Genus Fusarium Research Articles

Fusarium mindanaoense sp. nov., a New Fusarium Wilt Pathogen of Cavendish Banana from the Philippines Belonging to the F. fujikuroi Species Complex.

The pathogen causing Fusarium wilt in banana is reported to be Fusarium oxysporum f. sp. cubense (FOC). In 2019, wilt symptoms in banana plants (cultivar: Cavendish) in the Philippines were detected, i.e., the yellowing of the leaves and discoloration of the pseudostem and vascular tissue. The fungus isolated from the vascular tissue was found to be pathogenic to Cavendish bananas and was identified as a new species, F. mindanaoense, belonging to the F. fujikuroi species complex (FFSC); species classification was assessed using molecular phylogenetic analyses based on the tef1, tub2, cmdA, rpb1, and rpb2 genes and morphological analyses. A reciprocal blast search using genomic data revealed that this fungus exclusively included the Secreted in Xylem 6 (SIX6) gene among the SIX homologs related to pathogenicity; it exhibited a highly conserved amino acid sequence compared with that of species in the FFSC, but not with that of FOC. This was the first report of Fusarium wilt in Cavendish bananas caused by a species of the genus Fusarium other than those in the F. oxysporum species complex.

Features of microorganisms of zoned varieties from sugar beet seed

Quantitative accounting of microorganisms was carried out by seeding on nutrient media selected in accordance with their type. Thus, we have explored some features of development of pathogenic complex of microscopic fungi in soils of beet-growing farms in Almaty and Zhambyl regions. Soil microbial communities in two areas are represented by microorganisms such as bacteria genera: Pseudomonas, Bacillus, Mycobacterium, Mycococcus, Pseudobacterium, Lactobacterium. It is shown that Bacillus and Pseudomona prevail in soil samples. It is established that the dominant species of microorganisms are fungi genera: Fusarium, Alternaria, Penicillium which are a part of pathogenic complex that cause root decay. On the basis of the obtained data, a protective and stimulating composition for reducing the incidence of sugar beet seeds before sowing will be developed in soil samples No. 1-No. 4 of Almaty. The Fusarium genus prevailed in the Almaty Region, and Botrytis prevailed in the Zhambyl Region.

Seasonal variations in the composition and diversity of rhizosphere soil microbiome of bamboo plants as infected by soil-borne pathogen and screening of associated antagonistic strains

As the occurrence and severity of soil-borne diseases are strongly season-dependent, the ecological processes that shift plant microbiome compositions and functions upon pathogen infection in different seasons are rarely studied. In this study, we compared the differences in fungal and bacterial communities in rhizosphere soil between healthy and diseased bamboo plants throughout the four seasons at the main bamboo production site in China and investigated how basal rot disease caused by Fusarium proliferatum affected the composition, structure and ecological functions of rhizosphere-associated microorganisms. The results showed that diseased bamboo plants enriched the highest abundance of Fusarium genus in rhizosphere soil while receiving largely increased stem lesion area in summer. Microbiome analysis further proved that healthy bamboo plants harbored more ecologically beneficial microbial taxa that might function as biological protectants in their rhizosphere soil than diseased plants at the same season. Three individual strains with biocontrol potentials were further isolated and identified as Trichoderma spirale, Bacillus velezensis and Streptomyces mirabilis. The antagonistic tests further demonstrated their inhibition effects on the growth and pathogenicity of the pathogenic fungus F. proliferatum in vitro and in vivo. This study advances our understanding of soil-borne pathogen mediated changes in microbiome structure and function in plant rhizosphere soil and provides potential biocontrol strains for increasing plant resistance against basal rot disease.

Native Trichoderma Isolates from Soil and Rootstock to Fusarium spp. Control and Growth Promotion of Humulus lupulus L. Plantlets

