Fusaric Acid Research Articles

An fusaric acid-based CRISPR library screen identifies MDH2 as a broad-spectrum regulator of Fusarium toxin-induced cell death

Fusarium mycotoxins are of great concern because they are the most common food-borne mycotoxins and environmental contaminants worldwide. Fusaric acid (FA), Deoxynivalenol (DON), Zearalenone (ZEA), T-2 toxin (T-2), and Fumonisin B1 (FB1) are important Fusarium toxins contaminating feeds and food and can cause serious health problems. FA can synergize with some other Fusarium toxins to enhance overall toxicity. However, the underlying molecular mechanism remains poorly understood. In this study, our CRISPR screening revealed Malate dehydrogenase 2 (MDH2) and Pyruvate dehydrogenase E1 subunit beta (PDHB) are the key genes for FA-induced cell death. Pathways associated with mitochondrial function, notably the TCA cycle, play a significant role in FA cytotoxicity. We found that MDH2 and PDHB depletion reduced FA-induced cell death, ROS accumulation, and the expression of caspase-3 and HIF-1α. The cell viability assays and flow cytometry demonstrated that MDH2 knockout but not PDHB decreased DON, ZEA, T-2, and FB1-induced cytotoxicity, apoptosis, and ROS accumulation. MDH2 inhibitor LW6 also decreased DON, ZEA, T-2, and FB1-induced toxicity. This suggested that MDH2, but not PDHB, is a common regulator of broad-spectrum Fusarium toxin (FA, DON, ZEA, T-2, and FB1)-induced cell death. Our work provides new avenues for the treatment of Fusarium toxin toxicity.

Unlocking the Potential of Lactococcus lactis subsp. lactis BIONCL17752 strain on Fumonisin B1 production by Fusarium verticillioides

Mycotoxins are the potent toxic chemical agent's linked to food safety, pose a serious risk to human and animal health globally. The management of toxigenic fungi is a challenging task in food and feed industries. The present investigation aimed to use probiotic potentials of lactic acid bacteria (LAB), and fermented cell-free broth as antifungal agents and neutralization of carcinogenic mycotoxin, fumonisin B1 (FB1) in food and feed considered as “turned waste into treasure”. We strived to investigate the probiotic potential of Lactococcus lactis subsp. lactis BIONCL17752 strain on prevention of growth and neutralization of FB1 produced by Fusarium verticillioides BIONCL4 strain to emulate as as a food grade bio-preservative. The BIONCL17752 strain exhibited excellent inhibitory activity against BIONCL4 strain. It was cultivated in MRS medium, and obtained cells pellet (CP) and cell-free supernatant (CFS) was lyophilized, and used for their antifungal activity against BIONCL4 strain. The minimum fungicidal concentration (MFC) determined as 12.5 μg/mL. Nevertheless, CFS assessed for neutralization of FB1 production which exhibited complete inhibition and downregulation of FB1 encoding FUM1 gene expression using quantitative real-time PCR (qPCR). Furthermore, CFS induced transcriptomic studies against BIONCL4 strain endorsed a significant downregulation of virulence, FB1, fusaric acid, fusarin, and chitin biosynthetic pathway genes. The CFS and cells reticent spore germination and FB1 production in the range of 40–61% and 74–85%, respectively under stored maize for 60 days. The current findings suggest BIONCL17752 strain apprehend the fungal growth and inhibit the FB1, and other toxigenic molecules biosynthesis, and can be employed as food grade preservative in the food industries to ensure the food safety and human health.

