Fusarium Wilt Research Articles

Management of Fusarium Wilt of Lettuce

Abstract In recent years, Fusarium wilt, caused by Fusarium oxysporum f. sp. lactucae, has become the most important lettuce disease throughout the world. Since the pathogen is seed-transmitted, the disease spreads through infected seeds, favoured by the global commerce. We describe the biology and epidemiology of the pathogen, as well as the differentiation of four physiological races, with their distribution in different geographical areas. The reaction of the lettuce types and varieties to the pathogen are also described, as well as the diagnostic tools available for an appropriate detection of the pathogen, including the races. Like other soil-borne diseases, Fusarium wilt of lettuce is difficult to manage with a single product and/or with a single approach. At present, minimizing crop losses due to Fusarium wilt on lettuce entails the deployment of all available existing disease control tools within an integrated management programme. The first preventative strategy is the use of healthy seeds. Stock seeds should be produced in the areas associated with the lowest disease risk and subjected to standardized health analysis. Furthermore, seeds should be treated with chemical/physical or biological treatments. Among chemical tools, soil disinfestation is becoming very difficult due to the loss of registered fumigants. A careful monitoring of the race situation in the field would be useful for efficient use of genetic means of control. The seed industry is investing in the search of new varieties resistant to Fusarium wilt. Looking forward, the development of commercially acceptable cultivars of desired types of lettuce with high levels of resistance to Fusarium wilt as well as refinement of existing or development of new cultural, chemical and biofungicide tools should lead to more efficient and effective disease management. Information © The Authors 2024

Identification and biological characteristics of Fusarium tobaccum sp. nov., a novel species causing tobacco root rot in Jilin Province, China.

Fusarium wilt of tobacco (FWT), caused by Fusarium spp., has emerged as a severe threat to tobacco production in China. In all, 132 isolates of Fusarium were isolated from tobacco and pathogenic to tobacco-causing FWT in Jilin Province, China. In this study, we identified 7 of 132 isolates as a novel species Fusarium tobaccum sp. nov. Zhao Xie & Jie Gao, using multi-gene phylogenetic analyses of translation elongation factor (tef1), β-tubulin (tub2), calmodulin (cmdA), and RNA polymerase II second largest subunit (rpb2) genes, along with subtle morphological differences. Isolates of F. tobaccum sp. nov. were clustered in a distinct branch in the maximum parsimony phylogenetic tree generated from the sequences of tef1-rpb2-tub2-cmdA and can be distinguished from closely related species F. cugenangense, F. callistephi, and F. elaeidis. The morphological characteristics of F. tobaccum sp. nov. are distinct from other Fusarium species. F. tobaccum sp. nov. exhibits abundant aerial mycelia and pigment production on potato dextrose agar (PDA), microconidia with 0-1 septa, and macroconidia with 2-5 septa on carnation leaf-piece agar (CLA), and produces abundant chlamydospores on Spezieller Nährstoffarmer agar (SNA) and CLA. The mycelia of F. tobaccum exhibited optimal growth at a pH of 7.1 and a temperature of 23.6°C. Sucrose and NaNO3 significantly promoted the mycelial growth of F. tobaccum. PD medium was optimal for total sporulation. However, the sporulation ratios of the macrospores of F. tobaccum in PD, SN, and CMC were relatively low (0.48%, 2.51%, and 2.16%, respectively). These findings provided valuable insights into the morphological and biological characteristics of F. tobaccum.IMPORTANCEFusarium wilt of tobacco (FWT) is a prevalent issue in tobacco-growing regions globally, leading to significant losses in yield and quality. This study identified F. tobaccum sp. nov., a novel species of Fusarium causing FWT in China. The identification was based on multi-gene phylogenetic analyses and morphological characteristics. The effects of temperature, pH, carbon source, nitrogen source, medium, and light on the mycelial growth of F. tobaccum sp. nov. were determined. These findings might contribute to future research on the pathogenic mechanisms of this novel species and the development of strategies to control FWT.

