Search Results (15)

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 subglutinans and F. temperatum are widely distributed maize pathogens recognized as distinct species with a species-specific chemotype based on patterns of mycotoxins. Recent comparative genomic analysis revealed that genomes of both species carry a complete beauvericin (Bea) biosynthetic genes cluster, but the key gene Bea1 in F. subglutinans is not functional likely due to a large insertion (NRPS22ins) and multiple mutations (SNP298 and SNP528). We used the recently published genome sequences for these species to develop PCR markers for investigating the distribution of three main mutations in the Bea1 gene in a large collection of strains of both species from around the world. We also designed a PCR assay for a rapid and reliable discrimination of both species in the evaluation of crop exposure to mycotoxins. Overall, our results showed that SNP528 was the most common mutation, followed by NRPS22ins and SNP298. Moreover, phylogenetic analyses suggest that non-synonymous SNPs have occurred first, and that the resulting inactivation of BEA production has caused the accumulation of other polymorphisms, including the NRPS22ins, in the entire gene-coding region. The screening for genetic differences between these species could guide future crop management strategies. Full article

Maize, along with wheat and rice, is the most important crop for food security. Ear rots caused by Fusarium species are among the most important diseases of maize. The distribution of Fusarium species provides essential epidemiological information for disease management. The effect of weather conditions, climate change and geographic localization on the Fusarium population in Poland was evaluated between 2015 and 2018. Grain samples (n = 233) were collected from hybrids at 16 locations (L1–L16). The differences in altitude between locations ranged from 39 to 243 m above sea level, longitude varied between 15°55′ and 23°12′ E, and latitude spanned from 50°12′ to 54°01′ N. Isolates were identified using molecular techniques. The highest Fusarium species frequency was recorded for 2016 (30.70%) and 2017 (28.18%), and the lowest for 2018 (5.36%). F. verticillioides and F. temperatum were the most frequent. Altitude has an effect on F. vericillioides frequency: F. graminearum showed a negative correlation with both latitude and longitude. In Polish conditions, from silking to harvesting, the number of days with higher precipitation and lower temperatures is associated with an increased frequency of F. verticillioides, F. temperatum, F. graminearum and F. avenaceum. This suggests that the Fusarium presence in Poland is significantly influenced not only by climate change but also by extreme weather changes. Full article

Fusarium circinatum is an economically important pathogen of pine and resides in the Fusarium fujikuroi species complex. Here we investigated the molecular processes underlying growth in F. circinatum by exploring the association between growth and the nutritional environment provided by the pine host. For this purpose, we subjected a mapping population consisting of F. circinatum X F. temperatum hybrid progeny to an analysis of growth rate on a pine-tissue derived medium. These data, together with the available genetic linkage map for F. circinatum, were then used to identify Quantitative Trait Loci (QTLs) associated with growth. The single significant QTL identified was then characterized using the available genome sequences for the hybrid progeny’s parental isolates. This revealed that the QTL localized to two non-homologous regions in the F. circinatum and F. temperatum genomes. For one of these, the F. circinatum parent contained a two-gene deletion relative to the F. temperatum parent. For the other region, the two parental isolates encoded different protein products. Analysis of repeats, G+C content, and repeat-induced point (RIP) mutations further suggested a retrotransposon origin for the two-gene deletion in F. circinatum. Nevertheless, subsequent genome and PCR-based analyses showed that both regions were similarly polymorphic within a collection of diverse F. circinatum. However, we observed no clear correlation between the respective polymorphism patterns and growth rate in culture. These findings support the notion that growth is a complex multilocus trait and raise the possibility that the identified QTL contains multiple small-effect QTLs, of which some might be dependent on the genetic backgrounds. This study improved our current knowledge of the genetic determinants of vegetative growth in F. circinatum and provided an important foundation for determining the genes and processes underpinning its ability to colonize its host environment. Full article

