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At least 19 recordsLinked to original sources

PubMed2005

PCR detection assays for the trichothecene-producing species Fusarium graminearum, Fusarium culmorum, Fusarium poae, Fusarium equiseti and Fusarium sporotrichioides.

Contamination of small-grain cereals with the fungal species Fusarium graminearum, F. culmorum, F. poae, F. sporotrichioides and F. equiseti is an important source of trichothecenes, Zearalenone and other mycotoxins which cause serious diseases in human and animals. Additionally, these species contribute to Fusarium Head Blight, a disease which produces important losses in cereal yield. Early detection and control of these Fusarium species is crucial to prevent toxins entering the food chain and a useful tool in disease management practices. We describe the development of specific PCR assays to F. graminearum, F. culmorum, F. poae, F. sporotrichioides and F. equiseti using DNA from pure fungal cultures as well as from naturally infected wheat seeds, using in this case a rapid and easy protocol for DNA isolation. The specific primers were designed on the basis of IGS sequences (Intergenic Spacer of rDNA), a multicopy region in the genome that permits to enhance the sensitivity of the assay in comparison with PCR assays based on single-copy sequences.

DNA Primers↗

PubMed2004

IGS-RFLP analysis and development of molecular markers for identification of Fusarium poae, Fusarium langsethiae, Fusarium sporotrichioides and Fusarium kyushuense.

The intergenic spacer (IGS) regions of the rDNA of several Fusarium spp. strains obtained from the collaborative researchers (Int. J. Food Microbiol. (2003)) were amplified by polymerase chain reaction (PCR), and an IGS-RFLP analysis was performed. Restriction digestion with AluI, MspI and PstI allowed differentiation between the related Fusarium poae and Fusarium kyushuense species. Fusarium langsethiae was also separated from Fusarium sporotrichioides (including var. minus) on the basis of the banding patterns after MspI digestion, while specific XhoI, AluI and MspI restriction patterns were found in the IGS amplicons of F. sporotrichioides var. minus. According to the phylogenetic analysis of IGS-RFLP patterns, F. langsethiae (except for one strain), F. sporotrichioides, F. poae and F. kyushuense strains formed four well-supported clades with high-bootstrap values. Based on the sequence differences in the IGS region, species-specific primers were designed for the F. langsethiae/F. sporotrichioides group and for F. poae. The specificity and sensitivity of the primers were tested on various Fusarium species and isolates, and on several other important fungal genera associated with cereals. The F. poae-specific primers, designed in this study, showed the same specificity as primers Fp82f/Fp82r developed previously. The two phylogenetic subgroups of F. langsethiae, found by IGS sequencing analysis, were separated on the basis of size differences of the amplification products with primers CNL12/PulvIGSr specific for the F. langsethiae/F. sporotrichioides group. RFLP analysis of the amplified IGS region is a useful molecular assay for characterisation and a phylogenetic study of several related Fusarium species-F. langsethiae, F. sporotrichioides, F. sporotrichioides var. minus, F. poae and F. kyushuense. The primers designed in this study were highly specific and allowed identification of F. poae and the F. langsethiae/F. sporotrichioides group.

Base Sequence↗

PubMed2004

Phylogenetic analyses of the Fusarium poae, Fusarium sporotrichioides and Fusarium langsethiae species complex based on partial sequences of the translation elongation factor-1 alpha gene.

Phylogenetic relationships between four Fusarium species were studied using parts of the nuclear translation elongation factor-1 alpha (EF-1alpha) gene as a phylogenetic marker. Sequences from 12 isolates of Fusarium poae, 10 isolates of Fusarium sporotrichioides and 12 isolates of Fusarium langsethiae yielded 4, 5 and 5 haplotypes, respectively. In addition, we included one isolate of Fusarium kyushuense. The aligned sequences were subjected to neighbor-joining (NJ), maximum parsimony and maximum likelihood (ML) analyses. The results from the different analyses were highly concordant. The EF-1alpha-based phylogenies support the classification of F. langsethiae as a separate taxon in the section Sporotrichiella of Fusarium, as the closest sister taxon to F. sporotrichioides, while F. kyushuense is the sister taxon to F. poae. This corresponds well with the ability of F. langsethiae and F. sporotrichioides to produce T-2 and HT-2 toxins. In contrast, morphological characters indicate a closer relationship between F. langsethiae and F. poae on the one hand, and between F. sporotrichioides and F. kyushuense on the other hand.

