SUMOylation is critical for plant growth and defense, and the specific substrate recognition mediated by SUMO ligases dictates the biological processes in which SUMOylation functions. However, only four SUMO ligases involved in SUMOylation have been reported in plants. Here, we report MPEL1 as a new SUMO ligase in maize, which paradoxically exhibits SUMO ligase activity despite its sequence homology to SUMO-targeted ubiquitin ligases (STUbL). MPEL1 stabilizes the plant-specific mitogen-activated protein kinase 16 (MAPK16) via SUMOylation at Lys526 within C-terminal domain (CTD). MAPK16 directly binds to JAZ20 via its C-terminal domain and phosphorylates JAZ20 at Thr12/Ser13 residues, thereby triggering its proteasomal degradation and activating broad-spectrum resistance against two Fusarium pathogens. These pathogens cause devastating maize ear rot and stalk rot, leading to severe yield losses and serious food safety concerns worldwide. Notably, MAPK16 overexpression and JAZ20 knockout enhance disease resistance without yield penalty, highlighting their potential for crop improvement. These findings expand the plant SUMO ligase family and provide targets for breeding Fusarium-resistant crops.

Drought imposes one of the most damaging constraints on maize productivity, particularly during critical developmental period such as flowering and pollination, when water deficit most severely disrupts normal plant growth. The Bcl-2-associated athanogene (BAG) proteins constitute a highly conserved co-chaperone family whose members participate in extensive biological processes, ranging from developmental regulation to adaptive responses under abiotic stress. In the present study, a comprehensive genome-wide characterization of the maize (Zea mays L.) reference genome (Zm-B73-REFERENCE-NAM-4.0) identified 24 ZmBAG genes, named ZmBAG1-24, which were classified into seven distinct phylogenetic groups. All identified proteins share a conserved BAG domain, while subsets additionally carry either a ubiquitin-like (UBL) domain or a plant-specific isoleucine-glutamine (IQ) calmodulin-binding motif positioned toward the N-terminus. Promoter analysis of ZmBAGs uncovered an abundance of stress-responsive regulatory elements were present, pointing to this gene family in ABA-mediated and drought-responsive transcriptional programs. Further transcriptional profiling under drought-stress conditions revealed divergent expression characteristics among family members, indicating that individual ZmBAGs contribute differentially to the drought stress. Among them, ZmBAG14 showed lower expression under drought stress, compared to the control (well-watered). Functional characterization using bag14 EMS mutants demonstrated that diminished ZmBAG14 expression correlated with reduced reactive oxygen species (ROS) accumulation in stomatal guard cells and water loss rate, elevated activities of peroxidase (POD) and superoxide dismutase (SOD), and ultimately enhanced drought tolerance and yield improvements. Protein interaction studies further revealed that ZmBAG14 interacts with the inward-rectifying potassium channel ZmKZM2, which influences stomatal movement by modulating K+ influx in guard cells under drought stress. Together, these findings provide a new perspective for genome-wide identification and functional utilizing of ZmBAG genes to improve drought tolerance in maize.

Global soil salinization increasingly constrains crop growth and productivity. Stress-associated proteins (SAPs) are key regulators of plant stress responses and development. Here, we characterize two maize SAPs, ZmSAP1 and ZmSAP7, that confer enhanced salt tolerance. ZmSAP1 and ZmSAP7 genes harbor a 531 bp and 516 bp coding sequence (CDS), respectively, encoding intron-less A20/AN1-type zinc-finger proteins, and are ubiquitously expressed across maize tissues. Ectopic overexpression of ZmSAP1 or ZmSAP7 in Arabidopsis and rice significantly improved survival rate, root length, biomass, and relative water content (RWC) under salt stress. The transgenic lines also exhibited reduced relative electrical conductivity (REC), lower malondialdehyde (MDA) and hydrogen peroxide (H2O2) levels, and elevated superoxide dismutase (SOD) and peroxidase (POD) activities, indicating enhanced reactive oxygen species (ROS) scavenging in rice. Integrated RNA-seq and qRT-PCR analyses further revealed that ZmSAP1 and ZmSAP7 modulate the expression of multiple stress-responsive genes, thereby bolstering plant salt tolerance. These findings provide a basis for further elucidating the molecular mechanisms underlying SAP-mediated salt stress responses.