Novel antibody- and aptamer-based approaches for sensitive detection of mycotoxin fusaric acid in cereal

This study presents the first successful generation of polyclonal antibodies (pAbs) and oligonucleotide aptamers specifically targeting fusaric acid (FA). Utilizing these pAbs and aptamers, three highly sensitive and specific assays were developed for the detection of FA in cereals with limits of detection (LOD) ranging from 5 to 50 ng/g: an antibody-based enzyme-linked immunosorbent assay (ELISA), an aptamer-based enzyme-linked aptamer-sorbent assay (ELASA), and a hybrid enzyme-linked aptamer-antibody sandwich assay (ELAAA). The recovery rates of FA in spiked cereal samples ranged from 87 % to 112 % across all assays. Analysis of 15 cereal feed samples revealed FA contamination levels of 459 to 1743 ng/g (ELISA), 427 to 1960 ng/g (ELASA), and 381 to 1987 ng/g (ELAAA). These results were further validated by HPLC analysis, confirming high consistency within developed assays. Overall, the ELISA, ELASA, and ELAAA are promising tools for the rapid detection of FA, significantly contributing to food safety monitoring.

Pathogen-driven Pseudomonas reshaped the phyllosphere microbiome in combination with Pseudostellaria heterophylla foliar disease resistance via the release of volatile organic compounds

BackgroundContinuous monocropping obstacles are common in plants, especially medicinal plants, resulting in disease outbreaks and productivity reductions. Foliar disease, mainly caused by Fusarium oxysporum, results in a severe decrease in the yield of Pseudostellaria heterophylla annually. Determining an effective biomethod to alleviate this disease is urgently needed to improve its productivity and quality.ResultsThis study screened thirty-two keystone bacterial genera induced by pathogens in P. heterophylla rhizosphere soil under continuous monocropping conditions. Pseudomonas, Chryseobacterium, and Flavobacterium, referred to as the beneficial microbiota, were significantly attracted by pathogen infection. The P. palleroniana strain B-BH16-1 can directly inhibit the growth and spore formation of seven primary pathogens of P. heterophylla foliar disease by disrupting fusaric acid production via the emission of volatile organic compounds (VOCs). In addition, strain B-BH16-1 enhances the disease resistance of P. heterophylla by obliterating the pathogen and assembling beneficial microbiota.ConclusionPathogen-induced Pseudomonas reshaped phyllosphere microbial communities via direct antagonism of pathogens and indirect disruption of the pathogen virulence factor biosynthesis to enhance disease suppression and improve yields. These results show that inhibiting pathogen virulence biosynthesis to reshape the plant microbial community using disease-induing probiotics will be an innovative strategy for managing plant disease, especially under continuous monoculture conditions.

Fusarium andiyazi, a Pathogenic Species Associated with Rice Bakanae Disease in Malaysia.

Rice is the main staple food crops for the Malaysian population. Rice is also susceptible to bakanae diseases caused by some Fusarium species and reducing yield, and quality of rice also profit. In this study, several rice fields were surveyed to collect Fusarium isolates associated with bakanae disease. The morphological features of Fusarium andiyazi isolates found on infected rice plants were identified in this investigation. For biological species identification, MAT-1 (Mating type idiomorphs) bearing isolates were crossed with MAT-2 isolates. Crossing was succeeded between cross of two different mating type bearing field isolates. Consequently, there is a possibility of exchange of genetic material within the F. andiyazi population in Malaysia. The identity of the isolates was further determined up to the species level by comparing DNA sequences and phylogenetic analysis of two genes. The phylogenetic analyses of the joined dataset of translation elongation factor 1-alpha (TEF1-α) and RNA polymerase subunit II (RPB2) revealed that all the isolates were F. andiyazi. In pathogenicity tests, F. andiyazi were found to be pathogenic on the susceptible rice cultivars MR211 and MR220. Inoculated rice seedling produced typical bakanae symptom like elongation, thin and yellow leaves. F. andiyazi was further confirmed as pathogenic species by Ultra High-Performance Liquid Chromatography (UPLC) detection of Gibberellic acid (GA3) and Fusaric acid. In this study, F. andiyazi strains have been identified as the responsible pathogen for causing rice bakanae disease in Malaysia and it is the first report of F. andiyazi, as a pathogenic species on rice in Malaysia.

