Isolates Of Fusarium Oxysporum Research Articles

Isolation, identification, pathogenicity test and molecular characterization of Fusarium oxysporum f. sp. zingiberi causing Fusarium yellows disease from infected rhizomes of ginger (Zingiber officinale Rosc.)

Isolation, identification, pathogenicity test and molecular characterization of Fusarium oxysporum f. sp. zingiberi causing Fusarium yellows disease from infected rhizomes of ginger (Zingiber officinale Rosc.)

Evaluation of Copper Nanoparticle Synthesis by Fusarium oxysporum Antibacterial Activity Against Staphylococcus aureus

The creation of effective, environmentally friendly antimicrobial alternatives is becoming more and more important in light of the development of antibiotic resistance. The objective of the present study was to illustrate the biosynthetic process of copper (II) carbonate nanoparticles, CuCo3 NPs, by using Fusarium oxysporum culture filtrate as an antibacterial activity against multidrug-resistant (MDR) clinical bacterial isolates, Staphylococcus aureus. Fusarium oxysporum isolate was diagnosed by PCR. One hundred and sixty specimens of pathogenic bacteria were collected from different sources (wounds, urine, sputum) then the bacterial isolates were diagnosed as Staphylococcus aureus by conventional morphological examination, biochemical tests, and the Vitek-2 system. Fusarium oxysporum culture filtrate was prepared by a culture of the fungus on Czapek Dox broth media modified by adding cornmeal and incubated for 14 days with shaking at 27±2°C and filtered in the last stages using a Millipore. The biosynthesis of CuCo3 NPs was done by adding 1g of CuCo3 Cu (OH)2 to 10 ml of Fusarium oxysporum culture filtrate. The NPs were diagnosed using modern methods, including UV-VIS, FT-IR, AFM, FE-SEM, and EDX techniques. Multidrug-resistant Staphylococcus aureus was tested on the produced Cu NPs. The results indicated that the prepared CuCo3 NPs inhibited pathogenic bacterial isolates of Staphylococcus aureus at concentration of 500, 250, 125, and 62.5 mg/ml.

Secreted in xylem (SIX) gene SIX9 is highly conserved in Fusarium oxysporum f. sp. vasinfectum race 4 isolates from cotton in the United States

Many Fusarium oxysporum formae speciales produce small, infection-dependent effector proteins called ‘secreted in xylem’ (SIX) proteins. These proteins are secreted into the xylem of a plant during the infection process and are thought to promote virulence. In this study, a collection of Fusarium oxysporum isolates composed primarily of different races of Fusarium oxysporum f. sp. vasinfectum (FOV), was screened for the presence of fourteen SIX effector genes (SIX1-SIX14). Our results showed that some of the most virulent FOV races, FOV4 and FOV7, share a common SIX effector – SIX9. This effector is largely absent in other races of FOV in North America making SIX9 a potential target for rapid detection of these highly virulent FOV strains and enabling race specific FOV quantification in infected host plants.

Fusarium oxysporum; its enhanced entomopathogenic activity with acidic silver nanoparticles against Rhipicephalus microplus ticks.

Fusarium oxysporum is an entomopathogenic fungus, and it has anti-biological activity against arthropods. Ticks are blood sucking arthropods which are responsible for transmitting different diseases in humans and animals. The use of chemical insecticides against ticks is not eco-friendly option and results in the development of acaricide resistance. Previously, we had cultured a local isolate of Fusarium oxysporum from soil samples which were identified through microscopy and confirmed through molecular technique. In our previous experiments, we have prepared Silver nanoparticles (AgNP) at pH 7 and they had been characterized through X-Ray Diffraction (XRD), UV-visible and zeta-potential. In our current study, the AgNP were prepared at different pH conditions and characterized through Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The protein molecules of F. oxysporum were charged with Ag ions. F. oxysporum NP were observed to enhance anti-biological activity by killing Rhipicephalus microplus and they caused 100% mortality at pH 4 and pH 5 in 24 h in anti-tick biological assay. Our study is the first report to do biological assay against Rhipicehalus ticks by using Fusarium AgNP at acidic pH. Biological control using entomopathogenic fungi can be the best alternative of the chemical method to control the tick population.

