Amylopectin Induces Fumonisin B1 Production by Fusarium verticillioides During Colonization of Maize Kernels

Fusarium verticillioides, a fungal pathogen of maize, produces fumonisin mycotoxins that adversely affect human and animal health. Basic questions remain unanswered regarding the interactions between the host plant and the fungus that lead to the accumulation of fumonisins in maize kernels. In this study, we evaluated the role of kernel endosperm composition in regulating fumonisin B1 (FB1) biosynthesis. We found that kernels lacking starch due to physiological immaturity did not accumulate FB1. Quantitative polymerase chain reaction analysis indicated that kernel development also affected the expression of fungal genes involved in FB1 biosynthesis, starch metabolism, and nitrogen regulation. A mutant strain of F. verticillioides with a disrupted α-amylase gene was impaired in its ability to produce FB1 on starchy kernels, and both the wild-type and mutant strains produced significantly less FB1 on a high-amylose kernel mutant of maize. When grown on a defined medium with amylose as the sole carbon source, the wild-type strain produced only trace amounts of FB1, but it produced large amounts of FB1 when grown on amylopectin or dextrin, a product of amylopectin hydrolysis. We conclude that amylopectin induces FB1 production in F. verticillioides. This study provides new insight regarding the interaction between the fungus and maize kernel during pathogenesis and highlights important areas that need further study.

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HXK1 regulates carbon catabolism, sporulation, fumonisin B1 production and pathogenesis in Fusarium verticillioides

Microbiology ◽

10.1099/mic.0.052506-0 ◽

2011 ◽

Vol 157 (9) ◽

pp. 2658-2669 ◽

Cited By ~ 23

Author(s):

Hun Kim ◽

Jonathon E. Smith ◽

John B. Ridenour ◽

Charles P. Woloshuk ◽

Burton H. Bluhm

Keyword(s):

Carbon Source ◽

Regulatory Networks ◽

Sole Carbon Source ◽

Metabolic Response ◽

Fusarium Verticillioides ◽

Fumonisin B1 ◽

Genetic Regulatory Networks ◽

Wild Type ◽

Increased Sensitivity ◽

Maize Kernels

In Fusarium verticillioides, a ubiquitous pathogen of maize, virulence and mycotoxigenesis are regulated in response to the types and amounts of carbohydrates present in maize kernels. In this study, we investigated the role of a putative hexokinase-encoding gene (HXK1) in growth, development and pathogenesis. A deletion mutant (Δhxk1) of HXK1 was not able to grow when supplied with fructose as the sole carbon source, and growth was impaired when glucose, sucrose or maltotriose was provided. Additionally, the Δhxk1 mutant produced unusual swollen hyphae when provided with fructose, but not glucose, as the sole carbon source. Moreover, the Δhxk1 mutant was impaired in fructose uptake, although glucose uptake was unaffected. On maize kernels, the Δhxk1 mutant was substantially less virulent than the wild-type, but virulence on maize stalks was not impaired, possibly indicating a metabolic response to tissue-specific differences in plant carbohydrate content. Finally, disruption of HXK1 had a pronounced effect on fungal metabolites produced during colonization of maize kernels; the Δhxk1 mutant produced approximately 50 % less trehalose and 80 % less fumonisin B1 (FB1) than the wild-type. The reduction in trehalose biosynthesis likely explains observations of increased sensitivity to osmotic stress in the Δhxk1 mutant. In summary, this study links early events in carbohydrate sensing and glycolysis to virulence and secondary metabolism in F. verticillioides, and thus provides a new foothold from which the genetic regulatory networks that underlie pathogenesis and mycotoxigenesis can be unravelled and defined.

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Comparative Proteomics Reveals the Potential Targets of BcNoxR, a Putative Regulatory Subunit of NADPH Oxidase of Botrytis cinerea

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-11-16-0227-r ◽

2016 ◽

Vol 29 (12) ◽

pp. 990-1003 ◽

Cited By ~ 20

Author(s):

Hua Li ◽

Zhanquan Zhang ◽

Chang He ◽

Guozheng Qin ◽

Shiping Tian

Keyword(s):