Low molecular weight acids differentially impact Fusarium verticillioides transcription

Fusarium verticillioides is both an endophyte and pathogen of maize. During growth on maize, the fungus often synthesizes the mycotoxins fumonisins, which have been linked to a variety of diseases, including cancer in some animals. How F. verticillioides responds to other fungi, such as Fusarium proliferatum, Aspergillus flavus, Aspergillus niger, and Penicillium oxalicum, that coinfect maize, has potential to impact mycotoxin synthesis and disease. We hypothesize that low molecular weight acids produced by these fungi play a role in communication between the fungi in planta/nature. To address this hypothesis, we exposed 48-h maize kernel cultures of F. verticillioides to oxalic acid, citric acid, fusaric acid, or kojic acid and then compared transcriptomes after 30 min and 6 h. Transcription of some genes were affected by multiple chemicals and others were affected by only one chemical. The most significant positive response was observed after exposure to fusaric acid which resulted in >2-fold upregulation of 225 genes, including genes involved in fusaric acid synthesis. Exposure of cultures to the other three chemicals increased expression of only 3–15 genes. The predicted function and frequent co-localization of three sets of genes support a role in protecting the fungus from the chemical or a role in catabolism. These unique transcriptional responses support our hypothesis that these chemicals can act as signaling molecules. Studies with gene deletion mutants will further indicate if the initial transcriptional response to the chemicals benefit F. verticillioides.

Pseudomonas and Acinetobacter spp. capable of metabolizing aromatics displays multifarious plant growth promoting traits: Insights on strategizing consortium-based application to agro-ecosystems

The persistence and slow rate of natural attenuation of genotoxic and endocrine-disrupting aromatic pollutants has impacted the soil heath of agro-ecologies leading to various health and environmental issues. Ecotoxic-xenobiotic compounds degradation property along with plant growth promoting traits of microbes are beneficial for devising strategies for improved agricultural soil health and its clean-up. Present study assessed the multipartite plant growth promoting-, biocontrol- and niche adaptive- traits of five aromatic degrading soil bacteria viz. Pseudomonas bharatica CSV86T, Pseudomonas sp. C5pp, Pseudomonas sp. PP4, Pseudomonas sp. PPD and Acinetobacter sp. ISP4. Solubilization of rock phosphate (P) and feldspar (K), production of plant growth hormone (auxin; IAA), ammonia, siderophores and ACC deaminase by strain CSV86T, C5pp and PP4 were observed. Similarly, high fusaric acid resistance (MIC: 1–1.2 mg mL−1) and tolerance to salinity (5–7.5 %) was observed. In vitro application of CSV86T, C5pp, PP4 and ISP4 as consortium resulted in significant increase (P < 0.05) in the seedling shoot length (15–37 %), root length (65–150 %) and biomass (30–40 %) of wheat, mung bean and fenugreek. In-soil microcosm assay confirmed the plant growth promoting and phytoprotective ability of this consortium against toxicity of aromatics in contaminated soil. Antifungal activity against phytopathogenic fungi Magnaporthe oryzae and Aspergillus spp., ability to produce lytic enzymes and HCN suggests their biocontrol potential. Four aromatic degrading bacteria (as a consortium) exhibiting plant growth promotion and biocontrol activity could be used as an eco-friendly bioremediator-biofertilizer-biocontrol agent (bioformulation) for restoration of agricultural soil with improved crop productivity.

Metabolic engineering of Pseudomonas bharatica CSV86T to degrade Carbaryl (1-naphthyl-N-methylcarbamate) via the salicylate-catechol route.