Pathogenicity of Fusarium oxysporum f. sp. lycopersici (Sacc.) Isolates in Causing Tomato Wilt Disease on Two Tomato (Solanum lycopersicum L) Varieties

Pathogenicity test of Fusarium oxysporum isolates in causing tomato  wilt disease (TWD) was carried out on two tomato varieties (UC 82B  and Rio-grande) in a screen house located at the Teaching and  Research Farm of Federal University of Agriculture, Makurdi during  2015 cropping season. The experiment was a 2 x 11 factorial laid out  in Completely Randomized Design (CRD) and replicated three times.  F. oxysporum isolates tested were coded as: FoAs1, FoAs2, FoAg,  FoNb, FoSb, FoAm, FoAk, FoOr, FoAd and FoUAM together with an  uninoculated control. All the isolates of F. oxysporum tested were  pathogenic, causing wilt on the plants from 3 weeks after inoculation  (WAI), with severity of wilt been significantly higher (P≤0.05) in  FoUAM. Isolates of F. oxysporum showed significant difference  (P≤0.05) both in incidence and severity compared with the control.  Effect of F. oxysporum isolates on some agronomic characteristics  such as plant height, number of fruits, fruit weight and number of  branches on the two varieties of tomato at 12 weeks after sowing  (WAS) was significantly different (P≤0.05) with the control  experiment. Highest severity score of 5.00 was calculated in FoUAM  while the least of 4.33 was in FoSb compare with uninoculated value  of 2.50. It is therefore, concluded that the two tomato varieties are  pathogenic to F. oxysporum isolates and illicit disease in tomato hence  reduced the yield of the crop.  

Evaluation of the Humic Acid Efficiency and the Bioagent Chaetomium globosum in Controlling Fusarium Wilt Disease in Tomato

Fusarium wilt disease presents a significant menace to tomato plants, necessitating effective preventative measures. Five isolates of Fusarium oxysporum f.sp. lycopersici from infected tomato plants from different regions in Missan province, each showing varying levels of pathogenicity. Differences in the ability of tomato seedlings to be infected by these isolates were also observed during a pot experiment, ranging from highly pathogenic to non-pathogenic. To address this issue, the efficacy of the bioagent Chaetomium globosum and humic acid in controlling the pathogenic fungus F. oxysporum f.sp. lycopersici and improving the growth indicators of tomato plants in the presence of the causative fungus. Two concentrations of humic acid (8 and 4 mL/l) were tested to determine their efficacy in reducing the growth of pathogenic fungi in vitro. We found that the growth of the pathogenic fungi decreased to 41.06% at a concentration of 8 ml/l, compared to the control, which showed no growth. Moreover, when used alone or in combination with humic acid, C. globosum significantly reduced the percentage and severity of infection. The treatment involving the interaction between the bioagent and humic acid at a concentration of 8 ml/l recorded an infection percentage of 14.4% and an infection severity of 11.87%, compared to the pathogenic fungus treatment that resulted in 53% infection and 43.80% severity, respectively. Moreover, the use of C. globosum and different concentrations of humic acid raised all growth indices in all treatments whether in the presence or absence of pathogenic funus. These improvements included increased fresh and dry weight of the shoot and root, enhanced plant height and leaf area, as well as a significant increase in the content of total phenols and total chlorophyll in the leaves. The findings of this study highlight the potential of C. globosum and humic acid as effective control measures against fusarium wilt disease in tomato plants. The results indicate their ability to suppress the pathogenic fungus and promote plant growth. These findings hold promise for the development of sustainable agricultural practices.