Mechanism of a novel Bacillus subtilis JNF2 in suppressing Fusarium oxysporum f. sp. cucumerium and enhancing cucumber growth

Cucumber Fusarium wilt caused by Fusarium oxysporum f. sp. cucumerium (FOC), is a prevalent soil-borne disease. In this study, Bacillus subtilis JNF2, isolated from the high incidence area of cucumber Fusarium wilt in Luoyang, demonstrated significant inhibitory effects on FOC and promoted cucumber seedling growth. The biocontrol mechanism of strain JNF2 were elucidated through morphological observation, physiological and biochemical experiments, and whole genome sequence analysis. Pot experiments revealed an 81.33 ± 0.21% control efficacy against Fusarium wilt, surpassing the 64.10 ± 0.06% efficacy of hymexazol. Seedlings inoculated with JNF2 exhibited enhanced stem thickness and leaf area compared to control and hymexazol-treated plants. Physiological tests confirmed JNF2’s production of indole-3-acetic acid (IAA), siderophores, and hydrolytic enzymes, such as β-1,3-glucanase, amylase, and protease, which inhibited FOC growth and promoted plant development. Genome analysis identified genes encoding antimicrobial peptides and hydrolases, as well as a novel glycocin synthetic gene cluster. These findings underscore B. subtilis JNF2’s potential as a biocontrol agent for sustainable cucumber cultivation.

Characteristics of soil microbial community assembly patterns in fields with serious occurrence of tobacco Fusarium wilt disease

IntroductionFusarium wilt disease (FWD) of tobacco is a destructive disease caused by Fusarium spp. in tobacco-growing regions worldwide. The Fusarium spp. infection may alter the composition and structure of the tobacco root microbial community; however, the relationship between these factors under large-scale geographical conditions in China remains underexplored.MethodsIn the context of this investigation, soil samples from the rhizosphere of tobacco plants were procured from fields afflicted with FWD and those devoid of the disease in the Hanzhong region of Shaanxi province, as well as in the Sanmenxia and Nanyang regions of Henan province. These regions are recognized for the commercial cultivation of tobacco. The examination focused on discerning the influence of tobacco FWD on the composition and configuration of the rhizosphere microbial community, along with their co-occurrence patterns. This scrutiny was underpinned by targeted PCR amplification and high-throughput sequencing (amplicon sequencing) of the 16S rRNA gene and the ITS1 region.ResultsThe amplicon data analyses showed that FWD influenced the microbial structure and composition of the tobacco rhizosphere soil. FWD had a greater impact on the microbiome of the tobacco fungal community than on the microbiome of the bacterial community. Healthy plants had the ability to recruit potential beneficial bacteria. Diseased plants were more susceptible to colonization by other pathogenic fungi, but they still had the capacity to recruit potential beneficial bacteria. The analysis of microbial intra- and inter-kingdom networks further indicated that FWD destabilized microbial networks. In the overall microbial interaction, microorganisms primarily interacted within their boundaries, but FWD increased the proportion of interactions occurring across boundaries. In addition, FWD could disrupt the interactions within microbial network modules.DiscussionThis study provides evidence that FWD can cause changes in the composition and network of microbial communities, affecting the interactions among various microorganisms, including bacteria and fungi. These findings contribute to our understanding of how plant microbiomes change due to disease. Furthermore, they add to our knowledge of the mechanisms that govern the assembly and interactions of microbial communities under the influence of FWD.

An Algerian Soil-Living Streptomyces alboflavus Strain as Source of Antifungal Compounds for the Management of the Pea Pathogen Fusarium oxysporum f. sp. pisi

Fusarium wilt caused by Fusarium oxysporum f. sp. pisi (Fop) poses significant threats to pea cultivation worldwide. Controlling this disease is mainly achieved through the integration of various disease management procedures, among which biological control has proven to be a safe and effective approach. This study aims to extract and identify antifungal secondary metabolites from Streptomyces alboflavus KRO3 strain and assess their effectiveness in inhibiting the in vitro growth of Fop. This bacterial strain exerts in vitro antagonistic activity against Fop, achieving highly significant inhibition over one week. The ethyl acetate extract, obtained from its ISP2 agar medium culture, also exhibited strong antifungal activity, maintaining an inhibition rate of approximately 90% at concentrations up to 250 µg/plug compared to the control. Thus, the organic extract has been fractionated using chromatographic techniques and its bioguided purification allowed us to isolate the main bioactive compound. This latter was identified as metacycloprodigiosin using nuclear magnetic resonance (NMR) spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and specific optical rotation data. Metacycloprodigiosin demonstrates dose-dependent inhibitory activity against the phytopathogen with an effective concentration of 125 µg/plug. The other secondary metabolites present in the ethyl acetate extract were also identified by gas chromatography–mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR). This study highlighted the potential of S. alboflavus KRO3 strain and its antimicrobial compounds for the management of the pea pathogen Fusarium oxysporum f. sp. pisi.