Pseudomonas bharatica CSV86T displays the unique property of preferential utilization of aromatic compounds over simple carbon sources like glucose and glycerol and their co-metabolism with organic acids. Well-characterized growth conditions, aromatic compound metabolic pathways and their regulation, genome sequence, and advantageous eco-physiological traits (indole acetic acid production, alginate production, fusaric acid resistance, organic sulfur utilization, and siderophore production) make it an ideal host for metabolic engineering. Strain CSV86T was engineered for Carbaryl (1-naphthyl-N-methylcarbamate) degradation via salicylate-catechol route by expression of a Carbaryl hydrolase (CH) and a 1-naphthol 2-hydroxylase (1NH). Additionally, the engineered strain exhibited faster growth on Carbaryl upon expression of the McbT protein (encoded by the mcbT gene, a part of Carbaryl degradation upper operon of Pseudomonas sp. C5pp). Bioinformatic analyses predict McbT to be an outer membrane protein, and Carbaryl-dependent expression suggests its probable role in Carbaryl uptake. Enzyme activity and protein analyses suggested periplasmic localization of CH (carrying transmembrane domain plus signal peptide sequence at the N-terminus) and 1NH, enabling compartmentalization of the pathway. Enzyme activity, whole-cell oxygen uptake, spent media analyses, and qPCR results suggest that the engineered strain preferentially utilizes Carbaryl over glucose. The plasmid-encoded degradation property was stable for 75-90 generations even in the absence of selection pressure (kanamycin or Carbaryl). These results indicate the utility of P. bharatica CSV86T as a potential host for engineering various aromatic compound degradation pathways.IMPORTANCEThe current study describes engineering of Carbaryl metabolic pathway in Pseudomonas bharatica CSV86T. Carbaryl, a naphthalene-derived carbamate pesticide, is known to act as an endocrine disruptor, mutagen, cytotoxin, and carcinogen. Removal of xenobiotics from the environment using bioremediation faces challenges, such as slow degradation rates, instability of the degradation phenotype, and presence of simple carbon sources in the environment. The engineered CSV86-MEC2 overcomes these disadvantages as Carbaryl was degraded preferentially over glucose. Furthermore, the plasmid-borne degradation phenotype is stable, and presence of glucose and organic acids does not repress Carbaryl metabolism in the strain. The study suggests the role of outer membrane protein McbT in Carbaryl transport. This work highlights the suitability of P. bharatica CSV86T as an ideal host for engineering aromatic pollutant degradation pathways.

A ribonuclease T2 protein FocRnt2 contributes to the virulence of Fusarium oxysporum f. sp. cubense tropical race 4.

Banana Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), is a major disease of banana plants worldwide. Effector proteins play critical roles in banana-Foc TR4 interaction. Our previous studies highlighted a ribonuclease protein belonging to the T2 family (named as FocRnt2) in the Foc TR4 secretome, which was predicted to be an effector. However, its biological function in Foc TR4 infection is still unclear. Herein, we observed significant expression of FocRnt2 during the early stage of fungal infection in planta. A yeast signal sequence trap assay showed that FocRnt2 contained a functional signal peptide for secretion. FocRnt2 possessed ribonuclease activity that could degrade the banana total RNA invitro. Subcellular localization showed that FocRnt2 was localized in the nucleus and cytoplasm of Nicotiana benthamiana leaves. Transient expression of FocRnt2 suppressed the expression of salicylic acid- and jasmonic acid-signalling marker genes, reactive oxygen species accumulation, and BAX-mediated cell death in N. benthamiana. FocRnt2 deletion limited fungal penetration, reduced fusaric acid biosynthesis in Foc TR4, and attenuated fungal virulence against banana plants, but had little effect on Foc TR4 growth and sensitivity to various stresses. Furthermore, FocRnt2 deletion mutants induced higher expression of the defence-related genes in banana plants. These results suggest that FocRnt2 plays an important role in full virulence of Foc TR4, further improving our understanding of effector-mediated Foc TR4 pathogenesis.

