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SUMMARY: Plants synthesize an array of volatile compounds, many of which serve ecological roles in attracting pollinators, deterring herbivores, and communicating with their surroundings. Methyl anthranilate (MeAA) is an anti‐herbivory defensive volatile responsible for grape aroma that is emitted by several agriculturally relevant plants, including citrus, grapes, and maize. Unlike maize, which uses a one‐step anthranilate methyltransferase (AAMT), grapes have been thought to use a two‐step pathway for MeAA biosynthesis. By mining available transcriptomics data, we identified two AAMTs in Vitis vinifera (wine grape), as well as one ortholog in "Concord" grape. Many angiosperms methylate the plant hormone salicylic acid (SA) to produce methyl salicylate, which acts as a plant‐to‐plant communication molecule. Because the Citrus sinensis (sweet orange) SA methyltransferase can methylate both anthranilate (AA) and SA, we used this enzyme to examine the molecular basis of AA activity by introducing rational mutations, which identified several active site residues that increase activity with AA. Reversing this approach, we introduced mutations that imparted activity with SA in the maize AAMT, which uncovered different active site residues from those in the citrus enzyme. Sequence and phylogenetic analysis revealed that one of the Vitis AAMTs shares an ancestor with jasmonic acid methyltransferases, similar to the AAMT from strawberry (Frageria sp.). Collectively, these data demonstrate the molecular mechanisms underpinning AA activity across methyltransferases and identify one‐step enzymes by which grapes synthesize MeAA. Significance Statement: While the two‐step pathway responsible for the biosynthesis of the grape aroma molecule, methyl anthranilate, has remained incomplete in Vitis spp., we identified two one‐step anthranilate methyltransferases in wine and one in "Concord" grapes that can methylate the tryptophan pathway intermediate anthranilate. Tracing the molecular basis of anthranilate activity in the maize and sweet orange methyltransferases uncovered distinct active site amino acids that impart substrate specificity. [ABSTRACT FROM AUTHOR]

The plant kingdom harbors the Plasmodesmata Callose Binding Protein (PDCB) gene family, which plays essential roles in plant growth, development, environmental adaptation, and yield. PDCB genes are closely involved in regulating cell-to-cell communication and controlling callose deposition at plasmodesmata (PD) throughout the whole plant. Remarkably, their functions remain largely unknown in many crops, including maize. This study sought to identify the members of the PDCB gene family within the maize genome and analyze their physicochemical properties and expression patterns. Utilizing bioinformatics methodologies, a comprehensive genome-wide analysis of the PDCB gene family was performed. The findings revealed that PDCB genes were highly abundant in maize, with a total of 56 PDCB genes identified and categorized into six distinct groups. Members of the PDCB family were dispersed across all chromosomes. The PDCBs within each group exhibited significant similarity in their conserved motifs and gene structures; all members contained the X8 domain, comprising one to five exons, while displaying a straightforward genomic structure. Numerous cis-acting elements associated with plant growth and development, light response, stress-associated responses, and plant hormones were identified in the promoter regions of PDCB genes. Moreover, the PDCBs exhibited diverse expression patterns across various tissues. This study improves the comprehension of the PDCB gene family and provides a robust foundation for further research on maize. [ABSTRACT FROM AUTHOR]

Genetically modified (GM) maize DP910521 was developed to confer resistance against certain lepidopteran insect pests as well as tolerance to glufosinate herbicide; these properties were achieved by introducing the mo‐pat, pmi and cry1B.34 expression cassettes. The molecular characterisation data and bioinformatic analyses did not identify issues requiring food/feed safety assessment. None of the identified differences in the agronomic/phenotypic and compositional characteristics tested between maize DP910521 and its conventional counterpart needs further assessment except for the levels of iron in grain, which do not raise safety and nutritional concerns. The GMO Panel does not identify safety concerns regarding the toxicity and allergenicity of the Cry1B.34, PAT and PMI proteins as expressed in maize DP910521. The GMO panel finds no evidence that the genetic modification impacts the overall safety of maize DP910521. In the context of this application, the consumption of food and feed from maize DP910521 does not represent a nutritional concern in humans and animals. The GMO Panel concludes that maize DP910521 is as safe as its conventional counterpart and non‐GM maize varieties tested, and no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of maize DP910521 material into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize DP910521. The GMO Panel concludes that maize DP910521 is as safe as its conventional counterpart and the tested non‐GM maize varieties with respect to potential effects on human and animal health and the environment. [ABSTRACT FROM AUTHOR]

Genetically modified maize MON 95275 was developed to confer protection to certain coleopteran species. These properties were achieved by introducing the mpp75Aa1.1, vpb4Da2 and DvSnf7 expression cassettes. The molecular characterisation data and bioinformatic analyses reveal similarity to known toxins, which was further assessed. None of the identified differences in the agronomic/phenotypic and compositional characteristics tested between maize MON 95275 and its conventional counterpart needs further assessment. The GMO Panel does not identify safety concerns regarding the toxicity and allergenicity of the Mpp75Aa1.1 and Vpb4Da2 proteins and the DvSnf7 dsRNA and derived siRNAs as expressed in maize MON 95275 and finds no evidence that the genetic modification would change the overall allergenicity of maize MON 95275. In the context of this application, the consumption of food and feed from maize MON 95275 does not represent a nutritional concern in humans and animals. The GMO Panel concludes that maize MON 95275 is as safe as the conventional counterpart and non‐GM maize varieties tested, and no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of maize MON 95275 material into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize MON 95275. The GMO Panel concludes that maize MON 95275 is as safe as its conventional counterpart and the tested non‐GM maize varieties with respect to potential effects on human and animal health and the environment. [ABSTRACT FROM AUTHOR]

SUMMARY: The basal region of maize (Zea mays) kernels, which includes the pedicel, placenta‐chalazal, and basal endosperm transfer layers, serves as the maternal/filial interface for nutrient transfer from the mother plant to the developing seed. However, transcriptome dynamics of this maternal/filial interface remain largely unexplored. To address this gap, we conducted high‐temporal‐resolution RNA sequencing of the basal and upper kernel regions between 4 and 32 days after pollination and deeply analyzed transcriptome dynamics of the maternal/filial interface. Utilizing 790 specifically and highly expressed genes in the basal region, we performed the gene ontology (GO) term and weighted gene co‐expression network analyses. In the early‐stage basal region, we identified five MADS‐box transcription factors (TFs) as hubs. Their homologs have been demonstrated as pivotal regulators at the maternal/filial interface of rice or Arabidopsis, suggesting their potential roles in maize kernel development. In the filling‐stage basal region, numerous GO terms associated with transcriptional regulation and transporters are significantly enriched. Furthermore, we investigated the molecular function of three hub TFs. Through genome‐wide DNA affinity purification sequencing combined with promoter transactivation assays, we suggested that these three TFs act as regulators of 10 basal‐specific transporter genes involved in the transfer of sugars, amino acids, and ions. This study provides insights into transcriptomic dynamic and regulatory modules of the maternal/filial interface. In the future, genetic investigation of these hub regulators must advance our understanding of maternal/filial interface development and function. Significance Statement: Our study is the first systematic effort to generate high‐temporal‐resolution transcriptomic dynamics of this maternal/filial interface in the basal kernel region of maize. We identified 790 highly expressed genes in the basal region, providing a resource for understanding the development and functioning of this interface. We analyzed three previously unknown transcription factors that potentially play a critical role in regulating transporter genes related to sugar, amino acids, and ions. [ABSTRACT FROM AUTHOR]