Genetic Variability in Fusarium Wilt Resistant BC2F1 Lines of Yard Long Bean (Vigna unguiculata subsp. sesquipedalis (L.) Verdcourt) Variety Githika for Yield and its Related Traits

Yardlong bean is a highly popular and profitable vegetable traditionally cultivated in the humid tropics of Kerala and is an inexpensive source of vegetable protein. Developing sustainable host plant resistance mechanisms, such as using the backcross method to introduce single-gene resistance into susceptible crop varieties, is crucial for reducing losses due to Fusarium wilt. In the present study Thirty-five resistant backcross progenies (BC2F1) of Yardlong Bean (Vigna unguiculata subsp. sesquipedalis (L.) Verdcourt) variety Githika were evaluated for various genetic parameters for yield and its related traits using Completely Randomized Design at Department of Genetics and Plant Breeding, College of Agriculture, Vellayani, Trivandrum. High phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) were observed for traits such as the number of pods per plant, pod weight, pod yield per plant, crude protein content. High Heritability(H) and High Genetic advance as percent mean (GAM) were observed for traits such as Number of pods per plant, Pod weight, Pod length, Number of seeds per pod, Pod Yield per plant, Crude fibre and Crude protein content. This significantly suggest that additive gene action is predominant in these traits and low reliance by environmental factors on these traits, making such character a good candidate for direct selection. The study helps in assessing genetic variability to identify traits as well as lines with maximum similarity with recurrent parent which could be used for further crop improvement program.

Molecular identification of Fusarium species in commercial vanilla and crop wild relatives in Colombia.

Vanilla is an economically important crop for low-lying humid tropical regions, but cultivated plants face serious phytosanitary problems. Fusarium wilt is a devastating disease affecting vanilla crops, caused by the fungal pathogens Fusarium oxysporum f. sp. vanillae (Fov) and F. oxysporum f. sp. radicis-vanillae (Forv), part of the F. oxysporum species complex (FOSC). We characterized 29 fungal isolates from a vanilla crop and crop wild relatives (CWR) using molecular (EF1-α and ITS-rRNA loci) and morphological traits. Fusarium was the predominant genus, followed by Colletotrichum and Clonostachys. Four Fusarium species were identified: F. oxysporum (37.9%), Fusarium solani (20.7%), Fusarium pseudocircinatum (13.8%) and Fusarium concentricum (10.3%). The latter three species were isolated only from CWR and may represent latent pathogens. Fov was isolated from both the crop and CWR, while a Forv-affiliated isolate was also found in a vanilla crop, marking the first report in the neotropical region. The EF1-α locus provided greater genotype resolution, as well as having reference sequences for Forv. However, the fungal barcode ITS locus is widely applied. We recommend the continued use of both loci for Fusarium diagnosis in vanilla to facilitate early detection and the development of effective integrated crop management strategies.

First Report of Fusarium Wilt and Pink Rot of Phoenix canariensis in South Africa

ABSTRACTCanary Island date palm, Phoenix canariensis, is a popular ornamental species commonly planted in urban areas worldwide, including South Africa. In November 2023, symptoms typical of Fusarium wilt were detected on ornamental palms at the Waterfront in Cape Town, Western Cape Province, South Africa. Samples were collected from three wilting palms with one‐sided frond death and pink sporulation on the bark. Isolations to culture media yielded two fungal species, which were confirmed based on DNA sequence data as Fusarium oxysporum f.sp. canariensis (Foc) and Nalanthamala vermoesenii. Fusarium wilt, caused by Foc, is among the most serious diseases of these palms. There is no effective treatment for this vascular wilt disease and infected palms inevitably die. Pink rot, caused by N. vermoesenii, is commonly found as a secondary infection associated with Fusarium wilt in P. canariensis. This is the first detection of the Fusarium wilt and pink rot pathogens in South Africa.

Soil fungal networks exhibit sparser interactions than bacterial networks in diseased banana plantations.

Soil microorganisms are pivotal in mitigating soil-borne diseases. The intricate mechanisms underlying the interactions among microbes and their impact on disease occurrence remain enigmatic. This study underscores that a reduction in fungal network interactions correlates with the incidence of soil-borne Fusarium wilt.

