Fusarium Verticilliodes Research Articles

Effect of ethylene production by four pathogenic fungi on the postharvest diseases of green pepper (Capsicum annuum L.)

Ethylene produced by plants generally induces ripening and promotes decay, whereas the effect of ethylene produced by pathogens on plant diseases remains unclear. In this study, four ethylene-producing fungi including Alternaria alternata (A. alternata, Aa), Fusarium verticilliodes (F. verticillioides, Fv), Fusarium fujikuroi 1 (F. fujikuroi 1, Ff-1) and Fusarium fujikuroi 2 (F. fujikuroi 2, Ff-2) were severally inoculated in potato dextrose broth (PDB) media and postharvest green peppers, the ethylene production rates, disease indexes and chlorophyll fluorescence parameters were determined. The results showed that Ff-2 and Fv in the PDB media had the highest and almost the same ethylene production rates. After inoculation with green peppers, Ff-2 treated group still exhibited the highest ethylene production rate, whereas Aa treated group had a weak promotion effect on ethylene production. Moreover, the ethylene production rate of green peppers with mechanical injury was twice that without mechanical injury, and the ethylene production rates of green peppers treated with Aa, Ff-1, Ff-2 and Fv were 1.2, 2.6, 3.8 and 2.8 folds than those of green peppers without treatment, respectively. These results indicated that pathogen infection stimulated the synthesis of ethylene in green peppers. Correlation analysis indicated that the degreening of Fusarium-infected green pepper was significantly positively correlated with the ethylene production rate of green pepper, whereas the disease spot of Aa-infected green pepper had a significant positive correlations with the ethylene production rate of green peppers. Chlorophyll fluorescence results showed that the green peppers already suffered from severe disease after being infected with fungi for 4 days, and Fusarium infection caused early and serious stress, while the harm caused by A. alternata was relatively mild at the early stage. Our results clearly showed that α-keto-γ-methylthiobutyric acid (KMBA)-mediated ethylene synthesis was the major ethylene synthesis pathway in the four postharvest pathogenic fungi. All the results obtained suggested that ethylene might be the main infection factor of Fusarium spp. in green peppers. For pathogenic fungi, stimulating green peppers to produce high level of ethylene played a key role in the degreening of green peppers.

BIO-AEROSOLS AND THEIR VIRULENCE FACTORS IN EDONWHII BEACH ATMOSPHERE, EASTERN OBOLO LGA, NIGERIA

Standard microbiological techniques were used to evaluate bio-aerosols and associated virulence factors in the Edonwhii Beach Atmosphere in Eastern Obolo LGA, Nigeria. The microbial components of the beach atmosphere were evaluated using Settle Plate and Metagenomics methods. All the culturable bacteria but Escherischia coli, elaborated virulence factor(s), indicating potential to cause disease. At the molecular level, pathogenic genes fliC and hlyA that code for flagellin C and hemolysin A virulence factors were detected. Also detected were strains of Fusarium verticilliodes, Candida krusei, Candida albicans, Trichophytosporon sp and Cladosporium sp and are capable of causing keratitis or other dermal infections in human. High concentrations of microbial pollutants in Edonwhii beach atmosphere are a clear evidence of air pollution which can adversely impact on human health. As a result, continual monitoring of air quality, as well as devising and developing instruments to identify contaminants, is advised. Open defecation near the beach should be avoided, and overall environmental cleanliness should be maintained.

First report of Fusarium verticillioides causing Pokkah boeng disease on maize in India.