Aggressiveness of Fusarium oxysporum and F. verticillioides isolates on stone and scots pine under greenhouse conditions

AbstractScots pine (Pinus sylvestris) and Stone pine (Pinus pinea) are two important species used in re‐forestation that are subject to damage by damping‐off fungi in forest nurseries. Twenty‐two isolates of Fusarium oxysporum and F. verticillioides from diseased seedlings of eight different hosts were tested for aggressiveness on seeds and seedlings of both pine species, including the effects on seedling emergence and mortality. Scots pine was more susceptible to damping‐off than Stone pine, as indicated both by reduced seedling emergence and elevated seedling mortality. The impact of F. oxysporum and F. verticillioides on seeds and seedlings did not differ significantly for either pine species. Our findings support previous studies that found that these are damping‐off pathogens on the studied pines. Whereas most isolates proved to be pathogenic, some isolates of both Fusarium species showed to be non‐pathogenic.

Phytochemical analysis and antifungal activity of Azadirachta indica and Balanites aegyptiaca seed extracts against Fusarium oxysporum isolate on tomatoes

Fusarium oxysporum is the causative agent of tomato wilt and is an important disease of tomato crops worldwide. Management through chemical fungicides causes serious environmental damage and human health. This study assesses the antifungal potential of biochemical compounds of Azadirachta indica and Balanites aegyptiaca seeds extracts identified by GC-MS analytical method against F. oxysporum. Acetone, methanol and aqueous extracts of A. indica and B. aegyptiaca at 15, 30 and 60 μL/mL concentrations and synthetic fungicide (3.33 g/L) were tested in vitro in triplicate. Mycelial growth and Minimum inhibitory concentrations (MIC50, MIC90) were evaluated 8 days after inoculation (DAI). As results, 55 and 34 phytochemical compounds were identified in seed extracts of A. indica and B. aegyptiaca respectively. Methanol extract of A. indica and B. aegyptiaca at 60 μL/mL concentration showed a total inhibition (100%) of F. oxysporum mycelial growth. Low MIC50 values were obtained with aqueous extract of A. indica (8.77 μL/mL) and methanol extract of B. aegyptiaca (17.91 μL/mL). The tentative action mode showed that the methanol extract of both plants induced wall lysis of F. oxysporum. These results suggest that A. indica and B. aegyptiaca seed extracts have potent antifungal activity and could be used as an alternative to control F. oxysporum. Keywords: Neem, desert date, bioactive compounds, mycelial growth, antifungal activity, Fusarium oxysporum

Chitosan-Loaded Copper Oxide Nanoparticles: A Promising Antifungal Nanocomposite against Fusarium Wilt Disease of Tomato Plants

The extensive use of agrochemicals for crop protection is increasing their environmental risks. Due to the incredible antimicrobial potential of nanomaterials, research into their potential use in sustainable agriculture as alternatives to chemical fungicides is advancing rapidly. In this study, we evaluated the possible antifungal properties of copper oxide nanocomposite (CH@CuO NPs) coated with chitosan in order to fend off Fusarium wilt diseases in tomato plants caused by F. oxysporum f. sp. lycopersici (FOL) throughout in vitro and in vivo experiments. Here, we demonstrate some of the characteristics of a potential antifungal nanocomposite composed of copper oxide nanoparticles (CuO NPs), firmly immobilized on chitosan nanoparticle (CH) surfaces as dark spots, with an irregular shape and 54.22 nm in size, as indicated by Transmission electron microscope (TEM) analysis. Spectroscopic and microscopic investigations, as well as its antifungal efficacy, verified that the successful synthesis of the CH@CuO NPs at three different concentrations (1, 25, and 50) mg/L against three different wild isolates of the pathogenic Fusarium oxysporum that infect tomatoes was successfully proven to be effective. In vitro comparisons revealed that CH@CuO NPs showed stronger antifungal activity at only 1 mg/L (96.22 ± 1.35) than the classical chemical fungicide “Kocide 2000” at conc. 2.5 g/L (77.34 ± 0.33), for example, in the case of FOL1 isolate. In accordance with the in vivo data, tomato plants can be treated with only 1 mg/L of CH@CuO NPs for up to 75 days, by which time Fusarium wilt disease severity is reduced by 91.5% In contrast, 2.5 g/L of Kocide 2000 is required to reduce disease in tomato plants by about 90%. This research expands our understanding of agro-nanotechnology by outlining the characteristics of a unique, environmentally friendly, and economically viable nanopesticide for long-term plant protection.