Nadph Oxidase ◽

Botrytis Cinerea ◽

Proteomic Analysis ◽

Fungal Pathogens ◽

Molecular Mechanisms ◽

Quantitative Polymerase Chain Reaction ◽

Tomato Fruit ◽

Polymerase Chain Reaction Analysis ◽

Regulatory Subunit ◽

Wild Type

The NADPH oxidase (NOX) complex has been shown to play a crucial role in stress response and in the virulence of various fungal pathogens. The underlying molecular mechanisms of NOX, however, remain largely unknown. In the present study, a comparative proteomic analysis compared changes in protein abundance in wild-type Botrytis cinerea and ΔbcnoxR mutants in which the regulatory subunit of NOX was deleted. The ΔbcnoxR mutants exhibited reduced growth, sporulation, and impaired virulence. A total of 60 proteins, representing 49 individual genes, were identified in ΔbcnoxR mutants that exhibited significant differences in abundance relative to wild-type. Reverse transcription-quantitative polymerase chain reaction analysis demonstrated that the differences in transcript levels for 36 of the genes encoding the identified proteins were in agreement with the proteomic analysis, while the remainder exhibited reverse levels. Functional analysis of four proteins that decreased abundance in the ΔbcnoxR mutants indicated that 6-phosphogluconate dehydrogenase (BcPGD) played a role in the growth and sporulation of B. cinerea. The Δbcpgd mutants also displayed impaired virulence on various hosts, such as apple, strawberry, and tomato fruit. These results suggest that NOX can influence the expression of BcPGD, which has an impact on growth, sporulation, and virulence of B. cinerea.

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PAC1, a pH-Regulatory Gene from Fusarium verticillioides

Applied and Environmental Microbiology ◽

10.1128/aem.69.9.5222-5227.2003 ◽

2003 ◽

Vol 69 (9) ◽

pp. 5222-5227 ◽

Cited By ~ 116

Author(s):

Joseph E. Flaherty ◽

Anna Maria Pirttilä ◽

Burton H. Bluhm ◽

Charles P. Woloshuk

Keyword(s):

Fusarium Verticillioides ◽

Regulatory Gene ◽

Synthetic Medium ◽

Transcriptional Regulators ◽

Acidic Ph ◽

Alkaline Ph ◽

Wild Type ◽

Ph Responsive ◽

Alkaline Conditions ◽

Maize Kernels

ABSTRACT Fumonisins are a group of mycotoxins that contaminate maize and cause leukoencephalomalacia in equine, pulmonary edema in swine, and promote cancer in mice. Fumonisin biosynthesis in Fusarium verticillioides is repressed by nitrogen and alkaline pH. We cloned a PACC-like gene (PAC1) from F. verticillioides. PACC genes encode the major transcriptional regulators of several pH-responsive pathways in other filamentous fungi. In Northern blot analyses, a PAC1 probe hybridized to a 2.2-kb transcript present in F. verticillioides grown at alkaline pH. A mutant of F. verticillioides with a disrupted PAC1 gene had severely impaired growth at alkaline pH. The mutant produced more fumonisin than the wild type when grown on maize kernels and in a synthetic medium buffered at an acidic pH, 4.5. The mutant, but not the wild type, also produced fumonisin B1 when mycelia were resuspended in medium buffered at an alkaline pH, 8.4. Transcription of FUM1, a gene involved in fumonisin biosynthesis, was correlated with fumonisin production. We conclude that PAC1 is required for growth at alkaline pH and that Pac1 may have a role as a repressor of fumonisin biosynthesis under alkaline conditions.

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Fusarium Species and Mycotoxins Contaminating Veterinary Diets for Dogs and Cats

Microorganisms ◽

10.3390/microorganisms7010026 ◽

2019 ◽

Vol 7 (1) ◽

pp. 26 ◽

Cited By ~ 4

Author(s):

Natalia Witaszak ◽

Łukasz Stępień ◽

Jan Bocianowski ◽

Agnieszka Waśkiewicz

Keyword(s):

Animal Feed ◽

Fusarium Species ◽

Fusarium Verticillioides ◽

Animal Health ◽

Companion Animals ◽

Fumonisin B1 ◽

Additional Risk ◽

Two Samples ◽

The Mean ◽

The Eu

Veterinary diets are intended for diseased animals and may contain cereal grains, mainly maize and/or wheat. These, in turn, are often infected with pathogens of the Fusarium genus, which are able to produce numerous harmful mycotoxins. Forty-two samples of veterinary diets for dogs and cats were analyzed for the presence of Fusarium species and mycotoxins. Species were identified using molecular methods and the ergosterol and mycotoxins (fumonisin B1, deoxynivalenol, nivalenol and zearalenone) were quantified using HPLC methods. Two Fusarium species were identified: Fusarium proliferatum and Fusarium verticillioides. The highest concentrations of fumonisin B1, deoxynivalenol, nivalenol and zearalenone were 74.83, 2318.05, 190.90, and 45.84 ng/g, respectively. Only 9.5% of the samples were free from Fusarium mycotoxins. The acceptable limits of mycotoxin content in animal feed, specified by the EU regulations, were not exceeded in any of the samples tested. The mean mycotoxin content in veterinary diets for cats was lower than for dogs. Thus, it is recommended that veterinary diets are examined, since the mycotoxin contamination pose additional risk to animal health. The knowledge on Fusarium occurrence in veterinary diets is scarce and as far as we are aware this is the first report concerning the occurrence of Fusarium spp. and their important secondary metabolites—mycotoxins—in different types of veterinary diets for companion animals in Poland.

