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Wang Y, Ma S, Zhang D, Li C, Chen L, Tang B, An Y, Liu X, He G, Shi Y, Li Y, Wang T, Yang D, Li Y. Identification of RppSLN from an Elite Landrace: A Major Locus Conferring Resistance to Southern Corn Rust in Maize ( Zea mays L.). PLANTS (BASEL, SWITZERLAND) 2024; 13:3227. [PMID: 39599436 PMCID: PMC11598374 DOI: 10.3390/plants13223227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2024] [Revised: 11/11/2024] [Accepted: 11/13/2024] [Indexed: 11/29/2024]
Abstract
Southern corn rust (SCR) is one of the most destructive foliar diseases in maize (Zea mays L.), resulting in significant yield losses. Therefore, the continuous identification of disease-resistant germplasm and the deployment of resistant hybrids is essential for durably controlling SCR. The objective of this research was to identify and characterize resistance loci against SCR in maize to expand disease management strategies. Here, we identified a maize landrace with high resistance to SCR 'Silunuo' (SLN) approaching complete immunity. We backcrossed it with a susceptible inbred line, N531, to generate a stable SCR-resistant introgression line N531_R. By crossing it with F35 (a susceptible inbred line), we created a large F2 segregating population and mapped a major SCR-resistant locus on chromosome 10, known as RppSLN. Based on the genome assembly and annotation, we found that RppSLN harbors two NBS-LRR (nucleotide binding site-leucine-rich repeat) genes, namely Zmays10G000430 and Zmays10G000440. These NBS-LRR genes were significantly induced during artificial inoculation with Puccinia polysora, suggesting that they might be candidate genes collectively contributing to the resistance level at this locus. In conclusion, this study identified a major SCR resistance locus directly isolated from a landrace, providing valuable support and information for expanding new disease-resistant germplasms and promoting the utilization of landraces.
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Sun L, Wang L, Niu J, Yang W, Li Z, Liu L, Gao S. The maize gene ZmSBP17 encoding an SBP transcription factor confers osmotic resistance in transgenic Arabidopsis. FRONTIERS IN PLANT SCIENCE 2024; 15:1483486. [PMID: 39574449 PMCID: PMC11578699 DOI: 10.3389/fpls.2024.1483486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2024] [Accepted: 10/07/2024] [Indexed: 11/24/2024]
Abstract
Among the major abiotic stresses, salt and drought have considerably affected agricultural development globally by interfering with gene expression profiles and cell metabolism. Transcription factors play crucial roles in activating or inhibiting the expression of stress-related genes in response to abiotic stress in plants. In this study, the Zea mays L. SQUAMOSA promoter-binding protein gene (ZmSBP17) was identified, and the molecular regulatory mechanism of osmotic stress tolerance was analyzed. Phylogenetic analysis confirmed that ZmSBP17 is part of the SBP gene family and is closely related to OsSBP17. The ZmSBP17-GFP fusion protein exhibited green fluorescence in the nucleus, as determined via tobacco epidermal transient transformation system. Acting as a transcriptional activator, the overexpression of ZmSBP17 in Arabidopsis significantly enhanced the expression of genes encoding superoxide dismutases (CSD1/2, MSD1), catalases (CAT1/2), ascorbate peroxidase 1 (APX1), and myeloblastosis transcription factors (AtMYB53/65), which increased the activity of reactive oxygen species (ROS)-scavenging enzymes and reduced ROS levels. Additionally, the expression of abiotic stress-related genes, such as AtDREB2A and AtNHX1, was significantly upregulated by ZmSBP17. Furthermore, ZmSBP17 specifically bound to cis-acting elements containing GTAC core sequences in the promoters of stress-related genes, suggesting that ZmSBP17 regulates the transcription of certain genes by recognizing these sequences. These results indicate that the overexpression of ZmSBP17 in Arabidopsis thaliana significantly increased tolerance to osmotic stress during the germination and seedling stages, which may enhance our understanding of the biological functions of SBPs in maize under abiotic stresses.
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Liu D, Ning Q, Zhai L, Teng F, Li Y, Zhao R, Xiong Q, Zhan J, Li Z, Yang F, Zhang Z, Liu L. Coordinated control for the auricle asymmetric development by ZmIDD14 and ZmIDD15 fine-tune the high-density planting adaption in maize. PLANT BIOTECHNOLOGY JOURNAL 2024; 22:2675-2687. [PMID: 38816933 PMCID: PMC11536443 DOI: 10.1111/pbi.14382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 03/18/2024] [Accepted: 05/06/2024] [Indexed: 06/01/2024]
Abstract
Multiple distinct specialized regions shape the architecture of maize leaves. Among them, the fringe-like and wedge-shaped auricles alter the angle between the leaf and stalk, which is a key trait in crop plant architecture. As planting density increased, a small leaf angle (LA) was typically selected to promote crop light capture efficiency and yield. In the present study, we characterized two paralogous INDETERMINATE DOMAIN (IDD) genes, ZmIDD14 and ZmIDD15, which contain the Cys2-His2 zinc finger domain and function redundantly to regulate auricle development and LA in maize. Loss-of-function mutants showed decreased LA by reducing adaxial sclerenchyma thickness and increasing the colourless cell layers. In addition, the idd14;idd15 double mutant exhibited asymmetrically smaller auricles, which might cause by a failed maintenance of symmetric expression of the key auricle size controlling gene, LIGULELESS(LG1). The transcripts of ZmIDD14 and ZmIDD15 enriched in the ligular region, where LG1 was highly expressed, and both proteins physically interacted with ZmILI1 to promote LG1 transcription. Notably, the idd14;idd15 enhanced the grain yield of hybrids under high planting densities by shaping the plant architecture with a smaller LA. These findings demonstrate the functions of ZmIDD14 and ZmIDD15 in controlling the abaxial/adaxial development of sclerenchyma in the midrib and polar development along the medial-lateral axes of auricles and provide an available tool for high-density and high-yield breeding in maize.