New insights into the anti-inflammatory and anti-melanoma mechanisms of action of azelaic acid and other Fusarium solani metabolites via in vitro and in silico studies

Metabolites exploration of the ethyl acetate extract of Fusarium solani culture broth that was isolated from Euphorbia tirucalli root afforded five compounds; 4-hydroxybenzaldehyde (1), 4-hydroxybenzoic acid (2), tyrosol (3), azelaic acid (4), malic acid (5), and fusaric acid (6). Fungal extract as well as its metabolites were evaluated for their anti-inflammatory and anti-hyperpigmentation potential via in vitro cyclooxygenases and tyrosinase inhibition assays, respectively. Azelaic acid (4) exhibited powerful and selective COX-2 inhibition followed by fusaric acid (6) with IC50 values (2.21 ± 0.06 and 4.81 ± 0.14 μM, respectively). As well, azelaic acid (4) had the most impressive tyrosinase inhibitory effect with IC50 value of 8.75 ± 0.18 μM compared to kojic acid (IC50 = 9.27 ± 0.19 μM). Exclusive computational studies of azelaic acid and fusaric acid with COX-2 were in good accord with the in vitro results. Interestingly, this is the first time to investigate and report the potential of compounds 3–6 to inhibit cyclooxygenase enzymes. One of the most invasive forms of skin cancer is melanoma, a molecular docking study using a set of enzymes related to melanoma suggested pirin to be therapeutic target for azelaic acid and fusaric acid as a plausible mechanism for their anti-melanoma activity.

Fusaric acid mediates the assembly of disease-suppressive rhizosphere microbiota via induced shifts in plant root exudates

The plant health status is determined by the interplay of plant-pathogen-microbiota in the rhizosphere. Here, we investigate this tripartite system focusing on the pathogen Fusarium oxysporum f. sp. lycopersici (FOL) and tomato plants as a model system. First, we explore differences in tomato genotype resistance to FOL potentially associated with the differential recruitment of plant-protective rhizosphere taxa. Second, we show the production of fusaric acid by FOL to trigger systemic changes in the rhizosphere microbiota. Specifically, we show this molecule to have opposite effects on the recruitment of rhizosphere disease-suppressive taxa in the resistant and susceptible genotypes. Last, we elucidate that FOL and fusaric acid induce changes in the tomato root exudation with direct effects on the recruitment of specific disease-suppressive taxa. Our study unravels a mechanism mediating plant rhizosphere assembly and disease suppression by integrating plant physiological responses to microbial-mediated mechanisms in the rhizosphere.

Modes of action of Trichoderma virens Gl006 and Bacillus velezensis Bs006: decoding the arsenal of the microbial consortium

The consortium based on Trichoderma virens Gl006 and Bacillus velezensis Bs006 was selected in a previous study because the high effectiveness against Fusarium wilt of cape gooseberry (Fusarium oxysporum f. sp. physali—Foph). The compatibility among the strains was determined previously, but the modes of action exerted by the consortium remained unknown. In this study, the modes of action displayed by the Gl006 and Bs006 consortium against the Foph strain Map5 were determined and compared with the modes of action of the single microorganisms. Production of cell wall degrading enzymes (CWDE), cyclic lipopeptides (CLPs) by Bs006 and gliotoxin by Gl006, and fusaric acid (FA) production by Foph were evaluated in the co-culture of the strains in several culture media. Furthermore, the survival of the strains in the soil, the colonization of plant tissues and the induction of systemic responses through a split root model bioassay were evaluated. While Bs006 showed protease, β-1,3-glucanase, and chitobiosidase enzymatic activities, and production of CLPs, Gl006 showed β-N-acetylglucosaminidase, chitobiosidase, total chitinase, β-1,3-glucanase, and protease activities. All the metabolites produced by the single strains were also found in the consortium, but in a culture medium dependent manner. The FA was found in the experiment on the interaction of the consortium with Foph Map5 in the minimal basal medium and in potato dextrose broth. The population of Foph was reduced by the consortium in vitro, under the synthetic media that favored the production of all the CWDE tested. In soil conditions, the consortium reduced the population of Foph by 63% in a synergistic way. Bs006 was recovered from the inner tissues of the plant, where Gl006 prevented the entry of Foph to the roots and reduced the incidence of the disease under the split root model. These results suggest that the consortium of Gl006 and Bs006 displays modes of action through CWDE and CLP´s and indirectly through induction of systemic resistance, which could act complementary since neither of them were enhanced in consortium. Here we characterized a consortium capable of reducing the population of Foph in soil and control the disease in a synergistic way.