Main conclusion: The combined transcriptome outcome provides an important clue to the regulatory cascade centering on lncRNA GARR2 and CPS2 gene in GA response. Long non-coding RNAs (lncRNAs) serve as regulatory components in transcriptional hierarchy governing multiple aspects of biological processes. Dissecting regulatory mechanisms underpinning tetracyclic diterpenoid gibberellin (GA) cascade holds both theoretical and applied significance. However, roles of lncRNAs in transcriptional modulation of GA pathway remain largely elusive. Gypsy retrotransposon-derived GIBBERELLIN RESPONSIVE lncRNA2 (GARR2) has been reported as GA-responsive maize lncRNA. Here a novel GARR2-edited line garr2-1 was identified, characteristic of GA-induced phenotype of increased seedling height and elongated leaf sheath. Transcriptome analysis indicated that transcriptional abundance of five genes [ent-copalyl diphosphate synthase2 (CPS2), ent-kaurene synthase4 (KS4), ent-kaurene synthase6 (KS6), ent-kaurene oxidase2 (KO2), and ent-kaurenoic acid oxidase1/Dwarf3 (KAO1/D3)] was elevated in garr2-1 for early steps of GA biosynthesis. Five GA biosynthetic genes as hub regulators were interlaced to shape regulatory network of GA response. Different transcriptome resources were integrated to discover common differentially expressed genes (DEGs) in the independent GARR2-edited lines GARR2KO and garr2-1. A total of 320 common DEGs were retrieved. These common DEGs were enriched in diterpenoid biosynthetic pathway. Integrative transcriptome analysis revealed the common CPS2 encoding the CPS enzyme that catalyzes the conversion of the precursor trans-geranylgeranyl diphosphate to ent-copalyl diphosphate. The up-regulated CPS2 supported the GA-induced phenotype of slender seedlings observed in the independent GARR2-edited lines GARR2KO and garr2-1. Our integrative transcriptome analysis uncovers common components of the GA pathway regulated by lncRNA GARR2. These common components, especially for the GA biosynthetic gene CPS2, provide a valuable resource for further delineating the underlying mechanisms of lncRNA GARR2 in GA response. [ABSTRACT FROM AUTHOR]

Abstract Genetically modified maize MON 95275 was developed to confer protection to certain coleopteran species. These properties were achieved by introducing the mpp75Aa1.1, vpb4Da2 and DvSnf7 expression cassettes. The molecular characterisation data and bioinformatic analyses reveal similarity to known toxins, which was further assessed. None of the identified differences in the agronomic/phenotypic and compositional characteristics tested between maize MON 95275 and its conventional counterpart needs further assessment. The GMO Panel does not identify safety concerns regarding the toxicity and allergenicity of the Mpp75Aa1.1 and Vpb4Da2 proteins and the DvSnf7 dsRNA and derived siRNAs as expressed in maize MON 95275 and finds no evidence that the genetic modification would change the overall allergenicity of maize MON 95275. In the context of this application, the consumption of food and feed from maize MON 95275 does not represent a nutritional concern in humans and animals. The GMO Panel concludes that maize MON 95275 is as safe as the conventional counterpart and non‐GM maize varieties tested, and no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of maize MON 95275 material into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize MON 95275. The GMO Panel concludes that maize MON 95275 is as safe as its conventional counterpart and the tested non‐GM maize varieties with respect to potential effects on human and animal health and the environment.

Abstract Genetically modified (GM) maize DP910521 was developed to confer resistance against certain lepidopteran insect pests as well as tolerance to glufosinate herbicide; these properties were achieved by introducing the mo‐pat, pmi and cry1B.34 expression cassettes. The molecular characterisation data and bioinformatic analyses did not identify issues requiring food/feed safety assessment. None of the identified differences in the agronomic/phenotypic and compositional characteristics tested between maize DP910521 and its conventional counterpart needs further assessment except for the levels of iron in grain, which do not raise safety and nutritional concerns. The GMO Panel does not identify safety concerns regarding the toxicity and allergenicity of the Cry1B.34, PAT and PMI proteins as expressed in maize DP910521. The GMO panel finds no evidence that the genetic modification impacts the overall safety of maize DP910521. In the context of this application, the consumption of food and feed from maize DP910521 does not represent a nutritional concern in humans and animals. The GMO Panel concludes that maize DP910521 is as safe as its conventional counterpart and non‐GM maize varieties tested, and no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of maize DP910521 material into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize DP910521. The GMO Panel concludes that maize DP910521 is as safe as its conventional counterpart and the tested non‐GM maize varieties with respect to potential effects on human and animal health and the environment.

Genetically modified (GM) maize MON 94804 was developed to achieve a reduction in plant height by introducing the GA20ox_SUP suppression cassette. The molecular characterisation and bioinformatic analyses do not identify issues requiring food/feed safety assessment. None of the agronomic/phenotypic and compositional differences identified between maize MON 94804 and its conventional counterpart needs further assessment, except for ear height, plant height and levels of carbohydrates in forage, which do not raise safety or nutritional concerns. The Panel on Genetically Modified Organisms (GMO Panel) does not identify safety concerns regarding the toxicity and allergenicity of the GA20ox_SUP precursor‐miRNA and derived mature miRNA as expressed in maize MON 94804 and finds no evidence that the genetic modification would change the overall allergenicity of maize MON 94804. In the context of this application, the consumption of food and feed from maize MON 94804 does not represent a nutritional concern in humans and animals. The GMO Panel concludes that maize MON 94804 is as safe as the conventional counterpart and non‐GM maize varieties tested, and no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of viable maize MON 94804 grains into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize MON 94804. The GMO Panel concludes that maize MON 94804 is as safe as its conventional counterpart and the tested non‐GM maize varieties with respect to potential effects on human and animal health and the environment. [ABSTRACT FROM AUTHOR]

Mass spectrometry‐based plant metabolomics is frequently used to identify novel natural products or study the effect of specific treatments on a plant's metabolism. Reliable sample handling is required to avoid artifacts, which is why most protocols mandate shock freezing of plant tissue in liquid nitrogen and an uninterrupted cooling chain. However, the logistical challenges of this approach make it infeasible for many ecological studies. Especially for research in the tropics, permanent cooling poses a challenge, which is why many of those studies use dried leaf tissue instead. We screened a total of 10 extraction and storage approaches for plant metabolites extracted from maize leaf tissue across two cropping seasons to develop a methodology for agroecological studies in logistically challenging tropical locations. All methods were evaluated based on changes in the metabolite profile across a 2‐month storage period at different temperatures with the goal of reproducing the metabolite profile of the living plant as closely as possible. We show that our newly developed on‐site liquid–liquid extraction protocol provides a good compromise between sample replicability, extraction efficiency, material logistics, and metabolite profile stability. We further discuss alternative methods which showed promising results and feasibility of on‐site sample handling for field studies. [ABSTRACT FROM AUTHOR]

Genetically modified maize DP202216 was developed to confer tolerance to glufosinate‐ammonium‐containing herbicides and to provide an opportunity for yield enhancement under field conditions. These properties were achieved by introducing the mo‐pat and zmm28 expression cassettes. The molecular characterisation data and bioinformatic analyses do not identify issues requiring food/feed safety assessment. None of the identified differences in the agronomic/phenotypic and compositional characteristics tested between maize DP202216 and its comparator needs further assessment, except for the levels of stearic acid (C18:0), which do not raise nutritional and safety concerns. The GMO Panel does not identify safety concerns regarding the toxicity and allergenicity of the PAT and ZMM28 proteins as expressed in maize DP202216, and finds no evidence that the genetic modification would change the overall allergenicity of maize DP202216. In the context of this application, the consumption of food and feed from maize DP202216 does not represent a nutritional concern in humans and animals. The GMO Panel concludes that maize DP202216 is as safe as the comparator and non‐GM reference varieties tested, and no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of viable maize DP202216 grains into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize DP202216. The GMO Panel concludes that maize DP202216 is as safe as its comparator and the tested non‐GM reference varieties with respect to potential effects on human and animal health and the environment. [ABSTRACT FROM AUTHOR]