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Wang X, Qi X, Zhuang Z, Bian J, Li J, Chen J, Li Z, Peng Y. Interactions between Brassinosteroids and Strigolactones in Alleviating Salt Stress in Maize. Int J Mol Sci 2024; 25:10505. [PMID: 39408841 PMCID: PMC11477198 DOI: 10.3390/ijms251910505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2024] [Revised: 09/27/2024] [Accepted: 09/28/2024] [Indexed: 10/20/2024] Open
Abstract
Exogenous brassinolide (BR) and strigolactones (SLs) play an important role in alleviating salt stress in maize. We studied the morphological and physiological responses of the salt-sensitive genotype PH4CV and salt-tolerant genotype Zheng58 to BR (1.65 nM), SL (1 µM), and BS (1.65 nM BR + 1 µM SL) under salt stress. Phenotypic analysis showed that salt stress significantly inhibited the growth of maize seedlings and significantly increased the content of Na+ in the roots. Exogenous hormones increased oxidase activity and decreased Na+ content in the roots and mitigated salt stress. Transcriptome analysis showed that the interaction of BR and SL is involved in photosynthesis-antenna proteins, the TCA cycle, and plant hormone signal transduction pathways. This interaction influences the expression of chlorophyll a/b-binding protein and glucose-6-phosphate isomerase 1 chloroplastic, and aconitase genes are affected. Furthermore, the application of exogenous hormones regulates the expression of genes associated with the signaling pathways of cytokinin (CK), gibberellins (GA), auxin (IAA), brassinosteroid (BR), abscisic acid (ABA), and jasmonic acid (JA). Additionally, exogenous hormones inhibit the expression of the AKT2/3 genes, which are responsible for regulating ion transduction and potassium ion influx. Four candidate genes that may regulate the seedling length of maize were screened out through WGCNA. Respective KOG notes concerned inorganic ion transport and metabolism, signal transduction mechanisms, energy production and conversion, and amino acid transport and metabolism. The findings of this study provide a foundation for the proposition that BR and SL can be employed to regulate salt stress alleviation in maize.
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Tsang I, Atkinson JA, Rawsthorne S, Cockram J, Leigh F. Root hairs: an underexplored target for sustainable cereal crop production. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:5484-5500. [PMID: 38894654 PMCID: PMC11427827 DOI: 10.1093/jxb/erae275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 06/17/2024] [Indexed: 06/21/2024]
Abstract
To meet the demands of a rising human population, plant breeders will need to develop improved crop varieties that maximize yield in the face of increasing pressure on crop production. Historically, the optimization of crop root architecture has represented a challenging breeding target due to the inaccessibility of the root systems. Root hairs, single cell projections from the root epidermis, are perhaps the most overlooked component of root architecture traits. Root hairs play a central role in facilitating water, nutrient uptake, and soil cohesion. Current root hair architectures may be suboptimal under future agricultural production regimes, coupled with an increasingly variable climate. Here, we review the genetic control of root hair development in the world's three most important crops-rice, maize, and wheat-and highlight conservation of gene function between monocots and the model dicot species Arabidopsis. Advances in genomic techniques including gene editing combined with traditional plant breeding methods have the potential to overcome many inherent issues associated with the design of improved root hair architectures. Ultimately, this will enable detailed characterization of the effects of contrasting root hair morphology strategies on crop yield and resilience, and the development of new varieties better adapted to deliver future food security.
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Han J, Wang Q, Qian B, Liu Q, Wang Z, Liu Y, Chen Z, Wu W, Zhang C, Yin Y. Exploring the Roles of the Swi2/ Snf2 Gene Family in Maize Abiotic Stress Responses. Int J Mol Sci 2024; 25:9686. [PMID: 39273633 PMCID: PMC11396418 DOI: 10.3390/ijms25179686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2024] [Revised: 09/04/2024] [Accepted: 09/04/2024] [Indexed: 09/15/2024] Open
Abstract
The maize Snf2 gene family plays a crucial role in chromatin remodeling and response to environmental stresses. In this study, we identified and analyzed 35 members of the maize Snf2 gene family (ZmCHR1 to ZmCHR35) using the Ensembl Plants database. Each protein contained conserved SNF2-N and Helicase-C domains. Phylogenetic analysis revealed six groups among the Snf2 proteins, with an uneven distribution across subfamilies. Physicochemical analysis indicated that the Snf2 proteins are hydrophilic, with varied amino acid lengths, isoelectric points, and molecular weights, and are predominantly localized in the nucleus. Chromosomal mapping showed that these genes are distributed across all ten maize chromosomes. Gene structure analysis revealed diverse exon-intron arrangements, while motif analysis identified 20 conserved motifs. Collinearity analysis highlighted gene duplication events, suggesting purifying selection. Cis-regulatory element analysis suggested involvement in abiotic and biotic stress responses. Expression analysis indicated tissue-specific expression patterns and differential expression under various stress conditions. Specifically, qRT-PCR validation under drought stress showed that certain Snf2 genes were upregulated at 12 h and downregulated at 24 h, revealing potential roles in drought tolerance. These findings provide a foundation for further exploration of the functional roles of the maize Snf2 gene family in development and stress responses.
