Fusarium Verticillioides Isolates Research Articles

Assessment of Genetic Diversity and the Population Structure of Species from the Fusarium fujikuroi Species Complex Causing Fusarium Stalk Rot of Maize.

Fusarium stalk rot (FSR), caused by the Fusarium species complex, is an economic threat to maize cultivation all over the world. We investigated the population structure and genetic diversity of Fusarium species obtained from five major maize-growing regions in India. The Tef-1α locus was used for phylogenetic analysis of geographically distinct isolates of Fusarium verticillioides, F. andiyazi, F. proliferatum, F. nygamai, and F. acutatum causing FSR. A phylogenetic tree showed monophyletic, polyphyletic, and paraphyletic groupings reflecting the complex evolutionary history and genetic diversity within the genus. Monophyletic groupings depicting strong bootstrap support were shown to have a single common ancestor and genetic coherence with limited genetic divergence among sequences. Polyphyletic groupings also presented significant genetic differentiation within the F. verticillioides sequences from diverse ecological niches. Nucleotide diversity of moderate level 0.02471 reflected genetic variations within populations that were attributed to factors such as mutation, genetic drift, or varying selection pressures. The Fst value of 0.98205 is particularly indicative of high genetic differentiation, implying that most of the genetic variance is due to differences between populations rather than within them. F. verticillioides, with 57 sequences, showed low genetic diversity with three segregating sites and a low haplotype diversity of 0.19486, suggesting the founder effect, where a reduced population expands from a limited genetic pool. The total data estimates across all populations for haplotype analysis showed 72 sequences, 44 segregating sites, and 9 haplotypes with a haplotype diversity of 0.48513. The evolutionary dynamics showed genetic differentiations among Fusarium species causing FSR. AMOVA indicated high within-population variations, depicting a substantial genetic diversity within individual populations. The results offer a comprehensive framework for discussing the implications of genetic diversity in pathogen management and the evolutionary dynamics of the Fusarium species causing FSR in maize in the Indian subcontinent.

Occurrence of Fusarium Species and Determination of Their Toxins From Poultry Feeds During Storage.

At a global scale, grains and poultry feeds are the primary sources of feed. Due to their considerable significance, any fungi capable of infecting these feedstuffs can pose a threat to both food safety and security. Fusarium spp. are a highly significant group of organisms. Fumonisins (FBs), deoxynivalenol (DON), trichothecene (T-2), and zearalenone (ZEN) are classifications of mycotoxins that are synthesized by Fusarium species. Their presence is associated with a range of factors that occur during growth, processing, and storage. We have recorded the high occurrence of Fusarium spp. in grains and poultry feeds in all tested samples. Fusarium (F) oxysporum was the most common species that appeared in all tested two hundred samples. FB1 was the predominant toxin that appeared with the highest concentration in 56 pellet samples with the range of 10.34-1043 μg/kg. Also, it occurred with levels of 4.67-956 μg/kg in the tested ingredients samples. Fusarium verticillioides isolates were the highest producers of FB1. Fusarium spp. isolates showed positive FB1 production with 84.6%, 82.5%, 82.2%, and 78.1%, isolated from pellet feed samples that were collected from Alhassa, Jeddah, Qassim, and Riyadh, respectively. 31.6%, 76.9%, 23.1%, 83.3%, and 88% of tested Fusarium spp. strains exhibited FB1 production in samples of barley, corn, sorghum, soybean, and wheat bran, respectively, with the range of 18-655 μg/kg. Genes responsible for FB1, DON, T-2, and ZEN production were detected in the Fusarium spp. isolates.

Changes in polyamine contents during Fusarium graminearum and Fusarium verticillioides inoculation in maize seedlings with or without seed-priming

Maize (Zea mays L.) is the most produced field crop all over the world. One of its most critical diseases that results in economic loss is ear rot caused by various Fusarium species. Previous researches have shown that polyamines, found in all living cells, play crucial role in biotic stress responses. At the same time, biosynthesis of polyamines is of paramount importance not only for plants but also for their pathogens to promote stress tolerance and pathogenicity. In our study, we investigated the polyamine content changes induced in the seedlings of two maize genotypes of different susceptibility by isolates of Fusarium verticillioides and Fusarium graminearum, two Fusarium species of different lifestyles. Apart from that, it was examined how infection efficiency and changes in polyamine contents were modified by salicylic acid or putrescine seed soaking pre-treatments. Our observations confirmed that initial and stress-induced changes in the polyamine contents are not directly related to tolerance in either coleoptile or radicle. However, the two pathogens with different lifestyles induced remarkably distinct changes in the polyamine contents. The effect of the seed soaking pre-treatments depended on the pathogens and plant resistance as well: both salicylic acid and putrescine seed soaking had positive results against F. verticillioides, while in the case of infection with F. graminearum, seed soaking with distilled water alone affected biomass parameters positively in the tolerant genotype.