DNA, Fungal↗

PubMed2004

Phylogenetic relationship of Fusarium langsethiae to Fusarium poae and Fusarium sporotrichioides as inferred by IGS, ITS, beta-tubulin sequences and UP-PCR hybridization analysis.

Fusarium langsethiae was recently described to accommodate "powdery" isolates of Fusarium poae, which morphologically resemble F. poae, but whose metabolite profile is similar to that of Fusarium sporotrichioides. In order to investigate the phylogenetic relationship of F. langsethiae to closely related species, we sequenced the internal transcribed spacer (ITS) regions 1 and 2 and part of the intergenic spacer (IGS) region of the rDNA cluster and part of the beta-tubulin gene from 109 strains of F. poae, F. sporotrichioides, F. langsethiae and Fusarium kyushuense from different geographic origin. Sequence analysis of ITS1 and 2 was unable to separate all F. sporotrichioides strains from F. langsethiae strains. Sequence analysis of beta-tubulin distinguished all four species, but it did not resolve the phylogenetic relationship between these two species. Sequence analysis of the IGS region distinguished the four species and led to a higher number of subgroups of the individual species, of which that of F. sporotrichioides var. minus isolates was even better supported than that of F. poae and F. langsethiae. Neighbor-joining and POY analyses of all combined sequences reliably separated all species studied, including F. langsethiae, clearly from F. sporotrichioides. The high intraspecific variability of the IGS sequences were found useful to group isolates according to their geographic origin. These results are in accordance with the results of the UP-PCR hybridization analysis. In summary, our data offer molecular support for the description of F. langsethiae as a new species in section Sporotrichiella.

Base Sequence↗

PubMed2004

An integrated taxonomic study of Fusarium langsethiae, Fusarium poae and Fusarium sporotrichioides based on the use of composite datasets.

An integrated systematic study was carried out to clarify the taxonomical position and relationship of Fusarium langsethiae to other taxa within the Fusarium section Sporotrichiella. Strains of this species were compared with strains of the closely related species Fusarium poae and Fusarium sporotrichioides using a composite dataset. This set consisted of DNA sequences derived from the ribosomal internal transcribed spacer (ITS) regions, partial sequences of the ribosomal intergenic spacer (IGS) region, the beta-tubulin and translation elongation factor-1 alpha (EF-1alpha) genes, AFLP fingerprints, chromatographic data on secondary metabolites and morphological data and growth characteristics. From these combined data, a consensus matrix was calculated by taking the mean of all pairwise distances between single isolates over all separate datasets. The consensus matrix was used as the basis for the construction of a UPGMA dendrogram and a multidimensional scaling, both of which revealed a clear separation of the three taxa. Partial IGS, EF-1alpha and beta-tubulin sequence-as well as chromatography-and AFLP-derived similarities turned out to be comparably consistent, while ITS sequence- and morphology-derived similarity matrices were rather divergent.

Base Sequence↗

PubMed2004

Diversity in metabolite production by Fusarium langsethiae, Fusarium poae, and Fusarium sporotrichioides.