Molecular variability of Fusarium oxysporum f. sp. lini isolates by RAPD analysis

Seven isolates of Fusarium oxysporum f. sp. lini collected from different linseed growing areas in India were analyzed by random amplified polymorphic DNA-polymerase chain reaction. Two isolates (FOL 1 and FOL 2) found non-pathogenic to linseed crop. Twenty random decamer primers were used for amplification. All the primers revealed scorable polymorphism among the isolates and a total of 156 bands were recorded. Amplification patterns of non-pathogenic Fusarium isolates were entirely distinct from those of pathogenic isolates. Seventeen primers generated isolate specific bands which would be highly useful in the identification and characterization of Fusarium isolates. RAPD markers showed substantial genetic diversity among the different isolates with maximum of 0.89 between FOL1 and FOL6. UPGMA cluster analysis was used to generate a dendogram showing relationship between them. Isolates were clustered in to three groups corresponding to their genetic similarity and physiological reactions. RAPD markers can be quick and reliable alternative for differentiating isolates of Fusarium oxysporum f. sp. liniin to different groups.

First report of Fusarium oxysporum f. sp. fragariae race 2 causing Fusarium wilt of strawberry (Fragaria × ananassa) in California.

In California, Fusarium wilt of strawberry is widespread and causes significant yield losses. Resistant cultivars with the FW1 gene were protected against Fusarium wilt because all strains of Fusarium oxysporum f. sp. fragariae (Fof) in California were race 1 (i.e., avirulent to FW1-resistant cultivars) (Henry et al. 2017; Pincot, et al. 2018; Henry et al. 2021). In the fall of 2022, severe wilt disease was observed in an organic, summer-planted strawberry field in Oxnard, California. Fusarium wilt symptoms were common and included wilted foliage, deformed and highly chlorotic leaflets, and crown discoloration. The field was planted with Portola, a cultivar with the FW1 gene that is resistant to Fof race 1 (Pincot et al. 2018; Henry et al. 2021). Two samples, each consisting of four plants, were collected from two different locations within the field. Crown extracts from each sample were tested for Fof, Macrophomina phaseolina, Verticillium dahliae, and Phytophthora spp. by recombinase polymerase amplification (RPA) (Steele et al. 2022). Petioles were surface sterilized in 1% sodium hypochlorite for 2 minutes and plated on Komada's medium to select for Fusarium spp. (Henry et al. 2021; Komada, 1975). The RPA results were positive for M. phaseolina in one sample and negative for all four pathogens in the other sample. Salmon-colored, fluffy mycelia grew profusely from petioles of both samples. Colony morphology and non-septate, ellipsoidal microconidia (6.0-13 μm × 2.8-4.0 μm) borne on monophialides resembled F. oxysporum. Single hyphal tip isolation of fourteen cultures (P1-P14) was done to purify single genotypes. None of these pure cultures amplified with Fof-specific qPCR (Burkhardt et al. 2019), confirming the negative result obtained with RPA. Translation elongation factor 1-alpha (EF1α) was amplified using EF1/EF2 primers (O'Donnell et al. 1998) from three isolates. Amplicons were sequenced (GenBank OQ183721) and found through BLAST search to have 100% identity with an isolate of Fusarium oxysporum f. sp. melongenae (GenBank FJ985297). There was at least one nucleotide difference when compared to all known strains of Fof race 1 (Henry et al. 2021). Five isolates (P2, P3, P6, P12, and P13) and an Fof race 1 control isolate (GL1315) were tested for pathogenicity on Fronteras (FW1) and Monterey (fw1; susceptible to race 1). Five plants per isolate × cultivar combination were inoculated by dipping roots in 5 × 106 conidia per mL of 0.1% water agar, or in sterile 0.1% water agar for the negative control, and grown as described by Jenner and Henry (2022). After six weeks, all non-inoculated control plants remained healthy while plants of both cultivars inoculated with the five isolates were severely wilted. Petiole assays yielded colonies identical in appearance to the inoculated isolates. For Fof race 1-inoculated plants, wilt symptoms were observed in Monterey but not in Fronteras. This experiment was repeated with P2, P3, P12, and P13 on another FW1 cultivar, San Andreas, and the same results were observed. To our knowledge, this is the first report of F. oxysporum f. sp. fragariae race 2 in California. Losses to Fusarium wilt are likely to increase until genetic resistance to this strain of Fof race 2 is deployed in commercially viable cultivars.