Fusarium genus is a wide host phytopathogen causing significant losses in multiple crops, including hops. There is limited information on the sustainable management of Fusarium spp. in hop fields. Trichoderma is an endophytic fungus used in agriculture as a biological control agent (BCA) and as a plant growth promoter. It has been used to antagonize Fusarium spp. in other crops. The objective of the current study was to identify indigenous hop field Trichoderma isolates with biocontrol and hop growth promotion capabilities. Three isolates of Fusarium and eleven autochthonous Trichoderma isolates collected from sustainable hop fields were evaluated in this work. Direct confrontation tests (the physical interaction between the pathogen and BCA and their competition for space and nutrient resources) and membrane tests (the capacity of the BCA to produce metabolites or enzymes through a cellophane film and inhibit the development of the pathogen) assessed the antagonism of these Trichoderma isolates against Fusarium culmorum, F. sambucinum, and F. oxysporum. A bioassay with hop plantlets inoculated with a spore suspension of Trichoderma was performed to assess its hop growth enhancement. T. hamatum (T311 and T324), T. virens T312, and T. gamsii T327 showed high growth inhibition of Fusarium spp. phytopathogens and high plant growth promotion. Native Trichoderma isolates from sustainable hop-producing soils have great potential as BCAs and hop growth promoters.

The Microbial Terroir of the Nemea Zone Agiorgitiko cv.: A First Metataxonomic Approach

Vitis vinifera L. cv. Agiorgitiko is one of the most popular indigenous wine grape varieties in Greece, cultivated almost exclusively in the Nemea Protected Designation of Origin (PDO) zone. Here, the microbiota of soil, grapes, and wine, during controlled (CF) and spontaneous (SF) fermentations of Agiorgitko cv. from three vineyards in the PDO Nemea zone were explored, using both classical microbiological analysis and metataxonomics to get evidence about the microbial terroir of the PDO Nemea zone. The classical microbiological analysis revealed higher total mesophilic counts in soil, while in both grapes and wine samples, yeasts prevailed. Lactic acid bacteria and acetic acid bacteria counts were lower in grapes compared to wine and soil. Metataxonomic analysis revealed that, regarding yeasts/fungi, genera Fusarium, Sarea, and Alternaria dominated in soil; Aureobasidium, Cladosporium, and Penicillium in grapes; Saccharomyces in wine during CF; and Hanseniaspora and Saccharomyces in wine during SF. Regarding bacteria, genera Skermanella, Acidobacterium, and Ohtaekwangia dominated in soil, Sphingomonas, Micrococcus, and Rubrobacter in grapes, while Tatumella, Alcanivorax, and Komagateibacter in wine during both CF and SF. Finally, the factors that significantly influence the microbiota of soil, grapes, and wine samples were assessed, and potential microbial biomarkers were identified for the first time in a Greek grape variety.

Disentangling the Functional Role of Fungi in Cold Seep Sediment.

Cold seeps are biological oases of the deep sea fueled by methane, sulfates, nitrates, and other inorganic sources of energy. Chemolithoautotrophic bacteria and archaea dominate seep sediment, and their diversity and biogeochemical functions are well established. Fungi are likewise diverse, metabolically versatile, and known for their ability to capture and oxidize methane. Still, no study has ever explored the functional role of the mycobiota in the cold seep biome. To assess the complex role of fungi and fill in the gaps, we performed network analysis on 147 samples to disentangle fungal-prokaryotic interactions (fungal 18S and prokaryotic 16S) in the Haima cold seep region. We demonstrated that fungi are central species with high connectivity at the epicenter of prokaryotic networks, reduce their random-attack vulnerability by 60%, and enhance information transfer efficiency by 15%. We then scavenged a global metagenomic and metatranscriptomic data set from 10 cold seep regions for fungal genes of interest (hydrophobins, cytochrome P450s, and ligninolytic family of enzymes); this is the first study to report active transcription of 2,500+ fungal genes in the cold seep sediment. The genera Fusarium and Moniliella were of notable importance and directly correlated with high methane abundance in the sulfate-methane transition zone (SMTZ), likely due to their ability to degrade and solubilize methane and oils. Overall, our results highlight the essential yet overlooked contribution of fungi to cold seep biological networks and the role of fungi in regulating cold seep biogeochemistry. IMPORTANCE The challenges we face when analyzing eukaryotic metagenomic and metatranscriptomic data sets have hindered our understanding of cold seep fungi and microbial eukaryotes. This fact does not make the mycobiota any less critical in mediating cold seep biogeochemistry. On the contrary, many fungal genera can oxidize and solubilize methane, produce methane, and play a unique role in nutrient recycling via saprotrophic enzymatic activity. In this study, we used network analysis to uncover key fungal-prokaryotic interactions that can mediate methane biogeochemistry and metagenomics and metatranscriptomics to report that fungi are transcriptionally active in the cold seep sediment. With concerns over rising methane levels and cold seeps being a pivotal source of global methane input, our holistic understanding of methane biogeochemistry with all domains of life is essential. We ultimately encourage scientists to utilize state-of-the-art tools and multifaceted approaches to uncover the role of microeukaryotic organisms in understudied systems.

