Search Results (103)

The rapid evolution of pathogens and the limited genetic diversity of hosts are two major factors contributing to the plant pathogenic phenomenon known as the loss of disease resistance in maize (Zea mays L.). It has emerged as a significant biological stressor threatening the global food supplies and security. Based on previous cross-species homologous gene screening assays conducted in the laboratory, this study identified the maize disease-resistance candidate gene ZmNLR-7 to investigate the maize immune regulation mechanism against Bipolaris maydis. Subcellular localization assays confirmed that the ZmNLR-7 protein is localized in the plasma membrane and nucleus, and phylogenetic analysis revealed that it contains a conserved NB-ARC domain. Analysis of tissue expression patterns revealed that ZmNLR-7 was expressed in all maize tissues, with the highest expression level (5.11 times) exhibited in the leaves, and that its transcription level peaked at 11.92 times 48 h post Bipolaris maydis infection. Upon inoculating the ZmNLR-7 EMS mutants with Bipolaris maydis, the disease index was increased to 33.89 and 43.33, respectively, and the lesion expansion rate was higher than that in the wild type, indicating enhanced susceptibility to southern corn leaf blight. Physiological index measurements revealed a disturbance of ROS metabolism in ZmNLR-7 EMS mutants, with SOD activity decreased by approximately 30% and 55%, and POD activity decreased by 18% and 22%. Moreover, H₂O₂ content decreased, while lipid peroxide MDA accumulation increased. Transcriptomic analysis revealed a significant inhibition of the expression of the key genes NPR1 and ACS6 in the SA/ET signaling pathway and a decrease in the expression of disease-related genes ERF1 and PR1. This study established a new paradigm for the study of NLR protein-mediated plant immune mechanisms and provided target genes for molecular breeding of disease resistance in maize. Overall, these findings provide the first evidence that ZmNLR-7 confers resistance to southern corn leaf blight in maize by synergistically regulating ROS homeostasis, SA/ET signal transduction, and downstream defense gene expression networks. Full article

The SCARECROW (SCR) transcription factor governs cell-type patterning in plant roots and Kranz anatomy of leaves, serving as a master regulator of root and shoot morphogenesis. Foxtail millet (Setaria italica), characterized by a compact genome, self-pollination, and a short growth cycle, has emerged as a C₄ model plant. Here, we revealed two SCR paralogs in foxtail millet—SiSCR1 and SiSCR2—which exhibit high sequence conservation with ZmSCR1/1h (Zea mays), OsSCR1/2 (Oryza sativa), and AtSCR (Arabidopsis thaliana), particularly within the C-terminal GRAS domain. Both SiSCR genes exhibited nearly identical secondary structures and physicochemical profiles, with promoter analyses revealing five conserved cis-regulatory elements. Robust phylogenetic reconstruction resolved SCR orthologs into monocot- and dicot-specific clades, with SiSCR genes forming a sister branch to SvSCR from its progenitor species Setaria viridis. Spatiotemporal expression profiling demonstrated ubiquitous SiSCR gene transcription across developmental stages, with notable enrichment in germinated seeds, plants at the one-tip-two-leaf stage, leaf 1 (two days after heading), and roots during the seedling stage. Co-expression network analysis revealed that there is a correlation between SiSCR genes and other functional genes. Abscisic acid (ABA) treatment led to a significant downregulation of the expression level of SiSCR genes in Yugu1 roots, and the expression of the SiSCR genes in the roots of An04 is more sensitive to PEG6000 treatment. Drought treatment significantly upregulated SiSCR2 expression in leaves, demonstrating its pivotal role in plant adaptation to abiotic stress. Analysis of heterologous expression under the control of the 35S promoter revealed that SiSCR genes were expressed in root cortical/endodermal initial cells, endodermal cells, cortical cells, and leaf stomatal complexes. Strikingly, ectopic expression of SiSCR genes in Arabidopsis led to hypersensitivity to ABA, and ABA treatment resulted in a significant reduction in the length of the meristematic zone. These data delineate the functional divergence and evolutionary conservation of SiSCR genes, providing critical insights into their roles in root/shoot development and abiotic stress signaling in foxtail millet. Full article