Entomopathogenic fungi associated with cultivated honeybush, Cyclopia spp., in South Africa and their pathogenicity towards a leafhopper pest, Molopopterus sp. (Hemiptera: Cicadellidae)

The southern and eastern parts of the African Fynbos region favour the production of honeybush tea. Honeybush biomass and extracts are used to prepare a beverage both locally and internationally, mainly as herbal tea with health benefits. Honeybush tea is mostly grown organically requiring natural control measures for pests and diseases. The leafhopper, Molopopterus sp., is one of the most important pests of cultivated honeybush in South Africa, as its feeding compromises the quality and quantity of the yield through leaf discolouration and reduction of the photosynthetic area. Local entomopathogenic fungi (EPF) can provide a pool of potential biocontrol agents for this pest. Therefore, a total of 98 soil samples were collected from organically grown honeybush fields and vegetation surrounding the honeybush fields in the Western Cape province of South Africa. Entomopathogenic fungi were isolated using the insect bait method and were characterised using molecular techniques. Twenty fungal isolates of Metarhizium anisopliae and Fusarium oxysporum were recovered from soil samples, of which 70% were from honeybush fields and 30% were from surrounding vegetation. Fusarium oxysporum isolates comprised 20% of the recovered isolates; M. anisopliae the remainder. Laboratory bioassays of the recovered isolates against adults and nymphs of the leafhopper, showed that F. oxysporum isolates caused 10–45% mortality and M. anisopliae isolates 30–80% mortality. Metarhizium anisopliae isolates J S1, KF S3, KF S11, KF S13, LS1 and LS2 were the most virulent and induced over 60% mortality in both nymphs and adults at a concentration of 1 × 107 conidia/ml. 

Novel sources of resistance to fusarium wilt in Luffa species.

Fusarium wilt is a serious disease of cucurbit crops including cultivated Luffa species (Luffa aegyptiaca, Luffa acutangula) causing considerable amount of reduction in yield and quality. Luffa is starting to be used as rootstocks for major commercial cucurbit crops, but little is known of its resistance against soilborne diseases. Here, 63 Luffa accessions from the World Vegetable Center genebank were evaluated for resistance to an aggressive isolate of Fusarium oxysporum f. FoCu-1 (Fsp-66). According to visual screening based on disease severity rating, 14 accessions exhibited a high level of resistance against Fsp-66. These accessions were further evaluated for resistance against Fsp-66 and two more isolates FoCu-1 (isolated from infected cucumber plants) and FoM-6 (isolated from infected bitter gourd plants). Of the 14 accessions, 11 were confirmed resistant against isolate Fsp-66. In addition, 13 accessions showed high resistance against isolates FoCu-1 and FoM-6. This is the first report of Fusarium wilt resistance in Luffa and these sources will be valuable for the development of Luffa rootstocks/cultivars resistant to soil-borne pathogen to manage this serious disease.