Annotation of the 12th Chromosome of the Forest Pathogen Fusarium circinatum

The genus Fusarium comprises more than 300 species, and many of them are pathogens that cause severe diseases in agricultural, horticultural and forestry plants in both antropogenic and natural ecosystems. Because of their importance as plant pathogens, the genomes of several Fusarium spp. have been sequenced. Within this genus, Fusarium circinatum is one of the most harmful pathogens of pine trees attacking up to 60 Pinus species. Till now, the genomes of 13 strains of F. circinatum have been sequenced. The strain GL1327 we studied lacks a twelfth chromosome, which allows the study of virulence genes on this chromosome. Although the genome of several strains of F. circinatum has been sequenced, it is still almost completely unannotated, which severely limits the possibilities to further investigate the molecular mechanisms of virulence of Fusarium. Therefore, this study aimed to annotate the 12th chromosome of F. circinatum and integrate currently available resources. In silico annotation of the 12th chromosome of F. circinatum revealed the presence of 118 open reading frames (ORFs) encoding 141 proteins which were predicted using an ab initio gene prediction tool. The InterProScan and SMART analyses identified known domains in 30 proteins and eggNOG additionally in 12 of them. Among them, four groups can be distinguished: genes possibly related to heterokaryon incompatibility (4 genes), regulation of transcription (5 genes), plant cell wall degrading enzymes (7 genes) and trichothecene synthesis (3 genes). This study also integrated data of F.circinatum reference strain CMWF1803 assembled to chromosome level but not annotated with currently best annotated but assembled only to scaffold level strain NRRL 25331.

Association of soil fungal community composition with incidence of Fusarium wilt of banana in Malaysia

ABSTRACT Banana (Musa spp.), an important food crop in many parts of the world, is threatened by a deadly wilt disease caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 (TR4). Increasing evidence indicates that plant actively recruits beneficial microbes in the rhizosphere to suppress soil-borne pathogens. Hence, studies on the composition and diversity of the root-associated microbial communities are important for banana health. Research on beneficial microbial communities has focused on bacteria, although fungi can also influence soil-borne disease. Here, high-throughput sequencing targeting the fungal internal transcribed spacer (ITS) was employed to systematically characterize the difference in the soil fungal community associated with Fusarium wilt (FW) of banana. The community structure of fungi in the healthy and TR4-infected rhizospheres was significantly different compared with that of bulk soil within the same farm. The rhizosphere soils of infected plants exhibited higher richness and diversity compared with healthy plants, with significant abundance of Fusarium genus at 14%. In the healthy rhizosphere soil, Penicillium spp. were more abundant at 7% and positively correlated with magnesium. This study produced a detailed description of fungal community structure in healthy and TR4-infected banana soils in Malaysia and identified candidate biomarker taxa that may be associated with FW disease promotion and suppression. The findings also expand the global inventory of fungal communities associated with the components of asymptomatic and symptomatic banana plants infected by TR4.

