Search Results (89)

Maize ear rot, primarily caused by Fusarium verticillioides (Fusarium ear rot, FER) and Fusarium graminearum (Gibberella ear rot, GER), is a devastating disease that causes significant yield losses and mycotoxin contamination. Breeding resistant varieties is the most effective control strategy, but this requires the identification of stable genetic loci for resistance. In this study, we employed bulked segregant analysis (BSA) on two F₂ mapping populations to identify quantitative trait loci (QTLs) conferring resistance to FER and GER. We identified five and eleven QTLs for FER and GER, respectively. Notably, chromosome 4 was identified as a major hotspot for resistance to both diseases, and there was a co-localization of the FER QTL (qFER4.05) and GER QTL (qGER4.05-1) within a 58.58–71.34 Mb interval on bin 4.05, suggesting a potential locus for broad-spectrum resistance. Within this overlapping region, we identified 18 high-confidence candidate genes, including genes encoding leucine-rich repeat receptor-like kinases (LRR-RLKs), remorin, cytochrome P450 monooxygenases, and wall-associated receptor kinase-like (WAKL) protein, all with established roles in plant defense. These findings advance the understanding of the genetic architecture of ear rot resistance and provide critical resources for marker-assisted breeding to develop maize hybrids with durable resistance to both FER and GER. Full article

Fusarium ear rot (FER), caused by F. verticillioides, is a devastating disease in maize, leading to substantial yield losses and mycotoxin contamination. Therefore, revealing the molecular mechanisms underlying FER resistance is essential for crop breeding. Here, we performed integrated transcriptomic and metabolomic analyses on two maize inbred lines with contrasting FER resistance: the resistant line ZL30-12 (ZL30) and the susceptible line 92C0468U (92C). Following F. verticillioides inoculation, ZL30 exhibited sustained inhibition of fungal colonization and fumonisin accumulation, whereas 92C showed progressive disease development and elevated fumonisin levels. Both transcriptomic and metabolomic analyses converged on the phenylpropanoid pathway, with DEGs enriched in phenylpropanoid metabolism and DAMs enriched in phenylpropanoid biosynthesis, highlighting its central role in resistance. Further integrative analysis revealed that the lignin biosynthetic process, a key branch of phenylpropanoid metabolism, plays an important role in resistance. Several key DEGs (ZmPAL, ZmHCT, peroxidases, and ZmCOMT) and DAMs (sinapic acid, sinapaldehyde, coniferin, cinnamic acid, and caffeic acid) were differentially regulated between the two lines. Correlation analysis revealed a significant correlation between ZmCOMT expression and sinapic acid accumulation. RT-qPCR validation confirmed the expression patterns of key lignin-associated genes. The elevated activation of lignin biosynthesis in ZL30, via time-dependent induction of key genes (ZmPAL, ZmHCT, and peroxidases), suggests an increase in lignin accumulation, which likely reinforces cell wall integrity and restricts fungal invasion, thereby contributing to FER resistance. Collectively, these findings provide insights into the molecular mechanisms of FER resistance and identify key lignin-associated genes as promising targets for maize breeding. Full article

To cope with the increasing pressure from diseases and pests under climate change, the effect of 6 maize sowing dates on the plant health of an ultra-early maize variety (Pyroxenia, FAO 130) was analyzed in studies conducted from 2016 to 2018. The assessment of the response of the ultra-early variety to climate change will contribute to the identification of its predisposition to cultivation in terms of health recognition. The extent of plant damage caused by the frit fly (Oscinella frit L.), the European corn borer (Ostrinia nubilalis Hbn.), and the cereal leaf beetle (Oulema melanopus L.), as well as the severity of plant infection by Fusarium ear rot (Fusarium spp.) and maize smut (Ustilago maydis (D.C.) Corda), was assessed. Air temperature, precipitation, and the length of the growing period at individual sowing dates were also analyzed. The lowest level of insect damage and the highest level of disease infection were recorded in the final year of the study (2018), which was dry and had higher mean air temperature. Precipitation and temperature during the sowing dates ranged between 110.5 and 146.1 mm and 17.5 and 19.9 °C, respectively. The optimal sowing date for reducing maize losses caused by insect pests and diseases was found to be the earliest time points, i.e., between April 12 and 26. Full article