Phenotypic and Pathogenic Variability in Fusarium Wilt Pathogen Isolated from Bundelkhand Region.

Fusarium wilt is one of the most severe disease of chickpea crop caused by Fusarium Oxysporum f. sp ciceri (FOC). Which is a soil born pathogen and can stay for prolonged period in soil even in absence of favourable conditions. Moreover many research reports have been observed showing a great variation in Fusarium pathogenicity among pathogen isolates from chickpea rhizosphere. Because of which identification of pathogenic and non-pathogenic strains of wilt pathogen has been a big challenge so far and, has been difficult in development and selection of resistant variety for fusarium wilt management strategies. The possible solution is to study phenotypic and pathogenic variability in the Fusarium pathogen. Therefore, in the current research FOC isolates, isolated from two districts of Bundelkhand region and studied their phenotypic and pathogenic variability. Colony characteristics of Fusarium wilt pathogen such as shape, margin, texture etc. were observed for FOC identification. To study the phenotypic and pathogenic variability, FOC isolates were categorised based on the culture pigmentation and further tested their pathogenicity. Pigmentation of FOC isolates have a wide range includes cottony white, white with ting of orange and white with violet and pale-yellow pigmentation. Macro and microconidia with resting spores (Chlamydospores) were also observed. Pathogenic variability of FOC isolates was measured by pathogenicity test on JG-62 cultivar. Total seventeen FOC isolates were studied, Out of which five FOC isolates were found highly pathogenic, whereas only one isolate was found weakly pathogenic, rest FOC isolates were moderately pathogenic. Hence our results confirmed that all the isolates of Fusarium Oxysporum f. sp. ciceri have reported great variation in their both phenotypic as well as pathogenic variability, and the results are steppingstone for further building research in breeding and management strategies of fusarium wilt.

Induced Expression of CYP51a and HK1 Genes Associated with Penconazole and Fludioxonil Resistance in the Potato Pathogen Fusarium oxysporum.

Preventing antifungal resistance development and identifying pathogens with high, medium, and low risk of resistance development to a particular fungicide or fungicide class is crucial in the fight against phytopathogens. We characterized the sensitivity of potato wilt-associated Fusarium oxysporum isolates to fludioxonil and penconazole and assessed the effect of these fungicides on the expression of fungal sterol-14-α-demethylase (CYP51a) and histidine kinase (HK1) genes. Penconazole stunted the growth of F. oxysporum strains at all concentrations used. While all isolates were susceptible to this fungicide, concentrations of up to 1.0 μg/mL were insufficient to cause a 50% inhibition. At low concentrations (0.63 and 1.25 μg/mL), fludioxonil stimulated growth in F. oxysporum. With an increase in the concentration of fludioxonil, only one strain (F. oxysporum S95) exhibited moderate sensitivity to the fungicide. Interaction of F. oxysporum with penconazole and fludioxonil leads to respective elevated expressions of the CYP51a and HK1 genes, which upsurge with increasing concentration of the fungicides. The data obtained indicate that fludioxonil may no longer be suitable for potato protection and its continuous use could only lead to an increased resistance with time.

Identification of Fusarium oxysporum f. sp. lactucae Race 1 as the Causal Agent of Lettuce Fusarium Wilt in Greece, Commercial Cultivars' Susceptibility, and Temporal Expression of Defense-Related Genes.