Fresh purple corn (Zea mays L.) is rich in anthocyanins, and enhancing its anthocyanin content is crucial for improving its nutritional profile and commercial appeal. Strontium (Sr), an essential human micronutrient involved in physiological processes such as bone formation, exhibits low dietary bioavailability, making the consumption of Sr-enriched agricultural products a critical route for Sr supplementation. Given the biphasic effect of strontium on plant growth, characterized by low-dose stimulation and high-dose inhibition, elucidating its regulatory mechanism in fresh purple corn anthocyanin biosynthesis and breeding cultivars with dual high strontium and anthocyanin traits represents a biofortification strategy with considerable application potential. In this study, a pot experiment was conducted with fresh purple corn, and the anthocyanin and strontium contents in the kernels were quantified. To characterize the dynamic expression profiles of anthocyanin-related genes and metabolite accumulation under strontium treatment, an integrated transcriptomic and metabolomic approach was employed. Key differentially expressed genes were further validated by qRT-PCR. The results demonstrated that strontium treatment significantly increased the anthocyanin content in purple corn kernels relative to the control. Integrated multi-omics analysis revealed that strontium promotes anthocyanin synthesis by activating genes such as Zm00001d003015, Zm00001d015513 and Zm00001d016471, enhances the accumulation of pivotal hub metabolites (such as naringin chalcone, 4-coumaric acid), and optimizes the allocation of glycosylation donors by suppressing competing metabolic pathways such as coumarin biosynthesis. Collectively, this study provides the first systematic elucidation of how strontium, as a novel inducer, promotes anthocyanin synthesis in purple corn through a multi-level, temporally regulated network, providing a theoretical foundation and a practical biofortification strategy for developing Sr-enriched, high-anthocyanin maize.

Crop breeding faces mounting challenges from climate change, population growth, and shrinking farmland. While management and genetic improvement have contributed to yield gains, sustainable agriculture demands continuous progress to address local and future environmental stresses. Approximately 60% of past yield increases are attributed to improved abiotic stress resilience, yet further breeding advances are constrained by the complexity of environmental factors, which often co-occur dynamically within farming systems. Enviromics-an emerging field dedicated to high-throughput environmental characterization-enables comprehensive dissection of the "E" term in genotype × environment (G × E) interactions, improving predictive models for complex traits. Understanding how enviromics elucidates environmental effects and G × E will uncover novel mechanisms underlying crop resilience. In this perspective, we critically review the concepts of enviromics and abiotic enviromics and their impacts on plant stress responses. We further present a forward-looking view on enviromics-driven genetic improvement for abiotic stress adaptation, emphasizing that integrating enviromic-assembly with multi-omics and predictive modeling holds transformative potential for decoding molecular mechanisms and accelerating climate-smart variety development. This framework offers a strategic pathway toward sustainable agriculture and global food security.

SKI-INTERACTING PROTEINS (SKIPs), primarily known as splicing factors, control gene expression at the post-transcriptional level in stress responses in plants. However, little is known about SKIPs in regulating plant drought stress at the transcriptional level, particularly in maize (Zea mays L.). Here, we discover that ZmSKIP enhances drought tolerance in maize. ZmSKIP transgenic plants were generated to study how ZmSKIP positively regulates drought tolerance. Overexpression of ZmSKIP promoted stomatal closure and reduced water loss, whereas the opposite effect was observed in skip-aa mutants. ZmSKIP directly binds to the "TAATA" motif in the promoter of B-cell lymphoma 2-associated athanogene 8 (ZmBAG8). bag8 mutants exhibit the decreased water loss and reduced stomatal aperture phenotype under drought stress. Additionally, ZmSKIP can be recruited by ZmBAG8 in stress granules (SGs) to decrease its protein abundance in the nucleus. Increased ZmBAG8 expression leads to larger stomatal aperture and normal plant growth. Under drought stress, the interaction between ZmSKIP and ZmBAG8 was abolished, while ZmSnRK2.3 phosphorylates ZmSKIP at Ser236 and Ser244 to enhances drought tolerance by strengthening the ability of ZmSKIP to suppress ZmBAG8 expression. Thus, our findings demonstrate that ZmSnRK2.3-mediated phosphorylation of ZmSKIP reduces ZmBAG8 expression and stomatal aperture, thereby enhancing drought tolerance in maize.