Fusarium ear rot (FER) caused by Fusarium verticillioides is a major constraint on global maize production. The genetic basis of FER resistance is not yet fully understood, and the development of effective breeding strategies for improving FER resistance is still a critical priority. In the present study, a collection of 254 CIMMYT tropical maize lines genotyped with 955,690 high-quality SNPs was used to conduct genome-wide association studies (GWAS), complemented by QTL (quantitative trait locus) mapping in two recombinant inbred line populations. Additionally, genomic prediction (GP) exploring various statistical models and SNP selection schemes was implemented to optimize predictive accuracy for improving FER resistance. The broad-sense heritability estimates of FER resistance were 0.69–0.86 in the CML panel across six environments and 0.39–0.69 in the two RIL populations. At a p-value threshold of 2.61 × 10⁻⁷, GWAS identified 18 SNPs significantly associated with FER resistance across six environments, and in single environment analyses, their phenotypic variance explained (PVE) values ranged from 0.68 to 13.75%, with 13 SNPs exceeding a PVE of 5%. At a p-value threshold of 1 × 10⁻⁵, an additional 37 SNPs were detected, clustering within seven environmentally stable regions identified in at least two environments. Furthermore, 13 haplotype blocks exhibiting significant phenotypic differences were identified within these stable regions, with PVE values ranging from 2.39 to 15.24%, 9 of which exceeded 5%. QTL mapping in the two RIL populations revealed 27 moderate-effect QTLs at a LOD threshold of 2.5, including four detected repeatedly across environments, though only one QTL overlapped with the GWAS-identified region. Moderate genomic prediction accuracies of FER severity were achieved across models, with GBLUP and BayesB outperforming other models, and the prediction accuracies of these two models in the three populations were all around 0.5. Integrating the significant SNP set from genetic mapping results with a 100-SNP background set enhanced the stability of cross-population predictions. These results implied that FER resistance in tropical maize is controlled by multiple genomic regions with small-to-moderate genetic effects, whereas the consistency of genomic regions detected by GWAS and QTL mapping is low. Genomic prediction incorporating regions identified across different genetic backgrounds emerges as a promising tool for accelerating FER resistance breeding. Full article

Fusarium ear rot (FER), caused by Fusarium verticillioides, is a devastating disease that substantially reduces maize yield and compromises kernel quality. To investigate the genetic and molecular basis of resistance, an F₂ population derived from a cross between the resistant inbred line 3IBZ2 and the susceptible inbred line KW5G321 was analysed. By integrating bulked segregant analysis sequencing (BSA-Seq) with RNA sequencing (RNA-Seq), a major quantitative trait locus (QTL), designated qFER4, was identified on chromosome 4. Genetic analysis further demonstrated that qFER4 confers resistance through partial dominance. Transcriptome profiling of the resistant line revealed 7684 and 7906 differentially expressed genes (DEGs) at 36 and 72 h post inoculation (hpi), respectively. These DEGs were significantly enriched in defence-related biological processes and pathways, including phenylpropanoid biosynthesis, jasmonic acid signalling, MAPK cascades, and plant-pathogen interactions. By combining QTL mapping with transcriptome analyses, four candidate genes within the qFER4 interval were screened. Sequence analysis identified extensive structural variations in the promoter and coding regions of Zm00001d053393, including a premature stop codon predicted to lead to a gain-of-function mutation. In contrast, the other three genes exhibited only minor promoter polymorphisms with identical coding sequences between the parental lines. Overall, this study identifies a novel major-effect QTL and candidate gene associated with FER resistance, providing a foundation for gene function and a valuable genetic resource for breeding FER-resistant maize varieties. Full article

A complex of Fusarium species frequently infects maize, causing root, ear, and stem rot, yield losses, reduced seed quality, and mycotoxin accumulation. To quantify Fusarium species composition and mycotoxin contamination, we conducted a first nationwide monitoring in Swiss commercial grain maize over three years (2008–2010), followed by grain maize hybrid experiments across five sites (2011–2013). Samples were analysed for species incidence, fungal DNA, and the mycotoxins deoxynivalenol, zearalenone, and fumonisins. For each field, crop management data were collected. Fusarium graminearum, F. verticillioides, F. subglutinans, and F. proliferatum were predominant, and deoxynivalenol was the most frequent toxin, with 55% of the samples exceeding the European pig feed guidance value (0.9 mg kg⁻¹). Overall, fumonisin contamination was low: only 11% of samples were above the limit of detection. The year, the length of the growing period, and the timing of the harvest were the principal determinants of F. graminearum infection and deoxynivalenol/zearalenone accumulation, whereas other agronomic factors, including crop rotation, soil management, and maturity class, showed only limited or inconsistent effects. Results from this study provide evidence that farmers should avoid long growing periods and late harvests to reduce the risk of high deoxynivalenol/zearalenone content. The maize hybrid experiments confirmed the overriding influence of weather conditions on Fusarium species incidence and mycotoxin content, leading to high inter-annual variability. These results highlight the need for standardised, long-term field experiments to disentangle agronomic effects and environmental drivers. Full article