An Efficient Strategy Combining Immunoassays and Molecular Identification for the Investigation of Fusarium Infections in Ear Rot of Maize in Guizhou Province, China

Fusarium is one of the most important phytopathogenic and mycotoxigenic fungi that caused huge losses worldwide due to the decline of crop yield and quality. To systematically investigate the infections of Fusarium species in ear rot of maize in the Guizhou Province of China and analyze its population structure, 175 samples of rotted maize ears from 76 counties were tested by combining immunoassays and molecular identification. Immunoassay based on single-chain variable fragment (scFv) and alkaline phosphatase (AP) fusion protein was first employed to analyze these samples. Fusarium pathogens were isolated and purified from Fusarium-infected samples. Molecular identification was performed using the partial internal transcribed spacer (ITS) and translation elongation factor 1α (TEF-1α) sequences. Specific primers were used to detect toxigenic chemotypes, and verification was performed by liquid chromatography tandem mass spectrometry (LC–MS/MS). One-hundred and sixty three samples were characterized to be positive, and the infection rate was 93.14%. Sixteen species of Fusarium belonging to six species complexes were detected and Fusarium meridionale belonging to the Fusarium graminearum species complex (FGSC) was the dominant species. Polymerase chain reaction (PCR) identification illustrated that 69 isolates (56.10%) were potential mycotoxin-producing Fusarium pathogens. The key synthetic genes of NIV, NIV + ZEN, DON + ZEN, and FBs were detected in 3, 35, 7, and 24 isolates, respectively. A total of 86.11% of F. meridionale isolates carried both NIV- and ZEN-specific segments, while Fusarium verticillioides isolates mainly represented FBs chemotype. All the isolates carrying DON-producing fragments were FGSC. These results showed that there are different degrees of Fusarium infections in Guizhou Province and their species and toxigenic genotypes display regional distribution patterns. Therefore, scFv-AP fusion-based immunoassays could be conducted to efficiently investigate Fusarium infections and more attention and measures should be taken for mycotoxin contamination in this region.

Cadmium biosorption potential and kinetic behavior of endophytic Fusarium verticillioides and its green synthesized silver nanoparticles (GSNPs)

<p>Silver nanoparticles (GSNPs) were synthesized from extracellular metabolites of endophytic isolates of Fusarium verticillioides (KT587649) to evaluate their efficiency as new biosorbent agents for the exclusion of cadmium Cd (II) from aquatic systems. The GSNPs were characterized through X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results show that the most efficient Cd (II) removal rate by both biosorbents was at pH 7.0. The optimal contact times were 30 and 40 min by F. verticillioides and GSNPs, respectively. Langmuir adsorption isotherms revealed that the highest calculated adsorption capacities of F. verticillioides and GSNPs for Cd (II) were 185±0.25 mg/g and 176±0.18 mg/g, respectively. The harmonized adsorption isotherms (between the Freundlich isotherm and Langmuir models) indicated a high correlation coefficient (r2 > 0.97). The kinetics of the biosorption process fitted well with the pseudo-second-order kinetic model. This study has thus confirmed the biosorbent capacity of F. verticillioides and its GSNPs for the exclusion of Cd (II) from any contaminated aquatic system and shows it is an eco-friendly method with great feasibility and potential to convey economic and other benefits in wastewater treatment technologies</p>

Effects of Bunium persicum essential oil on the reduction of spore germination, growth, and expression of FUM1 and FUM14 genes in Fusarium verticillioides isolates.