Maize (Zea mays L.) seedlings are highly susceptible to low-temperature stress, which significantly impacts maize yield and quality. A zinc finger protein transcription factor (ZmZFP69) mutant and a control (B73) maize inbred line were subjected to low-temperature treatment, and changes in the phenotypic characteristics, hormone levels, and other indicators before and after the treatment were systematically identified. Subsequently, a combined RNA-seq and DAP-seq analysis was conducted to explore the influence of ZmZFP69 on the promoters of downstream genes. Finally, the proteins interacting with ZmZFP69 were examined using InterProDesign combined with BiFC and subcellular localization. The zmzfp69 homozygous mutant maize inbred line exhibited enhanced low-temperature tolerance compared to the control. RNA-seq and DAP-seq analyses revealed that ZmZFP69 binds to the ZmAOX2 gene promoter, significantly suppressing its expression. The interaction between ZmZFP69 and the downstream protein ZmBG6 was confirmed by InterProDesign, subcellular localization, and BiFC assays. ZmZFP69 negatively regulates maize seedling low-temperature tolerance by inhibiting ZmAOX2 expression and interacting with ZmBG6. Full article

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. Full article

Hydroxyproline O-arabinosyltransferase (HPAT), a critical enzyme in plant glycosylation pathways, catalyzes the transfer of arabinose to the hydroxyl group of hydroxyproline residues. This enzyme contains a canonical GT95 glycosyltransferase, a structural hallmark of this carbohydrate-active enzyme family. HPAT mediates arabinosylation of diverse cellular targets, including cell wall extension and small signaling peptides. Emerging evidence has shown that HPAT orthologs regulate plant development and symbiotic interactions through post-translational modification of CLV1/LRR Extracellular (CLE) peptides. Although the molecular functions of HPAT genes have been characterized in model plants such as Arabidopsis thaliana and Lotus japonicus, their roles remain unexplored in Zea mays L. In this study, we used ZmHPAT2 homozygous mutants to explore the function of the maize HPAT gene. Sequence analysis identified a N-terminal signal peptide targeting the Golgi apparatus and promoter elements responsive to AM fungal colonization. Phenotypic analysis revealed its negative regulatory role: zmhpat2 promotes vegetative growth (increased plant height and accelerated flowering) and enhances AM symbiosis (increased colonization rate). Mechanistic studies demonstrated that ZmHPAT2 possesses dual regulatory functions—the activation of auxin signaling and repression of ZmMYB1-mediated arbuscular degradation pathways. In addition, overexpression of ZmHPAT2 in Lotus japonicus inhibits growth (reduced plant height) and impairs symbiotic interactions. Our findings establish ZmHPAT2 as a critical node to regulate auxin and symbiotic signaling, providing novel insights into plant glycosylation-mediated development. This work not only advances our understanding of maize growth regulation but also identifies potential targets for crop improvement through arabinosylation pathway manipulation. Full article

Despite substantial progress in elucidating the stress-responsive mechanisms of 4-coumarate-CoA ligases (4CL) in various plant species, the maize (Zea mays L.) 4CL gene family remains underexplored, leaving a significant gap in our comprehension of its potential roles in abiotic stress tolerance and adaptive strategies. Through comprehensive genome-wide analysis, we identified and characterized 32 putative 4CL genes in maize, which were phylogenetically classified into seven distinct clades. Members within the same clade exhibited conserved gene structures and motif compositions. Expression profiling across various maize tissues and under multiple abiotic stress conditions revealed specific 4CL genes associated with stress tolerance. Notably, promoter analysis identified numerous stress-responsive cis-regulatory elements in Zm4CL genes. Among the identified genes, six exhibited significant induction under salt stress, while five showed upregulation during drought conditions. Particularly, Zm4CL8, a member of the 4CL clade, demonstrated dual responsiveness to both drought and salt stresses. Functional characterization through virus-induced gene silencing (VIGS) revealed that Zm4CL8-silenced plants displayed enhanced sensitivity to both drought and salt stresses, as evidenced by significantly reduced chlorophyll content and survival rate, which collectively suggests its positive regulatory role in stress adaptation mechanisms. These findings establish Zm4CL8 as a promising molecular target for enhancing drought and salt tolerance in maize, while significantly advancing our understanding of the functional characterization of 4CL genes in this crucial crop species. Full article