A copper(II)-based complex from mangrove endophytic fungus Fusarium proliferatum inhibits ovarian cancer in vitro via VEGF/VEGFR2 pathways and apoptosis factors

From a mangrove endophytic fungus, Fusarium proliferatum, four compounds were isolated. These compounds include a copper(II)-based complex (1), its ligand fusaric acid (2), and two fusaric acid derivatives (3, 4). Among them, compounds 1 and 4 are undescribed natural compounds. The elucidation of their structures, including absolute configurations, was accomplished through a combination of analytical techniques, including nuclear magnetic resonance (NMR), mass spectrometry (MS), and single-crystal X-ray analysis. Compound 1 has exhibited inhibitory effects on the growth of ovarian cancer SKOV3 in vitro, primarily through its induction of mitochondrial membrane potential collapse in SKOV3 cells. Additionally, it has demonstrated the ability to activate key signaling molecules within the vascular endothelial growth factor (VEGF) pathway, particularly focal adhesion kinase (FAK) and its phosphorylated form (p-FAK), as well as protein kinase B (AKT) and its phosphorylated form (p-AKT), and extracellular signal-regulated kinases 1/2 (ERK1/2) and their phosphorylated forms (p-ERK1/2). As a result of these findings, compound 1 is now considered a promising copper-based candidate for both anticancer and antiangiogenic therapeutic applications.

Exogenous application of mycotoxin fusaric acid improve the morphological, cytogenetic, biochemical and anatomical parameters in salt (NaCl) stressed Allium cepa L.

Salinity is one of the most important abiotic stress factors that negatively affect plant growth and development. In contrast, fusaric acid (FA), a mycotoxin produced by Fusarium and Giberella fungal genera, has biological and metabolic effects in various plants. In this study, it was aimed to investigate the protective effect of externally applied FA (0.1 nM) against the damage caused by salt (0.15 M NaCl) stress in onion (Allium cepa L.) plant. Salt stress resulted in an increase in the chromosomal aberrations (CAs) and micronucleus (MN) frequency, a decrease in the mitotic index (MI), fresh weight, root number, germination percentage, and root length. It promoted CAs such as irregular mitosis, bilobulated nuclei, chromosome loss, bridge, unequal seperation of chromosome, vagrant chromosome and polar slip in root meristem cells. In addition, salt stress caused a enhancement in free proline (PR), catalase (CAT), superoxide dismutase (SOD) and malondialdehyde (MDA) contents in the roots of onion plant. Moreover, it revealed damage and changes that include the accumulation of some chemical substances such as proline and sugars in epidermis and cortex layer cells, epidermal cell injury, flattening of the cell nucleus, wall thickening in cortex cells, necrotic areas and indistinct transmission tissue in the anatomical structure of onion roots. On the other hand, FA application promoted bulb germination and mitotic activity, strengthened the antioxidant defense system, and reduced chromosome and anatomical structure damages. In conclusion; it has been revealed that exogenous FA application may have a positive effect on increasing the resistance of onion plants to salt stress.

Secondary metabolites and transcriptomic analysis of novel pulcherrimin producer Metschnikowia persimmonesis KIOM G15050: A potent and safe food biocontrol agent