Background and Purpose: Black Cumin of Kerman (Bunium persicum) is an Iranian plant that is commonly used as an antispasmodic, carminative, and antimicrobial substance. The present study aimed to assess different components of the essence of B. persicum and its effect on antifungal activity, spore germination inhibition, and expressions of FUM1 and FUM14 genes in Fusarium verticillioides strains.Materials and Methods: The essence was extracted by hydrodistillation and analyzed through gas chromatography-mass spectroscopy. A broth microdilution method was used for the determination of the minimum inhibitory concentration (MIC). In addition, the expression of FUM1 and FUM14 genes of toxigenic F. verticillioides was assessed by using the real-time polymerase chain reaction (RT-PCR) technique.Results: Based on the findings, most of the essence consisted of γ-terpinene (15.56%), propanal, and 2-methyl-3-phenyl (14.18%). The oil showed a good antifungal activity (mean MIC value: 2556.8 μg/ml) as well as the inhibition of spore germination and mycelial growth (P<0.05). The RT-PCR demonstrated that the expression levels of FUM1 and FUM14 of B. persicum-treated F. verticillioides were 0.43 and 0.53 folds lower than the control samples, respectively.Conclusion: These findings revealed that the essential oil of B. persicum has different components responsible for the inhibition of mycelial growth and spore germination of F. verticillioides as well as reduction of expressions of FUM1 and FUM14 genes involving fumonisin production.

FUM gene expression and variation in fumonisin production of clonal isolates ofFusarium verticillioides MRC 826

B-series fumonisins (FBs) are a family of carcinogenic mycotoxins that commonly occur in maize. These mycotoxins cause multiple diseases in animals and are epidemiologically associated with several human diseases in populations for which maize is a dietary staple. FBs are produced by multiple genera of the fungiAspergillus,Fusarium andTolypocladium, but the plant pathogenFusarium verticillioides is considered the primary cause of FB contamination in maize. OneF. verticillioides strain, MRC 826, is reported to produce high levels of FBs. However, in the current study, 18 isolates derived from strain MRC 826 exhibited highly variable levels of FB, which negatively correlated (r=-0.333;P&lt;0.008) with fungal growth. Microsatellite analysis confirmed that all MRC 826 derived isolates examined were clonal, and 100% DNA sequence identity was observed across theFUM gene clusters of two high FB producing and two low FB producing isolates. At the gene expression level, qRT-PCR at each time point (7, 14, 21 and 28 days of incubation) showed differential upregulation of selectedFUM genes in the high compared to the low FB isolates. Variation in FB production appears due to differences inFUM gene expression, most likely caused by sequence differences at unexamined loci not part of theFUM cluster or from epigenetic influences. Clarification of the genetic/epigenetic basis for quantitative differences in fumonisin production among strains and isolates ofF. verticillioides has potential to reveal targets for reducing FB contamination in maize.

Effect of Temperature, Water Activity and Carbon Dioxide on Fungal Growth and Mycotoxin Production of Acclimatised Isolates of Fusarium verticillioides and F. graminearum.

Climate change is primarily manifested by elevated temperature and carbon dioxide (CO2) levels and is projected to provide suitable cultivation grounds for pests and pathogens in the otherwise unsuitable regions. The impacts of climate change have been predicted in many parts of the world, which could threaten global food safety and food security. The aim of the present work was therefore to examine the interacting effects of water activity (aw) (0.92, 0.95, 0.98 aw), CO2 (400, 800, 1200 ppm) and temperature (30, 35 °C and 30, 33 °C for Fusarium verticillioides and F. graminearum, respectively) on fungal growth and mycotoxin production of acclimatised isolates of F. verticillioides and F. graminearum isolated from maize. To determine fungal growth, the colony diameters were measured on days 1, 3, 5, and 7. The mycotoxins produced were quantified using a quadrupole-time-of-flight mass spectrometer (QTOF-MS) combined with ultra-high-performance liquid chromatography (UHPLC) system. For F. verticillioides, the optimum conditions for growth of fumonisin B1 (FB1), and fumonisin B2 (FB2) were 30 °C + 0.98 aw + 400 ppm CO2. These conditions were also optimum for F. graminearum growth, and zearalenone (ZEA) and deoxynivalenol (DON) production. Since 30 °C and 400 ppm CO2 were the baseline treatments, it was hence concluded that the elevated temperature and CO2 levels tested did not seem to significantly impact fungal growth and mycotoxin production of acclimatised Fusarium isolates. To the best of our knowledge thus far, the present work described for the first time the effects of simulated climate change conditions on fungal growth and mycotoxin production of acclimatised isolates of F. verticillioides and F. graminearum.