Pathogenic complex and recovery of cereal agrocenoses in the Steppe of Ukraine

Topicality. Changes in weather and climatic conditions affect the formation of pathogenic complexes of grain agrocenoses and the species composition of pathogens, which are typical for the Steppe zone of Ukraine. At the same time, changes in cultivation technologies accompanying the transition to new forms of management also play a significant role in the formation of pathogenic complexes. It is necessary to find out the features of the pathogenic mycoflora formation and plant immunity in order to scientifically substantiate measures to stabilize the phytosanitary state of agro-cenoses at the current stage of grain production. Purpose. To divide into appropriate groups of grain crop diseases in the Steppe zone in terms of the nature of development, harmfulness and hy-drothermal dependence of their pathogens. Materials and Methods. In 1999–2019, we conducted surveys of wheat (winter and spring), rye, barley (winter and spring), oats and maize for disease in-festation in the Northern Steppe of Ukraine according to generally accepted methods of phytopathological research. Results. Over the years of research, we identified 123 pathogens, which caused 135 diseases in grain crops. The most diverse composition of pathogens was observed on wheat and maize, 64 and 55 pathogens, and, 33 and 41 diseases, respectively. It should be noted a wide range for specialization of the widespread pathogens in the Northern Steppe of Ukraine. The pathogens of smut infects generally a certain type of grain crops, rusts are somewhat less specialized. Less specialized parasites, such as fungi from the genera Fusarium, Helminthosporium, Alternaria cause the same type of diseases in several plant species, and some of them affect different plant organs. Thus, among the pathogens of Fusarium root rot of wheat, rye, barley and maize, the fungus Fusarium moniliforme Sheld. was identified. On the maize, in particular, this pathogen caused seedling mold, root and stem rot, cob rot, and grain mold. Conclusions. It was established that the hydrothermal regime can affect the development of diseases not only due to its compliance with the pathogen's requirements, but also affect the resistance of plants. The problem of agrocenosis recovery can be successfully solved by adapting modern intensive technologies of growing grain crops that aimed to optimally utilized ecological resources by plants in the Steppe of Ukraine, and prevent the spread of harmful organisms. Key words: winter wheat, maize, pathogens, diseases, hydrothermal conditions, harmfulness

Impact of mycotoxins and their metabolites associated with food grains

Mycotoxins are secondary toxic metabolites synthesized by numerous filamentous fungi including members of the genus Fusarium, Penicillium, Drechslaria, Aspergillus, Claviceps, Monascum, Alternaria, Cephalosporium, Nigrospora, and Trichoderma. Among them, Aspergillus and Fusarium species are major plant pathogens recognized to induce infection and produce mycotoxins in food crops. More than 400 mycotoxins have been documented and among them, aflatoxin, fumonisins, trichothecenes, zearalenone, ochratoxin A, citrinin, ergot alkaloids, and patulin are the most prominent compounds linked to a variety of human and animal health disorders. Genus Fusarium and Aspergillus belong to a saprophytic group, which can infect and contaminate many crops at pre and post-harvest stages. Mycotoxins can have a variety of negative effects on health in both humans and animals. Mycotoxins and their metabolites can cause severe acute poisoning, which can result in death, as well as long-term negative health effects, such as cancer and immune-suppressive disorders in living beings (animals and humans). Mycotoxin contamination of agricultural goods has gained global significance, due to its toxic effects on living beings, as well as its importance to international trade. Our objective is to provide a consolidated information on the potential mycotixs in food grains and their significant impact on the health of the human beings.

Spécies Diversity and Physiological Characterization of Fusarium spp. Isolates Causing Potato (Solanum tuberosum L.) Fusariosis (Far-North, Cameroon)

Introduction: Potato production in the Far North Region, Cameroon is hampered by a wide range of fungi of the genus Fusarium.
 Aims: The aim of this work was to isolate and conduct physiological characterization of Fusarium spp. isolates responsible for potato Fusarium disease in the Far North Region, Cameroon.
 Methodology: Isolates were obtained from diseased organs (leaves) from fifteen villages in the district of Mogodé, Mokolo and Koza, Far North Cameroon. The species responsible for fusariosis were identified using several identification Keys on a base of symptoms and morphological spores characteristics (macroconidia, microconidia and chlamydospores). Fusarium incidence and rainfall were assessed. Radial growth, sporulation and pathogenicity of the isolates were use to evaluated the parameters of physiological characterization.
 Results: The overall average incidence of Fusarium head blight in the Far North Region, Cameroon is 29.36%. Furthermore, out of the 20 isolates obtained, six Fusarium species (Fusarium oxysporium, F. solani, F. equiseti, F. avenacearum, F. colmorum and F. sambicum) were identified. The highest growth rate (8.1 cm), the highest spore production (8 × 105) and the highest severity index (3%) were respectively obtained with the isolates FUROM 2 and FUTEK 3, FUMOG 1, FUMOG 2, FUROM 1 and FURAF from Mogodé District on PCA medium.
 Conclusion: Potato production in the Far North Region, Cameroon is confronted by various Fusarium species which have physiological characteristics that vary according to the area of origin of the isolates and the growing media.