Fusarium spp. are among the most important plant pathogens in the world. A survey on maize leaf blight was carried out in Heilongjiang province from 2019 to 2021. Based on morphological characteristics and a phylogenetic analysis on translation elongation factor (tef1) and second-largest subunit of RNA polymerase II (rpb2) genes, 146 Fusarium isolates were obtained and grouped into 14 Fusarium species, including F. ipomoeae (20.5%), F. compactum (17.1%), F. sporotrichioides (9.59%), F. graminearum (9.59%), F. citri (8.9%), F. asiaticum (6.85%), F. verticillioides (6.85%), F. acuminatum (5.48%), F. glycines (5.48%), F. temperatum (2.74%), F. armeniacum (2.74%), Fusarium sp. (2.05%), F. flagelliforme (1.4%), and F. annulatum (0.68%). The Fusarium incarnatum-equiseti species complex (FIESC, including F. ipomoeae, F. compactum, F. citri, and F. flagelliforme) was the most prevalent, indicating an evolving occurrence of the Fusarium species causing maize leaf blight. The typical symptoms observed on the maize leaves were oval to long strip lesions, with a gray to dark gray or brownish red coloration in the center and a chlorotic area at the edges. Based on the tef1 gene, seven haplotypes of FIESC were identified in Heilongjiang province, suggesting a population expansion. This is the first report of F. ipomoeae, F. compactum, F. flagelliforme, F. citri, F. sporotrichioides, F. graminearum, F. asiaticum, F. acuminatum, F. glycines, F. temperatum, F. armeniacum, Fusarium sp., and F. annulatum causing maize leaf blight in Heilongjiang province, China. The current research is informative for managing disease, exploring the phylogenetic relationship among Fusarium species, and clarifying the diversity of Fusarium species associated with maize leaf blight. Full article

Maize sheath rot is a prevalent maize disease in China. From 2020 to 2021, symptomatic samples were collected from the main maize-growing regions of Heilongjiang province. To clarify the population and genetic diversity, as well as the virulence of pathogens responsible for maize sheath rot, a total of 132 Fusarium isolates were obtained and used for follow-up studies. Ten Fusarium species were identified based on morphological characteristics, and phylogenetic analysis was conducted using the TEF-1α gene sequences, including F. verticillioides (50.00%), F. subglutinans (18.94%), the Fusarium incarnatum-equiseti species complex (14.39%), F. temperatum (5.30%), F. acuminatum (3.03%), F. solani (2.27%), F. sporotrichioides (2.27%), F. tricinctum (1.52%), F. asiaticum (1.52%), and F. proliferatum (0.76%). All 10 Fusarium species could produce oval-to-annular lesions on maize sheath, and the lesions were grayish yellow to dark brown in the center and surrounded by a dark gray-to-dark brown halo. Of these, F. tricinctum and F. proliferatum showed significantly higher virulence than the other Fusarium species. In addition, haplotype analysis based on the concatenated sequences of the ITS and TEF-1a genes showed that 99 Fusarium isolates which belonged to the Fusarium fujikuroi species complex—consisting of F. verticillioides isolates, F. subglutinans isolates, F. temperatum isolates, and F. proliferatum isolates—could be grouped into 10 haplotypes, including 5 shared haplotypes (Haps 1, 2, 4, 5, and 6) and 5 private haplotypes (Haps 3, 7, 8, 9, and 10). Furthermore, the F. verticillioides clade in the haplotype network was radial with the center of Hap 2, suggesting that population expansion occurred. This research showed that Fusarium species associated with maize sheath rot in Heilongjiang province are more diverse than previously reported, and this is the first time that F. subglutinans, F. temperatum, F. solani, F. sporotrichioides, F. tricinctum, and F. acuminatum have been confirmed as the causal agents of maize sheath rot in Heilongjiang province. Full article