Isopentyltransferase (IPT) is a key rate-limiting enzyme in cytokinin synthesis, playing a crucial role in plant growth, development, and response to adverse conditions. Although the IPT gene family has been studied in various plants, comprehensive identification and functional characterization of IPT genes in maize (Zea mays) remain underexplored. In this study, ten IPT gene family members (ZmIPT1–ZmIPT10) were identified in the maize genome, and their gene structure, physicochemical properties, evolutionary relationships, expression patterns, and stress response characteristics were systematically analyzed. The ZmIPT genes were found to be unevenly distributed across six chromosomes, with most proteins predicted to be basic and localized primarily in chloroplasts. Phylogenetic analysis grouped the ZmIPT family into four subfamilies, showing close evolutionary relationships with rice IPT genes. Conserved motif and gene structure analyses indicated that the family members were structurally conserved, with five collinear gene pairs being identified. Ka/Ks analysis revealed that these gene pairs underwent strong purifying selection during evolution.Cis-element analysis of promoter regions suggested that ZmIPT genes are widely involved in hormone signaling and abiotic stress responses. Tissue-specific expression profiling showed that ZmIPT5, ZmIPT7, and ZmIPT8 were highly expressed in roots, with ZmIPT5 exhibiting consistently high expression under multiple abiotic stresses. qRT-PCR validation confirmed that ZmIPT5 expression peaked at 24 h after stress treatment, indicating its key role in long-term stress adaptation. Protein interaction analysis further revealed potential interactions between ZmIPT5 and cytokinin oxidases (CKX1, CKX5), as well as FPP/GGPP synthase family proteins, suggesting a regulatory role in cytokinin homeostasis and stress adaptation. Overall, this study provides comprehensive insights into the structure and function of the ZmIPT gene family and identifies ZmIPT5 as a promising candidate for improving stress tolerance in maize through molecular breeding. Full article

The normal development of maize (Zea mays) seedling is a prerequisite for achieving high crop yields. Although numerous molecular pathways regulate seedling development, the role of RNA polymerases (RNAPs) in this process remains largely unclear, and the function of common RNAP subunits in plants are not well understood. Here, we characterized the loss-of-function mutant of common subunit ZmRPABC5b, defective kernel 701 (dek701), which displays delayed seedling development. To elucidate the role of ZmRPABC5b in maize seedling growth, we conducted transcriptomic and metabolomic analyses. This study found that the loss of ZmRPABC5b function severely impaired early seedling growth, leading to significant reductions in stem length, root length, as well as fresh and dry weight. Transcriptome analysis identified 3780 upregulated and 4385 downregulated differentially expressed genes (DEGs) in dek701 seedlings compared to wild type. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of DEGs revealed that significant enrichment in pathways related to RNA biosynthesis, carbohydrate metabolic, hormone stimulus, cellular transporter and ribosome activity. Metabolome analysis identified 501 differentially expressed metabolites (DEMs) in dek701 seedlings, which were significantly enriched in the amino acid metabolism, secondary metabolites, carbohydrate metabolism, lipid metabolism, transport and translation. These findings provide substantial insight into the ZmRPABC5b regulatory network, positioning it as a central hub for regulating seedling development in maize. Full article