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Chibane N, Revilla P, Yannam VRR, Marcet P, Covelo EF, Ordás B. Impact of irrigation, nitrogen fertilization, and plant density on stay-green and its effects on agronomic traits in maize. FRONTIERS IN PLANT SCIENCE 2024; 15:1399072. [PMID: 39309183 PMCID: PMC11414411 DOI: 10.3389/fpls.2024.1399072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Accepted: 08/05/2024] [Indexed: 09/25/2024]
Abstract
Introduction The stay-green (SG) or delayed leaf senescence enables crop plants to maintain their green leaves and photosynthetic capacity for a longer time after flowering. It is considered an important trait in maize breeding, which has contributed to gain in grain yield of modern varieties. It has been also used to improve the tolerance to drought and deficiencies in nitrogen fertilization (NF). However, the objective of this study is to evaluate the influence of water irrigation (WI), NF, and plant density (PD) on SG and the effect of SG on agronomic traits in maize. Methods Four SG lines and four non-stay-green (NSG) lines were evaluated in four contrasting environments under two WI, three NF, and two PD levels. Results and discussion As expected, the chlorophyll content of leaves at 45 days after flowering (Chlo45) was, on average, higher in the SG group of lines. The difference in Chlo45 between the SG and NSG genotypes was consistent across WI, NF, and PD and the environments. This is indicative that internal or developmental factors were more important than external signals in controlling the senescence. The effect of SG increasing thousand-kernel weight, stover yield at harvest, or moisture was not influenced by WI, NF, or PD but was altered by the background environment. Our results have implications for the application of SG as a secondary trait for enhancing abiotic stress tolerance. Future studies could consider a wider range of environmental conditions to assess the performance of SG traits under different climatic and soil conditions.
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Xia Z, Gong Y, Yang Y, Wu M, Bai J, Zhang S, Lu H. Effects of root-zone warming, nitrogen supply and their interactions on root-shoot growth, nitrogen uptake and photosynthetic physiological characteristics of maize. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2024; 214:108887. [PMID: 38943877 DOI: 10.1016/j.plaphy.2024.108887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 06/25/2024] [Accepted: 06/26/2024] [Indexed: 07/01/2024]
Abstract
In the context of climate change, the impact of root-zone warming (RW) on crop nutrient absorption and utilization has emerged as a significant concern that cannot be overlooked. Nitrogen (N) is an essential element for crop growth and development, particularly under stress. The comprehensive effect and relationship between RW and N level remains unclear. The objective of this experiment was to investigate the impact of RW on root-shoot growth and photosynthetic physiological characteristics of maize seedlings under varying N levels. The results demonstrated that optimal RW was beneficial to the growth of maize, while excessive root-zone temperature (RT) significantly impeded N uptake in maize. Under low N treatment, the proportion of N distribution in roots increased, and the root surface area increased by 41 %. Furthermore, under low N levels, the decline in root vitality and the increase in root MDA caused by high RT were mitigated, resulting in an enhancement of the root's ability to cope with stress. For the above-ground part, under the double stress of high RT and low N, the shoot N concentration, leaf nitrate reductase, leaf glutamine synthase, chlorophyll content, net photosynthetic rate and shoot dry matter accumulation decreased by 86 %, 60 %, 35 %, 53 %, 64 % and 59 %, respectively. It can be reasonably concluded that reasonable N management is an important method to effectively reduce the impact of high RT stress.
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Diniz GDFD, Figueiredo JEF, Canuto KM, Cota LV, Souza ASDQ, Simeone MLF, Tinoco SMDS, Ribeiro PRV, Ferreira LVS, Marins MS, de Oliveira-Paiva CA, Dos Santos VL. Chemical and genetic characterization of lipopeptides from Bacillus velezensis and Paenibacillus ottowii with activity against Fusarium verticillioides. Front Microbiol 2024; 15:1443327. [PMID: 39252841 PMCID: PMC11381237 DOI: 10.3389/fmicb.2024.1443327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Accepted: 08/02/2024] [Indexed: 09/11/2024] Open
Abstract
Introduction The fungus Fusarium verticillioides significantly threatens maize crops in tropical soils. In light of this, biological control has emerged as a promising strategy to reduce fungicide costs and environmental risks. In this study, we aimed to test the antifungal activity of cell-free supernatant (CFS) from three Bacillus velezensis (CT02, IM14, and LIS05) and one Paenibacillus ottowii (LIS04) against F. verticillioides, thereby contributing to the development of effective biocontrol measures. Methods The research employed a comprehensive approach. The antifungal activity of the bacterial strains was tested using cell-free supernatant (CFS) from three Bacillus velezensis (CT02, IM14, and LIS05) and one Paenibacillus ottowii (LIS04). The UPLC-MS evaluated the CFS to identify the main bioactive molecules involved in the inhibitory effect on F. verticillioides. Scanning electron microscopy (SEM) was used to assess the impact of CFS on spores and hyphae, and genome sequencing was conducted to identify the genes involved in biological control. These robust methodologies ensure the reliability and validate our findings. Results The CFS of the four strains demonstrated significant inhibition of fungal growth. The UPLC-MS analysis revealed the presence of lipopeptides with antifungal activity, including surfactin and fengycins A and B expressed by the three strains of Bacillus velezensis and iturin A expressed by strains LIS05 and IM14. For Paenibacillus ottowii, fusaricidins, ABCDE, and five previously unreported lipopeptides were detected. Scanning electron microscopy (SEM) showed that treatments with CFS led to significant distortion and breakage of the F. verticillioides hyphae, in addition to the formation of cavities in the membrane. Genome mining confirmed the presence of genes coding for the lipopeptides identified by UPLC-MS, including the gene for iturin in CTO2. Genomic sequencing revealed that CT02, IM14, and LIS05 belong to different strains of Bacillus velezensis, and LIS04 belongs to Paenibacillus ottowii, a species recently described. Discussion The four bacterial strains, including three novel strains identified as Bacillus velezensis and one as the recently described species Paenibacillus ottowii, demonstrate significant potential as biocontrol agents for managing fungal disease. This finding underscores the novelty and potential impact of our research.