Purple corn (Zea mays L.) is a nutraceutical crop of increasing economic importance in Peru, yet its productivity is highly influenced by genotype × environment (G × E) interactions across heterogeneous agro-ecological zones. Therefore, selecting suitable genotypes for specific environments is essential to optimize variety deployment and maximize site-specific yield. Five purple-maize genotypes (INIA-601, INIA-615, Canteño, PMV-581, and Sintético-MM) were evaluated in four contrasting Peruvian sites using a randomized complete-block design. Grain yield, field weight, anthesis–silking interval (ASI), plant height, and ear-rot incidence were analyzed with combined analysis of variance (ANOVA), the additive main effects and multiplicative interaction (AMMI), genotype and genotype-by-environment (GGE) biplots, Weighted Average of Absolute Scores (WAAS), weighted average of absolute scores and best yield index (WAASBY), and Y × WAAS indices. Environment accounted for 90.1% of field-weight variation (p < 0.0001) and 50.2% of grain-yield variation (p < 0.001), while significant G × E interactions (3.93% and 18.14%, respectively) justified bilinear modeling. AMMI1 and GGE “which-won-where” biplots identified INIA-615 and PMV-581 as broadly adapted, with INIA-615 achieving the highest WAASBY and positioning in quadrant IV of Y × WAAS (high yield, high stability). INIA-601 and Sintético-MM exhibited exceptional stability (low ASV) but moderate productivity; Canteño showed limited adaptability. Chumbibamba emerged as a key discriminating, high-productivity location. From an agronomic perspective, INIA-615 is recommended for high-productivity valleys such as Sulluscocha and Santa Rita, where its yield potential and stability are maximized. These findings underscore the potential of integrating multivariate stability metrics with physiological and disease-resistance traits to guide the selection of superior purple corn cultivars. Overall, INIA-615 represents a robust candidate for enhancing yield stability, supporting sustainable intensification, and expanding the nutraceutical value chain of purple corn in the Andean highlands. Full article

One open question regarding plant–microbe interactions is how a plant interacts molecularly with both a beneficial microbe and a pathogenic fungus. This study used RNA-seq to investigate molecular responses in maize roots during a tripartite interaction with the fungal pathogen Fusarium verticillioides (Fv), which causes stalk, ear, and root rot, and the endophytic biocontrol agent Bacillus cereus sensu lato B25, known to suppress Fv and promote plant growth. Roots of seven-day-old maize inoculated with Fv (Zm-Fv), B25 (Zm-B25), and co-inoculated (Zm-Fv-B25) were compared to uninoculated control (Zm). Differential Gene Expression (DEG), Gene Ontology (GO) and KEGG analysis revealed distinct molecular responses. Fv suppressed plant pathways related to DNA and protein synthesis and impaired root development. In contrast, B25 triggered defense priming and growth-related responses. In the co-inoculation experiment (Zm-B25-Fv), upregulated DEGs were associated with both defense-related metabolic pathways, including jasmonic acid signaling and secondary metabolite biosynthesis, and genes involved in plant growth processes. Co-expression networks using Arabidopsis orthologs supported the induction of defense- and growth and development-related genes. This study is the first RNA-seq analysis of maize root molecular responses during the tripartite interaction with a fungal pathogen and its bacterial biocontrol agent, providing new directions for further research to understand the detailed molecular mechanisms underlying this interaction fully. Full article