SUMMARY: As a maternal tissue, the pericarp supports and protects for other components of seed, such as embryo and endosperm. Despite the importance of maize pericarp in seed, the genome‐wide transcriptome pattern throughout maize pericarp development has not been well characterized. Here, we developed RNA‐seq transcriptome atlas of B73 maize pericarp development based on 21 samples from 5 days before fertilization (DBP5) to 32 days after fertilization (DAP32). A total of 25 346 genes were detected in programming pericarp development, including 1887 transcription factors (TFs). Together with pericarp morphological changes, the global clustering of gene expression revealed four developmental stages: undeveloped, thickening, expansion and strengthening. Coexpression analysis provided further insights on key regulators in functional transition of four developmental stages. Combined with non‐seed, embryo, endosperm, and nucellus transcriptome data, we identified 598 pericarp‐specific genes, including 75 TFs, which could elucidate key mechanisms and regulatory networks of pericarp development. Cell wall related genes were identified that reflected their crucial role in the maize pericarp structure building. In addition, key maternal proteases or TFs related with programmed cell death (PCD) were proposed, suggesting PCD in the maize pericarp was mediated by vacuolar processing enzymes (VPE), and jasmonic acid (JA) and ethylene‐related pathways. The dynamic transcriptome atlas provides a valuable resource for unraveling the genetic control of maize pericarp development. Significance Statement: This study provides a high temporal resolution transcriptome atlas for unraveling the genetic control of maize pericarp development. [ABSTRACT FROM AUTHOR]

Summary: Lipid biosynthesis and transport are essential for plant male reproduction. Compared with Arabidopsis and rice, relatively fewer maize lipid metabolic genic male‐sterility (GMS) genes have been identified, and the sporopollenin metabolon in maize anther remains unknown. Here, we identified two maize GMS genes, ZmTKPR1‐1 and ZmTKPR1‐2, by CRISPR/Cas9 mutagenesis of 14 lipid metabolic genes with anther stage‐specific expression patterns. Among them, tkpr1‐1/‐2 double mutants displayed complete male sterility with delayed tapetum degradation and abortive pollen. ZmTKPR1‐1 and ZmTKPR1‐2 encode tetraketide α‐pyrone reductases and have catalytic activities in reducing tetraketide α‐pyrone produced by ZmPKSB (polyketide synthase B). Several conserved catalytic sites (S128/130, Y164/166 and K168/170 in ZmTKPR1‐1/‐2) are essential for their enzymatic activities. Both ZmTKPR1‐1 and ZmTKPR1‐2 are directly activated by ZmMYB84, and their encoded proteins are localized in both the endoplasmic reticulum and nuclei. Based on protein structure prediction, molecular docking, site‐directed mutagenesis and biochemical assays, the sporopollenin biosynthetic metabolon ZmPKSB‐ZmTKPR1‐1/‐2 was identified to control pollen exine formation in maize anther. Although ZmTKPR1‐1/‐2 and ZmPKSB formed a protein complex, their mutants showed different, even opposite, defective phenotypes of anther cuticle and pollen exine. Our findings discover new maize GMS genes that can contribute to male‐sterility line‐assisted maize breeding and also provide new insights into the metabolon‐regulated sporopollenin biosynthesis in maize anther. [ABSTRACT FROM AUTHOR]

CMT2 and cpSRP43 are key factors in tolerance to heat stress, which have been revealed in Arabidopsis. It is largely unknown whether they play similar roles in heat stress resistance in monocotyledon species. Here we carried out genome-enabled identification of CHROMO domain genes in five monocots, to which both CMT2 and cpSRP43 belong. Results showed that gene copy numbers are similar in monocots to those in Arabidopsis. Phylogenetic analyses split the family into six major clades, among which CMT2 and cpSRP43 formed independent clades, respectively. Two CMT2s are present in the maize genome, while a single cpSRP43 exists in maize. Expression of the CTM2 homologs was elevated 2 and 48 h after heat stress in maize roots, while that of cpSRP43 was increased 2 and 48 h after stress in maize stalks. The genes identified here can be used as molecular targets for breeders to select for thermal-tolerant wheat lines, while phylogenetic and expression analyses of the CHROMO domain genes can be used as a knowledge base for molecular, biochemical and physiological characterization of the genes in monocots. [ABSTRACT FROM AUTHOR]

Abstract Genetically modified (GM) maize MON 94804 was developed to achieve a reduction in plant height by introducing the GA20ox_SUP suppression cassette. The molecular characterisation and bioinformatic analyses do not identify issues requiring food/feed safety assessment. None of the agronomic/phenotypic and compositional differences identified between maize MON 94804 and its conventional counterpart needs further assessment, except for ear height, plant height and levels of carbohydrates in forage, which do not raise safety or nutritional concerns. The Panel on Genetically Modified Organisms (GMO Panel) does not identify safety concerns regarding the toxicity and allergenicity of the GA20ox_SUP precursor‐miRNA and derived mature miRNA as expressed in maize MON 94804 and finds no evidence that the genetic modification would change the overall allergenicity of maize MON 94804. In the context of this application, the consumption of food and feed from maize MON 94804 does not represent a nutritional concern in humans and animals. The GMO Panel concludes that maize MON 94804 is as safe as the conventional counterpart and non‐GM maize varieties tested, and no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of viable maize MON 94804 grains into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize MON 94804. The GMO Panel concludes that maize MON 94804 is as safe as its conventional counterpart and the tested non‐GM maize varieties with respect to potential effects on human and animal health and the environment.

Abstract Mass spectrometry‐based plant metabolomics is frequently used to identify novel natural products or study the effect of specific treatments on a plant's metabolism. Reliable sample handling is required to avoid artifacts, which is why most protocols mandate shock freezing of plant tissue in liquid nitrogen and an uninterrupted cooling chain. However, the logistical challenges of this approach make it infeasible for many ecological studies. Especially for research in the tropics, permanent cooling poses a challenge, which is why many of those studies use dried leaf tissue instead. We screened a total of 10 extraction and storage approaches for plant metabolites extracted from maize leaf tissue across two cropping seasons to develop a methodology for agroecological studies in logistically challenging tropical locations. All methods were evaluated based on changes in the metabolite profile across a 2‐month storage period at different temperatures with the goal of reproducing the metabolite profile of the living plant as closely as possible. We show that our newly developed on‐site liquid–liquid extraction protocol provides a good compromise between sample replicability, extraction efficiency, material logistics, and metabolite profile stability. We further discuss alternative methods which showed promising results and feasibility of on‐site sample handling for field studies.

Abstract Genetically modified maize DP202216 was developed to confer tolerance to glufosinate‐ammonium‐containing herbicides and to provide an opportunity for yield enhancement under field conditions. These properties were achieved by introducing the mo‐pat and zmm28 expression cassettes. The molecular characterisation data and bioinformatic analyses do not identify issues requiring food/feed safety assessment. None of the identified differences in the agronomic/phenotypic and compositional characteristics tested between maize DP202216 and its comparator needs further assessment, except for the levels of stearic acid (C18:0), which do not raise nutritional and safety concerns. The GMO Panel does not identify safety concerns regarding the toxicity and allergenicity of the PAT and ZMM28 proteins as expressed in maize DP202216, and finds no evidence that the genetic modification would change the overall allergenicity of maize DP202216. In the context of this application, the consumption of food and feed from maize DP202216 does not represent a nutritional concern in humans and animals. The GMO Panel concludes that maize DP202216 is as safe as the comparator and non‐GM reference varieties tested, and no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of viable maize DP202216 grains into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize DP202216. The GMO Panel concludes that maize DP202216 is as safe as its comparator and the tested non‐GM reference varieties with respect to potential effects on human and animal health and the environment.

Abstract Soil salinity poses a significant challenge to crop growth and productivity, particularly affecting the root system, which is vital for water and nutrient uptake. To identify genetic factors that influence root elongation in stressful environments, we conducted a genome-wide association study (GWAS) to investigate the natural variation associated with total root length (TRL) under salt stress and normal conditions in maize seedlings. Our study identified 69 genetic variants associated with 38 candidate genes, among which a specific single nucleotide polymorphism (SNP) in ZmNAC087 was significantly associated with TRL under salt stress. Transient expression and transactivation assays revealed that ZmNAC087 encodes a nuclear-localized protein with transactivation activity. Further candidate gene association analysis showed that non-coding variations in ZmNAC087 promoter contribute to differential ZmNAC087 expression among maize inbred lines, potentially influencing the variation in salt-regulated TRL. In addition, through nucleotide diversity analysis, neutrality tests, and coalescent simulation, we demonstrated that ZmNAC087 underwent selection during maize domestication and improvement. These findings highlight the significance of natural variation in ZmNAC087, particularly the favorable allele, in maize salt tolerance, providing theoretical basis and valuable genetic resources for the development of salt-tolerant maize germplasm.