Maize is a widely grown cereal crop in India and ranks third to wheat and rice in production (https://iimr.icar.gov.in). During a field survey in Kharif season in 2018, foliar chlorosis at the base and middle of leaves, and twisted top symptoms were observed in 40-50 days old maize plants in Belagavi district, Karnataka, India. Again during Kharif season in 2021, similar symptoms were observed on commercial maize hybrids and sugarcane at Agricultural Research Station, Sankeshwar Karnataka. The symptoms resembled Pokkah boeng disease of sugarcane (Vishwakarma et al. 2013). Symptomatic sugarcane and maize leaves were sampled, surface sterilized with 1.0% sodium hypochlorite, and 70% ethanol, and transferred on Potato dextrose agar, incubated for 10 days at 27±1°C. Fungal growth initiated with white mycelium later turned to pinkish-white with hyaline spores. The morphological features and sporulation patterns of maize and sugarcane samples were similar (e-Xtra 1). Microconidia were formed in long chains and clusters with oval to club-shaped, 0-septate, monophialide-borne microspores. DNA from representative pure culture isolates was extracted using the CTAB protocol (Doyle and Doyle, 1990). The ITS region of r-DNA was amplified with ITS1/ITS4 primers and sequenced. BLAST analyses of sequences of maize and sugarcane culture isolates at NCBI database revealed 100% homology with Fusarium verticillioides MK264336 (Lin et al., 2016). PCR amplification with Fusarium verticilliodes specific primers VER1/VER2 (Mule et al., 2004) confirmed the organism. CBS-KNAW Fungal Biodiversity Centre's Fusarium MLST database also revealed over 98.89% homology with Fusarium verticilliodes (NRRL 46612). The fungal isolates were named Fusarium verticilliodes maize isolate SNK 01 (ON110289) and Fusarium verticilliodes sugarcane isolate SNK 01 (ON564879), and their sequences were deposited in the GenBank. To test pathogenicity, artificial inoculation using maize isolate SNK 01 and cross-inoculation of sugarcane isolate SNK 01 were done on ten maize plants by spraying a conidial suspension (2×106 conidia ml-1) on nonwounded leaves. The plants sprayed with sterile water were used as control. After ten days, typical Pokkah boeng symptoms were observed in the plants inoculated with both maize and sugarcane isolates. Diseased leaves turned pale yellowish-green with small brown spots and a chlorotic appearance, further, these developed into stripes (e-Xtra 2). Wrinkling of leaves was noticed followed by splitting and rotting. No symptoms were noticed in the water-treated control. The pathogens re-isolated from diseased plants inoculated with maize and sugarcane isolates were similar morphologically and identical to the original isolates, fulfilling Koch's postulates. Hitherto, Fusarium verticilliodes was known to cause post-flowering stalk rot in maize. However, this is the first report of Pokkah boeng disease on maize in India caused by F. verticillioides. Considering the economic value of the maize crop, this identification can help develop appropriate disease management strategies to control the disease. References Lee, S. B., et al. 1988. A rapid, high yield mini-prep method for isolation of total genomic DNA from fungi. Fungal Genet. Newsl. 35:23-24. Lin, Z., et al. 2016. Deciphering transcriptomic response of Fusarium verticillioides in relation to nitrogen availability and the development of sugarcane Pokkah boeng disease. Sci. Rep. 6, 29692. Mule, G., et al. 2004. A Species-Specific PCR assay based on the Calmodulin partial gene for identification of Fusarium verticillioides, F. proliferatum and F. subglutinans. European J. Plant Path. 110:495-502 Vishwakarma, S.K., et al. 2013. Pokkah Boeng: an emerging disease of sugarcane. J. Plant Pathol. Microb. 4(3):170. https://iimr.icar.gov.in. Director's desk, ICAR-Indian Institute of Maize Research. (Accessed September 8, 2022).

Nanomaterized zinc sulfide-meerschaum biomatrix efficiently suppressed Fusarium verticilloides with augmented rice seed quality benefits during storage.