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Lu S, Wang Q, Yin J, Zheng S, Gao T, Zhou X, Zhang J, Xing Y, Ma Y, Wang M, Zhou D, Lu M, Liu W, Wang P, Zhang Z. Screening and Validation of Leaf Width-Related Genes in Inbred Maize Lines. Life (Basel) 2024; 14:1057. [PMID: 39337842 PMCID: PMC11432761 DOI: 10.3390/life14091057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2024] [Revised: 08/21/2024] [Accepted: 08/21/2024] [Indexed: 09/30/2024] Open
Abstract
Leaf width is a key determinant of planting density and photosynthetic efficiency. In an effort to determine which genes regulate maize plant leaf width, we performed a genome-wide association study (GWAS) of 1.49 × 106 single nucleotide polymorphisms (SNPs) in 80 sequenced backbone inbred maize lines in Jilin Province, China, based upon phenotypic leaf width data from two years. In total, 14 SNPs were identified as being significantly related to leaf width (p < 0.000001), with these SNPs being located on chromosomes 1, 2, 3, 5, 6, 7, 8, and 9. A total of five candidate genes were identified within a mean linkage disequilibrium (LD) distance of 9.7 kb, with a significant SNP being identified within the Zm00001d044327 candidate gene. RNA was then isolated from 12 different inbred maize lines from this GWAS study cohort and was used to conduct qPCR analyses which revealed significant differences in Zm00001d044327 expression among strains exhibiting significant differences in leaf width. Based on an assessment of EMS mutant lines harboring a conserved amino acid stop mutation and two non-synonymous mutations in Zm00001d044327 that exhibited a narrow leaf width, these data suggested that Zm00001d044327 is a key regulator of maize leaf width.
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Yan Z, Hou J, Leng B, Yao G, Ma C, Sun Y, Liu Q, Zhang F, Mu C, Liu X. Genome-Wide Identification and Characterization of Maize Long-Chain Acyl-CoA Synthetases and Their Expression Profiles in Different Tissues and in Response to Multiple Abiotic Stresses. Genes (Basel) 2024; 15:983. [PMID: 39202344 PMCID: PMC11354158 DOI: 10.3390/genes15080983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Revised: 07/23/2024] [Accepted: 07/24/2024] [Indexed: 09/03/2024] Open
Abstract
Long-chain acyl-CoA synthetases (LACSs) are essential enzymes that activate free fatty acids to fatty acyl-CoA thioesters, playing key roles in fatty acid (FA) catabolism, lipid synthesis and storage, epidermal wax synthesis, and stress tolerance. Despite their importance, comprehensive information about LACS genes in maize, a primary food crop, remains scarce. In the present work, eleven maize LACS genes were identified and mapped across five chromosomes. Three pairs of segmentally duplicated genes were detected in the maize LACS gene family, which underwent significant purifying selection (Ka/Ks < 1). Subsequently, phylogenetic analysis indicated that ZmLACS genes were divided into four subclasses, as supported by highly conserved motifs and gene structures. On the basis of the PlantCARE database, analysis of the ZmLACS promoter regions revealed various cis-regulatory elements related to tissue-specific expression, hormonal regulation, and abiotic stress response. RT-qPCR analysis showed that ZmLACS genes exhibit tissue-specific expression patterns and respond to diverse abiotic stresses including drought and salt, as well as phytohormone abscisic acid. Furthermore, using the STRING database, several proteins involved in fatty acid and complex lipid synthesis were identified to be the potential interaction partners of ZmLACS proteins, which was also confirmed by the yeast two-hybrid (Y2H) assay, enhancing our understanding of wax biosynthesis and regulatory mechanisms in response to abiotic stresses in maize. These findings provide a comprehensive understanding of ZmLACS genes and offer a theoretical foundation for future research on the biological functions of LACS genes in maize environmental adaptability.
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Tyborski N, Koehler T, Steiner FA, Tung SY, Wild AJ, Carminati A, Mueller CW, Vidal A, Wolfrum S, Pausch J, Lueders T. Consistent prokaryotic community patterns along the radial root axis of two Zea mays L. landraces across two distinct field locations. Front Microbiol 2024; 15:1386476. [PMID: 39091306 PMCID: PMC11292614 DOI: 10.3389/fmicb.2024.1386476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 06/25/2024] [Indexed: 08/04/2024] Open
Abstract
The close interconnection of plants with rhizosphere- and root-associated microorganisms is well recognized, and high expectations are raised for considering their symbioses in the breeding of future crop varieties. However, it is unclear how consistently plant-mediated selection, a potential target in crop breeding, influences microbiome members compared to selection imposed by the agricultural environment. Landraces may have traits shaping their microbiome, which were lost during the breeding of modern varieties, but knowledge about this is scarce. We investigated prokaryotic community composition along the radial root axis of two European maize (Zea mays L.) landraces. A sampling gradient included bulk soil, a distal and proximal rhizosphere fraction, and the root compartment. Our study was replicated at two field locations with differing edaphic and climatic conditions. Further, we tested for differences between two plant developmental stages and two precipitation treatments. Community data were generated by metabarcoding of the V4 SSU rRNA region. While communities were generally distinct between field sites, the effects of landrace variety, developmental stage, and precipitation treatment were comparatively weak and not statistically significant. Under all conditions, patterns in community composition corresponded strongly to the distance to the root. Changes in α- and β-diversity, as well as abundance shifts of many taxa along this gradient, were similar for both landraces and field locations. Most affected taxa belonged to a core microbiome present in all investigated samples. Remarkably, we observed consistent enrichment of Actinobacteriota (particularly Streptomyces, Lechevalieria) and Pseudomonadota (particularly Sphingobium) toward the root. Further, we report a depletion of ammonia-oxidizers along this axis at both field sites. We identified clear enrichment and depletion patterns in microbiome composition along the radial root axis of Z. mays. Many of these were consistent across two distinct field locations, plant developmental stages, precipitation treatments, and for both landraces. This suggests a considerable influence of plant-mediated effects on the microbiome. We propose that the affected taxa have key roles in the rhizosphere and root microbiome of Z. mays. Understanding the functions of these taxa appears highly relevant for the development of methods aiming to promote microbiome services for crops.