In temperate regions, Fusarium ear rot (FER) caused by Fusarium spp. is among the most important limiting factors to maize yield and kernel quality. The role of genotype and sowing date in mitigating FER risk remains insufficiently explored, particularly under the variable climatic conditions of the Transylvanian Plain, Romania. A three-year field experiment (2021–2023) was conducted to evaluate twelve early to semi-early maize hybrids across four sowing dates (very early—SD1, early—SD2, optimum—SD3, late—SD4). FER incidence and severity were assessed at harvest, and yields were analyzed in relation to genotype, disease pressure, and seasonal climate variability. Mean FER incidence reached 74.9% and severity was 3.4%, with significant variation among years, sowing dates, and hybrids. Early sowings (SD1, SD2) recorded the highest infection levels (up to 83.6% incidence and 4.6% severity). In contrast, the latest sowing (SD4) exhibited the lowest disease pressure (59.1% and 2.5%, respectively) and achieved the highest yield (9.1 t ha⁻¹). Significant differences were noted between hybrids: Turda 332, Turda Star, and Turda 165 were highly susceptible, whereas Turda 380, HST 149, and Turda 2020 displayed higher levels of tolerance. A strong correlation between yield losses and FER severity was observed for very early sowing (r = 0.72, p < 0.01); this relationship was not evident under later sowing. These results indicate that choosing the sowing date according to seasonal climatic conditions, together with the use of the most tolerant hybrids, represents an effective strategy to reduce the risk of FER and to obtain stable maize yields in temperate regions. Full article

Maize ear rot is an important fungal disease in maize production, mainly caused by pathogens such as Fusarium graminearum, which seriously affects the yield and quality of maize. This study investigated the changes in the activity of defense-related enzymes in maize grains and their transcriptome response characteristics after exogenous SA treatment under Fusarium graminearum stress. The results showed that treatment with 0.01 mmol/L salicylic acid (SA) significantly inhibited the growth of Fusarium graminearum hyphae, while enhancing the activities of phenylalanine ammonia-lyase (PAL), superoxide dismutase (SOD), β-1,3-glucanase (β-1,3-GA), and polyphenol oxidase (PPO) in maize grains, and reducing the content of malondialdehyde (MDA), effectively alleviating the damage of Fusarium graminearum to the maize grain membrane system. Transcriptome analysis identified multiple key genes involved in SA-mediated disease resistance pathways, including disease-related proteins (PR10), acidic terpenoids, aspartic proteases, proteins containing BTB/POZ and MATH domains (BPM4), and PPT3 transporters. This study reveals the physiological and molecular mechanisms by which exogenous SA enhances maize resistance to ear rot, providing an important theoretical basis for further understanding the regulatory network of SA in plant disease resistance. Full article

Maize (Zea may L.) is one of the most important crops worldwide, but ear rot poses a significant threat to its production. Diverse pathogens cause ear rot in China, with Fusarium spp. being predominant, especially Fusarium graminearum and Fusarium verticillioides. Current methods for the control of ear rot are limited, making the use of resistant germplasm resources an effective and economical management strategy. Earlier research focused on resistance to Fusarium ear rot (FER; caused by F. verticillioides) and Gibberella ear rot (GER; caused by F. graminearum), but assessing maize resistance to multiple major Fusarium spp. is critical in ensuring maize production. Thus, the resistance of 343 maize germplasm resources to ear rot caused by six Fusarium spp. (F. verticillioides, F. graminearum, F. proliferatum, F. meridionale, F. subglutinans, and F. temperatum) was evaluated in this study. Over three years, 69 and 77 lines resistant to six and five ear rot diseases, respectively, and 139 lines resistant to both FER and GER were identified. Moreover, the 343 germplasm resources were divided into eight heterotic groups, of which PH4CV was the most resistant one, whereas NSS and Pioneer Female were the least resistant ones. These findings provide a basis for the development of maize cultivars with broad-spectrum ear rot resistance. Full article

Fusarium verticillioides is one of the pathogenic fungi causing maize ear rot, and its secreted fumonisins accumulated in plants pose significant threats to human health. To reduce the incidence of maize ear rot and fumonisin contamination, this study isolated numerous endophytic fungi from maize plants. Through inhibition zone and dual culture assays, an endophytic fungal strain, FJ284, demonstrating notable antifungal activity against F. verticillioides was screened. 18S rDNA gene sequencing was employed for fungal identification, and the sequences were deposited in NCBI GenBank. FJ284 was identified as Penicillium oxalicum. The ethyl acetate extract of P. oxalicum was analyzed using gas chromatography–mass spectrometry (GC-MS), revealing 52 compounds, including several secondary metabolites with documented anticancer, antimicrobial, and antioxidant activities. Furthermore, a spectroscopic method was developed to assess the inhibitory effect of strain FJ284 against F. verticillioides, showing maximum inhibition at 48 h. Finally, Ultra-High-Performance Liquid Chromatography–Mass Spectrometry (UHPLC-MS) analyses confirmed that FJ284 significantly inhibited three fumonisins (suppression rates > 50%), with efficacy ranked as fumonisin B3 (FB3) > fumonisin B2 (FB2) > fumonisin B1 (FB1). Full article