The production of mycotoxins and other metabolites by 109 strains of Fusarium langsethiae, Fusarium poae, Fusarium sporotrichioides, and F. kyushuense was investigated independently in four laboratories by liquid or gas chromatography analyses of cultural extracts with UV diode array, electron capture, or mass spectrometric detection systems. From the compiled results, it was found that F. langsethiae consistently produced the trichothecenes diacetoxyscirpenol (DAS), T-2 toxin (T-2), HT-2 toxin (HT-2), and neosolaniol (NEO) and, to a lesser extent, some additional trichothecene derivatives. F. langsethiae also produced culmorins, chrysogine (CHRYS), aurofusarin (AUF), and enniatin (EN). F. sporotrichioides showed a metabolite profile similar to that of F. langsethiae, while F. poae had a different profile as 41 of 49 strains produced nivalenol (NIV) and other 8-keto trichothecenes, in addition to DAS and derivatives of this metabolite. Only a trace amount of NIV was detected from one strain of F. kyushuense. In summary, all the three core taxa of this joint study were found to produce trichothecenes. Fusarin C (F-C) was not detected from F. langsethiae, but it was produced by F. poae and F. sporotrichioides. Aurofusarin was only detected from a few strains of F. langsethiae, while nearly all strains of F. poae and F. sporotrichioides produced this compound. In contrast, chrysogine was not detected from F. poae, but was produced by the other two taxa. Production of enniatins was scattered among the three main taxa of this study, whereas beauvericin (BEA) was produced by many strains of F. poae and F. sporotrichioides. Only one odd strain of F. langsethiae (IBT 9959) produced beauvericin. However, the status of this strain is uncertain. By a polyphasic approach using species-specific metabolite profiles, the fruity odour of F. poae, and morphological observations, it was concluded that F. langsethiae, F. poae, and F. sporotrichioides should be regarded as three significant taxa at a species level.

Chromatography, Gas↗

PubMed2006

Identification and characterization of non-pathogenic Fusarium oxysporum capable of increasing and decreasing Fusarium wilt severity.

Fusarium wilt of banana is a potentially devastating disease throughout the world. Options for control of the causal organism, Fusarium oxysporum f.sp. cubense (Foc) are limited. Suppressive soil sites have previously been identified where, despite the presence of Foc, Fusarium wilt does not develop. In order to understand some aspects of this disease suppression, endophytic Fusarium oxysporum isolates were obtained from banana roots. These isolates were genetically characterized and compared with an isolate of Fusarium oxysporum previously identified as being capable of suppressing Fusarium wilt of banana in glasshouse trials. Three additional isolates were selected for glasshouse trials to assess suppression of Fusarium wilt in two different cultivars of banana, Cavendish and Lady Finger. One isolate (BRIP 29089) was identified as a potential biocontrol organism, reducing the disease severity of Fusarium wilt in Lady Finger and Cavendish cultivars. Interestingly, one isolate (BRIP 45952) increased Fusarium wilt disease severity on Cavendish. The implications of an isolate of Fusarium oxysporum, non-pathogenic on banana, increasing disease severity and the potential role of non-pathogenic isolates of Fusarium oxysporum in disease complexes are discussed.

Fusarium↗

PubMed1998

Colonization of maize grain by Fusarium moniliforme and Fusarium proliferatum in the presence of competing fungi and their impact on fumonisin production.

This study was carried out to determine the effect of water activity (aw) and temperature on the patterns of colonization of maize grain by isolates of Fusarium moniliforme and F. proliferatum in the presence of interacting spoilage fungi, such as Aspergillus flavus, A. niger, A. ochraceus, and Penicillium implicatum, over 4-week incubation periods. The impact that such interactions have on Fusarium infection of maize grain and populations and on the production of fumonisins were all evaluated. At 0.93 and 0.95 aw, interactions of the two Fusarium spp. with other species to a large extent resulted in mutual inhibition on contact or overgrowth by the Aspergillus and Penicillium spp., regardless of temperature and growth rates of the species. Seed infection by the Fusarium spp. at 25 degrees C was influenced mainly by A. flavus and A. niger, with a reduction of infection by up to 45 and 30%, respectively, after 2 weeks. At 15 degrees C and lowered aw levels, infection was reduced, and sometimes completely inhibited, by A. niger, A. ochraceus, and P. implicatum. By contrast, populations of the Fusarium spp. (CFU per gram grain) were reduced mainly by A. flavus and P. implicatum. A. niger reduced populations of the Fusarium spp. at 0.93 and 0.95 aw, particularly after 4 weeks of incubation. Interaction with A. niger, A. ochraceus, and A. flavus at 15 and 25 degrees C and 0.98 aw resulted in a significant stimulation in fumonisin production by both Fusarium spp. Interaction with P. implicatum resulted in a decrease in fumonisin production by F. moniliforme. However, interaction with F. proliferatum resulted in an enhanced production at both temperatures and 0.95 and 0.98 aw. This study has shown that fungal interactions may act as an additional control factor in Fusarium spp. development on grain. However, although interactions lead to a decreased colonization by Fusarium, mainly at lower aw, a decrease in fumonisin production accumulation does not occur at the same time. Knowledge of these interactions is essential for improving effective control procedures for preventing growth and mycotoxin production by such fungi.