Compact maize architecture is crucial for high planting densities and yields, which is a key breeding objective. In this study, a maize T-DNA insertion mutant with compact plant architecture (cpa) was identified, showing reduced leaf curling, drooping angle, plant and ear height, leaf dimensions, internode and tassel length, tassel branch number, and yield compared to WT. Paraffin section analysis showed reduced vein cross-sectional area, epidermal cell width, and increased vein density in the cpa mutant. Genetic analysis revealed that T-DNA was inserted into the first exon of a gene encoding TATA-box binding protein-associated factor (TAF) in the cpa mutant, which was named ZmTAF11. ZmTAF11 exhibited ubiquitous expression across various tissues and nuclear localization. Loss-of-function Zmtaf11 mutants generated by CRISPR/Cas9 exhibited the characteristic compact phenotype, which was consistent with that of the cpa mutant. ZmTAF11 directly binds to the promoters of leaf morphogenesis-related genes ZmAXL and ZmBOB1, thereby promoting their transcription. Furthermore, four SNPs in ZmTAF11 were significantly associated with ear height index (EHI), and the AGTG haplotype showed a lower EHI. This haplotype was predominantly found in temperate maize lines and geographically distributed across North America. These findings reveal the role of ZmTAF11 in regulating maize architecture and its potential application in high-density maize breeding.

Global agriculture faces critical challenges due to the overreliance on chemical pesticides, driving an urgent need for eco-friendly biopesticides and biostimulants (BioP&S). Plant-derived peptides, evolved as natural regulators of growth, development, and stress adaptation, offer immense potential as biodegradable and biocompatible alternatives. However, their commercialization remains constrained by limited exploration of the diversity and activity, high production costs, incomplete ecological risk evaluations, and undefined application scenarios. This Perspective overviews emerging discoveries and proposes integrated frameworks for plant peptide identification, molecular design, biomanufacturing, and ecological impact assessments integrated with germplasm development and field application systems. To overcome existing bottlenecks, we discuss the integrative potential of emerging technologies that synergistically combine artificial intelligence for high-throughput peptide discovery and de novo structural refinement, nanotechnology for enhancing environmental resilience and targeted delivery, and synthetic biology for developing industrial biomanufacturing platforms. We emphasize the need to align phytopeptide BioP&S with compatible germplasm resources, stage-specific crop requirements, and complementary chemical pesticides to maximize their efficacy, cost-effectiveness, and trait-specific agronomic performance by integrating with precision agriculture systems. Future advancements will rely on interdisciplinary innovations and policy support to unlock their full potential in enhancing crop resilience, productivity, and quality while ensuring ecological sustainability.

Photoperiod sensitivity poses a major obstacle to the expansion, breeding, and production of maize (Zea mays) in temperate regions. While the photoperiod-dependent FLOWERING LOCUS T (FT)/ZCNs pathway modulates floral development, the mechanism by which crops perceive specific light wavelengths and regulate flowering remains largely unknown. In this study, we demonstrate that the rhythmic expression of the blue light receptor FLAVIN-BINDING KELCH REPEAT F-BOX 1a (ZmFKF1a) is finely controlled by the Evening Complex (EC) components of LUX ARRHYTHMO 2 (ZmLUX2). ZmFKF1a interacts with GIGANTEA 1 (ZmGI1), stabilizing it and promoting its nuclear localization via a blue light-dependent mechanism. In the nucleus, ZmGI1 directly binds and activates Zea mays MADS-box 4 (ZMM4), a MADS-box gene specifically expressed in the shoot apical meristem, which drives floral transition. Genetic analyses revealed that ZmGI1 is epistatic to ZmFKF1a in promoting shoot apex development and accelerating flowering in maize. Our findings elucidate a ZmLUX2-ZmFKF1a-ZmGI1-ZMM4 regulatory module that fine-tunes photoperiodic flowering of day-neutral temperate maize lines, functioning independently of ZEA CENTRORADIALISs (ZCNs). Furthermore, transgenic maize overexpressing ZmFKF1a exhibited accelerated flowering and enhanced yield specifically in photoperiod-sensitive tropical maize lines under extreme natural long-day conditions, underscoring its potential application in improving maize production through precise manipulation of flowering traits. These insights advance our understanding of how blue light signaling orchestrates flowering time in maize and offer a promising strategy for optimizing crop performance in diverse environments.