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Holz M, Mundschenk E, Pusch V, Remus R, Dubbert M, Oburger E, Staudinger C, Wissuwa M, Zarebanadkouki M. Visualizing and quantifying 33P uptake and translocation by maize plants grown in soil. FRONTIERS IN PLANT SCIENCE 2024; 15:1376613. [PMID: 38947946 PMCID: PMC11211545 DOI: 10.3389/fpls.2024.1376613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 05/20/2024] [Indexed: 07/02/2024]
Abstract
Phosphorus (P) availability severely limits plant growth due to its immobility and inaccessibility in soils. Yet, visualization and measurements of P uptake from different root types or regions in soil are methodologically challenging. Here, we explored the potential of phosphor imaging combined with local injection of radioactive 33P to quantitatively visualize P uptake and translocation along roots of maize grown in soils. Rhizoboxes (20 × 40 × 1 cm) were filled with sandy field soil or quartz sand, with one maize plant per box. Soil compartments were created using a gravel layer to restrict P transfer. After 2 weeks, a compartment with the tip region of a seminal root was labeled with a NaH2 33PO4 solution containing 12 MBq of 33P. Phosphor imaging captured root P distribution at 45 min, 90 min, 135 min, 180 min, and 24 h post-labeling. After harvest, 33P levels in roots and shoots were quantified. 33P uptake exhibited a 50% increase in quartz sand compared to sandy soil, likely attributed to higher P adsorption to the sandy soil matrix than to quartz sand. Notably, only 60% of the absorbed 33P was translocated to the shoot, with the remaining 40% directed to growing root tips of lateral or seminal roots. Phosphor imaging unveiled a continuous rise in 33P signal in the labeled seminal root from immediate post-labeling until 24 h after labeling. The highest 33P activities were concentrated just above the labeled compartment, diminishing in locations farther away. Emerging laterals from the labeled root served as strong sinks for 33P, while a portion was also transported to other seminal roots. Our study quantitatively visualized 33P uptake and translocation dynamics, facilitating future investigations into diverse root regions/types and varying plant growth conditions. This improves our understanding of the significance of different P sources for plant nutrition and potentially enhances models of plant P uptake.
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Qi X, Zhuang Z, Ji X, Bian J, Peng Y. The Mechanism of Exogenous Salicylic Acid and 6-Benzylaminopurine Regulating the Elongation of Maize Mesocotyl. Int J Mol Sci 2024; 25:6150. [PMID: 38892338 PMCID: PMC11172663 DOI: 10.3390/ijms25116150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 05/29/2024] [Accepted: 05/31/2024] [Indexed: 06/21/2024] Open
Abstract
The elongation of the mesocotyl plays an important role in the emergence of maize deep-sowing seeds. This study was designed to explore the function of exogenous salicylic acid (SA) and 6-benzylaminopurine (6-BA) in the growth of the maize mesocotyl and to examine its regulatory network. The results showed that the addition of 0.25 mmol/L exogenous SA promoted the elongation of maize mesocotyls under both 3 cm and 15 cm deep-sowing conditions. Conversely, the addition of 10 mg/L exogenous 6-BA inhibited the elongation of maize mesocotyls. Interestingly, the combined treatment of exogenous SA-6-BA also inhibited the elongation of maize mesocotyls. The longitudinal elongation of mesocotyl cells was the main reason affecting the elongation of maize mesocotyls. Transcriptome analysis showed that exogenous SA and 6-BA may interact in the hormone signaling regulatory network of mesocotyl elongation. The differential expression of genes related to auxin (IAA), jasmonic acid (JA), brassinosteroid (BR), cytokinin (CTK) and SA signaling pathways may be related to the regulation of exogenous SA and 6-BA on the growth of mesocotyls. In addition, five candidate genes that may regulate the length of mesocotyls were screened by Weighted Gene Co-Expression Network Analysis (WGCNA). These genes may be involved in the growth of maize mesocotyls through auxin-activated signaling pathways, transmembrane transport, methylation and redox processes. The results enhance our understanding of the plant hormone regulation of mesocotyl growth, which will help to further explore and identify the key genes affecting mesocotyl growth in plant hormone signaling regulatory networks.
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Yao Q, Feng Y, Wang J, Zhang Y, Yi F, Li Z, Zhang M. Integrated Metabolome and Transcriptome Analysis of Gibberellins Mediated the Circadian Rhythm of Leaf Elongation by Regulating Lignin Synthesis in Maize. Int J Mol Sci 2024; 25:2705. [PMID: 38473951 DOI: 10.3390/ijms25052705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 02/08/2024] [Accepted: 02/24/2024] [Indexed: 03/14/2024] Open
Abstract
Plant growth exhibits rhythmic characteristics, and gibberellins (GAs) are involved in regulating cell growth, but it is still unclear how GAs crosstalk with circadian rhythm to regulate cell elongation. The study analyzed growth characteristics of wild-type (WT), zmga3ox and zmga3ox with GA3 seedlings. We integrated metabolomes and transcriptomes to study the interaction between GAs and circadian rhythm in mediating leaf elongation. The rates of leaf growth were higher in WT than zmga3ox, and zmga3ox cell length was shorter when proliferated in darkness than light, and GA3 restored zmga3ox leaf growth. The differentially expressed genes (DEGs) between WT and zmga3ox were mainly enriched in hormone signaling and cell wall synthesis, while DEGs in zmga3ox were restored to WT by GA3. Moreover, the number of circadian DEGs that reached the peak expression in darkness was more than light, and the upregulated circadian DEGs were mainly enriched in cell wall synthesis. The differentially accumulated metabolites (DAMs) were mainly attributed to flavonoids and phenolic acid. Twenty-two DAMs showed rhythmic accumulation, especially enriched in lignin synthesis. The circadian DEGs ZmMYBr41/87 and ZmHB34/70 were identified as regulators of ZmHCT8 and ZmBM1, which were enzymes in lignin synthesis. Furthermore, GAs regulated ZmMYBr41/87 and ZmHB34/70 to modulate lignin biosynthesis for mediating leaf rhythmic growth.