The seed-borne mycopathogen Fusarium verticilliodes is a serious and deleterious pathogen causing substantial losses of rice seeds and grains. Rice seeds are prone to infestation at all points of the production chain and the fungal pathogen continues dormant devastation even during storage, adversely affecting the seed parameters. Its control is compromised due to the nonavailability of recommended fungicides during storage. Nanotechnological interventions can provide effective and ecofriendly alternative against mycopathogens during resting periods. Herein, the zinc sulfide-meerschaum nano bio-matrix (nZnS-MR) is presented to show this strategy, which worked well against F. verticilliodes when applied on freshly harvested rice seeds during 6 months of storage. The healthy, smooth and rounded girths of F. verticilloides mycelium were reduced with loss of turgidity, disrupting the hyphal exterior architecture, during in vitro treatment with nZnS-MR, endorsed by staining methodology, crystal violet and intracellular soluble protein leakage assays. In vivo application on rice seeds optimized 750 μg g-1 of nano zinc sulfide (nZnS) for 6 months of application during storage with maximum reduction of disease parameters [seedling blight (1.19%) and seed rot (5.43%)] and most augmented quality parameters [maximum germination (94.14%), seedling length (22.50 cm), dry weight (0.121 g) and vigor index (11.37)]. nZnS-MR acted as a slow release nanoformulation of nZnS for long-term antifungal activity. nZnS-MR is presented as an ecofriendly, biocompatible, bio-efficient, profertilization, cost-effective green material for the control of F. verticilliodes with rice seed invigorating effect, describing it as new a nano-generation material for efficient storage application.

Determination of the Antifungal Effect of Bacterial Metabolites of Xenorhabdus szentirmaii Against Some Phytopathogenic Fungi

This study was carried out to determine the antifungal effects of the supernatant produced by the bacterium Xenorhabdus szentirmaii, which is associated with soil-inhabiting entomopathogenic nematodes, on important plant pathogenic fungi, Fusarium verticilliodes, Fusarium oxysporum f.sp lycopersici, Fusarium oxysporum f.sp radicis lycopersici, Botrytis cinerea, Sclerotinia sclerotiorum and Phytophthora nicotianae. The effects of 1, 3, 5 and 7% concentrations of the supernatant produced by X. szentirmaii bacteria on mycelium growth of the fungal pathogens was determined at 3, 7 and 14 days after application (dap). The effects of the supernatant on the formation of sporangia and the emergence of zoospores from the sporangium of Phytophthora nicotianae was also determined. According to the results of the study, the highest dose of the supernatant (7% concentration) prevented mycelium development of all tested pathogens. The effect of the supernatant decreased at 14 dap against F. verticilliodes, F. oxysporum f.sp lycopersici, F. oxysporum f.sp radicis lycopersici. The antifungal effect on S. sclerotiorum completely disappeared in 14 days whereas the effect continued even in 14 days against B. cinerea and P. nicotianae. Xenorhabdus szentirmaii supernatant at a concentration of 7% was highly efficacious on the formation of sporangia and the emergence of zoospores within the sporangium of P. nicotianae at a concentration of 7%.

Detection of Fusarium verticillioides in maize sold at some markets in Ibadan Metropolis, Nigeria

Fusarium is a prominent fungal genus connected with maize in Africa. In this genus, there are two most common species (F. verticillioides and F. proliferatum) that have many toxigenic features and produce fumonisins. Fumonisins are a collection of economically significant mycotoxins that are widely found in maize-based foods and feeds across the globe. This preliminary study was conducted to detect the occurrence of Fusarium verticilliodes in infected maize collected from four main markets in the Ibadan metropolis. A total of ninety-five (95) maize samples were collected from three major commercial markets in Ibadan. Maize seeds were prepared following standard sterilization procedure after which, ten (10) seeds each were then plated on PDA media in triplicates and incubated at 25 oC for six days. Identification of isolates was performed using conventional cultural and morphological characteristics. Results show that the maize samples obtained from Apata market had the highest occurrence of Fusarium verticilliodes with 28.2% while the least occurrence of 22.3% was found in maize samples obtained from Bodija market. Other species of fungi, Aspergillus flavus, Aspergillus niger, and Botryodiplodia Theobroma, were also detected with a negligible count. The study also revealed that there was a significant difference at p = 0.002 in the occurrence of Fusarium verticilliodes between the yellow and white maize seeds studied. These findings call for great concern as it detected that maize and maize-based feed consumed could be infected with Fusarium and fumonisin toxin.