Aspergillus↗

PubMed2001

Quantification of trichothecene-producing Fusarium species in harvested grain by competitive PCR to determine efficacies of fungicides against Fusarium head blight of winter wheat.

We developed a PCR-based assay to quantify trichothecene-producing Fusarium based on primers derived from the trichodiene synthase gene (Tri5). The primers were tested against a range of fusarium head blight (FHB) (also known as scab) pathogens and found to amplify specifically a 260-bp product from 25 isolates belonging to six trichothecene-producing Fusarium species. Amounts of the trichothecene-producing Fusarium and the trichothecene mycotoxin deoxynivalenol (DON) in harvested grain from a field trial designed to test the efficacies of the fungicides metconazole, azoxystrobin, and tebuconazole to control FHB were quantified. No correlation was found between FHB severity and DON in harvested grain, but a good correlation existed between the amount of trichothecene-producing Fusarium and DON present within grain. Azoxystrobin did not affect levels of trichothecene-producing Fusarium compared with those of untreated controls. Metconazole and tebuconazole significantly reduced the amount of trichothecene-producing Fusarium in harvested grain. We hypothesize that the fungicides affected the relationship between FHB severity and the amount of DON in harvested grain by altering the proportion of trichothecene-producing Fusarium within the FHB disease complex and not by altering the rate of DON production. The Tri5 quantitative PCR assay will aid research directed towards reducing amounts of trichothecene mycotoxins in food and animal feed.

Antifungal Agents↗

PubMed1993

Fusarium poae and Fusarium sporotrichioides in cereal grains of the Slovak Republic.

The occurrence of Fusarium poae and F. sporotrichioides was examined in 37,172 cereal grains of 229 samples from the Slovak Republic. In an area where strains of Fusarium parasitized. 40% of grains on average, owing to unfavourable weather, 5 strains of F. poae were isolated (0.5% out of 1,015 strains of Fusarium). In an area where the situation was less unfavourable, Fusarium spp. contaminated on average 4.1% of grains, F. poae were present in 6.1% out of 82 strains of Fusarium. When cereal ripened and harvested under climatically favourable conditions. Fusarium spp. were isolated, on average, out of 3.0% of grains, but the strains of F. poae made an essential part of the mycoflora (25.5% out of 985 isolated Fusarium strains). In three samples there were ascertained 5%, 15% and 19.5% of grains contaminated by strains of F. poae, F. sporotrichioides was isolated only 5 times.

Climate↗

PubMed2004

Development of PCR assays for the detection and differentiation of Fusarium sporotrichioides and Fusarium langsethiae.

Isolates of the type-A trichothecene producing Fusarium sporotrichioides and Fusarium langsethiae were grouped and differentiated in a phylogenetic tree using ITS sequence dissimilarity. An attempt was made to develop a PCR-based assay for the detection and differentiation of Fusarium sporotrichiodes from other Fusarium species using the 5'-region of the tri5 gene as a template. However, this assay was unable to differentiate, to a satisfactory level, between isolates of Fusarium sporotrichioides and Fusarium langsethiae, providing further genetic evidence for their close genetic relationship. A robust and repeatable PCR-assay was developed for the detection and differentiation of both species based on sequence determined from differentially amplified RAPD-PCR products. These assays were able to detect both species in samples of grain taken from the field.

Base Sequence↗

PubMed2004

Fusarium species and Fusarium wilt pathogens associated with native Gossypium populations in Australia.