Fusarium oxysporum f. sp. apii Race 4 Threatening Celery Production in South Florida.

Fusarium wilt, caused by Fusarium oxysporum f. sp. apii (Foa), is a vascular disease affecting celery. This soilborne pathogen is classified into four distinct pathogenic races: 1, 2, 3, and 4. Notably, race 4 emerges as the most virulent, representing the latest evolutionary development of this pathogen, which was first reported in 2013 in California. In 2022, celery plants in South Florida exhibited typical Fusarium wilt symptoms, with the disease reaching a 100% incidence and causing yield losses ranging from 20 to 100%. Given the significance of celery as a vegetable crop and the severity of this outbreak, the primary objective of this study was to identify and characterize the causal agent of Fusarium wilt in South Florida. The second goal aimed to test the pathogenicity and virulence of the Fusarium isolates from Florida on celery and parsley plants. Using race-specific primers and dual-loci phylogenetic analyses, the isolates surveyed in this study were identified as Foa race 4. Pathogenicity assays in the greenhouse showed that the Foa race 4 isolate from celery induced disease not only on the two celery cultivars (Duda 30 and Duda 71) but also on two commonly cultivated parsley varieties (curly and Italian). Our study also revealed that the Foa race 4 significantly (P < 0.05) affected plant health attributes in all cultivars, including plant height, total plant weight, and root weight. Interestingly, the pathogen exhibited higher (P < 0.0001) virulence on parsley than celery based on vascular discoloration. These findings strongly indicate the urgency of comprehending and managing Fusarium wilt on celery and related crops. Furthermore, the ability of Foa race 4 to affect different plant species highlights a potential threat to agricultural production, emphasizing the need for proactive measures to mitigate the impact of this virulent pathogen.

Hot pepper wilt intensity, management practices, and pathogenic variability of Fusarium oxysporum f. sp. capsici (FOC) isolates in northwest Ethiopia

Hot pepper (Capsicum annuum L.) is essential in Ethiopian agriculture but is increasingly threatened by Fusarium wilt, caused by Fusarium oxysporum f. sp. capsici, which severely affects yields and farmer livelihoods in Northwest Ethiopia. This study assessed wilt incidence, severity, and farmer practices across four districts in West Gojjam Zone (Womberma, Burie Zuria, Jabi Tehinan, and Dembecha Zuria). Surveys from 128 farmers and tests on 67 fungal isolates revealed that Burie Zuria faced the highest disease incidence (56.6%) and severity (52.5%), while Womberma had the lowest rates. The most pathogenic isolate, 4WBG1, showed 100% incidence and high severity (82.5%) and 100% AUDPC value. Agronomic practices like seed sourcing and crop rotation influenced disease control, yet only 23.4% of farmers used chemical or cultural controls, with 11% applying Mancozeb. These findings highlight the need for improved management strategies and resistant varieties to safeguard hot pepper production.

Integrated control of Fusarium wilt in banana by Bacillus velezensis EB1 and potassium sorbate

Fusarium wilt of banana, caused by Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), is a widely distributed soilborne disease that poses a serious threat to banana production. Many control measures have been implemented but have not been effective. Here, we evaluated a combined strategy for Fusarium wilt control that involves a biological agent (Bacillus velezensis strain EB1) and a bioactive compound (potassium sorbate). Our results showed that potassium sorbate inhibited Foc TR4 in a dose-dependent manner. Potassium sorbate did not limit the growth of EB1 in vitro; instead, it promoted the growth and antagonistic ability of EB1 by upregulating the expression of antagonism-related genes. In greenhouse experiments, the combined application of EB1 and potassium sorbate significantly reduced the disease index of Fusarium wilt by suppressing fungal growth in the roots and promoting plant growth. Overall, our results demonstrated that potassium sorbate and B. velezensis EB1 can be used together for the sustainable management of banana Fusarium wilt.