The manzano pepper (Capsicum pubescens) is an exportation product that generates substantial earnings for local producers in Mexico. Herein we report on the most relevant metabolic changes that occur during the postharvest rot of manzano peppers caused by Fusarium temperatum. Simultaneously, we describe the effect of the Zanthoxylum limoncello leaf essential oil (ZlEO) and its major volatiles on the control of this devastating disease. According to our results, ZlEO, 2-undecanone (34%), 2-undecenal (32%), and 2-dodecenal (8%) exerted in vitro fungicide activity on F. temperatum (MIC, 104.6–218.3 mg L⁻¹) and a strong in situ fungistatic effect in manzano peppers previously infected with F. temperatum. A differential fungistatic activity was observed for the natural agents assayed. However, the best results were confirmed with 2-dodecenal, which improved the shelf life of infected peppers up to 16 d post-inoculation. The protective effect of ZlEO and its major volatiles resulted in the conservation of fruit firmness, pH, protein, fat, fiber, ascorbic acid, and nutraceuticals of manzano peppers (carotenoids and capsaicinoids). Our findings endorse the potential use of ZlEO and its major volatiles as natural antifungals to prevent the soft rot triggered by F. temperatum. Full article

The Fusarium fujikuroi species complex (FFSC) includes socioeconomically important pathogens that cause disease for numerous crops and synthesize a variety of secondary metabolites that can contaminate feedstocks and food. Here, we used comparative genomics to elucidate processes underlying the ability of pine-associated and grass-associated FFSC species to colonize tissues of their respective plant hosts. We characterized the identity, possible functions, evolutionary origins, and chromosomal positions of the host-range-associated genes encoded by the two groups of fungi. The 72 and 47 genes identified as unique to the respective genome groups were potentially involved in diverse processes, ranging from transcription, regulation, and substrate transport through to virulence/pathogenicity. Most genes arose early during the evolution of Fusarium/FFSC and were only subsequently retained in some lineages, while some had origins outside Fusarium. Although differences in the densities of these genes were especially noticeable on the conditionally dispensable chromosome of F. temperatum (representing the grass-associates) and F. circinatum (representing the pine-associates), the host-range-associated genes tended to be located towards the subtelomeric regions of chromosomes. Taken together, these results demonstrate that multiple mechanisms drive the emergence of genes in the grass- and pine-associated FFSC taxa examined. It also highlighted the diversity of the molecular processes potentially underlying niche-specificity in these and other Fusarium species. Full article

Fusarium temperatum Scaufl. & Munaut is a newly described taxon belonging to the Fusarium fujikuroi species complex (FFSC) and a frequent causative factor of maize ear rot. The aim of the present study was to determine the responses to the disease in maize populations differing in endosperm features that were classified to flint, dent, and a group of plants with intermediate kernel characteristics. In inoculation studies, substantial variation of host response to the fungus was found among the tested maize types. The dent-type kernels contained significantly less amylose (28.27%) and exhibited significantly higher rates of infection (I_FER = 2.10) and contamination by beauvericin (7.40 mg kg⁻¹) than plants of the flint maize subpopulation. The study documents a significant positive correlation between the Fusarium ear rot intensity (I_FER) and ergosterol content (the R value ranged from 0.396 in 2015 to 0.735 in 2018) and between I_FER and the presence of beauvericin (the R value ranged from 0.364 in 2015 to 0.785 in 2017). The negative correlation between (I_FER) and amylose content (ranging from R = −0.303 to R= −0.180) stresses the role of the endosperm starch composition in the kernel resistance to Fusarium ear rot. The conducted study indicated that the risk of kernel infection and contamination with fungal metabolites (beauvericin and ergosterol) was associated with the maize type kernels. Full article

Fusarium subglutinans is a plant pathogenic fungus infecting cereal grain crops. In 2011, the species was divided in Fusarium temperatumsp. nov. and F. subglutinans sensu stricto. In order to determine the occurrence and significance of F. temperatum and F. subglutinans on maize, a monitoring of maize ears and stalks was carried out in Germany in 2017 and 2018. Species identification was conducted by analysis of the translation elongation factor 1α (TEF-1α) gene. Ninety-four isolates of F. temperatum and eight isolates of F. subglutinans were obtained during two years of monitoring from 60 sampling sites in nine federal states of Germany. Inoculation of maize ears revealed a superior aggressiveness for F. temperatum, followed by Fusarium graminearum, Fusarium verticillioides, and F. subglutinans. On maize stalks, F. graminearum was the most aggressive species while F. temperatum and F. subglutinans caused only small lesions. The optimal temperature for infection of maize ears with F. temperatum was 24 °C and 21 °C for F. subglutinans. All strains of F. temperatum and F. subglutinans were pathogenic on wheat and capable to cause moderate to severe head blight symptoms. The assessment of mycotoxin production of 60 strains of F. temperatum cultivated on rice revealed that all strains produced beauvericin, moniliformin, fusaric acid, and fusaproliferin. The results demonstrate a higher prevalence and aggressiveness of F. temperatum compared to F. subglutinans in German maize cultivation areas. Full article