Fusarium isolates were extracted from stems and rhizosphere soils of 79 populations of four Gossypium species native to two regions of inland Australia in 2001. Six Fusarium species were isolated from 31 (3%) of the 919 stem samples. F. semitectum was predominant, occurring mostly in G. bickii populations and accounting for 81% of the isolates recovered. Twenty Fusarium species were isolated from 68 (87%) of the 78 composite soil samples, with F. solani (71%), F. compactum (8%), F. oxysporum (5%), F. graminearum (3%), and F. crookwellense (3%) being the most prevalent. Significant differences in the relative densities indicated that F. solani was more common in the soil from G. sturtianum populations than from G. bickii populations, and that F. crookwellense was more common in South Australian soils than in Queensland and Northern Territory soils. Fusarium oxysporum had a relatively greater relative density in the rhizosphere soils of G. australe plants than in that of sympatrically growing G. sturtianum plants. Fifteen (17%) of the 89 F. oxrysporum isolates produced typical Fusarium wilt symptoms on cultivated cotton (G. hirsutum cv. 'Siokra 1-4'), therefore they were classified as wild Fov. Soil samples collected from G. sturtianum populations in the Arkaroola-Leigh Creek region in South Australia had the highest incidence of wild Fov (24%). Two wild Fov isolates were similar in virulence to a cotton field Fov isolate in the glasshouse experiments, indicating that they could incite Fusarium wilt disease in cotton fields. The presence of wild Fov in native Gossypium populations suggests that the Fov occurring in Australian cotton fields may be of indigenous origins.

Fusarium↗

PubMed2002

Arabidopsis is susceptible to the cereal ear blight fungal pathogens Fusarium graminearum and Fusarium culmorum.

The fungal pathogens Fusarium graminearum and F. culmorum cause ear blight disease on cereal crops worldwide. The disease lowers both grain quality and grain safety. Disease prevalence is increasing due to changes in cropping practices and the difficulties encountered by plant breeders when trying to introgress the polygene-based resistance. The molecular basis of resistance to Fusarium ear blight in cereal species is poorly understood. This is primarily due to the large size of cereal genomes and the expensive resources required to undertake gene function studies in cereals. We therefore explored the possibility of developing various model floral infection systems that would be more amenable to experimental manipulation and high-throughput gene function studies. The floral tissues of tobacco, tomato, soybean and Arabidopsis were inoculated with Fusarium conidia and this resulted in disease symptoms on anthers, anther filaments and petals in each plant species. However, only in Arabidopsis did this initial infection then spread into the developing siliques and seeds. A survey of 236 Arabidopsis ecotypes failed to identify a single genotype that was extremely resistant or susceptible to Fusarium floral infections. Three Arabidopsis floral mutants that failed to develop anthers and/or functional pollen (i.e. agamous-1, apetala1-3 and dad1) were significantly less susceptible to Fusarium floral infection than wild type. Deoxynivalenol (DON) mycotoxin production was also detected in Fusarium-infected flowers at >1 ppm. This novel floral pathosystem for Arabidopsis appears to be highly representative of a serious cereal crop disease.

AGAMOUS Protein, Arabidopsis↗

PubMed1979

Comparative studies with regard to the influence of carbon and nitrogen ratio on sporulation in Fusarium oxysporum and Fusarium moniliforme v. subglutinans.

Carbon/nitrogen ratio as a factor for sporulation, expressed in terms of magnitude of population variation of macroconidia and microconidia in the cultures of Eusarium oxysporum Schlecht ex. Fr., Fusarium moniliforme v. subglutinans Wr. and Rg., and of chlamydospores (only in Fusarium oxysporum) was investigated. It has been found that the amount of carbon source shapes the course of macro- and micro. conidial production in a linear fashion, being enhanced parallel to the increase in its amount-Nitrogen level, limiting proliferation and effectively diminishing the macro- and micro-conidial population, varies for the two species, namely Fusarium oxysporum and Fusarium moniliforme v-subglutinans. For chlamydomspore production, higher carbon and still higher nitrogen concentration favours profuse proliferation in case of Fusarium oxysporum.