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Lu X, Liu P, Tu L, Guo X, Wang A, Zhu Y, Jiang Y, Zhang C, Xu Y, Chen Z, Wu X. Joint-GWAS, Linkage Mapping, and Transcriptome Analysis to Reveal the Genetic Basis of Plant Architecture-Related Traits in Maize. Int J Mol Sci 2024; 25:2694. [PMID: 38473942 DOI: 10.3390/ijms25052694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/04/2024] [Accepted: 02/22/2024] [Indexed: 03/14/2024] Open
Abstract
Plant architecture is one of the key factors affecting maize yield formation and can be divided into secondary traits, such as plant height (PH), ear height (EH), and leaf number (LN). It is a viable approach for exploiting genetic resources to improve plant density. In this study, one natural panel of 226 inbred lines and 150 family lines derived from the offspring of T32 crossed with Qi319 were genotyped by using the MaizeSNP50 chip and the genotyping by sequence (GBS) method and phenotyped under three different environments. Based on the results, a genome-wide association study (GWAS) and linkage mapping were analyzed by using the MLM and ICIM models, respectively. The results showed that 120 QTNs (quantitative trait nucleotides) and 32 QTL (quantitative trait loci) related to plant architecture were identified, including four QTL and 40 QTNs of PH, eight QTL and 41 QTNs of EH, and 20 QTL and 39 QTNs of LN. One dominant QTL, qLN7-2, was identified in the Zhangye environment. Six QTNs were commonly identified to be related to PH, EH, and LN in different environments. The candidate gene analysis revealed that Zm00001d021574 was involved in regulating plant architecture traits through the autophagy pathway, and Zm00001d044730 was predicted to interact with the male sterility-related gene ms26. These results provide abundant genetic resources for improving maize plant architecture traits by using approaches to biological breeding.
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Liu B, Wang N, Yang R, Wang X, Luo P, Chen Y, Wang F, Li M, Weng J, Zhang D, Yong H, Han J, Zhou Z, Zhang X, Hao Z, Li X. ZmADF5, a Maize Actin-Depolymerizing Factor Conferring Enhanced Drought Tolerance in Maize. PLANTS (BASEL, SWITZERLAND) 2024; 13:619. [PMID: 38475468 DOI: 10.3390/plants13050619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 02/09/2024] [Accepted: 02/11/2024] [Indexed: 03/14/2024]
Abstract
Drought stress is seriously affecting the growth and production of crops, especially when agricultural irrigation still remains quantitatively restricted in some arid and semi-arid areas. The identification of drought-tolerant genes is important for improving the adaptability of maize under stress. Here, we found that a new member of the actin-depolymerizing factor (ADF) family; the ZmADF5 gene was tightly linked with a consensus drought-tolerant quantitative trait locus, and the significantly associated signals were detected through genome wide association analysis. ZmADF5 expression could be induced by osmotic stress and the application of exogenous abscisic acid. Its overexpression in Arabidopsis and maize helped plants to keep a higher survival rate after water-deficit stress, which reduced the stomatal aperture and the water-loss rate, as well as improved clearance of reactive oxygen species. Moreover, seventeen differentially expressed genes were identified as regulated by both drought stress and ZmADF5, four of which were involved in the ABA-dependent drought stress response. ZmADF5-overexpressing plants were also identified as sensitive to ABA during the seed germination and seedling stages. These results suggested that ZmADF5 played an important role in the response to drought stress.
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Xing J, Zhang J, Wang Y, Wei X, Yin Z, Zhang Y, Pu A, Dong Z, Long Y, Wan X. Mining genic resources regulating nitrogen-use efficiency based on integrative biological analyses and their breeding applications in maize and other crops. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 117:1148-1164. [PMID: 37967146 DOI: 10.1111/tpj.16550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 10/08/2023] [Accepted: 11/05/2023] [Indexed: 11/17/2023]
Abstract
Nitrogen (N) is an essential factor for limiting crop yields, and cultivation of crops with low nitrogen-use efficiency (NUE) exhibits increasing environmental and ecological risks. Hence, it is crucial to mine valuable NUE improvement genes, which is very important to develop and breed new crop varieties with high NUE in sustainable agriculture system. Quantitative trait locus (QTL) and genome-wide association study (GWAS) analysis are the most common methods for dissecting genetic variations underlying complex traits. In addition, with the advancement of biotechnology, multi-omics technologies can be used to accelerate the process of exploring genetic variations. In this study, we integrate the substantial data of QTLs, quantitative trait nucleotides (QTNs) from GWAS, and multi-omics data including transcriptome, proteome, and metabolome and further analyze their interactions to predict some NUE-related candidate genes. We also provide the genic resources for NUE improvement among maize, rice, wheat, and sorghum by homologous alignment and collinearity analysis. Furthermore, we propose to utilize the knowledge gained from classical cases to provide the frameworks for improving NUE and breeding N-efficient varieties through integrated genomics, systems biology, and modern breeding technologies.
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Li H, Che R, Zhu J, Yang X, Li J, Fernie AR, Yan J. Multi-omics-driven advances in the understanding of triacylglycerol biosynthesis in oil seeds. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 117:999-1017. [PMID: 38009661 DOI: 10.1111/tpj.16545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 11/01/2023] [Indexed: 11/29/2023]
Abstract
Vegetable oils are rich sources of polyunsaturated fatty acids and energy as well as valuable sources of human food, animal feed, and bioenergy. Triacylglycerols, which are comprised of three fatty acids attached to a glycerol backbone, are the main component of vegetable oils. Here, we review the development and application of multiple-level omics in major oilseeds and emphasize the progress in the analysis of the biological roles of key genes underlying seed oil content and quality in major oilseeds. Finally, we discuss future research directions in functional genomics research based on current omics and oil metabolic engineering strategies that aim to enhance seed oil content and quality, and specific fatty acids components according to either human health needs or industrial requirements.