Impact of silver nanoparticles size on SERS for detection and identification of filamentous fungi

Using the proper size of nanoparticles as an active substrate, Surface-enhanced Raman scattering (SERS) can provide a reliable technique for detecting and identifying fungi, including Alternaria alternata, Aspergillus flavus, Fusarium verticilliodes, and Aspergillus parasiticus that have been associated to biodeterioration and biodegradation of cultural heritage materials. In this research spherical silver nanoparticles (AgNPs) of average size of 10, 30 and 60 nm were synthesized using the wet chemical method with good yield and their size and shape distributions were examined using small-angle X-ray scattering (SAXS). The protocol for fungi sample preparation proved to be critical for producing high-quality and reproducible SERS spectra. We found that the effect of AgNPs on SERS signal enhancement is size dependent under the same experimental conditions; the SERS intensity of fungal strains using 60 nm achieved up to 2.3x105 enhancement, about twice as intense as those produced with 30 nm, and 10 nm produced a minor broad weak peak barely discernible around 1400 cm−1, similar to the NR spectra profile in the 550–1700 cm−1 spectral region, and the SERS signals using 60 nm showed high reproducibility, with less than 20% variance. Furthermore, we used principal component analysis (PCA) to statistically classify the SERS spectrum into four separate clusters with 99 percent variability so that the four fungal strains could be clearly detected and identified. The SERS technique, in combination with the PCA developed in this study, provides a simple, rapid, accurate, and cost-effective analytical tool for detecting and identifying filamentous fungal strains.

Ananas comosus peel–mediated green synthesized magnetite nanoparticles and their antifungal activity against four filamentous fungal strains

Despite the potent antimicrobial activity of magnetite nanoparticles (MtNPs), research on the antifungal activity of MtNP against filamentous fungi is rare. In this study, MtNP was synthesized by an inexpensive and easy green approach using the aqueous extract of Ananas comosus (pineapple) peels (AP), and applied as an antifungal agent against the filamentous fungal pathogens Fusarium verticilliodes, Aspergillus flavus, and Alternaria alternata (CGJM3078 and CGJM3006). The AP-mediated MtNP (AP-MtNP) was characterized by the XRD, UV-Visible, FTIR, BET, TGA, SEM, TEM, and EDX techniques. These characterizations revealed the successful synthesis of AP-MtNP by the reducing and stabilizing action of the aqueous extract of AP. The BET analysis showed a high surface area of 233.8 m2/g, while high thermal stability of AP-MtNP was displayed by the TGA. The SEM and TEM images mostly showed spherical AP-MtNPs with an average size of 17.87 nm and a somewhat dispersed and porous surface morphology. The newly synthesized AP-MtNPs exhibited effective antifungal activity against the four fungal strains.

One-pot synthesis of zinc oxide nanoparticles via chemical precipitation for bromophenol blue adsorption and the antifungal activity against filamentous fungi

In this research, zinc oxide nanoparticles (ZnONPs) were prepared via a facile one-pot chemical precipitation approach and applied in the adsorption of bromophenol blue (BRB) and as antifungal agents against the filamentous fungi and plant pathogens; Alternaria alternata CGJM3078, Alternaria alternata CGJM3006 and Fusarium verticilliodes CGJM3823. The ZnONPs were characterized by the UV–Vis, FTIR, XRD, TGA, BET, SEM, TEM, and EDX techniques, which showed efficient synthesis. The characteristics ZnO UV–Vis absorption band was observed at 375 nm, while the XRD showed an average ZnONPs crystalline size of 47.2 nm. The SEM and TEM images showed an irregular shaped and aggregated porous structure of 65.3 nm average-sized ZnONPs. The TGA showed 22.9% weight loss at 800 °C indicating the high thermal stability of ZnONPs, while BET analysis revealed a surface area, pore volume and pore diameter of 9.259 m2/g, 0.03745 cm3/g and 9.87 nm respectively. The Freundlich, pseudo-second-order, and intra-particle diffusion models showed R2 > 0.9494 and SSE < 0.7412, thus, exhibited the best fit to the isotherm and kinetics models. Thermodynamics revealed feasible, endothermic, random, and spontaneous adsorption of BRB onto the synthesized ZnONPs. The antifungal assay conducted depicts strong antifungal activities against all three tested fungi. Noticeably, ZnONPs (0.002–5 mg/mL) showed maximum activities with the largest zone of inhibition against A. alternata CGJM 3006 from 25.09 to 36.28 mm. This was followed by the strain F. verticilliodes CGJM 3823 (range from 23.77 to 34.77 mm) > A. alternata CGJM3078 (range from 22.73 to 30.63 mm) in comparison to Bleach 5% (positive control). Additionally a model was proposed based on the possible underlying mechanisms for the antifungal effect. This research demonstrated the potent use of ZnONPs for the adsorption of BRB and as effective antifungal agents.