In vitro Antifungal Effect of Mangrove extracts on Fusarium verticillioides Isolates

The present study was conducted to identify the antifungal activity of phenolic compounds extracted from the mangrove, Rhizophora mangle against the Fusarium verticillioides isolates DA42, F64 and PO3. The total phenolic content was calculated using the Folin-Ciocalteu method. The in vitro inhibition test was performed according to the poisoned food technique. Stem extracts had the highest total phenolic content (9.5 mg GAE/g DM) and displayed major inhibition percentages against all F. verticillioides isolates. Furthermore, the concentration of this extract required to inhibit the three fungal isolates by 50 %, is 2 to 3 times greater on average than that required for leaf and root extracts. This study demonstrated the inhibitory activity of ethanol extracts of Rhizophora mangle roots, stems and leaves against different isolates of Fusarium verticillioides.

Pathogenicity and toxigenicity of Fusarium verticillioides isolates collected from maize roots, stems and ears in South Africa

Fusarium verticillioides is most frequently associated with maize in South Africa. It colonises maize roots, stems and ears endophytically and causes diseases such as Fusarium ear rot (FER) and stalk rot. Fusarium verticillioides can produce fumonisins, which are toxic secondary metabolites harmful to humans and animals. It is, however, unknown whether endophytic and pathogenic isolates from distinct maize tissues differ in their ability to cause disease and produce fumonisins. In this study, Fusarium spp. were collected from maize roots, stems and kernels for phylogenetic analysis and the F. verticillioides isolates were subjected to pathogenic and toxigenic comparison. The translation elongation 1-α (TEF1) gene of the isolates was sequenced, and a phylogenetic tree constructed with maximum likelihood (ML) and Bayesian interference (BI) inferred. Fumonisin production of F. verticillioides isolates was determined in vitro and in planta by using high performance liquid chromatography, and virulence of the isolates was determined by silk channel inoculation of maize ears under field conditions. F. verticillioides was the species with the highest number of isolates followed by F. temperatum and then F. subglutinans. Phylogenetic analyses clustered the different Fusarium spp. according to species. Fumonisin production by F. verticillioides isolates varied from 0 to 21.3 mg/kg in vitro, and 0–16.2 mg/kg in planta. All the F. verticillioides isolates produced FER symptoms, including isolates from roots and stems. Fusarium verticillioides isolates in South Africa thus presented a species highly diverse in toxigenicity, but not in virulence. This finding has implications for managing mycotoxins in maize, as visible symptoms might be misleading to the actual toxin level present, for example low level of disease severity might represent high fumonisin levels and vice versa. The high numbers of F. temperatum, also a mycotoxin producer highlights the concern that kernels could be contaminated with more than one mycotoxin. Integrated disease management of not only F. verticillioides but all Fusarium spp. should thus focus strongly on reducing fungal contamination of maize and the detoxification of grain with focus on using regionally adapted maize varieties.

Morphological, pathological and mycotoxicological variations among Fusarium verticillioides isolated from cereals.

Among the 194 Fusarium verticillioides isolates screened from 127 cereal samples, 176 were fumonisin producers and others were non-producers. Representative nine Fusarium verticillioides strains along with one reference standard strain MTCC156 were selected to study their morphological, pathological and mycotoxicological variations by conventional and molecular approaches. Fusarium verticillioides strains FVM86, FVM146, FV200 and FVS3 showed significant pathogenicity and also in pigmentation production but varied in fumonisin production. Fusarium verticillioides strain FVP19 recorded variations in all the assays. Fusarium verticillioides strain FVM42 showed drastic phenotypic variation and it also produced fumonisin. Genetic variation among the strains was independent of geographic area of origin but depended on their ability to produce fumonisin. The strains were independent in their cultural characteristics, pigmentation production, pathogenicity assays, fumonisin production and in their genetic variability without having any correlation.