Metschnikowia persimmonesis, a novel endophytic yeast strain isolated from Diospyros kaki calyx, possesses strong antimicrobial activity. We investigated its potential use as an environmentally safe food biocontrol agent through genomics, transcriptomics, and metabolomics. Secondary metabolites were isolated from M. persimmonesis, followed by chemical structure elucidation, PUL gene cluster identification, and RNA sequencing. Pulcherrimin was isolated using 2 M NaOH, its structure was confirmed, and the yield was quantified. Biocontrol efficacy of M. persimmonesis on persimmon fruits and calyx was evaluated by assessing lesion diameter and disease incidence. Following compounds were isolated from M. persimmonesis co-culture with Botrytis cinerea and Fusarium oxysporum: fusaric acid, benzoic acid, benzeneacetic acid, 4-hydroxybenzeneacetic acid, 4-(-2-hydoxyethyl)-benzoic acid, cyclo (Leu-Leu), benzenemethanol, 4-hydroxy-benzaldehide, 2-hydroxy-4-methoxy-benzoic acid, 4-hydroxy-benzoic acid, lumichrome, heptadecanoic acid, and nonadecanoic acid. Exposing M. persimmonesis to different growth media conditions (with or without sugar) resulted in the isolation of five compounds: Tyrosol, Cyclo (Pro-Val), cyclo(L-Pro-L-Tyr), cyclo(Leu-Leu), and cyclo(l-tyrosilylicine). Differentially expressed gene analysis revealed 3264 genes that were significantly expressed (fold change ≥2 and p-value ≤0.05) during M. persimmonesis growth in different media, of which only 270 (8.27%) showed altered expression in all sample combinations with Luria–Bertani Agar as control. Minimal media with ferric ions and tween-80 triggered the most gene expression changes, with the highest levels of PUL gene expression and pulcherrimin yield (262.166 mg/L) among all media treatments. M. persimmonesis also produced a higher amount of pulcherrimin (209.733 mg/L) than Metschnikowia pulcherrima (152.8 mg/L). M. persimmonesis inhibited the growth of Fusarium oxysporum in persimmon fruit and calyx. Toxicity evaluation of M. persimmonesis extracts showed no harmful effects on the liver and mitochondria of zebrafish, and no potential risk of cardiotoxicity in hERG-HEK293 cell lines. Thus, M. persimmonesis can be commercialized as a potent and safe biocontrol agent for preserving food products.

Endophytic Alternaria and Fusarium species associated to potato plants (Solanum tuberosum L.) in Iran and their capability to produce regulated and emerging mycotoxins

Endophytic fungi live inside virtually every plant species, without causing any apparent disease or damage to the host. Nevertheless, under particular conditions, mutualistic lifestyle of endophytes may change to pathogenic. In this study, the biodiversity of Alternaria and Fusarium species, the two most abundant endophytic fungi isolated from healthy potato plants in two climatically different regions of Iran, Ardebil in the north-west and Kerman in the south-east, was investigated. Seventy-five Fusarium strains and 83 Alternaria strains were molecularly characterized by multi-locus gene sequencing. Alternaria strains were characterized by the sequences of gpd and caM gene fragments and the phylogenetic tree was resolved in 3 well-separated clades. Seventy-three strains were included in the clade A, referred as Alternaria section, 6 strains were included in clade B, referred as Ulocladioides section, and 4 strains were included in clade C, referred as Infectoriae section. Fusarium strains, identified by sequencing the translation elongation factor 1α (tef1), β-tubulin (tub2) and internal transcribed spacer (ITS) genomic regions, were assigned to 13 species, viz. F. brachygibosum, F. clavum, F. equiseti, F. flocciferum, F. incarnatum, F. nirenbergiae, F. nygamai, F. oxysporum, F. proliferatum, F. redolens, F. sambucinum, F. solani and F. thapsinum. Twenty-six selected strains, representative of F. equiseti, F. nirenbergiae, F. oxysporum, F. nygamai, F. proliferatum, and F. sambucinum, were also tested for production of the mycotoxins deoxynivalenol (DON), nivalenol (NIV), diacetoxyscirpenol (DAS), T-2 toxin (T-2), beauvericin (BEA), enniatins (ENNs), fumonisins (FBs), fusaric acid (FA) and moniliformin (MON). None of the tested strains produced trichothecene toxins (DON, NIV, DAS and T-2). Two out of 2 F. equiseti isolates, 1/6 F. oxysporum, 1/3 F. proliferatum, and 1/9 F. nygamai did not produce any of the tested toxins; the rest of strains produced one or more BEA, ENNs, FBs, FA and MON toxins. The most toxigenic strain, F. nygamai ITEM-19012, produced the highest quantities of FBs (7946, 4693 and 4333 μg/g of B1, B2, and B3 respectively), along with the highest quantities of both BEA (4190 μg/g) and MON (538 μg/g). These findings suggest that contamination of potato tubers with mycotoxins in the field or at post-harvest, due to a change in lifestyle of endophytic microflora, should be carefully considered and furtherly investigated.