Biocontrol Agents Inhibit Banana Fusarium Wilt and Alter the Rooted Soil Bacterial Community in the Field

Banana is an important fruit and food crop in tropical and subtropical regions worldwide. Banana production is seriously threatened by Fusarium wilt of banana (FWB), a disease caused by Fusarium oxysporum f. sp. cubense, and biological control is an important means of curbing this soil-borne disease. To reveal the effects of biocontrol agents on inhibiting FWB and altering the soil bacterial community under natural ecosystems, we conducted experiments at a banana plantation. The control efficiency of a compound microbial agent (CM), Paenibacillus polymyxa (PP), Trichoderma harzianum (TH), and carbendazim (CA) on this disease were compared in the field. Meanwhile, the alterations in structure and function of the rooted soil bacterial community in different treatments during the vigorous growth and fruit development stages of banana were analyzed by microbiomics method. The results confirmed that the different biocontrol agents could effectively control FWB. In particular, CM significantly reduced the incidence of the disease and showed a field control efficiency of 60.53%. In terms of bacterial community, there were no significant differences in the richness and diversity of banana rooted soil bacteria among the different treatments at either growth stage, but their relative abundances differed substantially. CM treatment significantly increased the ratios of Bacillus, Bryobacter, Pseudomonas, Jatrophihabitans, Hathewaya, and Chujaibacter in the vigorous growth stage and Jatrophihabitans, Occallatibacter, Cupriavidus, and 1921-3 in the fruit development stage. Furthermore, bacterial community function in the banana rooted soil was affected differently by the various biocontrol agents. CM application increased the relative abundance of multiple soil bacterial functions, including carbohydrate metabolism, xenobiotic biodegradation and metabolism, terpenoid and polyketide metabolism, lipid metabolism, and metabolism of other amino acids. In summary, our results suggest that the tested biocontrol agents can effectively inhibit the occurrence of banana Fusarium wilt and alter the soil bacterial community in the field. They mainly modified the relative abundance of bacterial taxa and the metabolic functions rather than the richness and diversity. These findings provide a scientific basis for the use of biocontrol agents to control banana Fusarium wilt under field conditions, which serves as a reference for the study of the soil microbiological mechanisms of other biocontrol agents.

Efficacy of L-arabinose in managing cucumber Fusarium wilt and the underlying mechanism of action.

Cucumber Fusarium wilt (CFW), triggered by Fusarium oxysporum f. sp. cucumerinum, leads to substantial yield reductions in global cucumber (Cucumis sativus L.) production. Common management strategies for CFW include soil fumigation, grafting, and crop rotation. However, these methods have limitations regarding safety and efficacy stability, necessitating the development of new, cost-effective, and eco-friendly control strategies. Our prior research demonstrated that L-arabinose, an inexpensive and safe sugar commonly used in food and beverages, effectively suppressed bacterial wilt in tomatoes. This study explores the potential of L-arabinose in managing CFW and investigates its mechanism of action. Soil applications of L-arabinose, ranging from 0.00001 to 0.01%, effectively suppressed CFW. The most significant suppressive effect was observed at 0.01%, reducing the disease severity index by 67.5% compared to the control treatment. Microscopic examination of transverse root sections showed that pathogen hyphae colonized the epidermis but seldom penetrated the cortical layer of roots in L-arabinose-treated seedlings. In contrast, the entire root tissue of control seedlings was colonized by the pathogen. Quantitative real-time PCR revealed a significant increase in the expression of defense-related genes dependent on salicylic acid, jasmonic acid, and ethylene in L-arabinose-treated plants compared to control plants, 6 and 10 days post pathogen inoculation. This study demonstrated that soil application of L-arabinose can effectively suppress CFW by priming root tissues for multiple defense signaling pathways. Therefore, L-arabinose holds potential as a new fungicide for managing CFW. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

A Detailed Proteomics and Metabolomics Landscape Sheds Light on the Mechanistic Insights Into the Resistance Response of Transgenic Pigeon Pea Against Wilt Stress.

Pigeon pea, vital for farmers in semi-arid regions, suffers yield losses from Fusarium wilt caused by Fusarium udum. This study demonstrates that introducing the rice oxalate oxidase 4 (Osoxo4) gene significantly boosts wilt resistance. Enhanced resistance in transgenic lines was confirmed through gene expression analysis, enzyme activity assays, biochemical assessments, histochemical staining and in vitro and in vivo bioassays, including spore germination tests. We performed proteomics and metabolomics analyses to investigate mechanisms of enhanced resistance. LC-MS/MS-based label-free proteomics of wilt-infected transgenic and wild-type pigeon pea leaves identified 2386 proteins, with 1048 showing significant abundance changes-738 upregulated and 310 downregulated-in transgenic plants. Notably, proteins such as HMG1/2-like protein, Putative nucleosome assembly protein C364.06, DEAD-box ATP-dependent RNA helicase 3, Lipoxygenase 1, Annexin D1 and Annexin-like protein RJ4 were significantly upregulated, indicating their potential role in developing wilt-resistant cultivars. Metabolomic analysis showed elevated levels of amino acids, sugars, oxalic acid, sugar alcohols and myo-inositol in transgenic pigeon pea, with upregulated pathways in Sugar and Starch Metabolism and Inositol Phosphate Metabolism, indicating enhanced resilience to wilt stress. This study highlights unique regulatory proteins and metabolites, offering insights into stress adaptation and guiding genetic interventions for breeding disease-resistant pigeon pea varieties.