Optical and surface properties of Zn doped CdO nanorods and antimicrobial applications

The present work describes the synthesis of pure and Zn doped CdO (CdO:Zn) nanorods synthesized by a simple low-cost combustion technique. The optical, structural, morphological, and surface properties, as well as antimicrobial activities of the CdO:Zn nanoparticles were studied with respect to pure CdO. UV–Vis spectrometry and photoluminescence were used to study the optical properties of the pure and CdO:Zn samples. X-ray diffraction confirmed the presence of a cubic phase of the CdO as well as a minor CdO2 phase with no additional phase after doping with Zn. Field emission scanning electron microscope and Transmission electron microscope results confirmed a nanorod shaped morphology with spherical shaped nanoparticle distributed along the surface of the CdO nanorods for the pure and CdO:Zn. X-ray photoelectron spectroscopy was used to study the chemical state of the CdO:Zn. CdO:Zn samples exhibited significant antibacterial activities against Escherichia coli, Staphylococcus aureus and an excellent antifungal activities against Aspergillus flavus; Fusarium verticilliodes with a change in antimicrobial behavior as compared to the pure CdO structures. The results revealed that the CdO nanorods based morphology can be used in the biomedical and pharmaceutical sectors as a good antibacterial agent.

Production, characterization, and antifungal activity of a biosurfactant produced by Rhodotorula babjevae YS3

BackgroundSophorolipids are one of the most promising glycolipid biosurfactants and have been successfully employed in bioremediation and various other industrial sectors. They have also been described to exhibit antimicrobial activity against different bacterial species. Nevertheless, previous literature pertaining to the antifungal activity of sophorolipids are limited indicating the need for further research to explore novel strains with wide antimicrobial activity. A novel yeast strain, Rhodotorula babjevae YS3, was recently isolated from an agricultural field in Assam, Northeast India. This study was primarily emphasized at the characterization and subsequent evaluation of antifungal activity of the sophorolipid biosurfactant produced by R. babjevae YS3.ResultsThe growth kinetics and biosurfactant production by R. babjevae YS3 was evaluated by cultivation in Bushnell-Haas medium containing glucose (10% w/v) as the sole carbon source. A reduction in the surface tension of the culture medium from 70 to 32.6 mN/m was observed after 24 h. The yield of crude biosurfactant was recorded to be 19.0 g/l which might further increase after optimization of the growth parameters. The biosurfactant was characterized to be a heterogeneous sophorolipid (SL) with both lactonic and acidic forms after TLC, FTIR and LC–MS analyses. The SL exhibited excellent oil spreading and emulsifying activity against crude oil at 38.46 mm2 and 100% respectively. The CMC was observed to be 130 mg/l. The stability of the SL was evaluated over a wide range of pH (2–10), salinity (2–10% NaCl) and temperature (at 120 °C for time intervals of 30 up to 120 min). The SL was found to retain surface-active properties under the extreme conditions. Additionally, the SL exhibited promising antifungal activity against a considerably broad group of pathogenic fungi viz. Colletotrichum gloeosporioides, Fusarium verticilliodes, Fusarium oxysporum f. sp. pisi, Corynespora cassiicola, and Trichophyton rubrum.ConclusionsThe study reports, for the first time, the biosurfactant producing ability of R. babjevae, a relatively lesser studied yeast. The persistent surface active properties of the sophorolipid in extreme conditions advocates its applicability in diverse environmental and industrial sectors. Further, antifungal activities against plant and human pathogens opens up possibilities for development of efficient and eco-friendly antifungal agents with agricultural and biomedical applications.