Soil salinity poses a significant challenge to crop growth and productivity, particularly affecting the root system, which is vital for water and nutrient uptake. To identify genetic factors that influence root elongation in stressful environments, we conducted a genome-wide association study (GWAS) to investigate the natural variation associated with total root length (TRL) under salt stress and normal conditions in maize seedlings. Our study identified 69 genetic variants associated with 38 candidate genes, among which a specific single nucleotide polymorphism (SNP) in ZmNAC087 was significantly associated with TRL under salt stress. Transient expression and transactivation assays revealed that ZmNAC087 encodes a nuclear-localized protein with transactivation activity. Further candidate gene association analysis showed that non-coding variations in ZmNAC087 promoter contribute to differential ZmNAC087 expression among maize inbred lines, potentially influencing the variation in salt-regulated TRL. In addition, through nucleotide diversity analysis, neutrality tests, and coalescent simulation, we demonstrated that ZmNAC087 underwent selection during maize domestication and improvement. These findings highlight the significance of natural variation in ZmNAC087, particularly the favorable allele, in maize salt tolerance, providing theoretical basis and valuable genetic resources for the development of salt-tolerant maize germplasm. [ABSTRACT FROM AUTHOR]

In nature, arbuscular mycorrhizal fungi (AMF) play a crucial role in the root systems of plants. They can help enhance the resistance of host plants by improving the compartmentalization of toxic metal contaminants in the cell walls (CWs). However, the functions and responses of various CW subfractions to mycorrhizal colonization under Cd exposure remain unknown. Here we conducted a study to investigate how Cd is stored in the cell walls of maize roots colonized by Funneliformis mosseae. Our findings indicate that inoculating the roots with AMF significantly lowers the amount of Cd in the maize shoots (63.6 ± 6.54 mg kg−1 vs. 45.3 ± 2.19 mg kg−1, p < 0.05) by retaining more Cd in the mycorrhized roots (224.0 ± 17.13 mg kg−1 vs. 289.5 ± 8.75 mg kg−1, p < 0.01). This reduces the adverse effects of excessive Cd on the maize plant. Additional research on the subcellular distribution of Cd showed that AMF colonization significantly improves the compartmentalization of 88.2% of Cd in the cell walls of maize roots, compared to the 80.8% of Cd associated with cell walls in the non-mycorrhizal controls. We observed that the presence of AMF did not increase the amount of Cd in pectin, a primary binding site for cell walls; however, it significantly enhanced the content of lignin and the proportion of Cd in the total root cell walls. This finding is consistent with the increased activity of lignin-related enzymes, such as PAL, 4CL, and laccase, which were also positively impacted by mycorrhizal colonization. Fourier transform infrared spectroscopy (FTIR) results revealed that AMF increased the number and types of functional groups, including −OH/−NH and carboxylate, which chelate Cd in the lignin. Our research shows that AMF can improve the ability of maize plants to tolerate Cd by reducing the amount of Cd transferred from the roots to the shoots. This is achieved by increasing the amount of lignin in the cell walls, which binds with Cd and prevents it from moving through the plant. This is accomplished by activating enzymes related to lignin synthesis and increasing the exposure of Cd-binding functional groups of lignin. However, more direct evidence on the immobilization of Cd in the mycorrhiza-altered cell wall subfractions is needed. [ABSTRACT FROM AUTHOR]

Fusarium ear rot (FER) is a destructive fungal disease of maize caused by Fusarium verticillioides. FER resistance is a typical complex quantitative trait controlled by micro‐effect genes, leading to difficulty in identifying the host resistance genes. SIZ1 encodes a SUMO E3 ligase regulating a wide range of plant developmental processes and stress responses. However, the function of ZmSIZ1 remains poorly understood. In this study, we demonstrate that ZmSIZ1a and ZmSIZ1b possess SUMO E3 ligase activity, and that the Zmsiz1a/1b double mutant, but not the Zmsiz1a or Zmsiz1b single mutants, exhibits severely impaired resistance to FER. Transcriptome analysis showed that differentially expressed genes were significantly enriched in plant disease resistance‐related pathways, especially in plant–pathogen interaction, MAPK signalling, and plant hormone signal transduction. Thirty‐five candidate genes were identified in these pathways. Furthermore, the integration of the transcriptome and metabolome data revealed that the flavonoid biosynthesis pathway was induced by F. verticillioides infection, and that accumulation of flavone and flavonol was significantly reduced in the Zmsiz1a/1b double mutant. Collectively, our findings demonstrate that ZmSIZ1a and ZmSIZ1b play a redundant, but indispensable role against FER, and provide potential new gene resources for molecular breeding of FER‐resistant maize cultivars. [ABSTRACT FROM AUTHOR]

SUMMARY: PROTEIN l‐ISOASPARTYL O‐METHYLTRANSFERASE (PIMT) affects seed vigor by repairing damaged proteins. While PIMT is capable of isoaspartyl (isoAsp) repair in all proteins, those proteins most susceptible to isoAsp formation have not been well characterized, and the mechanisms by which PIMT affects seed vigor remain largely unknown. Using co‐immunoprecipitation and LC‐MS/MS, we found that maize (Zea mays) PIMT2 (ZmPIMT2) interacted predominantly with both subunits of maize 3‐METHYLCROTONYL COA CARBOXYLASE (ZmMCC). ZmPIMT2 is specifically expressed in the maize embryo. Both mRNA and protein levels of ZmPIMT2 increased during seed maturation and declined during imbibition. Maize seed vigor was decreased in the zmpimt2 mutant line, while overexpression of ZmPIMT2 in maize and Arabidopsis thaliana increased seed vigor upon artificial aging. ZmPIMT2 was localized in the mitochondria, as determined by subcellular localization assays using maize protoplasts. ZmPIMT2 binding to ZmMCCα was confirmed by luciferase complementation tests in both tobacco (Nicotiana benthamiana) leaves and maize protoplasts. Knockdown of ZmMCCα decreased maize seed aging tolerance. Furthermore, overexpression of ZmPIMT2 decreased the accumulation of isoAsp of ZmMCCα protein in seed embryos that underwent accelerated aging treatment. Taken together, our results demonstrate that ZmPIMT2 binds ZmMCCα in mitochondria, repairs isoAsp damage, and positively affects maize seed vigor. Significance Statement: PROTEIN l‐ISOASPARTYL METHYLTRANSFERASE (PIMT) positively affects orthodox seed vigor, repairing abnormal protein isoaspartate (isoAsp) to Asp; however, how seed vigor is exactly affected remains unclear. Maize (Zea mays) mitochondrial 3‐METHYLCROTONYL COA CARBOXYLASE (ZmMCC) positively influences seed vigor, yet accrues isoAsp. ZmPIMT2, also mitochondrially localized, interacts with, and repairs, the isoAsp‐damaged ZmMCC. These results have led to a better understanding of the foundations of seed vigor. [ABSTRACT FROM AUTHOR]

Chlorophyll is an essential component that captures light energy to drive photosynthesis. Chlorophyll content can affect photosynthetic activity and thus yield. Therefore, mining candidate genes of chlorophyll content will help increase maize production. Here, we performed a genome-wide association study (GWAS) on chlorophyll content and its dynamic changes in 378 maize inbred lines with extensive natural variation. Our phenotypic assessment showed that chlorophyll content and its dynamic changes were natural variations with a moderate genetic level of 0.66/0.67. A total of 19 single-nucleotide polymorphisms (SNPs) were found associated with 76 candidate genes, of which one SNP, 2376873-7-G, co-localized in chlorophyll content and area under the chlorophyll content curve (AUCCC). Zm00001d026568 and Zm00001d026569 were highly associated with SNP 2376873-7-G and encoded pentatricopeptide repeat-containing protein and chloroplastic palmitoyl-acyl carrier protein thioesterase, respectively. As expected, higher expression levels of these two genes are associated with higher chlorophyll contents. These results provide a certain experimental basis for discovering the candidate genes of chlorophyll content and finally provide new insights for cultivating high-yield and excellent maize suitable for planting environment. [ABSTRACT FROM AUTHOR]