Environmental and pathological factors affecting the hatching success of the two northernmost loggerhead sea turtle (Caretta caretta) nests

In recent years, the report of loggerhead sea turtle (Caretta caretta) Mediterranean nesting range has expanded together with new records of nests becoming northward on the Italian coastline of the Tyrrhenian and Adriatic seas. These areas are characterized by intensive human activities, such as tourism, fishery, and marine traffic, all possibly involved in the influence of the use of coastal habitat by marine species. These anthropic threats, in addition to the natural ones and the changing environmental characteristics of the beach, may influence the growth of microorganisms causing hatching failures. Among microorganisms, fungal infection by the genus Fusarium (Link, 1809) is considered one of the main causes of globally declining sea turtle populations. In summer 2021, the two northernmost worldwide loggerhead sea turtle nests were monitored along the Northern Adriatic coastline (Veneto, Italy). These first records may potentially candidate this area as suitable for a large part of the loggerhead turtle’s life cycle and it could represent a minor sea turtle nesting area that, according to Prato and colleagues, remained unnoticed due to the lack of specific monitoring. Sea Turtle Egg Fusariosis (STEF) was deemed to have deeply compromised the hatching success of the northmost one. Climate change and anthropogenic impacts have been scored as one of the highest hazards to sea turtle health and could have played a role in the STEF development. Environmental changes, human activities, and emerging pathogens deserve the highest attention in terms of health research, and conservation management.

Identification and Characterization of Fusarium Species Causing Watermelon Fruit Rot in Northern Thailand.

Fruit rot caused by phytopathogenic fungi is one of the major diseases affecting watermelons (Citrullus lanatus) around the world, which can result in unmarketable fruits and significant economic losses. Fruit rot was observed on watermelons throughout the postharvest storage periods in Phayao Province, northern Thailand in 2022. For the present study, a total of ten fungal isolates were isolated from the rot lesions of watermelons. All obtained fungal isolates were then characterized in terms of their pathogenicity. The results indicated that only four fungal isolates caused rot disease with similar symptoms during the postharvest storage period. Based on their morphological characteristics, these four fungal isolates were identified as belonging to the genus Fusarium. Using multi-gene phylogenetic analyses with a combination of the translation elongation factor 1-alpha (tef-1), calmodulin (cam), and RNA polymerase second largest subunit (rpb2) genes, the fungal isolates were subsequently identified as Fusarium compactum and F. paranaense. Taken together, the results of this study indicate that F. compactum and F. paranaense cause fruit rot disease in watermelons. To the best of our knowledge, this is the first study to report F. compactum and F. paranaense as novel pathogens of watermelon fruit rot both in Thailand and elsewhere in the world.

Diversity of Fungi Isolated from Potato Nematode Cysts in Guizhou Province, China.

Potatoes rank third in terms of human consumption after rice and wheat. Globodera spp. are significant pests of potato crop worldwide. Globodera rostochiensis was found in Weining County, Guizhou Province, China, in 2019. We collected soil from the rhizosphere zone from infected potato plants and separated mature cysts through simple floatation and sieving methods. The selected cysts were surface-sterilized, and the colonized fungi were isolated and purified. At the same time, the preliminary identification of fungi and fungi parasites on the cysts of nematodes was carried out. This study aimed to define the species and frequency of fungi-colonizing cysts of G. rostochiensis collected from Weining County, Guizhou Province, China, and provide a basis for the control of G. rostochiensis. As a result, 139 strains of colonized fungi were successfully isolated. Multigene analyses showed that these isolates included 11 orders, 17 families, and 23 genera. The genera Fusarium (with a separation frequency of 59%), Penicillium (11%), Edenia (3.6%), and Paraphaeosphaeria (3.6%) were the most frequently occurring. Among the 44 strains, 27 had a colonization rate of 100% on the cysts of G. rostochiensis. Meanwhile, the functional annotation of 23 genera indicated that some fungi have multitrophic lifestyles combining endophytic, pathogenic, and saprophytic behavior. In conclusion, this study showed the species composition and lifestyle diversity of colonized fungi from G. rostochiensis and demonstrated these isolates as potential sources of biocontrol agents. Colonized fungi were isolated from G. rostochiensis for the first time in China, and the taxonomic diversity of fungi from G. rostochiensis was clarified.