Maize plants are often infected with fungal pathogens of the genus Fusarium. Taxonomic characterization of these species by microscopic examination of pure cultures or assignment to mating populations is time-consuming and requires specific expertise. Reliable taxonomic assignment may be strengthened by the analysis of DNA sequences. Species-specific PCR assays are available for most Fusarium pathogens, but the number of species that infect maize increases the labor and costs required for analysis. In this work, a diagnostic assay for major Fusarium pathogens of maize based on the analysis of melting curves of PCR amplicons was established. Short segments of genes RPB2 and TEF-1α, which have been widely used in molecular taxonomy of Fusarium, were amplified with universal primers in a real-time thermocycler and high-resolution melting (HRM) curves of the products were recorded. Among major Fusarium pathogens of maize ears, F. cerealis, F. culmorum, F. graminearum, F. equiseti, F. poae, F. temperatum, F. tricinctum, and F. verticillioides, all species except for the pair F. culmorum/F. graminearum could be distinguished by HRM analysis of a 304 bp segment of the RPB2 gene. The latter two species could be differentiated by HRM analysis of a 247 bp segment of the TEF-1α gene. The assay was validated with DNA extracted from pure cultures of fungal strains, successfully applied to total DNA extracted from infected maize ears and also to fungal mycelium that was added directly to the PCR master mix (“colony PCR”). HRM analysis thus offers a cost-efficient method suitable for the diagnosis of multiple fungal pathogens. Full article

Fusarium species are common pathogens on maize and reduce the product quality through contamination with mycotoxins thus jeopardizing safety of both animal feed and human food products. Monitoring of Fusarium infected maize ears and stalks was conducted in Germany to determine the range of Fusarium species present in the field and to assess the impact of tillage, crop rotation, and weather conditions on the frequency of Fusarium species. From 2016 till 2018, a total of 387 infected ears and 190 stalk segments from 58 locations in Germany were collected. For each sample location, site-specific agronomic data on tillage and previous crops as well as meteorological data on precipitation, air temperature, and relative humidity during the vegetation period were recorded. The most frequent Fusarium species detected in maize ears were Fusarium graminearum, F. verticillioides and F. temperatum, whereas, F. graminearum, F. equiseti, F. culmorum, and F. temperatum were the species prevailing on maize stalks. Differences in the local species composition were found to be primarily associated with weather variations between the years and the microclimate at the different locations. The results indicate that mean temperature and precipitation in July, during flowering, has the strongest impact on the local range of Fusarium spp. on ears, whereas the incidence of Fusarium species on stalks is mostly affected by weather conditions during September. Ploughing significantly reduced the infection with F. graminearum and F. temperatum, while crop rotation exerted only minor effects. Full article