Summary: Parallel veins are characteristic of monocots, including grasses (Poaceae). Therefore, how parallel veins develop as the leaf grows in the medial–lateral (ML) dimension is a key question in grass leaf development.Using fluorescent protein reporters, we mapped auxin, cytokinin (CK), and gibberellic acid (GA) response patterns in maize (Zea mays) leaf primordia. We further defined the roles of these hormones in ML growth and vein formation through combinatorial genetic analyses and measurement of hormone concentrations.We discovered a novel pattern of auxin response in the adaxial protoderm that we hypothesize has important implications for the orderly formation of 3° veins early in leaf development. In addition, we found an auxin transport and response pattern in the margins that correlate with the transition from ML to proximal–distal growth. We present evidence that auxin efflux precedes CK response in procambial strand development. We also determined that GA plays an early role in the shoot apical meristem as well as a later role in the primordium to restrict ML growth.We propose an integrative model whereby auxin regulates ML growth and vein formation in the maize leaf through control of GA and CK. [ABSTRACT FROM AUTHOR]

The European Commission requested the Panel on Genetically Modified Organisms of the European Food Safety Authority (EFSA GMO Panel) to assess new scientific information on maize MIR162, and to indicate whether the previous conclusions on the safety of maize MIR162 as a single event and as a part of stacked events remain valid. The new information is included in a European patent that reports a decrease in male fertility in some MIR162 inbred lines, pointing to a potential link between such decrease and the Vip3 protein expressed by maize MIR162. The EFSA GMO Panel evaluated the data provided by the patent owner and found scarce support for a causal link between Vip3 and decreased fertility. The general hypothesis of an association between event MIR162 and altered fertility could not be confirmed. The EFSA GMO Panel conducted the safety assessment based on the conservative assumption that such an association exists. The EFSA GMO Panel concluded that a decrease in male fertility would have no impact on the previous conclusions on maize MIR162 and stacked events containing MIR162. [ABSTRACT FROM AUTHOR]

Transcription factors (TFs) are important regulators of numerous gene expressions due to their ability to recognize and combine cis-elements in the promoters of target genes. The INDETERMINATE DOMAIN (IDD) gene family belongs to a subfamily of C2H2 zinc finger proteins and has been identified only in terrestrial plants. Nevertheless, little study has been reported concerning the genome-wide analysis of the IDD gene family in maize. In total, 22 ZmIDD genes were identified, which can be distributed on 8 chromosomes in maize. On the basis of evolutionary relationships and conserved motif analysis, ZmIDDs were categorized into three clades (1, 2, and 3), each owning 4, 6, and 12 genes, respectively. We analyzed the characteristics of gene structure and found that 3 of the 22 ZmIDD genes do not contain an intron. Cis-element analysis of the ZmIDD promoter showed that most ZmIDD genes possessed at least one ABRE or MBS cis-element, and some ZmIDD genes owned the AuxRR-core, TCA-element, TC-rich repeats, and LTR cis-element. The Ka:Ks ratio of eight segmentally duplicated gene pairs demonstrated that the ZmIDD gene families had undergone a purifying selection. Then, the transcription levels of ZmIDDs were analyzed, and they showed great differences in diverse tissues as well as abiotic stresses. Furthermore, regulatory networks were constructed through the prediction of ZmIDD-targeted genes and miRNAs, which can inhibit the transcription of ZmIDDs. In total, 6 ZmIDDs and 22 miRNAs were discovered, which can target 180 genes and depress the expression of 9 ZmIDDs, respectively. Taken together, the results give us valuable information for studying the function of ZmIDDs involved in plant development and climate resilience in maize. [ABSTRACT FROM AUTHOR]

SUMMARY: Drought stress is one of the major constraints of global crop production. Raffinose, a non‐reducing trisaccharide, has been considered to regulate positively the plant drought stress tolerance; however, evidence that augmenting raffinose production in leaves results in enhanced plant drought stress tolerance is lacking. The biochemical mechanism through which raffinose might act to mitigate plant drought stress remains unidentified. ZmRAFS encodes Zea mays RAFFINOSE SYNTHASE, a key enzyme that transfers galactose from the galactoside galactinol to sucrose for raffinose production. Overexpression of ZmRAFS in maize increased the RAFS protein and the raffinose content and decreased the water loss of leaves and enhanced plant drought stress tolerance. The biomass of the ZmRAFS overexpressing plants was similar to that of non‐transgenic control plants when grown under optimal conditions, but was significantly greater than that of non‐transgenic plants when grown under drought stress conditions. In contrast, the percentage of water loss of the detached leaves from two independent zmrafs mutant lines, incapable of synthesizing raffinose, was greater than that from null segregant controls and this phenomenon was partially rescued by supplementation of raffinose to detached zmrafs leaves. In addition, while there were differences in water loss among different maize lines, there was no difference in stomata density or aperture. Taken together, our work demonstrated that overexpression of the ZmRAFS gene in maize, in contrast to Arabidopsis, increased the raffinose content in leaves, assisted the leaf to retain water, and enhanced the plant drought stress tolerance without causing a detectable growth penalty. Significance Statement: Raffinose has been positively correlated with drought tolerance but its mechanism of action remains obscure. The amounts of raffinose increased in leaves of maize plants constitutively overexpressing its RAFFINOSE SYNTHASE gene, which then assisted the leaf to retain water, and enhanced the plant drought stress tolerance without a growth penalty. Raffinose exerts its protective effect independent of leaf stomata density, and aperture or the cell plasma membrane structure; presumably through its in vitro demonstrable physical, hygroscopic properties. [ABSTRACT FROM AUTHOR]

The toxins produced by Aspergillus flavus can significantly inhibit the use of maize. As a result of climate change, toxin production is a problem not only in tropical and subtropical areas but in an increasing number of European countries, including Hungary. The effect of meteorological factors and irrigation on mould colonization and aflatoxin B1 (AFB1) mycotoxin production by A. flavus were investigated in natural conditions, as well as the inoculation with a toxigenic isolate in a complex field experiment for three years. As a result of irrigation, the occurrence of fungi increased, and toxin production decreased. The mould count of fungi and toxin accumulation showed differences during the examined growing seasons. The highest AFB1 content was found in 2021. The main environmental factors in predicting mould count were temperature (Tavg, Tmax ≥ 30 °C, Tmax ≥ 32 °C, Tmax ≥ 35 °C) and atmospheric drought (RHmin ≤ 40%). Toxin production was determined by extremely high daily maximum temperatures (Tmax ≥ 35 °C). At natural contamination, the effect of Tmax ≥ 35 °C on AFB1 was maximal (r = 0.560–0.569) in the R4 stage. In the case of artificial inoculation, correlations with environmental factors were stronger (r = 0.665–0.834) during the R2–R6 stages. [ABSTRACT FROM AUTHOR]

The respiratory burst oxidase homolog (RBOH), as the key producer of reactive oxygen species (ROS), plays an essential role in plant development. In this study, a bioinformatic analysis was performed on 22 plant species, and 181 RBOH homologues were identified. A typical RBOH family was identified only in terrestrial plants, and the number of RBOHs increased from non-angiosperms to angiosperms. Whole genome duplication (WGD)/segmental duplication played a key role in RBOH gene family expansion. Amino acid numbers of 181 RBOHs ranged from 98 to 1461, and the encoded proteins had molecular weights from 11.1 to 163.6 kDa, respectively. All plant RBOHs contained a conserved NADPH_Ox domain, while some of them lacked the FAD_binding_8 domain. Plant RBOHs were classified into five main subgroups by phylogenetic analysis. Most RBOH members in the same subgroup showed conservation in both motif distribution and gene structure composition. Fifteen ZmRBOHs were identified in maize genome and were positioned in eight maize chromosomes. A total of three pairs of orthologous genes were found in maize, including ZmRBOH6/ZmRBOH8, ZmRBOH4/ZmRBOH10 and ZmRBOH15/ZmRBOH2. A Ka/Ks calculation confirmed that purifying selection was the main driving force in their evolution. ZmRBOHs had typical conserved domains and similar protein structures. cis-element analyses together with the expression profiles of the ZmRBOH genes in various tissues and stages of development suggested that ZmRBOH was involved in distinct biological processes and stress responses. Based on the RNA-Seq data and qRT-PCR analysis, the transcriptional response of ZmRBOH genes was examined under various abiotic stresses, and most of ZmRBOH genes were up-regulated by cold stress. These findings provide valuable information for further revealing the biological roles of ZmRBOH genes in plant development and abiotic stress responses. [ABSTRACT FROM AUTHOR]

The presented research is about the effect of seed treatment with γ-radiation on the development of the maize plant and on the chlorophyll synthesis under salt stress. It has been revealed that separately high doses of radiation and low or high NaCl concentrations inhibit the plant growth as well as chlorophyll synthesis in the leaves, while pre-sowing irradiation of the seeds with a dose of 50 Gy stimulates the growth of the plant and chlorophyll synthesis even at high concentrations of NaCl.