Phytochemical Profile and Activity against Fusarium Species of Tamarix gallica Bark Aqueous Ammonia Extract

French tamarisk, Tamarix gallica L. (family Tamaricaceae) is a deciduous tree that, like other halophytes, grows in a wide variety of saline habitats thanks to its powerful phenolics-based antioxidant system. Given that antioxidant properties are usually linked to the presence of compounds with antifungal properties, in the work presented herein the antimicrobial activity of T. gallica bark extract was investigated against four phytopathogenic species of genus Fusarium. According to the results of gas chromatography–mass spectroscopy, the phytochemical profile of the aqueous ammonia extract included 1-(2,4,6-trihydroxyphenyl)-2-pentanone; 3,5-dimethoxy-4-hydroxycinnam aldehyde; trans-squalene; 4-hydroxy-3,5-dimethoxy-benzaldehyde; dihydro-3-methylene-2,5-furandione; 1-(4-hydroxy-3,5-dimethoxyphenyl)-ethanone; and 4-hydroxy-3,5-dimethoxy-benzoic acid as main constituents. Concerning in vitro antifungal activity, EC90 effective concentrations in the 335–928 μg·mL−1 range were obtained against F. acuminatum, F. culmorum, F. equiseti, and F. graminearum, remarkably lower than those of two conventional fungicides (viz. mancozeb and fosetyl-Al). The antifungal activity of the extract was tested further in wheat and maize grain protection bioassays, confirming that the treatment effectively controlled F. graminearum at a concentration of 375 µg·mL−1. Given this promising activity, T. gallica bark extracts may be susceptible to valorization as a natural and sustainable biorational for Fusarium spp. control.

The fungal pathogen Fusarium solani poses an increasing threat to tomato production in Northern China

ABSTRACT Greenhouse cultivation conditions, such as low light intensity, high humidity and limited crop rotation, result in an increased severity of foot rot disease. Here, we isolated a fungal pathogen from tomato plants infected with foot rot disease to investigate its pathogenicity and establish an inoculation system to distinguish tomato susceptible and resistant varieties. Microscopic analyses of the fungal spores suggested that the pathogen belonged to the genus Fusarium, while polymerase chain reaction amplification of internal transcribed spacer (ITS), translation elongation factor-1 alpha (EF-1α) and mitochondrial small subunit (mtSSU) rDNA fragments revealed that it was an isolate of Fusarium solani. Phylogenetic analyses indicated that the ITS, EF-1α and mtSSU sequences were distinct from other isolates identified in this region, suggesting that this fungus has recently arrived here. Reinoculation of this fungus on tomato seedlings grown on Murashige and Skoog medium and in pots filled with soil resulted in foot rot disease, but disease symptoms appeared more rapidly in the medium-grown seedlings. Together, our results demonstrate that this new F. solani isolate is causing tremendous losses of tomato production in greenhouse cultivation. Fungal inoculation on both medium-grown and soil-grown seedlings will facilitate resistance screening of tomato germplasm against infection by this pathogen.

Triazoles and Strobilurin Mixture Affects Soil Microbial Community and Incidences of Wheat Diseases.

Pesticides are widely used in agriculture as a pest control strategy. Despite the benefits of pesticides on crop yields, the persistence of chemical residues in soil has an unintended impact on non-targeted microorganisms. In the present study, we evaluated the potential adverse effects of a mixture of fungicides (difenoconazole, epoxiconazole, and kresoxim-methyl) on soil fungal and bacterial communities, as well as the manifestation of wheat diseases. In the fungicide-treated soil, the Shannon indices of both fungal and bacterial communities decreased, whereas the Chao1 indices did not differ compared to the control soil. Among bacterial taxa, the relative abundances of Arthrobacter and Sphingomonas increased in fungicide-treated soil due to their ability to utilize fungicides and other toxic compounds. Rhizopus and plant-beneficial Chaetomium were the dominant fungal genera, with their prevalence increasing by 2-4 times in the fungicide-treated soil. The genus Fusarium, which includes phytopathogenic species, which are notably responsible for root rot, was the most abundant taxon in each of the two conditions but its relative abundance was two times lower in fungicide-treated soils, consistent with a lower level of disease incidence in plants. The prediction of metabolic pathways revealed that the soil bacterial community had a high potential for degrading various pollutants, and the soil fungal community was in a state of recovery after the application of quinone outside inhibitor (QoI) fungicides. Fungicide-treated soil was characterized by an increase in soil microbial carbon, compared with the control soil. Collectively, the obtained results suggest that the application of difenoconazole, epoxiconazole, and kresoxim-methyl is an effective approach for pest control that does not pose a hazard for the soil ecosystem in the short term. However, it is necessary to carry out additional sampling to take into account the spatio-temporal impact of this fungicide mixture on the functional properties of the soil.