In this study, two Burkholderia strains, strain KNU17BI2 and strain KNU17BI3, were isolated from maize rhizospheric soil, South Korea. The 16S rRNA gene and multilocus sequence analysis and typing (MLSA-MLST) were used for the identification of the studied strains. Strain KNU17BI2, which belonged to Burkholderia cenocepacia, was of a novel sequence type (ST) designated ST-1538, while strain KNU17BI3 had a similar allelic profile with the seven loci of Burkholderia contaminans strain LMG 23361. The strains were evaluated in vitro for their specific plant growth promoting (PGP) traits, such as zinc solubilization, phosphate solubilization, ammonia production, 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity, indole acetic acid (IAA) production, siderophore, and hydrolytic enzyme activity. Interestingly, the strains exhibited a positive effect on all of the tested parameters. The strains also showed broad-spectrum antifungal activity against economically important phytopathogens in the dual culture assay. Furthermore, the strains were evaluated under greenhouse conditions for their in vivo effect to promote plant growth and to suppress the root rot of maize that is caused by Fusarium temperatum on four Korean maize cultivars. The results of the greenhouse study revealed that both of the strains were promising to significantly suppress fusarium root rot and enhance plant growth promotion on the four maize cultivars. This study, for the first time, reported in vitro antifungal potential of B. cenocepacia of novel ST against economically important plant pathogens viz., F. temperatum, Fusarium graminearum, Fusarium moniliforme, Fusarium oxysporum f.sp. melonis, Fusarium subglutinans, Phytophthora drechsleri, and Stemphylium lycopersici. This is also the first report of zinc solubilization by B. cenocepacia. Moreover, the present research work reports, for the first time, about the potential of B. cenocepacia and B. contaminans to control the root rot of maize that is caused by F. temperatum. Therefore, we recommend further studies to precisely identify the bioactive chemical compounds behind such activities that would be novel sources of natural products for biological control and plant growth promotion of different crops. Full article

Fusarium root rot and stalk rot are becoming a threat to maize production worldwide. However, there is still limited information about the aggressiveness of Fusarium subglutinans Edwards and Fusarium temperatum and their relationship with fumonisin production. In this study, for the first time, the reaction of seven Korean maize cultivars to F. subglutinans and F. temperatum was investigated. The results showed that among the maize cultivars, Hik-chal and Miheung-chal had the highest Fusarium-induced root rot and stalk rot severity, while De Hack-chal had the lowest disease severity regardless of the Fusarium species. Furthermore, the disease resistant cv. De Hack-chal accumulated low levels of fumonisins (FUM) in the infected stalk, while cv. Hik-chal and Miheung-chal had the highest level of FUM. It is worth to note that, plants infected with F. temperatum had a higher FUM concentration compared to cultivars infected with F. subglutinans. The present study shows a significant correlation between stalk rot ratings and FUM levels and it also presents new information about the potential risk of FUM contamination of maize stalk with F. subglutinans and F. temperatum in South Korea. In addition, enzyme activities like polyphenol oxidase (PPO), peroxidase (POD), and the amount of total phenol content (TPC) were studied in selected susceptible cultivar Miheung-chal and resistant cultivar De Hack-chal. The activity of PPO, POD and concentration of TPC were generally higher in the roots of the resistant cultivar than the susceptible cultivar. Moreover, following inoculation of either F. subglutinans or F. temperatum, there was a significant increase in PPO and POD activity in the roots of both cultivars. Hence, the information provided in this study could be helpful to better understand the mechanisms of resistance response to infection of Fusarium root rot pathogens. Full article

In this study, twenty of the most common Fusarium species were molecularly characterized and inoculated on potato dextrose agar (PDA), rice and maize medium, where thirty three targeted mycotoxins, which might be the secondary metabolites of the identified fungal species, were detected by liquid chromatography–tandem mass spectrometry (LC-MS/MS). Statistical analysis was performed with principal component analysis (PCA) to characterize the mycotoxin profiles for the twenty fungi, suggesting that these fungi species could be discriminated and divided into three groups as follows. Group I, the fusaric acid producers, were defined into two subgroups, namely subgroup I as producers of fusaric acid and fumonisins, comprising of F. proliferatum, F. verticillioides, F. fujikuroi and F. solani, and subgroup II considered to only produce fusaric acid, including F. temperatum, F. subglutinans, F. musae, F. tricinctum, F. oxysporum, F. equiseti, F. sacchari, F. concentricum, F. andiyazi. Group II, as type A trichothecenes producers, included F. langsethiae, F. sporotrichioides, F. polyphialidicum, while Group III were found to mainly produce type B trichothecenes, comprising of F. culmorum, F. poae, F. meridionale and F. graminearum. A comprehensive picture, which presents the mycotoxin-producing patterns by the selected fungal species in various matrices, is obtained for the first time, and thus from an application point of view, provides key information to explore mycotoxigenic potentials of Fusarium species and forecast the Fusarium infestation/mycotoxins contamination. Full article