Abstract The European Commission requested the Panel on Genetically Modified Organisms of the European Food Safety Authority (EFSA GMO Panel) to assess new scientific information on maize MIR162, and to indicate whether the previous conclusions on the safety of maize MIR162 as a single event and as a part of stacked events remain valid. The new information is included in a European patent that reports a decrease in male fertility in some MIR162 inbred lines, pointing to a potential link between such decrease and the Vip3 protein expressed by maize MIR162. The EFSA GMO Panel evaluated the data provided by the patent owner and found scarce support for a causal link between Vip3 and decreased fertility. The general hypothesis of an association between event MIR162 and altered fertility could not be confirmed. The EFSA GMO Panel conducted the safety assessment based on the conservative assumption that such an association exists. The EFSA GMO Panel concluded that a decrease in male fertility would have no impact on the previous conclusions on maize MIR162 and stacked events containing MIR162.

Genetically modified maize MON 87419 was developed to confer tolerance to dicamba‐ and glufosinate‐based herbicides. These properties were achieved by introducing the dmo and pat expression cassettes. The molecular characterisation data and bioinformatic analyses do not identify issues requiring food/feed safety assessment. None of the identified differences in the agronomic/phenotypic and compositional characteristics tested between maize MON 87419 and its conventional counterpart needed further assessment, except for the levels of arginine and protein in grains which did not raise safety and nutritional concerns. The GMO Panel does not identify safety concerns regarding the toxicity and allergenicity of the dicamba mono‐oxygenase (DMO) and phosphinothricin N‐acetyltransferase (PAT) proteins as expressed in maize MON 87419. The GMO Panel finds no evidence that the genetic modification impacts the overall safety of maize MON 87419. In the context of this application, the consumption of food and feed from maize MON 87419 does not represent a nutritional concern in humans and animals. The GMO Panel concludes that maize MON 87419 is as safe as the conventional counterpart and non‐GM maize varieties tested, and no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of viable maize MON 87419 grains into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize MON 87419. The GMO Panel concludes that maize MON 87419 is as safe as its conventional counterpart and the tested non‐GM maize varieties with respect to potential effects on human and animal health and the environment. [ABSTRACT FROM AUTHOR]

Genetically modified maize GA21 × T25 was developed by crossing to combine two single events: GA21 and T25. The GMO Panel previously assessed the two single maize events and did not identify safety concerns. No new data on the single maize events were identified that could lead to modification of the original conclusions on their safety. The molecular characterisation, comparative analysis (agronomic, phenotypic and compositional characteristics) and the outcome of the toxicological, allergenicity and nutritional assessment indicate that the combination of the single maize events and of the newly expressed proteins in maize GA21 × T25 does not give rise to food and feed safety and nutritional concerns. The GMO Panel concludes that maize GA21 × T25, as described in this application, is as safe as its conventional counterpart and the non‐GM reference varieties tested, and no post‐market monitoring of food and feed is considered necessary. In the case of accidental release of viable maize GA21 × T25 grains into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize GA21 × T25. Post‐market monitoring of food and feed is not considered necessary. The GMO Panel concludes that maize GA21 × T25 is as safe as its conventional counterpart and the non‐GM reference varieties tested, with respect to potential effects on human and animal health and the environment. [ABSTRACT FROM AUTHOR]

Introduction: Protein kinases play an important role in plants in response to environmental changes through signal transduction. As a large family of protein kinases, sucrose non-fermenting-1 (SNF1)-related kinases (SnRKs) were found and functionally verified in many plants. Nevertheless, little is known about the SnRK family of Zea mays. Methods: Evolutionary relationships, chromosome locations, gene structures, conserved motifs, and cis-elements in promoter regions were systematically analyzed. Besides, tissue-specific and stress-induced expression patterns of ZmSnRKs were determined. Finally, functional regulatory networks between ZmSnRKs and other proteins or miRNAs were constructed. Results and Discussion: In total, 60SnRKgenes locatedon10chromosomeswere discovered in maize. ZmSnRKs were classified into three subfamilies (ZmSnRK1, ZmSnRK2, and ZmSnRK3), consisting of 4, 14, and 42 genes, respectively. Gene structure analysis showed that 33 of the 42 ZmSnRK3 genes contained only one exon. Most ZmSnRK genes contained at least one ABRE, MBS, and LTR cis-element and a few ZmSnRK genes had AuxRR-core, P-box, MBSI, and SARE ciselements in their promoter regions. The Ka:Ks ratio of 22 paralogous ZmSnRK gene pairs revealed that the ZmSnRK gene family had experienced a purifying selection. Meanwhile, we analyzed the expression profiles of ZmSnRKs, and they exhibited significant differences in various tissues and abiotic stresses. In addition, A total of eight ZmPP2Cs, which can interact with ZmSnRK proteins, and 46 miRNAs, which can target 24 ZmSnRKs, were identified. Generally, these results provide valuable information for further function verification of ZmSnRKs, and improve our understanding of the role of ZmSnRKs in the climate resilience of maize. [ABSTRACT FROM AUTHOR]

Genetically modified maize DP4114 × MON 89034 × MON 87411 × DAS‐40278‐9 was developed by crossing to combine four single events: DP4114, MON 89034, MON 87411 and DAS‐40278‐9. The GMO Panel previously assessed the four single maize events and two of the subcombinations and did not identify safety concerns. No new data on the single maize events or the assessed subcombinations were identified that could lead to modification of the original conclusions on their safety. The molecular characterisation, comparative analysis (agronomic, phenotypic and compositional characteristics) and the outcome of the toxicological, allergenicity and nutritional assessment indicate that the combination of the single maize events and of the newly expressed proteins in the four‐event stack maize does not give rise to food and feed safety and nutritional concerns. Therefore, no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of viable four‐event stack maize grains into the environment, this would not raise environmental safety concerns. The GMO Panel assessed the likelihood of interactions among the single events in eight of the maize subcombinations not previously assessed and concludes that these are expected to be as safe as the single events, the previously assessed subcombinations and the four‐event stack maize. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize DP4114 × MON 89034 × MON 87411 × DAS‐40278‐9. Post‐market monitoring of food/feed is not considered necessary. The GMO Panel concludes that the four‐event stack maize and its subcombinations are as safe as its non‐GM comparator and the tested non‐GM maize varieties with respect to potential effects on human and animal health and the environment. [ABSTRACT FROM AUTHOR]

