoretical basis for breeding drought tolerance maize variety.

Phytophthora root and stem infection by Phytophthora sojae is a global and devastating disease of soybeans. Selecting disease-resistant varieties is the most economical and effective measure for controlling this disease. Delving into the disease resistance and defense molecular mechanisms can lay a theoretical foundation for solving this problem. Here, we screened the soybean genome and identified 78 GmDof genes distributed on nineteen chromosomes. Subcellular localization analysis revealed that the majority of GmDof proteins were located in the cell nucleus. Phylogenetic analysis categorized these genes into nine subfamilies. Gene structure analysis showed that all GmDofs contained 0 to 2 introns, and most of them did not have introns. Motif and conserved domain analysis showed that all GmDofs contained a common motif (motif-1) and a typical conserved C₂-C₂ domain. The prediction of cis-acting elements in promoter regions revealed numerous cis-regulatory elements responsible for stress responses, plant growth and development, plant hormone responses, and light responses. RNA-seq and quantitative real-time PCR results showed that GmDof63 (Glyma.16G145000) was specifically expressed at high levels after P. sojae infection. GmDof63 was strongly induced by SA and ETH treatments. The soybean seedlings overexpressing GmDof63 displayed enhanced resistance to P. sojae infection compared with the wild-type soybean seedlings. Further experiments indicated that the expression levels of pathogenesis-related protein genes PR1a, PR4, PR5a, and PR10 were significantly up-regulated in GmDof63-overexpressing transgenic soybean seedlings. Taken together, these findings reveal the mechanism by which GmDof63 directly or indirectly regulates the expression of PR genes to modulate the soybean response to P. sojae infection.