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Ma P, Liu E, Zhang Z, Li T, Zhou Z, Yao W, Chen J, Wu J, Xu Y, Zhang H. Genetic variation in ZmWAX2 confers maize resistance to Fusarium verticillioides. PLANT BIOTECHNOLOGY JOURNAL 2023; 21:1812-1826. [PMID: 37293701 PMCID: PMC10440989 DOI: 10.1111/pbi.14093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/16/2023] [Accepted: 05/19/2023] [Indexed: 06/10/2023]
Abstract
Fusarium verticillioides (F. verticillioides) is a widely distributed phytopathogen that incites multiple destructive diseases in maize, posing a grave threat to corn yields and quality worldwide. However, there are few reports of resistance genes to F. verticillioides. Here, we reveal that a combination of two single nucleotide polymorphisms (SNPs) corresponding to ZmWAX2 gene associates with quantitative resistance variations to F. verticillioides in maize through a genome-wide association study. A lack of ZmWAX2 compromises maize resistance to F. verticillioides-caused seed rot, seedling blight and stalk rot by reducing cuticular wax deposition, while the transgenic plants overexpressing ZmWAX2 show significantly increased immunity to F. verticillioides. A natural occurrence of two 7-bp deletions within the promoter increases ZmWAX2 transcription, thus enhancing maize resistance to F. verticillioides. Upon Fusarium stalk rot, ZmWAX2 greatly promotes the yield and grain quality of maize. Our studies demonstrate that ZmWAX2 confers multiple disease resistances caused by F. verticillioides and can serve as an important gene target for the development of F. verticillioides-resistant maize varieties.
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Mahmud S, Kamruzzaman M, Bhattacharyya S, Alharbi K, Abd El Moneim D, Mostofa MG. Acetic acid positively modulates proline metabolism for mitigating PEG-mediated drought stress in Maize and Arabidopsis. FRONTIERS IN PLANT SCIENCE 2023; 14:1167238. [PMID: 37538054 PMCID: PMC10394635 DOI: 10.3389/fpls.2023.1167238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 05/25/2023] [Indexed: 08/05/2023]
Abstract
Introduction Osmotic imbalance is one of the major consequences of drought stress, negatively affecting plant growth and productivity. Acetic acid has modulatory roles in osmotic balance in plants; however, the mechanistic insights into acetic acid-mediated osmotic adjustment under drought stress remains largely unknown. Methods Here, we investigated how seed priming and seedling root treatment with acetic acid enabled maize plants overcoming polyethylene glycol (PEG)-induced drought effects. Results Maize seeds primed with acetic acid showed better growth performance when compared with unprimed seeds under PEG application. This growth performance was mainly attributed to improved growth traits, such as fresh weight, dry weight, length of shoots and roots, and several leaf spectral indices, including normalized difference vegetation index (NDVI) and chlorophyll absorption in reflectance index (MCARI). The levels of oxidative stress indicators hydrogen peroxide (H2O2) and malondialdehyde (MDA) did not alter significantly among the treatments, but proline content as well as the expression of proline biosynthetic gene, Δ1-PYRROLINE-5-CARBOXYLATE SYNTHETASE 1 (P5CS1) was significantly elevated in plants receiving acetic acid under PEG-treatments. On the other hand, treating the seedlings root with acetic acid led to a significant recovery of maize plants from drought-induced wilting. Although growth traits remained unchanged among the treatments, the enhancement of leaf water content, photosynthetic rate, proline level, expression of P5CS1, and antioxidant enzyme activities along with reduced level of H2O2 and MDA in acetic acid-supplemented drought plants indicated a positive regulatory role of acetic acid in maize tolerance to drought. Moreover, the high expression of P5CS1 and the subsequent elevation of proline level upon acetic acid application were further validated using wild type and proline biosynthetic mutant p5cs1 of Arabidopsis. Results showed that acetic acid application enabled wild type plants to maintain better phenotypic appearance and recovery from drought stress than p5cs1 plants, suggesting a crosstalk between acetic acid and proline metabolism in plants under drought stress. Discussion Our results highlight the molecular and intrinsic mechanisms of acetic acid conferring plant tolerance to drought stress.
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Sun W, He Q, Liu J, Xiao X, Wu Y, Zhou S, Ma S, Wang R. Dynamic monitoring of maize grain quality based on remote sensing data. FRONTIERS IN PLANT SCIENCE 2023; 14:1177477. [PMID: 37426960 PMCID: PMC10325687 DOI: 10.3389/fpls.2023.1177477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 05/31/2023] [Indexed: 07/11/2023]
Abstract
Remote sensing data have been widely used to monitor crop development, grain yield, and quality, while precise monitoring of quality traits, especially grain starch and oil contents considering meteorological elements, still needs to be improved. In this study, the field experiment with different sowing time, i.e., 8 June, 18 June, 28 June, and 8 July, was conducted in 2018-2020. The scalable annual and inter-annual quality prediction model for summer maize in different growth periods was established using hierarchical linear modeling (HLM), which combined hyperspectral and meteorological data. Compared with the multiple linear regression (MLR) using vegetation indices (VIs), the prediction accuracy of HLM was obviously improved with the highest R 2, root mean square error (RMSE), and mean absolute error (MAE) values of 0.90, 0.10, and 0.08, respectively (grain starch content (GSC)); 0.87, 0.10, and 0.08, respectively (grain protein content (GPC)); and 0.74, 0.13, and 0.10, respectively (grain oil content (GOC)). In addition, the combination of the tasseling, grain-filling, and maturity stages further improved the predictive power for GSC (R 2 = 0.96). The combination of the grain-filling and maturity stages further improved the predictive power for GPC (R 2 = 0.90). The prediction accuracy developed in the combination of the jointing and tasseling stages for GOC (R 2 = 0.85). The results also showed that meteorological factors, especially precipitation, had a great influence on grain quality monitoring. Our study provided a new idea for crop quality monitoring by remote sensing.