In-vitro Evaluation of Some Fungicides against Botrydiplodia theobromae: Causal Pathogen of Pineapple Dieback

Aims: Dieback is an economically important disease known to cause major losses in food and tree crops. The causal pathogen of pineapple dieback was investigated and the efficacies of some fungicides were evaluated in-vitro. Study Design: Pineapple suckers were planted with a spacing of 0.5 m x 0.5 m and separated by 1.0 m. Leaf and soil samples were randomly collected from diseased pineapple plants and the rhizosphere of the pineapple respectively. Place and Duration of Study: The experiment was conducted at the National Horticultural Research Institute field in 2014. Methodology: The samples were inoculated on potato dextrose agar and pure culture of fungal Original Research Article Oyedeji and Kareem; AJEA, 11(5): 1-7, 2016; Article no.AJEA.23238 2 pathogen responsible for pineapple dieback obtained. The efficacies of three fungicides namely: Zforce (a. i 80% Mancozeb), Forcelet (a.i 50% carbendazim), and Funguforce (63% mancozeb + 12.5% carbendazim) were tested in-vitro on mycelial growth inhibition of the causal agent. Results: Pathogens isolated from diseased leaves were Botrydiplodia theobromae and Aspergillus niger while Aspergillus niger, Aspergillus tamari, Botrydiplodia theobromae and Fusarium verticilliodes were isolated from the rhizosphere. On the infected leaf samples, B. theobromae had the highest occurrence (93.3%) while Aspergillus niger had the least occurrence (6.7%). Similar trend was observed in the soil samples where B. theobromae had the highest occurrence of 80% while A. tamari and F. verticilliodes had the least frequency of occurrence of 4%. Pathogenicity test revealed that B. theobromae was the causal pathogen of pineapple dieback. The three fungicides evaluated were able to inhibition the mycelial growth of B. theobromae. Conclusion: The study revealed that B. theobromae was responsible for pineapple dieback and the three fungicides were able to control it in-vitro.

English

Six novel piperidine derivatives, compounds 5 to 10, have been synthesized and their antimicrobial and anti-oxidant activities evaluated using agar disc diffusion (antimicrobial) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity (antioxidant). Compound 9 revealed the least antibacterial activity. Compound 6 exhibited the strongest inhibitory activity and the best minimum inhibitory concentration (MIC) results against the seven bacteria tested in comparison to the other piperidine derivatives (5, 7, 8, 9, and 10). All six piperidine compounds displayed no activity against fungal species, Fusarium verticilliodes, Candida utilus and Penicillium digitatium. Compounds 7 and 8 revealed no activity against all seven fungi tested. Compounds 5, 6, 9, and 10 revealed varying degree of inhibition against Aspergillus niger, Aspergillus flavus, Saccharomyces cerevisiae and Candida albicans. Compound 8 demonstrated the highest scavenging capacity of 78% at 1000 µg/ml and compound 6 demonstrated the least percentage of scavenging potential of 49% at 1000 µg/ml. All piperidine derivatives tested, revealed antioxidant potentials greater than 49% at 1 mg/ml as compared to the control Rutin, which displayed 97% scavenging capacity at the same concentration. All piperidine derivatives revealed varying degree of antimicrobial and antioxidant activities. Key words: 1,2,5,6-Tetrahydropyridine (THP), piperidine derivatives, antibacterial, antifungal, antioxidant.

Resistance source detection against Stalk Rot (Fusarium Verticilliodes) under different seasons by two disease assessment methods

Hundred maize genotypes along with two checks were grown in Maize and Millet Research Institute (MMRI) Sahiwal-Pakistan in autumn (2009) and spring (2010) to check severity of stalk rot (Fusarium Verticilliodes) under natural infection and artificial inoculation. The disease was recorded using SR (stalk rating) and LL (lesion length). Classification of genotypes was performed by using rank-sum analysis. Means of severity recorded on the basis of SR and LL in autumn were higher than spring under both methods of disease assessment. SR only exhibited significant results (P < 0.05) in autumn under natural infection while LL in natural infection and SR and LL in artificial inoculation showed highly significant results (P < 0.01) in both seasons. Genotype-season interaction was highly significant (P < 0.01) for both severity scale and seasons except for SR (P < 0.05) under natural infection. Means of SR for both seasons showed highly significant results (P < 0.01) under artificial inoculation. In natural infection, significant positive correlation (r = 0.90 to 0.93; P < 0.01) was noted between SR and LL while same correlation (r = 0.82 to 0.90; P < 0.01) was also studied under artificial inoculation between SR and LL under autumn and spring season respectively. Inbred lines (EL7, EL17, and Y11) showed highly resistance against stalk rot under both seasons and disease assessment methods. These highly resistance genotypes may be used as donor of resistant gene or genes in highly adaptive and productive susceptible varieties in further breeding programms.