Calmodulin (CaM) family members play crucial roles in the response to various abiotic stresses. However, the functions of CaMs in the response to drought stress in maize are unclear. In this study, a CaM gene, ZmCaM2-1, was isolated from the maize (Zea mays L.) inbred line B73. The coding sequence (CDS) of ZmCaM2-1 was 450 bp with a protein of 149 aa which contains four EF-hand motifs. The ZmCaM2-1 protein was located in the cell nucleus and membrane, and is able to bind to Ca²⁺. ZmCaM2-1 was strongly induced by drought, NaCl, and low-temperature treatments, except for abscisic acid (ABA) treatment. Overexpression of ZmCaM2-1 in Arabidopsis was found to decrease the drought tolerance with lower antioxidant enzyme activity and greater reactive oxygen species (ROS) production. Moreover, there was no significant difference in the phenotype and ABA-related gene expression levels between ZmCaM2-1-overexpressing Arabidopsis and the wild type (WT) under ABA treatment. These results indicate that ZmCaM2-1 negatively regulates the tolerance of Arabidopsis to drought stress through the ABA-independent pathway. Full article

The photosynthetic system of maize (Zea mays) leaves is sensitive to low temperatures and suffers from irreversible damage induced by cold exposure, making cold stress a major factor limiting maize yield. Identifying genes that improve the recovery of photosynthesis from low temperatures in maize will help enhance the cold tolerance of this crop and ensure stable yields. Here, we demonstrate the role of starch phosphorylase 2 (ZmPHOH) in promoting photosynthetic recovery from cold damage. Chlorotic leaf3 (chl3), a null mutant of ZmPHOH, which undergoes chlorophyll degradation and chlorosis earlier than under normal growth conditions after brief exposure to 8 °C and restoration to normal. We determined that chl3 plants could not repair the damage to their photosynthetic system caused by short-term cold exposure after the temperature returned to normal. Metabolome and transcriptome profiling indicated that the soluble sugar content in chl3 leaves was significantly increased after cold treatment and could not be catabolized promptly, leading to repression of photosynthetic gene expression. Our results reveal that ZmPHOH enhances post-cold photosynthetic recovery by promoting the decomposition and metabolism of soluble sugars, thereby regulating the low-temperature resilience in maize, which provides new insights into the chilling tolerance mechanism of maize. Full article

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. Full article

Background/Objectives: Maize (Zea mays L.), a crop of worldwide importance, owes its adaptability to diverse environments to its genetic variation. However, tropical maize exhibits intrinsic photoperiod sensitivity, limiting its adaptability to temperate regions. Photoperiod sensitivity significantly affects the flowering time and other agronomic traits, but the underlying molecular mechanisms remain poorly understood. In this study, the aim is to elucidate the transcriptional regulatory networks mediating photoperiod responses in tropical maize inbred line Su65, providing insights into improving photoperiod adaptability. Methods: RNA-seq analysis was carried out to investigate photoperiod-responsive genes and pathways in tropical line Su65 exposed to varying photoperiod conditions. Differential expression analysis, functional enrichment, and the construction of protein–protein interaction (PPI) networks were carried out to investigate transcriptional dynamics. Additionally, qRT-PCR was employed to confirm the expression patterns of key candidate genes and generate detailed temporal expression profiles. Results: A total of 1728 differentially expressed genes (DEGs) were identified, with significant enrichment in pathways such as stress responses, redox homeostasis, and secondary metabolite biosynthesis. A set of new key hub genes (such as Zm00001d048531, Zm00001d018821, Zm00001d034892, etc.) were identified through PPI network analysis. Temporal expression profiling of ZmPHYB1, ZmPHYC1, ZmFKF2, ZmGI2, and ZmPRR37a, the key genes involved in circadian rhythms, revealed distinct regulatory patterns of photoperiod-sensitive genes at different time points, highlighting their roles in flowering time regulation and developmental transitions. Conclusions: In this study, critical molecular networks underlying photoperiod sensitivity in tropical maize are uncovered and a foundation is provided for improving photoperiod adaptability through genetic improvement. By integrating RNA-seq and qRT-PCR, the research offers valuable insights into transcriptional dynamics and their role in maize development under photoperiodic regulation. Full article