Fumonisins production potential of Fusarium verticillioides isolated from Serbian maize and wheat kernels

The production of fumonisins by potentially toxigenic Fusarium verticillioides isolates originating from Serbian maize and wheat kernels was tested in vitro. A total of six F. verticillioides isolates were incubated on yeast extract sucrose medium (YESA) for 4 weeks at 25 ?C in the dark. Their toxin production potential was tested by applying a modified HPLC method for determination of fumonisins in cereals, since the TLC method gave no results. Analyses were performed on a HPLC-FLD system after sample extraction from YESA and extract cleanup on a SPE column. Although the isolates were tested for fumonisin B1, B2 and B3, only fumonisin B1 was detected. The results showed that all tested isolates had toxigenic potential for fumonisin B1 production. The average fumonisin B1 production of the isolates ranged from 7 to 289 ?g/kg, thus indicating a highly variable toxigenic potential among the isolates. Isolate 1282 expressed the highest toxigenic potential for fumonisin B1 production (289 ?g/kg), while isolate 2533/A showed a questionable potential for fumonisin production (7 ?g/kg).

Evaluating three commonly used growth media for assessing fumonisin analogues FB1, FB2 and FB3 production by nine Fusarium verticillioides isolates

ABSTRACTMaize is most often infected by the fumonisin-producing Fusarium verticillioides. Total fumonisins of natural infected grain is made up of FB1, FB2 and FB3 with FB1 occurring naturally at higher levels. A maize plant can be infected with more than one F. verticillioides isolate, and finding a reliable method to elucidate the toxigenic potential of these isolates is important to extrapolate the possible fumonisin risk to consumers of grain. It is not clear whether F. verticillioides produces similar fumonisin levels, as well as fumonisin analogue ratios, across media. In this study, nine F. verticillioides isolates were subjected to three methods of fumonisin testing using liquid media, maize patties and a field trial (silk inoculation of grain) in Potchefstroom, South Africa. Spore concentrations of 1 × 106 conidia ml–1 of each isolate were used to inoculate the different media and levels fumonisin analogues were measured using HPLC. Fumonisin production per isolate was highly variable and was influenced by the two-way interaction of F. verticillioides isolate × growth media. Total fumonisins produced in the liquid medium ranged from 0 to 21.3 ppm, on maize patties fumonisins they ranged from 0 to 21.5 ppm, and in the silk inoculation technique they ranged from 0 to 15.5 ppm. The fumonisin analogue FB1 occurred at higher levels followed by FB3 in both in vitro studies. In the silk inoculation technique, fumonisin analogue FB2 was the second highest occurring analogue after FB1. Isolate GCI 282 produced higher FB2 and FB3 levels than FB1 in the patties and grain, respectively. In order not to miscalculate the fumonisin and analogue ratio levels per F. verticillioides isolate, the growth medium will have to be optimised for each isolate and more than one growth medium used.

Genetic variation among Fusarium verticillioides isolates associated with Ethiopian maize kernels as revealed by AFLP analysis

Amplified fragment length polymorphism (AFLP) was used to study the genetic variation among 80 F. verticillioides isolates from kernels of Ethiopian maize, collected from 20 different maize growing areas in four geographic regions. A total of 213 polymorphic fragments were obtained using six EcoRI/MseI primer combinations. Analysis of the data based on all 213 polymorphic AFLP fragments revealed high level of genetic variation in the F. verticillioides entities in Ethiopia. About 58% of the fragments generated were polymorphic. The genetic similarity among F. verticillioides isolates varied from 46% to 94% with a mean Dice similarity of 73%. Unweighted Pair Group Method with Arithmetic Average (UPGMA) analysis revealed two main groups and four subgroups. The principal coordinate analysis (PCO) also displayed two main groups that agreed with the results of UPGMA analysis, and there was no clear pattern of clustering of isolates according to geographic origin. Analysis of molecular variance: (AMOVA) showed that only 1.5% of the total genetic variation was between geographic regions, while 98.5% was among isolates from the same geographic regions of Ethiopia. Eighty distinct haplotypes were recognized among the 80 isolates analyzed. Hence, breeding efforts should concentrate on quantitative resistance that is effective against all genotypes of the pathogen.