Survey of Aspergillus and Fusarium species and their mycotoxins in raw materials and poultry feeds from Córdoba, Argentina

The aims of the present work were: (1) to determine both mycobiota in raw materials and finisher poultry feed, as well as the ability to produce aflatoxin B1 by A. flavus strains, and (2) to evaluate the natural co-occurrence of aflatoxins (AFs), fumonisins (FBs), gliotoxin, diacetoxyscirpenol (DAS), HT-2 toxin, and T-2 toxin in poultry feed by LC-MS/MS. Nineteen percent of raw materials and 79% of finisher poultry feed samples exceeded the maximum allowed total fungal count (1 × 10(4) CFU g(-1)) to ensure hygienic quality. Aspergillus flavus was the only species belonging to section Flavi which was isolated while Fusarium verticilliodes was the prevalent species. Forty-seven percent of A. flavus strains were aflatoxin B1 producers and the highest frequency of aflatoxigenic strains was isolated from finisher poultry feeds. Principal component analysis showed that corn grains are closely related with total fungal and Fusarium counts. This positive relationship suggests that total fungal and Fusarium spp. counts in poultry feed might come mainly from corn grains. Regarding poultry feeds, in ground finisher type, Aspergillus spp. counts increased as water activity (aw) diminished. A positive relationship among aw, total fungal and Fusarium spp. counts was observed in both ground finisher and ground starter feed. Several mycotoxins were monitored in feeds by applying the LC MS/MS technique. One hundred percent of poultry samples were contaminated with FB1, and the highest levels were detected in pelleted finisher poultry. AFB1, gliotoxin, DAS, HT-2 toxin, and T-2 toxin were not detected in any poultry feed. The scarcity of available mycotoxicological studies from Argentinean poultry feed using a multitoxin analysis technique enhances the contribution of the findings of this report.

Rhizosphere Fungi of Red Pepper (&lt;i&gt;Capsicum frutescens&lt;/i&gt;)

Fungi present in the rhizosphere and rhizoplane of Capsicum frutescens at different stages of plant growth were studied. The experimental soil was loamy sand in texture. The pH of the rhizosphere soil in the field ranged from 6.4 to 6.7 and in the pots, it ranged from 6.3 to 6.8. The fungi isolated were Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Aspergillus candidus, Penicillium expansum, Fusarium oxysporum, Fusarium poae, Penicillium citrinum, Mucor racemosus, Mucor mucedo, Verticillium lateritium, Fusarium avenaceum, Trichophyton mentagrophyte, Fusarium verticilliodes, Aspergillus ustus, Saccharomyces cerevisiae and Aspegillus fumigatus. The most frequently isolated fungi were Rhizopus stolonifer, Aspergillus nigers and Mucor mucedo. The highest fungal number occurred on the 30th day of plant growth for pots and field.Key words : Fungi , rhizosphere, rhizoplane, plant

VIRULENCE OF Fusarium verticilliodes (SACC.) NIRENBERG (G) ISOLATES ON MAIZE PLANTS ASSOCIATED WITH FUMONISINS PRODUCTION