Complete genome sequence of Bacillus velezensis B31, a potential biocontrol agent with ability of tolerance to fusaric acid and antagonism against Fusarium oxysporum.

Bacillus velezensis B31 is tolerant to fusaric acid, exhibits antagonism against Fusarium oxysporum, and has an excellent control effect on tomato fusarium wilt. Here, we present the complete genome sequence of B31, which contains 4,056,755 bp DNA with a G + C ratio of 46.39%. The genome has 3,838 protein-coding genes.

Effect of culture filtrate containing fusaric acid of Fusarium oxysporum f. sp. ciceris on defence enzymes in chickpea

Effect of culture filtrate containing fusaric acid of Fusarium oxysporum f. sp. ciceris on defence enzymes in chickpea

In vitro production of gibberellic acid and fusaric acid by Fusarium spp. and their role in bakanae disease development

Gibberellic acid (GA3) and fusaric acid (FA) are directly correlated with the symptom development of bakanae disease in rice plants. The role of GA3 and FA, produced in vitro by several Fusarium species associated with bakanae disease, was studied to understand the disease’s etiology and its impact on symptom development. In total, 121 Fusarium strains were obtained from bakanae-infected rice plants collected from various rice cultivation regions in Bangladesh. Finally, 18 highly virulent Fusarium strains were selected based on virulence assay and further evaluated for GA3 and FA production through ultra-performance liquid chromatography analysis. Among the Fusarium strains, Fusarium fujikuroi strains produced a high amount of GA3 and a low amount of FA. In contrast, Fusarium proliferatum and Fusarium verticillioides strains produced a high amount of FA and a low amount of GA3. In exception, the Fusarium strain BD117R of F. fujikuroi produced no GA3 but a high amount of FA. Interestingly, Fusarium commune produced only FA in high concentration. In bakanae disease development, GA3 production was positively related to elongation symptoms whereas FA contributes to stunting symptoms. This is the first record of the production of GA3 and FA by Fusarium species causing bakanae disease of rice in Bangladesh.

Involvement of FoVEL1 and FoLAE1 in conidiation, virulence and secondary metabolism of Fusarium oxysporum f. sp. Niveum

The velvet protein family plays a key factor in coordinating development and secondary metabolism in many pathogenic fungi. However, no previous research has investigated the function of the velvet protein family in Fusarium oxysporum f. sp. Niveum (FON), which causes a highly destructive disease on watermelon. In this study, ∆fovel1 and ∆folae1 deletion mutants and ∆fovel1-C and ∆folae1-C corresponding complementation mutants of FON were confirmed. Meanwhile, effects of phenotype, biochemistry and virulence of the deletion mutants were protected. Compared with the wild-type strains, the ∆fovel1 and ∆folae1 mutants showed different mycelia phenotype, depressed of conidiation and reduced production of bikaverin and fusaric acid. Moreover, their virulence on watermelon plant roots was significant decreased. In addition, all of these alterations in mutants were restored in corresponding complementation strains. Importantly, yeast two hybrid results indicated an interaction relationship between FoVel1 and FoLae1. The results of this study indicated that FoVEL1 and FoLAE1 play critical roles in secondary metabolisms, conidiation, and virulence in FON. These information will deepen our understanding on the genetic and functional roles of the VEL1 and LAE1 in pathogenic fungi.