Background/Objectives: Abiotic stresses impose significant constraints on crop growth, development, and yield. However, the comprehensive characterization of the maize (Zea mays) lipoxygenase (LOX) gene family under stress conditions remains limited. LOXs play vital roles in plant stress responses by mediating lipid oxidation and signaling pathways. Methods: In this study, 13 ZmLOX genes were identified in maize and characterized to explore their functions under abiotic stresses. Results: Phylogenetics revealed that ZmLOX genes share evolutionary origins with LOX genes in Arabidopsis and rice. Promoter analysis identified cis-acting elements associated with growth, light response, hormone signaling, and stress response, indicating their diverse biological roles. Gene Ontology (GO) and KEGG enrichment analyses showed that ZmLOX genes are involved in jasmonic acid metabolism, lipid signaling, and photosynthetic processes, while protein–protein interaction (PPI) analysis positioned ZmLOX proteins as central hubs in stress-related regulatory networks. Differential expression and qRT-PCR analyses revealed stress-specific (including heat, drought, salt, and cold) expression patterns, with ZmLOX2 and ZmLOX13 showing key roles in drought and cold tolerance, respectively. Conclusions: These findings provide new insights into the regulatory functions of ZmLOX genes, offering potential targets for enhancing maize resilience to abiotic stresses and improving agricultural productivity. Full article

Using male sterile (MS) lines instead of normal inbred maternal lines in hybrid seed production can increase the yield and quality with lower production costs. Therefore, developing a new MS germplasm is essential for maize hybrid seed production in the future. Here, we reported a male sterility gene ms*-N125, cloned from a newly found MS mutant ms*-N125. This mutant has an underdeveloped tassel that showed impaired glumes and shriveled anthers without pollen grains. The MS locus of ms*-N125 was mapped precisely to a 112-kb-interval on the chromosome 5. This interval contains only three candidate genes, Zm958, Zm959, and Zm960. Sequencing results showed that only candidate Zm960 harbored a 548-bp transposable element (TE) in its 9th exon, and the two other candidate genes were found to have no genetic variations between the mutant and wild type (WT). Thus, Zm960 is the only candidate gene for male sterility of the mutant ms*-N125. In addition, we screened another recessive MS mutant, ms*-P884, which exhibited similar male sterility phenotypes to ms*-N125. Sequencing Zm960 in ms*-P884 showed a 600-bp TE located in its 2nd exon. Zm960 encodes an ATP-binding cassette in the G subfamily of ABC (ABCG) transporters, ZmABCG2a, with both mutants which harbored an Ac/Ds-like transposon in each. To verify the function of ZmABCG2a for male sterility further, we found an ethyl methanesulfonate (EMS) mutant, zmabcg2a*, which displayed male sterility and tassel phenotypes highly similar to ms*-N125 and ms*-P884, confirming that ZmABCG2a must be the gene for male sterility in maize. In addition, the results of lipid metabolome analysis of ms*-N125 young tassels showed that the total lipid content of the mutant was significantly lower than that of the WT, with 15 subclasses of lipids, including PE (phosphatidylethanolamine), PC (phosphatidylcholine), DG (digalactosyldiacylglycerols), and MGDG (monogalactosyldiacylglycerol) which were significantly down-regulated in the ms*-N125 mutant versus its wild type. In summary, we identified alternate mutations of the ZmABCG2a gene, which may be a potential germplasm for hybrid seed production in maize. Full article

Drought is one of the most serious environmental stresses affecting crop production. NAC transcription factors play a crucial role in responding to various abiotic stresses in plants. Here, we identified a maize NAC transcription factor, ZmSNAC06, between drought-tolerant and drought-sensitive inbred lines through RNA-seq analysis and characterized its function in Arabidopsis. ZmSNAC06 had five transcripts, of which ZmSNAC06-T02 had a typical NAC domain, while ZmSNAC06-P02 was localized in the nucleus of maize protoplasts and had transactivation activity in yeasts. The expression of ZmSNAC06 in maize was induced by drought. The overexpression of ZmSNAC06-T02 in Arabidopsis resulted in hypersensitivity to abscisic acid (ABA) at the germination stage, and overexpression lines exhibited higher survival rates and higher antioxidant enzyme activities compared with the wild-type under drought stress. These results suggest that ZmSNAC06 acts as a positive regulator in drought tolerance and may be used to improve drought tolerance in crops. Full article