Fusarium wilt of lettuce is found throughout the world, causing significant yield losses. Lettuce is the most-cultivated leafy vegetable in Greece, affected by a large number of foliar and soil-borne pathogens. In this study, 84 isolates of Fusarium oxysporum, obtained from soil-grown lettuce plants exhibiting wilt symptoms, were characterized as belonging to race 1 of F. oxysporum f. sp. lactucae based on sequence analysis of the translation elongation factor 1-alpha (TEF1-α) gene and the rDNA intergenic spacer (rDNA-IGS) region. The isolates were also assigned to one single race through PCR assays with specific primers targeting race 1 and race 4 of the pathogen. In addition, four representative isolates were confirmed to be associated with race 1 based on the pathogenicity tests with a set of differential lettuce cultivars. Artificial inoculations on the most commonly cultivated lettuce cultivars in Greece revealed that the tested cultivars varied regarding their susceptibility to F. oxysporum f. sp. lactucae race 1. Cultivars (cvs.) "Cencibel" and "Lugano" were found to be highly susceptible, while cvs. "Sandalina" and "Starfighter" were the most resistant ones. Expression analysis of 10 defense-related genes (PRB1, HPL1, LTC1, SOD, ERF1, PAL1, LOX, MPK, BG, and GST) was carried out on artificially inoculated lettuce plants of the four above cultivars at different time points after inoculation. In resistant cultivars, a higher induction rate was observed for all the tested genes in comparison with the susceptible ones. Moreover, in resistant cultivars, all genes except LTC1, MPK, and GST showed their highest induction levels in their earliest stages of infection. The results of this study are expected to contribute to the implementation of an integrated management program to control Fusarium wilt of lettuce, based mainly on the use of resistant cultivars.

Toprak örneklerinden bakteri izolatlarının izolasyonu ve nohut solgunluğu hastalığına neden olan Fusarium oxysporum f. sp. ciceris’e karşı in vitro antagonistik potansiyellerinin belirlenmesi

In 2021, post-harvest soil samples were taken from fields where chickpea and wheat were grown in Yozgat province to isolate bacteria. Of 74 isolates obtained from soil samples, 14 nonpathogenic isolates were evaluated for their inhibitory potential against two pathogenic isolates (YBUFoc9 and YBUFoc2) of Fusarium wilt disease agent Fusarium oxysporum f. sp. ciceris. Antagonistic bacterial isolates were identified as Bacillus spp. by Blastn analysis based on their 16S rDNA nucleotide sequences. Among them, 2 isolates were identified as B. amyloliquefaciens (BM23 and BM40), 3 isolates as B. subtilis (BM8, BM32, and BM105), 6 isolates as B. cereus (BM10, BM69, BM70, BM104, BM111 and BM215), 2 isolates as B. megaterium (BM44 and BM135) and 1 isolate as B. pumilus (BM28). No effective isolate of any genus other than Bacillus spp. was found. They inhibited mycelial growth of isolates YBUFoc9 and YBUFoc2 from 0 to 78.50% and from 0 to 58.33%, respectively. Among the 5 different species, B. amyloliquefaciens (BM23 and BM40) and B. subtilis (BM8, BM32, and BM105) showed the strongest inhibitory activity against the two fungal isolates under in vitro conditions. In further studies, the biocontrol properties of the most effective isolates (BM23, BM40, BM8, BM32 and BM105) will be investigated and compared with approved fungicides for their fungicidal activity.

Pathogenicity of Fusarium oxysporum and Fusarium proliferatum isolates from symptomless onions (Allium cepa) and onions with Fusarium basal rot