Disseminated fusariosis against the background of polychemotherapy in a patient with acute leukemia

Fusariosis is a dangerous disease caused by imperfect fungi of the genus Fusarium; it is a severe opportunistic infection characterized by rapid dissemination of the mycotic process and high mortality. Currently, there is an increase in the frequency of invasive mycoses all over the world, especially in oncohematological patients. This is due not only to the improvement of methods for diagnosing mycoses, but also to more «aggressive» schemes of cytostatic therapy and the widespread use of hematopoietic stem cell and organ transplantation as a rescue therapy.

Fungal species characterization associated with vanilla root rot in the Totonacapan, Veracruz, Mexico

Vanilla (Vanilla planifolia) is a crop of great biocultural importance in the Totonacapan region in Mexico; however, producers face various phytosanitary problems that decrease production. The main one being crop loss caused by the fungus, Fusarium oxysporum f. sp. vanillae, a pathogen that causes a disease whose symptomatology is root rot that in severe cases causes the death of plants. Therefore, the study of the pathogen is crucial, due to the scarcity of genetic variability of vanilla, a condition that makes the crops equally susceptible to the pathogen. The present work aimed to generate and molecularly and pathogenically characterize a fu-ngal isolates collection obtained from V. planifolia with root rot. Roots with rot were collected in six municipalities of the Totonacapan region, for fungal isolation, a semiselective culture medium was used, later, the molecular characterization was carried out through the amplification and sequencing of the partial region of the translational elongation factor 1α gene (TEF1). The pathogenic characterization was carried out on vanilla leaves in a humid chamber, inoculating medium discs with mycelium, and making observations for 18 days every 48 h. As results, 94 strains were obtained, of which 81 belong to the genus Fusarium (42 F. oxysporum strains), eight to Colletotrichum, three to Trichoderma and two it was not possible to identify them, only 23 Fusarium oxysporum strains showed to be pathogenic on vanilla leaves with different degrees of virulence. The results of the molecular and pathogenic characterization will be crucial for further studies of comparative genomics of Fusarium oxysporum.

ВИРУЛЕНТНОСТЬ ГРИБОВ РОДА FUSARIUM, ПАРАЗИТИРУЮЩИХ НА ЗЕРНОВЫХ КУЛЬТУРАХ В СРЕДНЕВОЛЖЬЕ

Infectious diseases caused by fungi from the Fusarium genus are one of the main reasons for the decrease in yield and quality of grain crops. The aim of the study is to identify the most virulent fungal isolates of the Fusarium genus inhabiting the territory of the Tatarstan Republic and its neighbouring regions of the Volga Federal District. Wheat and rye spikes were collected in the summer of 2022 at the spike ripening stage. Thirteen fungal strains were isolated from obtained plant material and preliminary attributed as Fusarium species based on morphological characteristics. By analyzing the nucleotide sequences of the ITS2 (internal transcribed spacer) region of ribosomal genes, the obtained fungal isolates were confirmed to belong to the Fusarium genus. Most of these isolates were attributed to the species F. sporotrichioides, F. culmorum, F. oxysporum, F. poae, while some isolates were identified at the genus level. Using virulence assays with wheat grain and rye plants in vitro, four isolated fungal strains were characterized as highly virulent. Based on the analysis of ITS2 sequences, the highly virulent Fusarium strains were assigned to F. sporotrichioides (1 strain), F. culmorum (1 strain), and F. oxysporum (2 strains). Other fungal strains (9 isolates) were characterized as low- or moderately virulent. In addition to the pronounced virulence properties, the detected Fusarium species have the potential ability to produce mycotoxins dangerous for humans and farm animals, which actualizes the need for detailed phytosanitary studies on the territory of the Tatarstan Republic and its neighbouring regions of the Volga Federal District.