Circular RNAs (circRNAs), a type of head-to-tail closed RNA molecules, have been implicated in various aspects of plant development and stress responses through transcriptome sequencing; however, the precise functional roles of circRNAs in plants remain poorly understood. In this study, we identified a highly expressed circular RNA, circZmMED16, derived from exon 8 of the mediator complex subunit 16 (ZmMED16) across different maize (Zea mays L.) inbred lines using circRNA-seq analysis. This circRNA is predominantly expressed in maize tassels and functions in the cytoplasm. Overexpression of circZmMED16 resulted in increased expression of ZmMED16/AtMED16 and delayed flowering in both maize and Arabidopsis thaliana, compared with that in wild-type plants. In contrast, overexpression of the parent gene ZmMED16 did not alter the flowering time of transgenic plants in Arabidopsis, suggesting that circZmMED16 plays a specific role in regulating flowering, distinct from that of linear ZmMED16. To further understand the mechanisms underlying the regulation of flowering time by circZmMED16, we performed RNA pull-down, dual-luciferase, RNA interference (RNAi), and ribonuclease protection assays (RPA). These results indicate that circZmMED16 interacts with small subunit 1 of ADP-glucose pyrophosphorylase (APS1) mRNA in both maize and Arabidopsis. The knockdown of circZmMED16 increased the expression of ZmAPS1, whereas the overexpression of circZmMED16 led to the downregulation of ZmAPS1 RNA and protein. By affecting ZmAPS1 expression, circZmMED16 reduced ADP-glucose pyrophosphorylase (AGPase) activity and led to delayed flowering. These results revealed a novel regulatory mechanism for circRNAs in flowering time and shed light on their functional and regulatory roles in plants.

With the escalating soil salinization, salt stress has emerged as a critical constraint on plant growth and development, reducing crop productivity and impeding agricultural advancement. The AP2/EREBP transcription factors play a key role in regulating plant growth and abiotic stress responses. However, the role of DREB subclade within the AP2/EREBP superfamily in regulating salt stress response in maize remains largely elusive. In this study, the maize ZmEREB199 gene was cloned, and its expression profiles, sequence features, subcellular localization, transcriptional activation activity, and function in mediating salt stress tolerance were investigated. It was found that the ZmEREB199 gene is intronless, encodes a 230-amino-acid protein containing a single conserved AP2 domain, belongs to the DREB subfamily, localizes to the nucleus, and shows transcriptional activation activity. RT-qPCR analysis revealed that ZmEREB199 expression in maize was significantly upregulated under salt stress. Overexpression of ZmEREB199 significantly impaired salt tolerance in transgenic Arabidopsis and rice, as evidenced by marked reductions in root length, decreases in chlorophyll a, chlorophyll b, and total chlorophyll contents, lower relative water content (RWC), and superoxide dismutase (SOD) and peroxidase (POD) activities, accompanied by significant increases in relative electrical conductivity (REC), malondialdehyde (MDA) and H2O2 contents, as well as deeper NBT and DAB staining, under salt stress conditions. Integrated analyses of RNA-seq, RT-qPCR, and dual-luciferase (dual-LUC) reporter assays demonstrated that ZmEREB199 modulates salt stress tolerance by regulating the transcription of stress-responsive genes. This study provides insights into the function and regulatory mechanism of ZmEREB199 in mediating maize responses to salt stress.