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Wang D, He Y, Nie L, Guo S, Tu L, Guo X, Wang A, Liu P, Zhu Y, Wu X, Chen Z. Integrated IBD Analysis, GWAS Analysis and Transcriptome Analysis to Identify the Candidate Genes for White Spot Disease in Maize. Int J Mol Sci 2023; 24:10005. [PMID: 37373152 DOI: 10.3390/ijms241210005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/01/2023] [Accepted: 06/08/2023] [Indexed: 06/29/2023] Open
Abstract
Foundation parents (FPs) play an irreplaceable role in maize breeding practices. Maize white spot (MWS) is an important disease in Southwest China that always seriously reduces production. However, knowledge about the genetic mechanism of MWS resistance is limited. In this paper, a panel of 143 elite lines were collected and genotyped by using the MaizeSNP50 chip with approximately 60,000 single nucleotide polymorphisms (SNPs) and evaluated for resistance to MWS among 3 environments, and a genome-wide association study (GWAS) and transcriptome analysis were integrated to reveal the function of the identity-by-descent (IBD) segments for MWS. The results showed that (1) 225 IBD segments were identified only in the FP QB512, 192 were found only in the FP QR273 and 197 were found only in the FP HCL645. (2) The GWAS results showed that 15 common quantitative trait nucleotides (QTNs) were associated with MWS. Interestingly, SYN10137 and PZA00131.14 were in the IBD segments of QB512, and the SYN10137-PZA00131.14 region existed in more than 58% of QR273's descendants. (3) By integrating the GWAS and transcriptome analysis, Zm00001d031875 was found to located in the region of SYN10137-PZA00131.14. These results provide some new insights for the detection of MWS's genetic variation mechanisms.
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Mullins E, Bresson JL, Dalmay T, Dewhurst IC, Epstein MM, Firbank LG, Guerche P, Hejatko J, Moreno FJ, Naegeli H, Nogué F, Rostoks N, Sánchez Serrano JJ, Savoini G, Veromann E, Veronesi F, Ardizzone M, De Sanctis G, Federici S, Fernandez A, Gennaro A, Gómez Ruiz JÁ, Goumperis T, Kagkli DM, Lenzi P, Camargo AM, Neri FM, Raffaello T. Assessment of genetically modified maize Bt11 × MIR162 × MIR604 × MON 89034 × 5307 × GA21 and 30 subcombinations, for food and feed uses, under Regulation (EC) No 1829/2003 (application EFSA-GMO-DE-2018-149). EFSA J 2023; 21:e08011. [PMID: 37284025 PMCID: PMC10240405 DOI: 10.2903/j.efsa.2023.8011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023] Open
Abstract
Genetically modified maize Bt11 × MIR162 × MIR604 × MON 89034 × 5307 × GA21 was developed by crossing to combine six single events: Bt11, MIR162, MIR604, MON 89034, 5307 and GA21, the GMO Panel previously assessed the 6 single maize events and 27 out of the 56 possible 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 six-event stack maize does not give rise to food and feed safety and nutritional concerns. The GMO Panel concludes that six-event stack maize, as described in this application, 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 six-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 29 of the maize subcombinations not previously assessed and covered by the scope of this application and concludes that these are expected to be as safe as the single events, the previously assessed subcombinations and the six-event stack maize. The post-market environmental monitoring plan and reporting intervals are in line with the intended uses of maize Bt11 × MIR162 × MIR604 × MON 89034 × 5307 × GA21. The GMO Panel concludes that six-event stack maize and the 30 subcombinations covered by the scope of the application are 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.
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Chen S, Dang D, Liu Y, Ji S, Zheng H, Zhao C, Dong X, Li C, Guan Y, Zhang A, Ruan Y. Genome-wide association study presents insights into the genetic architecture of drought tolerance in maize seedlings under field water-deficit conditions. FRONTIERS IN PLANT SCIENCE 2023; 14:1165582. [PMID: 37223800 PMCID: PMC10200999 DOI: 10.3389/fpls.2023.1165582] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 03/24/2023] [Indexed: 05/25/2023]
Abstract
Introduction Drought stress is one of the most serious abiotic stresses leading to crop yield reduction. Due to the wide range of planting areas, the production of maize is particularly affected by global drought stress. The cultivation of drought-resistant maize varieties can achieve relatively high, stable yield in arid and semi-arid zones and in the erratic rainfall or occasional drought areas. Therefore, to a great degree, the adverse impact of drought on maize yield can be mitigated by developing drought-resistant or -tolerant varieties. However, the efficacy of traditional breeding solely relying on phenotypic selection is not adequate for the need of maize drought-resistant varieties. Revealing the genetic basis enables to guide the genetic improvement of maize drought tolerance. Methods We utilized a maize association panel of 379 inbred lines with tropical, subtropical and temperate backgrounds to analyze the genetic structure of maize drought tolerance at seedling stage. We obtained the high quality 7837 SNPs from DArT's and 91,003 SNPs from GBS, and a resultant combination of 97,862 SNPs of GBS with DArT's. The maize population presented the lower her-itabilities of the seedling emergence rate (ER), seedling plant height (SPH) and grain yield (GY) under field drought conditions. Results GWAS analysis by MLM and BLINK models with the phenotypic data and 97862 SNPs revealed 15 variants that were significantly independent related to drought-resistant traits at the seedling stage above the threshold of P < 1.02 × 10-5. We found 15 candidate genes for drought resistance at the seedling stage that may involve in (1) metabolism (Zm00001d012176, Zm00001d012101, Zm00001d009488); (2) programmed cell death (Zm00001d053952); (3) transcriptional regulation (Zm00001d037771, Zm00001d053859, Zm00001d031861, Zm00001d038930, Zm00001d049400, Zm00001d045128 and Zm00001d043036); (4) autophagy (Zm00001d028417); and (5) cell growth and development (Zm00001d017495). The most of them in B73 maize line were shown to change the expression pattern in response to drought stress. These results provide useful information for understanding the genetic basis of drought stress tolerance of maize at seedling stage.
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