Maize MON 87429 was developed to confer tolerance to dicamba, glufosinate, quizalofop and 2,4‐D herbicides. The molecular characterisation data and bioinformatic analyses do not identify issues requiring food/feed safety assessment. None of the identified differences in the agronomic/phenotypic and compositional characteristics tested between maize MON 87429 and its conventional counterpart needs further assessment, except for the levels of phytic acid in grains, which do not raise nutritional and safety concerns. The GMO Panel does not identify safety concerns regarding the toxicity and allergenicity of the DMO, PAT, FT_T and CP4 EPSPS proteins as expressed in maize MON 87429. The GMO Panel finds no evidence that the genetic modification impacts the overall safety of maize MON 87429. In the context of this application, the consumption of food and feed from maize MON 87429 does not represent a nutritional concern in humans and animals. The GMO Panel concludes that maize MON 87429 is as safe as the conventional counterpart and non‐GM maize reference varieties tested, and no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of viable maize MON 87429 grains into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize MON 87429. The GMO Panel concludes that maize MON 87429, as described in this application, is as safe as its conventional counterpart and the tested non‐GM maize reference varieties with respect to potential effects on human and animal health and the environment. [ABSTRACT FROM AUTHOR]

Genetically modified maize MON 95379 was developed to confer insect protection against certain lepidopteran species. These properties were achieved by introducing the cry1B.868 and cry1Da_7 expression cassettes. The molecular characterisation data and bioinformatic analyses do not identify issues requiring food/feed safety assessment. None of the identified differences in the agronomic/phenotypic and compositional characteristics tested between maize MON 95379 and its conventional counterpart needs further assessment. The GMO Panel does not identify safety concerns regarding the toxicity and allergenicity of the Cry1B.868 and Cry1Da_7 proteins as expressed in maize MON 95379. The GMO Panel finds no evidence that the genetic modification impacts the overall safety of maize MON 95379. In the context of this application, the consumption of food and feed from maize MON 95379 does not represent a nutritional concern in humans and animals. Therefore, no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of viable maize MON 95379 grains into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize MON 95379. The GMO Panel concludes that maize MON 95379 is as safe as its conventional counterpart and the tested non‐GM maize varieties with respect to potential effects on human and animal health and the environment. [ABSTRACT FROM AUTHOR]

Aflatoxins are carcinogenic secondary metabolites produced by several species of Aspergillus, including Aspergillus flavus, an important ear rot pathogen in maize. Most commercial corn hybrids are susceptible to infection by A. flavus, and aflatoxin contaminated grain causes economic damage to farmers. The creation of inbred lines resistant to Aspergillus fungal infection or the accumulation of aflatoxins would be aided by knowing the pertinent alleles and metabolites associated with resistance in corn lines. Multiple Quantitative Trait Loci (QTL) and association mapping studies have uncovered several dozen potential genes, but each with a small effect on resistance. Metabolic pathway analysis, using the Pathway Association Study Tool (PAST), was performed on aflatoxin accumulation resistance using data from four Genome-wide Association Studies (GWAS). The present research compares the outputs of these pathway analyses and seeks common metabolic mechanisms underlying each. Genes, pathways, metabolites, and mechanisms highlighted here can contribute to improving phenotypic selection of resistant lines via measurement of more specific and highly heritable resistance-related traits and genetic gain via marker assisted or genomic selection with multiple SNPs linked to resistance-related pathways. [ABSTRACT FROM AUTHOR]

In nature, arbuscular mycorrhizal fungi (AMF) play a crucial role in the root systems of plants. They can help enhance the resistance of host plants by improving the compartmentalization of toxic metal contaminants in the cell walls (CWs). However, the functions and responses of various CW subfractions to mycorrhizal colonization under Cd exposure remain unknown. Here we conducted a study to investigate how Cd is stored in the cell walls of maize roots colonized by Funneliformis mosseae. Our findings indicate that inoculating the roots with AMF significantly lowers the amount of Cd in the maize shoots (63.6 ± 6.54 mg kg−1 vs. 45.3 ± 2.19 mg kg−1, p < 0.05) by retaining more Cd in the mycorrhized roots (224.0 ± 17.13 mg kg−1 vs. 289.5 ± 8.75 mg kg−1, p < 0.01). This reduces the adverse effects of excessive Cd on the maize plant. Additional research on the subcellular distribution of Cd showed that AMF colonization significantly improves the compartmentalization of 88.2% of Cd in the cell walls of maize roots, compared to the 80.8% of Cd associated with cell walls in the non-mycorrhizal controls. We observed that the presence of AMF did not increase the amount of Cd in pectin, a primary binding site for cell walls; however, it significantly enhanced the content of lignin and the proportion of Cd in the total root cell walls. This finding is consistent with the increased activity of lignin-related enzymes, such as PAL, 4CL, and laccase, which were also positively impacted by mycorrhizal colonization. Fourier transform infrared spectroscopy (FTIR) results revealed that AMF increased the number and types of functional groups, including −OH/−NH and carboxylate, which chelate Cd in the lignin. Our research shows that AMF can improve the ability of maize plants to tolerate Cd by reducing the amount of Cd transferred from the roots to the shoots. This is achieved by increasing the amount of lignin in the cell walls, which binds with Cd and prevents it from moving through the plant. This is accomplished by activating enzymes related to lignin synthesis and increasing the exposure of Cd-binding functional groups of lignin. However, more direct evidence on the immobilization of Cd in the mycorrhiza-altered cell wall subfractions is needed.

Abstract Genetically modified maize GA21 × T25 was developed by crossing to combine two single events: GA21 and T25. The GMO Panel previously assessed the two single maize events and did not identify safety concerns. No new data on the single maize events were identified that could lead to modification of the original conclusions on their safety. The molecular characterisation, comparative analysis (agronomic, phenotypic and compositional characteristics) and the outcome of the toxicological, allergenicity and nutritional assessment indicate that the combination of the single maize events and of the newly expressed proteins in maize GA21 × T25 does not give rise to food and feed safety and nutritional concerns. The GMO Panel concludes that maize GA21 × T25, as described in this application, is as safe as its conventional counterpart and the non‐GM reference varieties tested, and no post‐market monitoring of food and feed is considered necessary. In the case of accidental release of viable maize GA21 × T25 grains into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize GA21 × T25. Post‐market monitoring of food and feed is not considered necessary. The GMO Panel concludes that maize GA21 × T25 is as safe as its conventional counterpart and the non‐GM reference varieties tested, with respect to potential effects on human and animal health and the environment.

Abstract Genetically modified maize MON 87419 was developed to confer tolerance to dicamba‐ and glufosinate‐based herbicides. These properties were achieved by introducing the dmo and pat expression cassettes. The molecular characterisation data and bioinformatic analyses do not identify issues requiring food/feed safety assessment. None of the identified differences in the agronomic/phenotypic and compositional characteristics tested between maize MON 87419 and its conventional counterpart needed further assessment, except for the levels of arginine and protein in grains which did not raise safety and nutritional concerns. The GMO Panel does not identify safety concerns regarding the toxicity and allergenicity of the dicamba mono‐oxygenase (DMO) and phosphinothricin N‐acetyltransferase (PAT) proteins as expressed in maize MON 87419. The GMO Panel finds no evidence that the genetic modification impacts the overall safety of maize MON 87419. In the context of this application, the consumption of food and feed from maize MON 87419 does not represent a nutritional concern in humans and animals. The GMO Panel concludes that maize MON 87419 is as safe as the conventional counterpart and non‐GM maize varieties tested, and no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of viable maize MON 87419 grains into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize MON 87419. The GMO Panel concludes that maize MON 87419 is as safe as its conventional counterpart and the tested non‐GM maize varieties with respect to potential effects on human and animal health and the environment.

Abstract Genetically modified maize MON 95379 was developed to confer insect protection against certain lepidopteran species. These properties were achieved by introducing the cry1B.868 and cry1Da_7 expression cassettes. The molecular characterisation data and bioinformatic analyses do not identify issues requiring food/feed safety assessment. None of the identified differences in the agronomic/phenotypic and compositional characteristics tested between maize MON 95379 and its conventional counterpart needs further assessment. The GMO Panel does not identify safety concerns regarding the toxicity and allergenicity of the Cry1B.868 and Cry1Da_7 proteins as expressed in maize MON 95379. The GMO Panel finds no evidence that the genetic modification impacts the overall safety of maize MON 95379. In the context of this application, the consumption of food and feed from maize MON 95379 does not represent a nutritional concern in humans and animals. Therefore, no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of viable maize MON 95379 grains into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize MON 95379. The GMO Panel concludes that maize MON 95379 is as safe as its conventional counterpart and the tested non‐GM maize varieties with respect to potential effects on human and animal health and the environment.