Population Genetic Structure among Iranian Isolates of Fusarium verticillioides

The genetic structure among Iranian populations of Fusarium verticillioides from the main corn growing areas of five provinces including Ardabil, Fars, Mazandaran, Khorasan, and Khuzestan were evaluated using VCG, RAPD and rep-PCR. Sixty-one isolates of F. verticillioides were placed in 14 Vegetative Compatibility Groups and 19 haplotypes. VCG3 with 14 members (23% of all isolates) was the most frequent VCG. RAPD-PCR and rep-PCR generated multiple distinct products demonstrated considerable variability among the isolates of different VCGs. Haplotype 1(HP1) had the highest frequency (0.57) in the population and was present in isolates from the majority of the locations in this study. All molecular phenotypes were distributed randomly across the various locations. Although there are some consistent between geographical origin of the isolates and their genetic similarity but VCG groups were distributed among different geographical locations and there was no correlation between geographical distribution and VCG groups. Gene diversity was 0.2909 and populations of F. verticillioides were placed in five distinct groups based on geographical origin. The highest genetic distance observed between Fars and Khuzestan (0.1801) and the smallest genetic distance was obtained between Ardabil and Khuzestan (0.0589). Analysis of molecular variance (AMOVA) showed a significant difference among populations of F. verticillioides. According to our results PhiPT was equal to 0.176 (p<= 0.001) and 82% of genetic variance occurred within populations and only 18% was found among populations. Moghan in Ardabil province is the main site for seed producing in Iran and the seeds that are produced there are distributed all over the country. In this study isolates of Moghan were located besides the isolates from other regions in different clusters. So it is presumed that the infected seeds from Moghan can be a major source for the spreading of the disease through all corn growing areas in Iran.

Combined effect of chitosan and water activity on growth and fumonisin production by Fusarium verticillioides and Fusarium proliferatum on maize-based media

The objectives of the present study were to determine the in vitro efficacy of chitosan (0.5, 1.0, 2.0 and 3.0mg/mL) under different water availabilities (0.995, 0.99, 0.98, 0.96 and 0.93) at 25°C on lag phase, growth rate and fumonisin production by isolates of Fusarium verticillioides and Fusarium proliferatum. The presence of chitosan affected growth and fumonisin production, and this effect was dependent on the dose and aW treatment used. The presence of chitosan increased the lag phase, and reduced the growth rate of both Fusarium species significantly at all concentrations used, especially at 0.93 aW. Also, significant reduction of fumonisin production was observed in both Fusarium species at all conditions assayed. The present study has shown the combined effects of chitosan and aW on growth and fumonisin production by the two most important Fusarium species present on maize. Low molecular weight (Mw) chitosan with more than 70% of degree of deacetylation (DD) at 0.5mg/mL was able to significantly reduce growth rate and fumonisin production on maize-based media, with maximum levels of reduction in both parameters obtained at the highest doses used. As fumonisins are unavoidable contaminants in food and feed chains, their presence needs to be reduced to minimize their effects on human and animal health and to diminish the annual market loss through rejected maize. In this scenario post-harvest use of chitosan could be an important alternative treatment.

Evaluation of ear rot (Fusarium verticillioides) resistance and fumonisin accumulation in Italian maize inbred lines

Mycotoxin contamination of maize ( Zea mays L.) grain is a global threat to the safety of both human food and animal feed. Hence, the development of maize genotypes with reduced mycotoxin accumulation in grain is of major importance. In order to find maize germplasm sources of resistance to Fusarium ear rot, 34 Italian and six public inbred lines were evaluated by means of artificial inoculation in field experiments during 2009 and 2010. Relationships between ear rot and fumonisin concentration in the ears were investigated. Primary ears were challenged with a mixture of two Fusarium verticillioides isolates from Northern Italy, through kernel inoculation, and ear rot severity was assessed.The average number of visibly infected kernels per ear, after inoculation, ranged from 2 to 68 in 2009 and from 0 to 120 in 2010. Fumonisin concentrations in the inoculated ears were greater than in the experimental controls for both years. Variability was found between the inbred lines: fumonisin accumulation ranged from 0.56 to 240.83 mg kg-1 in 2009 and from 1.09 to 190.60 mg kg-1 in 2010. In both years, six inbred lines showed high fumonisin content (≥100 mg kg-1), while the other genotypes were almost equally split into two groups, low (≤10 mg kg-1) and medium (from 11 to 100 mg kg-1) fumonisin content. The number of infected kernels after artificial inoculation correlated with fumonisin concentration both in 2009 (r = 0.94; P≤0.01) and 2010 (r = 0.67; P≤0.01). Additionally, the percentage of internally infected kernels correlated positively with fumonisin concentration (r = 0.37; P≤0.01) and with the number of infected kernels (r = 0.29; P≤0.05). This research has demonstrated that Italian maize germplasm is a valid source of resistance to Fusarium ear rot. Furthermore, there is a strong association of visible Fusarium symptoms with fumonisin concentration, suggesting that selection in maize for reduced visible moulds should reduce the risk of mycotoxin contamination.