Background: Maize, one of the world’s most important food and feed crops, is often threatened by fungal infections that not only reduce yields but also contaminate grains with harmful mycotoxins. Methods: This study evaluated the biocontrol potential of Trichoderma harzianum K179 as an eco-friendly alternative to synthetic fungicides for protecting maize from two major pathogens, Fusarium graminearum and Aspergillus flavus. T. harzianum K179 was cultivated in a lab-scale bioreactor, and its antifungal activity was assessed through in vitro inhibition assays and two-year field trials. During the field trial, maize ear disease severity, yield, and mycotoxin levels in maize samples were monitored to assess the efficacy of the produced Trichoderma biopreparation. Results: In laboratory tests, T. harzianum K179 significantly inhibited both target pathogens. Field trials demonstrated that seed treatments with the Trichoderma bioagent reduced ear rot severity and increased grain yield compared to untreated and chemically treated controls. Notably, maize samples from T. harzianum-treated plots contained lower concentrations of key mycotoxins, including fumonisins and aflatoxins. Conclusions: These findings highlight the usefulness of T. harzianum K179 in integrated pest management strategies, offering a sustainable solution that enhances crop safety and productivity while mitigating the environmental risks associated with chemical fungicides. Full article

In this study, the gene ZmPR5, associated with resistance to ear rot, was identified through transcriptome data analysis of the maize inbred line J1259. The gene was subsequently cloned and its function was investigated. The ZmPR5 gene comprises an open reading frame of 525 base pairs, encoding a protein of 175 amino acids. ZmPR5 was overexpressed in Arabidopsis and the ZmPR5EMS mutant in maize, and they were subjected to q-PCR and measurements of antioxidant enzyme activities (POD, SOD, CAT, MDA), electrical conductivity, and chlorophyll content. The results indicate that the expression of ZmPR5 is up-regulated upon infection by Fusarium verticillioides, with significant differences observed in the activities of POD, SOD, CAT, MDA, electrical conductivity, and chlorophyll content. The study found that ZmPR5 is localized in the nucleus and interacts with Zm00001d020492 (WRKY53) and Zm00001d042140 (glucA). Trypan blue staining revealed that the stained area in the ZmPR5EMS mutant of maize was significantly larger than that in B73. The expression of ZmPR5 is closely associated with resistance to maize ear rot. Full article

Fusarium verticillioides can systematically infect maize through seeds, triggering stalk rot and ear rot at a later stage, thus resulting in yield loss and quality decline. Seeds carrying F. verticillioides are unsuitable for storage and pose a serious threat to human and animal health due to the toxins released by the fungus. Previously, the candidate gene ZmC2GnT was identified, using linkage and association analysis, as potentially implicated in maize seed resistance to F. verticillioides; however, its disease resistance mechanism remained unknown. Our current study revealed that ZmC2GnT codes an N-acetylglucosaminyltransferase, using sequence structure and evolutionary analysis. The candidate gene association analysis revealed multiple SNPs located in the UTRs and introns of ZmC2GnT. Cloning and comparing ZmC2GnT showed variations in the promoter and CDS of resistant and susceptible materials. The promoter of ZmC2GnT in the resistant parent contains one extra cis-element ABRE associated with the ABA signal, compared to the susceptible parent. Moreover, the amino acid sequence of ZmC2GnT in the resistant parent matches that of B73, but the susceptible parent contains ten amino acid alterations. The resistant material BT-1 and the susceptible material N6 were used as parents to observe the expression level of the ZmC2GnT. The results revealed that the expression of ZmC2GnT in disease-resistant maize seeds was significantly up-regulated after infection with F. verticillioides. After treatment with F. verticillioides or ABA, the expression activity of the ZmC2GnT promoter increased significantly in the resistant material, but no discernible difference was detected in the susceptible material. When ZmC2GnT from resistant and susceptible materials was overexpressed in Arabidopsis thaliana, the seeds’ resistance to F. verticillioides increased, although there was no significant difference between the two types of overexpressed plants. Our study revealed that ZmC2GnT could participate in the immune process of plants against pathogenic fungus. ZmC2GnT plays a significant role in regulating the disease-resistance process of maize seeds, laying the foundation for future research into the regulatory mechanism and the development of new disease-resistant maize varieties. Full article