Abstract Maize MON 87429 was developed to confer tolerance to dicamba, glufosinate, quizalofop and 2,4‐D herbicides. The molecular characterisation data and bioinformatic analyses do not identify issues requiring food/feed safety assessment. None of the identified differences in the agronomic/phenotypic and compositional characteristics tested between maize MON 87429 and its conventional counterpart needs further assessment, except for the levels of phytic acid in grains, which do not raise nutritional and safety concerns. The GMO Panel does not identify safety concerns regarding the toxicity and allergenicity of the DMO, PAT, FT_T and CP4 EPSPS proteins as expressed in maize MON 87429. The GMO Panel finds no evidence that the genetic modification impacts the overall safety of maize MON 87429. In the context of this application, the consumption of food and feed from maize MON 87429 does not represent a nutritional concern in humans and animals. The GMO Panel concludes that maize MON 87429 is as safe as the conventional counterpart and non‐GM maize reference varieties tested, and no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of viable maize MON 87429 grains into the environment, this would not raise environmental safety concerns. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize MON 87429. The GMO Panel concludes that maize MON 87429, as described in this application, is as safe as its conventional counterpart and the tested non‐GM maize reference varieties with respect to potential effects on human and animal health and the environment.

Abstract Genetically modified maize DP4114 × MON 89034 × MON 87411 × DAS‐40278‐9 was developed by crossing to combine four single events: DP4114, MON 89034, MON 87411 and DAS‐40278‐9. The GMO Panel previously assessed the four single maize events and two of the subcombinations and did not identify safety concerns. No new data on the single maize events or the assessed subcombinations were identified that could lead to modification of the original conclusions on their safety. The molecular characterisation, comparative analysis (agronomic, phenotypic and compositional characteristics) and the outcome of the toxicological, allergenicity and nutritional assessment indicate that the combination of the single maize events and of the newly expressed proteins in the four‐event stack maize does not give rise to food and feed safety and nutritional concerns. Therefore, no post‐market monitoring of food/feed is considered necessary. In the case of accidental release of viable four‐event stack maize grains into the environment, this would not raise environmental safety concerns. The GMO Panel assessed the likelihood of interactions among the single events in eight of the maize subcombinations not previously assessed and concludes that these are expected to be as safe as the single events, the previously assessed subcombinations and the four‐event stack maize. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize DP4114 × MON 89034 × MON 87411 × DAS‐40278‐9. Post‐market monitoring of food/feed is not considered necessary. The GMO Panel concludes that the four‐event stack maize and its subcombinations are as safe as its non‐GM comparator and the tested non‐GM maize varieties with respect to potential effects on human and animal health and the environment.

Soil salinity is a major constraint that restricts crop productivity worldwide. Lateral roots (LRs) are important for water and nutrient acquisition, therefore understanding the genetic basis of natural variation in lateral root length (LRL) is of great agronomic relevance to improve salt tolerance in cultivated germplasms. Here, using a genome-wide association study, we showed that the genetic variation in ZmSULTR3;4, which encodes a plasma membrane-localized sulfate transporter, is associated with natural variation in maize LRL under salt stress. The transcript of ZmSULTR3;4 was found preferentially in the epidermal and vascular tissues of root and increased by salt stress, supporting its essential role in the LR formation under salt stress. Further candidate gene association analysis showed that DNA polymorphisms in the promoter region differentiate the expression of ZmSULTR3;4 among maize inbred lines that may contribute to the natural variation of LRL under salt stress. Nucleotide diversity and neutrality tests revealed that ZmSULTR3;4 has undergone selection during maize domestication and improvement. Overall, our results revealed a regulatory role of ZmSULTR3;4 in salt regulated LR growth and uncovered favorable alleles of ZmSULTR3;4, providing an important selection target for breeding salt-tolerant maize cultivar. [ABSTRACT FROM AUTHOR]

Genetically modified maize MON 89034 × 1507 × MIR162 × NK603 × DAS‐40278‐9 was developed by crossing to combine five single events: MON 89034, 1507, MIR162, NK603 and DAS‐40278‐9. The GMO Panel previously assessed the five single maize events and 16 of the subcombinations and did not identify safety concerns. No new data on the single maize events or the assessed subcombinations were identified that could lead to the modification of the original conclusions on their safety. The molecular characterisation, comparative analysis (agronomic, phenotypic and compositional characteristics) and the outcome of the toxicological, allergenicity and nutritional assessment indicate that the combination of the single maize events and of the newly expressed proteins in the five‐event stack maize does not give rise to food and feed safety and nutritional concerns. The GMO Panel concludes that five‐event stack maize, as described in this application, is as safe as the non‐GM comparator and non‐GM maize varieties tested. In the case of accidental release of viable five‐event stack maize grains into the environment, this would not raise environmental safety concerns. The GMO Panel assessed the likelihood of interactions among the single events in nine of the maize subcombinations not previously assessed and concludes that these are expected to be as safe as the single events, the previously assessed subcombinations and the five‐event stack maize. The post‐market environmental monitoring plan and reporting intervals are in line with the intended uses of maize MON 89034 × 1507 × MIR162 × NK603 × DAS‐40278‐9. Post‐market monitoring of food/feed is not considered necessary. The GMO Panel concludes that the five‐event stack maize and its subcombinations are as safe as its non‐GM comparator and the tested non‐GM maize varieties with respect to potential effects on human and animal health and the environment. [ABSTRACT FROM AUTHOR]

Raffinose mitigates plant heat, drought, and cold stresses; however, whether raffinose contributes to plant waterlogging tolerance is unknown. The maize raffinose synthase mutant zmrafs-1 had seedlings that lack raffinose, generated fewer and shorter adventitious roots, and were more sensitive to waterlogging stress, while overexpression of the raffinose synthase gene, ZmRAFS, increased raffinose content, stimulated adventitious root formation, and enhanced waterlogging tolerance of maize seedlings. Transcriptome analysis of null segregant seedlings compared with zmrafs-1, particularly when waterlogged, revealed that the expression of genes related to galactose metabolism and the auxin biosynthetic pathway were up-regulated by raffinose. Additionally, indole-3-acetic acid content was significantly decreased in zmrafs-1 seedlings and increased in ZmRAFS-overexpressing seedlings. Inhibition of the hydrolysis of raffinose by 1-deoxygalactonojirimycin decreased the waterlogging tolerance of maize seedlings, the expression of genes encoding proteins related to auxin transport-related genes, and the indole-3-acetic acid level in the seedlings, indicating that the hydrolysis of raffinose is necessary for maize waterlogging tolerance. These data demonstrate that raffinose catabolism stimulates adventitious root formation via the auxin signaling pathway to enhance maize waterlogging tolerance., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Pentatricopeptide repeat (PPR) proteins are a large group of eukaryote-specific RNA-binding proteins that play pivotal roles in plant organelle gene expression. Here, we report the function of PPR21 in mitochondrial intron splicing and its role in maize kernel development. PPR21 is a typical P-type PPR protein targeted to mitochondria. The ppr21 mutants are arrested in embryogenesis and endosperm development, leading to embryo lethality. Null mutations of PPR21 reduce the splicing efficiency of nad2 intron 1, 2, and 4 and impair the assembly and activity of mitochondrial complex I. Previous studies show that the P-type PPR protein EMP12 is required for the splicing of identical introns. However, our protein interaction analyses reveal that PPR21 does not interact with EMP12. Instead, both PPR21 and EMP12 interact with the small MutS-related (SMR) domain-containing PPR protein 1 (PPR-SMR1) and the short P-type PPR protein 2 (SPR2). PPR-SMR1 interacts with SPR2, and both proteins are required for the splicing of many introns in mitochondria, including nad2 intron 1, 2, and 4. These results suggest that a PPR21-(PPR-SMR1/SPR2)-EMP12 complex is involved in the splicing of nad2 introns in maize mitochondria., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2024. Published by Elsevier Ltd.)