Biological and chemical detection of fumonisins produced on agar medium by Fusarium verticillioides isolates collected from corn in Sohag, Egypt

Fusarium verticillioides (Sacc.) Nirenberg is among the most common Fusarium species corn pathogens worldwide, and has been recognized as a fumonisin B1 (FB1) and fumonisin B2 (FB2) producer. In the present work, extracts of 58 F. verticillioides isolates from corn samples collected from Sohag Governorate, Egypt, were tested for their biotoxicity and production of fumonisin toxins. Forty-four Fusarium verticillioides isolates out of 58 tested produced FB1 or FB1 and FB2 (15 and 29 isolates, respectively) on potato-sucrose agar medium, detected by TLC, whereas the other 14 isolates did not produce fumonisin toxins. HPLC crude extract analysis confirmed the results from TLC plates. Brine shrimp larvae as well as the Gram-negative bacteria Pseudomonas aeuroginosa showed low bio-sensitivity towards the F. verticillioides crude extract toxicity, whereas the Gram-positive bacteria Bacillus cereus and Bacillus subtilis, especially B. subtilis, showed higher sensitivity towards the tested Fusarium crude extracts. These results enabled us to bio-evaluate and chemically detect fumonisin mycotoxins using a simple agar medium technique.

Sensitivity of Fusarium verticillioides isolates from rice to a novel cyanoacrylate fungicide

The baseline sensitivity of Fusarium verticillioides to the novel cyanoacrylate fungicide 2-cyano-3-amino-3-phenylancryic acetate (experimental code JS399-19) was established, and its impact on the germination of rice seeds and efficacy in controlling rice bakanae disease by seed treatment were evaluated. The EC50 values for JS399-19 inhibiting mycelial growth of wild-type F. verticillioides isolates ranged from 0.162 to 0.559 μg/ml (a 3.5-fold difference between the lowest and highest value), and the average (±SE) EC50 value was 0.316 ± 0.072 μg/ml. The sensitivity curve was unimodal over the sensitive range and the sensitivity data can be used as a baseline for monitoring any future changes in sensitivity to JS399-19 by F. verticillioides populations. Germination of healthy seeds was greater than 77% for all the selected cultivars, and was unaffected by treatment with JS399-19. Treatment of infected seeds (harvested from diseased plants) with all concentrations of JS399-19 in this study significantly decreased the abnormal elongation and damping-off of seedlings in plastic bottles in the greenhouse, indicating that JS399-19 has excellent efficacy in controlling rice bakanae disease, and was safe to rice seeds. It could be used as a disinfectant of rice seeds infected by F. verticillioides. The results also suggested that the F. verticillioides isolates exhibited little sensitivity shift to this fungicide after a single application. If properly applied, JS399-19 might be used as a major fungicide or a good companion fungicide for the control of rice bakanae disease in China.

Fusarium verticillioides from sugarcane, vegetative compatibility groups and pathogenicity

Sugarcane plant samples affected by the disease pokkah boeng were collected from the major sugarcane producing areas in Iran. Fifty isolates of Fusarium verticillioides were recovered from diseased sugarcanes. Results of pathogenicity tests revealed that all isolates were pathogenic to sugarcane. Four hundred and eighty-five nitrate non-utilising mutants were generated from F. verticillioides isolates. Media used for nit mutant generation included potato dextrose agar, minimal medium and Czapeck agar amended with 1.8%, 2%, 2.5%, and 3% potassium chlorate. Nit mutants were divided into three phenotypic (nit1, nit3, and nitM) classes based on their growth on different nitrogen sources in the culture media. Among the isolates tested, 280, 115 and 90 nit1, nit3, and nit&amp;nbsp;M were generated, respectively. Nit mutants were used to force the heterokaryon formation to determine the distribution of VCGs and their relation to pathogenicity and geographic origin. Forty-eight VCGs of F. verticillioides were isolated from sugarcane. Forty-six of the VCGs were represented by a single isolate, whereas the remaining two comprised two isolates. None of the VCGs was common.