The Glucanase Enzyme Activity from Rhizospheric Streptomyces spp. in Inhibiting Growth and Damaging the Cell Walls of the Mycelium of Fusarium oxysporum

Fusarium oxysporum, a phytopathogenic fungus responsible for fusarium wilt in more than 120 plant species, is primarily managed using synthetic fungicides, which pose environmental hazards. Therefore, alternative biological control methods are urgently needed. Actinomycetes isolated from maize rhizosphere, which produce β-1.3-glucanase enzymes that degrade fungal cell wall glucans, offer promising potential as biocontrol agents. This study aimed to evaluate glucanase activity, identify genes of actinomycetes, and assess their antifungal activity against F. oxysporum. Actinomycetes demonstrating glucanase production, Streptomyces sp. ARJ 22, Streptomyces tendae ARJ 42, Streptomyces sp. ARJ 44, and Streptomyces sp. ARJ 81, were selected. Streptomyces isolates exhibited activity values ranging from 10.38 to 24.08 U/mg of protein. The presence of the bglS gene, encoding endo-β-1.3-glucanase from glycoside hydrolase family 16, supports the production of glucanase. The amino acid sequence was constructed to 3D structural model. This model exhibited high similarity to endo-β-1.3-glucanase from Nocardiopsis sp. F96. In vitro assays demonstrated that all isolates inhibited hyphal growth of F. oxysporum. Direct inhibition assays showed an average inhibition of 26.18%, whereas the filtrate culture method showed 29.38% inhibition. Enzymes from Streptomyces sp. ARJ 44 was partially purified using acetone, resulting in a specific activity of 46.34 U/mg of protein and a purity increase of up to 1.92-fold. The purified enzyme inhibited the growth of F. oxysporum mycelia by 35.80%. This inhibition was confirmed by observing damage to F. oxysporum hyphae using scanning electron microscopy. The study concluded that the four Streptomyces sp. strains producing β-1.3-glucanase enzymes have potential as biocontrol agents against F. oxysporum.

Identification of Fusarium Wilt Disease Causal Agents in Pistachio Fields and Determination of Efficacy of Some Fungicides Controlling of The Disease

Pistachio (Pistacia vera) propagation is commonly carried out by seedlings and new orchards are mostly set by in situ grafting of rootstocks. Pathogenic and molecular characterization of wilt and desiccation agents observed in nurseries and young orchards were carried out and the causal species were identified as Fusarium oxysporum and F. solani. In vitro inhibition of mycelial development and conidia germination were carried out with seven fungicides selected against the disease. The plant protection product containing Prothioconazole + Spiroxamine was found to be 100% effective in mycelial growth trials in F. oxysporum isolates from 20 mgL-1 and in F. solani from 100 mL-1 at all increasing doses. . The fungicide containing phosphoric acid was found to be 18.3%-33.3% effective on both species at 2.5 times the recommended dose. On conidial germination, Prothioconazole + Spiroxamine and Captan provided 100% inhibition even at the lowest doses in all isolates tested. The EC50 values of Prothioconazole + Spiroxamine, which was determined as the most effective chemical in mycelial development and conidial germination, were 3.67 ml and 3.72 ml in F. oxysporum isolates and 56.83 ml in F. solani, respectively.