Carbon↗

PubMed2001

Suppression of maize root diseases caused by Macrophomina phaseolina, Fusarium moniliforme and Fusarium graminearum by plant growth promoting rhizobacteria.

A plant growth-promoting isolate of a fluorescent Pseudomonas sp. EM85 and two bacilli isolates MR-11(2) and MRF, isolated from maize rhizosphere, were found strongly antagonistic to Fusarium moniliforme, Fusarium graminearum and Macrophomina phaseolina, causal agents of foot rots and wilting, collar rots/stalk rots and root rots and wilting, and charcoal rots of maize, respectively. Pseudomonas sp. EM85 produced antifungal antibiotics (Afa+), siderophore (Sid+), HCN (HCN+) and fluorescent pigments (Flu+) besides exhibiting plant growth promoting traits like nitrogen fixation, phosphate solubilization, and production of organic acids and IAA. While MR-11(2) produced siderophore (Sid+), antibiotics (Afa+) and antifungal volatiles (Afv+), MRF exhibited the production of antifungal antibiotics (Afa+) and siderophores (Sid+). Bacillus spp. MRF was also found to produce organic acids and IAA, solubilized tri-calcium phosphate and fixed nitrogen from the atmosphere. All three isolates suppressed the diseases caused by Fusarium moniliforme, Fusarium graminearum and Macrophomina phaseolina in vitro. A Tn5:: lacZ induced isogenic mutant of the fluorescent Pseudomonas EM85, M23, along with the two bacilli were evaluated for in situ disease suppression of maize. Results indicated that combined application of the two bacilli significantly (P = 0.05) reduced the Macrophomina-induced charcoal rots of maize by 56.04%. Treatments with the MRF isolate of Bacillus spp. and Tn5:: lacZ mutant (M23) of fluorescent Pseudomonas sp. EM85 significantly reduced collar rots, root and foot rots, and wilting of maize caused by Fusarium moniliforme and F. graminearum (P = 0.05) compared to all other treatments. All these isolates were found very efficient in colonizing the rhizotic zones of maize after inoculation. Evaluation of the population dynamics of the fluorescent Pseudomonas sp. EM85 using the Tn5:: lacZ marker and of the Bacillus spp. MRF and MR-11(2) using an antibiotic resistance marker revealed that all the three isolates could proliferate successfully in the rhizosphere, rhizoplane and endorhizosphere of maize, both at 30 and 60 days after seeding. Four antifungal compounds from fluorescent Pseudomonas sp. EM85, one from Bacillus sp. MR-11(2) and three from Bacillus sp. MRF were isolated, purified and tested in vitro and in thin layer chromatography bioassays. All these compounds inhibited R. solani, M. phaseolina, F. moniliforme, F. graminearum and F. solani strongly. Results indicated that antifungal antibiotics and/or fluorescent pigment of fluorescent Pseudomonas sp. EM85, and antifungal antibiotics of the bacilli along with the successful colonization of all the isolates might be involved in the biological suppression of the maize root diseases.

Antibiosis↗

PubMed2026

Fusarium oxysporum f. sp. crypti, a novel forma specialis causing Fusarium wilt of mitsuba, Cryptotaenia japonica.

Fusarium oxysporum isolates causing Fusarium wilt in mitsuba (Cryptotaenia japonica Hassk.; also referred to as Japanese honeywort, Japanese honewort, or Japanese parsley) have traditionally been classified as f. sp. apii. However, some reports have indicated that the host-pathogenic F. oxysporum isolates derived from mitsuba are nonpathogenic to celery, the principal host of f. sp. apii. In this study, we aimed to elucidate the differences among isolates from mitsuba, coriander, and celery in terms of host range, phylogenetic relationships, genomic synteny, and effector profiles. Inoculation assays revealed a clear distinction in host range between the mitsuba, coriander, and celery isolates. Phylogenetic analyses based on the rDNA intergenic spacer and translation elongation factor sequences indicated a distant relationship between mitsuba isolates and those from coriander and celery. Whole-genome analysis based on high-quality de novo-assembled genomes, including telomere-to-telomere-level assemblies of isolates from mitsuba, coriander, and celery, showed that the mitsuba isolates possess conserved accessory chromosomal regions absent in celery and coriander isolates. Moreover, effector profiling identified a specific pattern of effector repertoires shared by the mitsuba isolates. These findings suggest that the host-pathogenic F. oxysporum isolates derived from mitsuba represent a forma specialis distinct from f. sp. apii. Thus, we propose designating the F. oxysporum isolates from mitsuba that cause Fusarium wilt as Fusarium oxysporum f. sp. crypti forma specialis nova.