Conserved non-coding sequences (CNS) are islands of non-coding sequences conserved across species and play an important role in regulating the spatiotemporal expression of genes. Identification of CNS provides valuable information about potentially functional genomic elements, regulatory regions, and helps to gain insights into the genetic basis of crop agronomic traits. Here, we comprehensively analyze CNS in maize, by comparing the genomes of maize inbred line B73 (Zea mays ssp. mays), its close wild relative Zea mays spp. mexicana, and other grasses in Poaceae, including sorghum (Sorghum bicolor), foxtail millet (Setaria italica) and two adlay (Coix lacryma) cultivars. There were 289,931 CNS found in two syntenic gene pairs, while 51,701 CNS were conserved within at least three species. To explore the regulatory characteristics of the CNS identified, the flanking regions of CNS were compared with the peaks called using both transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) and chromatin immunoprecipitation with high-throughput sequencing (ChIP-Seq) data of histone modifications. It was found that CNS in maize were enriched in open chromatin regions compared with randomly selected non-coding regions of similar length. A significant enrichment of transcription factor binding sites was found within CNS sequences, including different transcription factors involved in abiotic stress response, such as OBP (OBF-BINDING PROTEIN) family and Adof1 (Encodes dof zinc finger protein). To investigate the epigenetic modification patterns in CNS, ChIP-Seq data for histone modifications H3K9ac, H3K4me3, H3K36me3, H3K9me3, and H3K27ac were further analyzed to depict the changes along CNS. Our findings revealed significantly elevated levels of transcription-promoting histone modifications in the CNS regions compared to randomly selected non-coding sequences with an equal number and similar length. Notably, CNS were also identified on both Vgt1 (Vegetative to generative transition 1) and ZmCCT10. In addition, CNS with potential functions were identified based on SNPs within CNS significantly associated with various agronomic traits in maize, which holds potential utility in molecular breeding for maize. In summary, we identified and characterized CNS in maize through genomic comparative analysis, which provides valuable insights into their potential regulatory effects on gene expression and phenotypic variation.

To elucidate the molecular function of SHORT AND SWOLLEN ROOT1 (SSR1), we screened for suppressors of the ssr1-2 (sus) was performed and identified over a dozen candidates with varying degrees of root growth restoration. Among these, the two most effective suppressors, sus1 and sus2, resulted from G87D and T55M single amino acid substitutions in HSCA2 (At5g09590) and ISU1 (At4g22220), both crucial components of the mitochondrial iron-sulfur (Fe-S) cluster assembly machinery. SSR1 displayed a robust cochaperone-like activity and interacted with HSCA2 and ISU1, facilitating the binding of HSCA2 to ISU1. In comparison to the wild-type plants, ssr1-2 mutants displayed increased iron accumulation in root tips and altered expression of genes responsive to iron deficiency. Additionally, the enzymatic activities of several iron-sulfur proteins and the mitochondrial membrane potential were reduced in ssr1-2 mutants. Interestingly, SSR1 appears to be exclusive to plant lineages and is induced by environmental stresses. Although HSCA2G87D and ISU1T55M can effectively compensate for the phenotypes associated with SSR1 deficiency under favorable conditions, their compensatory effects are significantly diminished under stress. Collectively, SSR1 represents a new and significant component of the mitochondrial Fe-S cluster assembly (ISC) machinery. It may also confer adaptive advantages on plant ISC machinery in response to environmental stress.

The APETALA2/Ethylene Response Element Binding Protein (AP2/EREBP) is a kind of plant-specific transcription factor and plays a pivotal role in governing plant growth, ontogenesis, and stress acclimation processes. However, the AP2 members modulating plant height and seed morphogenesis remain largely unelucidated. In the present study, the maize ZmEREB130 gene was cloned and functionally validated in modulating growth and seed size development. Our findings demonstrated that ZmEREB130 protein harbors two conserved AP2 domains, localized to the nucleus, exhibits no self-activation activity, and is a canonical AP2 transcription factor. The results of Y2H, BiFC, and split-LUC assays revealed that ZmEREB130 undergoes homodimerization via its AP2 domain, and interacts with ZmFdx1/5. The ZmEREB130 exhibited predominant expression in maize seeds. Heterologous expression of ZmEREB130 in Arabidopsis resulted in the suppression of plant growth and reduction of seed dimensions. Phenotypic analyses demonstrated that five transgenic lines manifested reduced seedling size, diminished biomass accumulation, delayed flowering, decreased plant height, and significantly reductions in seed length, width, and weight compared to wild type plants. The results of RNA-seq, qRT-PCR, and dual-LUC assays implied that ZmEREB130 binds to the promoters of development-associated genes, modulating their transcription and ultimately impeding growth and ontogenesis of transgenic Arabidopsis. This study provides evidence that ZmEREB130 functions as a negative regulator of plant growth and development, thereby presenting a novel candidate gene for maize genetic improvements aiming to achieve high-yield traits via genome-editing technologies.