Inhibitory effects of wild Origanum elongatum extracts on Fusarium oxysporum mycelium growth and spores germination: Evidence from in-vitro, in-planta, and in-silico experiments

Fusarium wilt, caused by Fusarium oxysporum, is one of the most devastating diseases to crops including potatoes. This fungus is widespread and dispersed via resistant spores. In this study, organic (methanol, hexane, and chloroform) and aqueous extracts of the aerial parts of wild Origanum elongatum were tested against mycelium and spores of F. oxysporum in both in-vitro (using the poisoned food technique) and in-planta assays. Further, the chemical composition of the extract was identified via HPLC-PDA-MS/MS. Then, molecular modeling was used to clarify the antifungal activity of identified biomolecules. The obtained results showed that organic and aqueous extracts showed significant antifungal and anti-sporulation activities with different effectiveness depending on the extract, concentration, and application test. In in-vitro assays of the aqueous extract, the highest antifungal activity was recorded at concentrations of 10 mg mL−1, while the highest anti-sporulation activity (91.79 %) was observed at 50 mg mL−1. In the organic extracts, methanol was the most effective against fungus with 100 % inhibition of mycelium at 5 mg mL −1 and the highest anti-sporulation effect (73.58 %) at 20 mg mL−1. In in-planta assays, the methanolic extract at 20 mg mL−1 achieved 0 % disease severity, while the aqueous extract at 50 mg mL−1 reduced severity to 7 %, both significantly more effective than the untreated control. Therefore, methanol was the most effective and these biological properties are supported by a wide range of bioactive molecules, including 56 molecules compared to only 28 molecules in the aqueous extract. These include glycosides of apigenin and kaempferol and salvianolic acid b. However, more research is needed to clarify the inhibition action of the individual components and their synergetic actions in controlled and field conditions.

Calcium-Binding Protein and Polymorphism in Musa spp. Somaclones Resistant to Fusarium oxysporum

The fresh fruits of ‘Grande Naine’ (Cavendish AAA—Musa spp.) dominate the world market, especially in countries with a population in a situation of social vulnerability. However, Fusarium wilt, caused by the fungus Fusarium oxysporum f.sp. cubense race 4 Subtropical (Foc ST4), emerges as a serious threat to banana production, requiring the development of resistant cultivars based on biotechnological strategies, such as the induction of mutation in tissue culture. This study aimed to identify and characterize genetic variation in somaclones resistant to Fusarium oxysporum f.sp. cubense subtropical race 4 (Foc ST4), derived from ‘Grand Naine’ bananas, by molecular markers based on retrotransposons IRAP (Inter-retrotransposon Amplified Polymorphism) and REMAP (Retrotransposon-Microsatellite Amplified Polymorphism). Nine combinations of IRAP and six combinations of REMAP primers were used. The low number of polymorphic bands did not allow for genetic diversity studies; however, ten polymorphic bands between the somaclones and control were sequenced. Of these, three presented good base calling and were aligned, namely, 1AF, 2AF, and 3AF bands. Only the 1AF band presented function related to stress response with homology to a calcium-binding protein. These proteins act early in plant infection as secondary messengers activated by pathogen-associated molecular patterns (PAMPs), initiating the cascade of plant defense signals. The fact that this band is present in all somaclones reinforces previous assessments of their resistance to Foc ST4. The use of markers IRAP and REMAP produced polymorphic bands that can, through future primer design and field validations, accelerate the identification of resistant banana genotypes for use in banana genetic breeding programs.

Antifungal activity of citral against Fusarium wilt in tomatoes and induction of the upregulation of glucanase, chitinase, and thaumatin-like protein plant defense genes

Fusarium wilt of tomatoes, caused by the soil-borne fungus Fusarium oxysporum f. sp lycopersici (FOL), is one of the devastating diseases of tomatoes, causing substantial economic losses worldwide. It is primarily controlled with chemical fungicides. The present study assessed the antifungal activity of citral against FOL under greenhouse conditions and investigated its effects on three plant defense genes: glucanase, chitinase, and thaumatin-like protein (TLP) using Real-time- quantitative PCR (RT-qPCR). Greenhouse experiments demonstrated that citral oil at 1024 and 512 µg/mL significantly reduced wilt severity from 61.7 % to 28.3 and 33.3 %, respectively. RT-qPCR results revealed that citral upregulates the expression of the three defense genes to varying extents, highlighting their role in resistance induction in tomatoes against FOL. Chitinase showed the highest differential expression with a 9.54-fold increase at 12 hours post-treatment (hpt), followed by TLP with a 6.96-fold increase at 12hpt, and glucanase with a 3.68-fold increase at 24hpt. These findings suggest citral is a promising biocontrol agent against fusarium wilt in tomatoes. However, field trials are recommended to validate these results under open field conditions.