Fusarium verticilliodes (Sacc.) Nirenberg (G) is a well known phytopathogenic fungus capable to infect a wide range of plants including maize. In addition; its toxic metabolites fumonisin (FB1 and FB2) are associated with Equina Leukoencephalo Malacia and induced hepatotoxic and carcinogenic effects in animals. Twenty two isolates of F. verticilliodes obtained from corn samples and grown on Barley medium, were added to sterile soil two weeks before sowing maize grains to test their ability to cause corn seedling damping-off. Thirteen isolates caused pre-emergence damping-off, and two of them were significant. In addition one F. verticilliodes isolate was significantly affecting post emergency and four isolates exhibited the highest disease index. F. verticilliodes isolates which caused significant pre and post emergence damping-off as well as disease index were found to be fumonisin producers. Fourteen out of twenty two detached and moistened maize leaves showed necrotic lesions when they inoculated by F. verticilliodes spore suspensions. Further more the crude extracts of the tested F. verticilliodes isolates showed leaf lesions when they were spotted on the moisted maize leaf cuts, in addition to FB1 standard. Twelve of the pathogenic F. verticilliodes isolates produced fumonisins (eight; FB1 and four; FB1 & FB2); whereas fumonisins could not been detected in only two of the pathogenic isolates according to TLC.. These results suggest the great role of fumonisins that may be played as a virulence factor of F. verticilliodes on maize.

Evaluation of antibacterial and antifungal activity of root and root callus extracts of Trianthema decandra L.

Trianthema decandra L. root and root callus extracts of different solvents viz., petroleum ether, chloroform, ethyl acetate and ethanol were tested against both Gram positive and Gram negative bacteria and also against Fusarium spp. Root callus extract of chloroform and ethanol showed significant activity against Bacillus subtilis , B. cereus . Staphylococcus aureus, Staph. epidermis and also against the other spp. of Gram negative bacteria viz., Pseudomonas aeruginosa, Klebseilla pneumonia, Alcaligens faecalis, Proteus vulgaris Enterobacter aerogenes, Salmonella typhi, Salmonella tyhimurium, Salmonella paratyphi A and Salmonella enterica subsp. enterica with a MIC of 3.12 to 12.50 μg/ml when compared to root extract of chloroform, ethyl acetate and ethanol of Trianthema decandra . Root callus extract of chloroform, ethyl acetate and ethanol showed activity against Fusarium verticilliodes, F. anthophilum, F. oxysporum and F. proliferatum with a lowest MIC of 3.12 μg/ml when compared to root extract of Trianthema decandra . The result shows that antibacterial and antifungal activity was more in root callus extract than root extract. Key words: Trianthema decandra , antibacterial and antifungal activity, petroleum ether, root callus extracts.

Synthesis of Fumonisin B1

Fumonisin B1 is a mycotoxin isolated from the Fusarium verticilliodes. It is fatal to horses and pigs (”moldy corn poisoning") and it is associated with oesophagal cancer and birth defects in humans. Hydrolysis of the two tricarballylic esters in vivo followed by N-palmitoylation gives a compound which is more cytotoxic to HT29 ­human colon cancer cells than fumonisin B1.

Increased resistance to Ustilago zeae and Fusarium verticilliodes in maize inbred lines bred for Fusarium graminearum resistance

Preliminary field observations in our maize breeding nurseries indicated that breeding for improved resistance to gibberella ear rot (Fusarium graminearum) in maize may indirectly select for resistance to another ear disease, common smut (Ustilago zeae). To investigate this, we compared the disease severity ratings obtained on 189 maize inbreds, eight of which included our inbreds developed with selection for gibberella ear rot resistance after field inoculation and breeding for 8–10 years. No correlation was found between disease severities for the 189 inbreds but the eight gibberella-resistant lines were consistently more resistant to smut. To further examine this relationship and to determine if these eight inbreds would be useful for developing inbreds with either common smut or fusarium ear rot (F. verticilliodes) resistance, we conducted a Griffing’s diallel analysis on six inbreds of maize, four with high levels of gibberella ear rot resistance representing all of the pedigree groups in our eight gibberella lines, and two with very low levels. Our most gibberella ear rot resistant inbreds, CO433 and CO441, had the lowest disease ratings for all three diseases, the consistently largest general combining ability effects and several significant specific combining ability effects. It was concluded that some inbreds bred specifically for gibberella ear rot would also be useful in breeding for resistance to common smut and fusarium ear rot.