Maize, a cornerstone of global food security, has undergone remarkable transformations through breeding, yet further increase in global maize production faces mounting challenges in a changing world. In this Perspective paper, we overview the historical successes of maize breeding that laid the foundation for present opportunities. We examine both the specific and shared breeding goals related to diverse geographies and end-use demands. Achieving these coordinated breeding objectives requires a holistic approach to trait improvement for sustainable agriculture. We discuss cutting-edge solutions, including multi-omics approaches from single-cell analysis to holobionts, smart breeding with advanced technologies and algorithms, and the transformative potential of rational design with synthetic biology approaches. A transition toward a data-driven future is currently underway, with large-scale precision agriculture and autonomous systems poised to revolutionize farming practice. Realizing these futuristic opportunities hinges on collaborative efforts spanning scientific discoveries, technology translations, and socioeconomic considerations in maximizing human and environmental well-being.

BES1/BZR1, a kind of plant-specific transcription factor (TF), has been reported to regulate growth, development, and stress response. However, the maize BES1/BZR1 members are still largely unknown. In this study, we investigated the function and regulatory mechanism of maize ZmBES1/BZR1-4 in regulating drought response and seed development. The ZmBES1/BZR1-4 was localized in the nucleus depending on its bHLH domain and showed no self-transactivation activity. The transcription level of ZmBES1/BZR1-4 was induced by drought stress and was predominantly higher in seeds 25 days after pollination. Overexpression of ZmBES1/BZR1-4 reduced drought tolerance but produced bigger seeds with higher seed weight in transgenic Arabidopsis, rice, and maize. Inversely, the ZmBES1/BZR1-4 mutant Mu4-1 and Mu4-2 showed enhancement of drought tolerance and decreased seed size and weight. The ZmBES1/BZR1-4 could directly bind to E-box elements in the ZmMBP1 and ZmPum6 promoters to activate their transcription. Furthermore, the interaction between ZmBES1/BZR1-4 and ZmTLP5 enhanced the ZmMBP1 and ZmPum6 transcription. Moreover, ZmMBP1 and ZmPum6 positively regulated seed size and weight, but ZmPum6 negatively regulated drought tolerance. Therefore, our findings reveal that ZmBES1/BZR1-4 recruits ZmTLP5 to regulate drought tolerance and seed development by regulating ZmMBP1 and ZmPum6, which contributes to uncovering the function of BES1/BZR1s regulating growth, development, and stress response in crops.

In this study, we demonstrate that red light is the most critical light component for promoting healthy maize growth during Fusarium verticillioides infection. Red light receptors PHYTOCHROME B (PHYB) and C (PHYC) play essential roles in maize defense against this pathogen. Overexpression of PHYC in maize enhances resistance to F. verticillioides. Additionally, we identified two defense-related gene networks and some metabolites that reliant on PHYCs, involving key contributors such as WRKY transcription factors and metabolites like histamine and thiamine. Notably, the application of 50 μM histamine significantly boosts resistance, particularly under high-density conditions, marking the first report of the role of histamine in disease resistance in plants.