Cryptotaenia japonica↗

PubMed1992

Cytotoxicity of Fusarium species mycotoxins and culture filtrates of Fusarium species isolated from the medicinal plant Tribulus terrestris to mammalian cells.

Ayurvedic medicine, which uses decoctions made of medicinal plants, is used to cure diseases in many Asian countries including Sri Lanka. Although proper storage facilities for medicinal plants are unavailable in Sri Lanka, neither the potential for growth of toxigenic fungi nor their ability to produce mycotoxins in stored medicinal plants has been investigated. We isolated three Fusarium species, F. culmorum, F. acuminatum and F. graminearum from the medicinal plant Tribulus terrestris. Culture extracts of the 3 Fusarium spp. were cytotoxic to mammalian cell lines BHK-21 and HEP-2. Three toxic metabolites produced by Fusarium spp; T-2 toxin, zearalenone, and diacetoxyscirpenol were also cytotoxic to the mammalian cell lines. The 3 Fusarium spp. grown on rice media produced zearalenone. Plant material destined for medicinal use should be stored under suitable conditions to prevent growth of naturally occurring toxigenic fungi prior to its use.

Animals↗

PubMed2006

Influence of plant root exudates, germ tube orientation and passive conidia transport on biological control of fusarium wilt by strains of nonpathogenic Fusarium oxysporum.

In earlier studies, biological control of Fusarium wilt of cucumber induced by Fusarium oxysporum f. sp. cucumerinum was demonstrated using nonpathogenic strains C5 and C14 of Fusarium oxysporum. Strain C14 induced resistance and competed for infection sites whether roots were wounded or intact, whereas strain C5 required wounds to achieve biocontrol. In the current work, additional attributes involved in enhanced resistance by nonpathogenic biocontrol agents strains to Fusarium wilt of cucumber and pea were further investigated. In pre-penetration assays, pathogenic formae specials exhibited a significantly higher percentage of spore germination in 4-day-old root exudates of cucumber and pea than nonpathogens. Also, strain C5 exhibited the lowest significant reduction in spore germination in contrast to strain C14 or control. One-day-old cucumber roots injected with strain C14 resulted in significant reduction in germ tube orientation towards the root surface, 48-96 h after inoculation with F. o. cucumerinum spores, whereas strain C5 induced significantly lower spore orientation of the pathogen and only at 72 and 96 h after inoculation. In post-penetration tests, passive transport of microconidia of pathogenic and nonpathogens in stems from base to apex were examined when severed plant roots were immersed in spore suspension. In repeated trials, strain C5, F. o. cucumerinum and F. o. pisi were consistently isolated from stem tissues of both cucumber and pea at increasing heights over a 17 days incubation period. Strain C14 however, was recovered at a maximum translocation distance of 4.6 cm at day 6 and later height of isolation significantly declined thereafter to 1.2 cm at day 17. In pea stem, the decline was even less. Significant induction of resistance to challenge inoculation by the pathogen in cucumber occurred 72 and 96 h after pre-inoculation with biocontrol agents. Nonetheless, strain C14 induced protection as early as 48 h and the maximum resistance was reached at 96 h. The presented data confirm the previous findings that attributes important for nonpathogenic fusaria to induce resistant are: rapid spore germination and orientation in response to root exudate; active root penetration and passive conidia transport in stem to initiate defence reaction without pathogenicity and enough lag period between induction and challenge inoculation. Strain C14 possesses all these qualifications and hence its ability to enhance host resistance is superior than strain C5.

Biological Transport↗