AbstractSeveral Fusarium species cause disease in onion (Allium cepa), resulting in significant yield losses. In this study, isolates of Fusarium oxysporum and Fusarium proliferatum from diseased and symptomless mature onion bulbs were tested for pathogenicity on onion seedlings and mature bulbs. For F. oxysporum isolates, the outcome of the test on mature bulbs correlated well with the symptom status of the original bulb, whereas for F. proliferatum, such a correlation was not seen, suggesting a different mechanism of symptom development. Those F. oxysporum isolates that carried the Secreted In Xylem (SIX) genes, CRX genes and C5 gene were significantly more aggressive on both seedlings and mature bulbs. However, the SIX‐negative F. oxysporum isolates also significantly reduced the emergence of onion seedlings, and thus a division into pathogenic and nonpathogenic F. oxysporum isolates was not obvious. On mature bulbs, those SIX‐negative isolates that carried the gene CRX2 were significantly more virulent than those without CRX2. The F. proliferatum isolates were all pathogenic to onion and carried one SIX2 gene homologue, SIX2‐1. The majority of F. proliferatum isolates also carried another homologue, SIX2‐2. Several isolates negative for SIX2‐2 had another potential virulence gene, CRX2, suggesting that these two genes could encode overlapping functions. The SIX2‐2 sequence was identical in all those isolates harbouring it, while SIX2‐1 showed variation that agreed with the phylogeny based on the translation elongation factor 1‐α sequence. This suggests that the two SIX2 genes of F. proliferatum might have been acquired separately.

Fusaric Acid Production by Different Isolates of Fusarium oxysporum f. sp. ciceris and Effect of Selected Culture Filtrate Containing Fusaric Acid on Dynamics of Plant Pigments in Chickpea

Background: Biochemical variation with respect to fusaric acid (FA) production by various isolates of Fusarium oxysporum f. sp. ciceris (Foc) was not known and the effect of FA on the pigment dynamics of chickpea was not studied earlier. Methods: The quantity of FA production by 14 isolates of Foc was estimated through HPLC. Further, the effect of culture filtrate (CF) containing FA of ITCC 7682 and ITCC 7681 on the dynamics of plant pigments was studied on resistant cv. WR315 and susceptible cv. JG 62 under Phytotron growing conditions during 2019-2021. Result: Isolate ITCC 7681 was recorded to produce the lowest quantity of FA (126.88±5.56 mg L-1); whereas isolate ITCC 7682 produced the highest quantity of FA (820.51±13.37 mgL-1). Isolates ITCC 7682 and ITCC 7680 were recorded to be highly virulent initiating wilt symptoms within 19-24 hours of inoculation in chickpea seedlings of susceptible cv. JG 62. Culture filtrates of ITCC 7682 and ITCC 7681 caused a reduction of chlorophyll a (15.13-72.38% and 9.24-72.38%), chlorophyll b (16.28-89.83% and 13.95-97.74%), total chlorophyll (48.68-73.17% and 38.87-70.33%) and carotenoid (58.33-88.23% and 48.14-82.56%) contents 3 and 6 days after inoculation respectively. Reduction of all these pigments was significantly higher in susceptible cv. JG 62 than resistant cv. WR 315.

IDENTIFICATION OF VIRAL INFECTION AND STUDY OF THE POTATO BREEDING MATERIAL RESISTENCE TO FUSARIUM DRY ROT

Potato suffers from severe viral and fungal pathogens infection in the process of production. Identification of pathogen resistance germplasm is of great significance in the breeding program.This study presents the results of tubers of foreign potato breeding lines for virus transmissionand subsequent artificial infection with the causative agent of dry fusarium rot. Potato viruses X-, Y-, S-, and M were identified in the studied samples by the ELISA method (DAS–ELISA). The third tuberous generation of PRC lines grown in the conditions of the Tselinograd district of the Akmola region was affected by individual viruses: PVM and PVX and their complexes, including PVM, PVY, PVX and PVS. It was established that potato breeding material was mainly infected with PVM (48.6%) and PVY (21.6%). Using microscopic analysis and the classical PCR method, 3 local isolates of the phytopathogenic fungus Fusarium oxysporum were identified in tuber samples of potatoes with Fusarium symptoms. On virus-free tuber material of 18 potato breeding lines, resistance to the Kazakh isolate of dry Fusarium rot "Nevsky" was studied in laboratory conditions. The average degree of resistance to F. oxisporum micromycetes was established in the potato breeding line: Z 861-1 and relatively high in the lines: Z 440-3. These lines can be considered as a high-quality source material in the breeding process when creating new competitive potato varieties.