Maize is highly sensitive to water deficit but has high transpiration and biomass production, leading to a substantial water demand. Genetic engineering can overcome reproductive isolation and utilize drought-tolerant genes from distant species. Ammopiptanthus nanus is a relic of the Tertiary glaciation that can adapt to harsh environmental conditions. In our previous study, five maize homozygous T8 lines overexpressing the AnVP1 gene from Ammopiptanthus nanus were generated and showed the enhancement of drought tolerance. However, the recipient inbred line Zh-1 was poor in yield and agronomic performance. In the present study, the AnVP1 gene was backcrossed from donor parent L10 (one of the five T8 lines) into recurrent parent Chang 7-2 (one of the elite parents of the commercial hybrid Zhengdan 958). In total, 103 InDel markers were developed and used for assisted background selection. After two generations of foreground selection through glufosinate spraying, the detection of CP4 EPSP MAb1 strips, and the PCR amplification of the AnVP1 gene, along with the similarity of agronomic traits to the recurrent parent, and background selection assisted by these InDel markers, the transgenic AnVP1 gene became homozygous in the BC2 lines. The average recovery rate of the genetic background of the recurrent parent reached 74.80% in the BC1 population and 91.93% in the BC2 population, respectively. The results of RT-PCR and RT-qPCR indicated the stable expression of the AnVP1 gene in the two ultimately selected BC2F3 lines, BC2-36-12 and BC2-5-15. The drought tolerance of these two BC2F3 lines were significantly improved compared to the recurrent parent Chang 7-2, as revealed by their wilting phenotype and survival rate of seedlings. This improvement was related to the enhancement of water-retention ability, as indicated by higher RWC and the reduction in damage, as shown by the decrease in REL, MDA, and H2O2 under drought stress. The result of field evaluation in two arid and semi-arid environments indicated that the drought tolerance of Chang 7-2 was significantly improved. This study suggests that the improved Chang 7-2 can be crossed with Zheng 58 to develop the transgenic commercial hybrid Zhengdan 958.

Lateral organ boundary domain (LBD) proteins are plant-specific transcription factors (TFs), featuring a highly conserved N-terminal lateral organ boundary (LOB) domain and a variable C-terminal region. Initially recognized as key regulators of organ development in plants, recent studies have rarely expanded their role to include stress response regulation. In this study, we isolated a maize protein ZmLBD1 and expressed it in Arabidopsis thaliana. While ZmLBD1 transcript levels remained consistent across wild-type (WT) and transgenic plants under low inorganic phosphate (Pi), NaCl, and drought stress, its protein accumulation increased in response to these stresses over time. ZmLBD1 transgenic Arabidopsis exhibited enhanced tolerance to low Pi, NaCl, and drought stress, with improved root development. Under low Pi conditions, transgenic plants showed higher leaf and root Pi content and increased transcript levels of PHO2. Additionally, transgenic plants displayed better drought tolerance traits, including reduced leaf wilting and curling, higher chlorophyll fluorescence (Fv/Fm), and lower ion leakage. RNA-seq and RT-qPCR revealed that PGIP1 was significantly upregulated under low Pi, NaCl, and drought stress transgenic plants, with ZmLBD1 binding to the ABRE motif in the promoter of PGIP1 to enhance its transcription. Protein interaction studies showed that ZmLBD1 interacts with ZmCDC48, which mediates ZmLBD1 degradation and affects its activity. Taken together, our findings indicate that ZmLBD1 is a versatile gene with potential for developing crops with improved tolerance to multiple abiotic stresses.

Maize is one of the most successful crops with regard to the utilization of heterosis. The haploid induction technique is one of the fastest methods to obtain pure maize material at the present stage. However, the molecular mechanism of haploid doubling is rarely reported. In this study, we treated B73 and ZNC442 haploid young shoots with colchicine for 0 h, 6.2 h, and 10 h, and analyzed the differentially expressed genes (DEGs). We found that colchicine treatment for 6.2 h and 10 h compared to 0 h resulted in a total of 4868 co-DEGs. GO enrichment analysis and KEGG metabolic pathway analysis found significantly enriched 282 GO terms and 31 significantly pathways, respectively. Additionally, The GO term and KEGG pathway genes of spindle, cytoskeleton, microtubules and nuclear division were selected for analysis, and three candidate genes were screened by taking intersections. Zm00001d033112, Zm00001d010525, and Zm00001d043386 were annotated as kinesin-associated protein 13, kinesin-like protein KIN-10C, and kinesin light-chain LC6, respectively. The real-time fluorescence quantification (RT-PCR) results revealed that Zm00001d033112, Zm00001d010525, and Zm00001d043386 had the same trends as RNA-seq. Interestingly, Zm00001d033112 is homologous gene AT3G20150 in Arabidopsis, which was involved in the regulation of chromosome movement and mitotic spindle assembly. Our study suggests that kinesin genes may play an important role in doubling chromosomes, thus providing valuable information for future studies on the molecular mechanisms of chromosome doubling in maize.