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In planta reduction of maize seedling stalk lesions by the bacterial endophyteBacillus mojavensis

Canadian Journal of Microbiology ◽

10.1139/w11-031 ◽

2011 ◽

Vol 57 (6) ◽

pp. 485-492 ◽

Cited By ~ 20

Author(s):

Charles W. Bacon ◽

Dorothy M. Hinton

Keyword(s):

Fusarium Verticillioides ◽

Fusaric Acid ◽

Maize Seedling ◽

Wild Type ◽

In Planta ◽

Lesion Development ◽

Bacillus Mojavensis ◽

Acid Tolerant ◽

Bacteria And Fungi ◽

Maize Kernels

Maize ( Zea mays L.) is susceptible to infection by Fusarium verticillioides through autoinfection and alloinfection, resulting in diseases and contamination of maize kernels with the fumonisin mycotoxins. Attempts at controlling this fungus are currently being done with biocontrol agents such as bacteria, and this includes bacterial endophytes, such as Bacillus mojavensis . In addition to producing fumonisins, which are phytotoxic and mycotoxic, F. verticillioides also produces fusaric acid, which acts both as a phytotoxin and as an antibiotic. The question now is Can B. mojavensis reduce lesion development in maize during the alloinfection process, simulated by internode injection of the fungus? Mutant strains of B. mojavensis that tolerate fusaric acid were used in a growth room study to determine the development of stalk lesions, indicative of maize seedling blight, by co-inoculations with a wild-type strain of F. verticillioides and with non-fusaric acid producing mutants of F. verticillioides. Lesions were measured on 14-day-old maize stalks consisting of treatment groups inoculated with and without mutants and wild-type strains of bacteria and fungi. The results indicate that the fusaric-acid-tolerant B. mojavensis mutant reduced stalk lesions, suggesting an in planta role for this substance as an antibiotic. Further, lesion development occurred in maize infected with F. verticillioides mutants that do not produce fusaric acid, indicating a role for other phytotoxins, such as the fumonisins. Thus, additional pathological components should be examined before strains of B. mojavensis can be identified as being effective as a biocontrol agent, particularly for the control of seedling disease of maize.

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Comparison of Fumonisin B1 Biosynthesis in Maize Germ and Degermed Kernels by Fusarium verticillioides

Journal of Food Protection ◽

10.4315/0362-028x-66.11.2116 ◽

2003 ◽

Vol 66 (11) ◽

pp. 2116-2122 ◽

Cited By ~ 34

Author(s):

WON-BO SHIM ◽

JOSEPH E. FLAHERTY ◽

CHARLES P. WOLOSHUK

Keyword(s):

Time Course ◽

Polyketide Synthase ◽

Safety Issue ◽

Fusarium Verticillioides ◽

Fumonisin B1 ◽

Tissue Expression ◽

Polyketide Synthase Gene ◽

Time Course Experiment ◽

Kernel Growth ◽

Maize Kernels

Fusarium verticillioides produces a group of mycotoxins known as fumonisins in maize kernels. Fumonisins are associated with a variety of mycotoxicoses in humans and animals; thus, their presence in food is a considerable safety issue. This study addressed fumonisin B1 (FB1) production in two components of the maize kernel, namely the germ tissues and the degermed kernel. Growth of F. verticillioides was similar in colonized germ tissue and degermed kernels, but FB1 production was at least five times higher in degermed maize kernels than in germ tissue. Expression of the fumonisin polyketide synthase gene, FUM1, as measured by β-glucuronidase (GUS) and Northern blot analysis, followed the same pattern as FB1 production. Also correlated to FB1 was a concomitant drop in pH of the colonized degermed kernels. A time course experiment showed that degermed kernels inoculated with F. verticillioides became acidified over time (from pH 6.4 to 4.7 after 10 days of incubation), whereas colonized germ tissue became alkaline over the same period (from pH 6.5 to 8.5). Because conditions of acidic pH are conducive to FB1 production and alkaline pH is repressive, the observed correlation between the acidification of degermed kernels and the increase in FB1 provides one explanation for the observed differences in FB1 levels.

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Glycosyltransferase FvCpsA Regulates Fumonisin Biosynthesis and Virulence in Fusarium verticillioides

Toxins ◽

10.3390/toxins13100718 ◽

2021 ◽

Vol 13 (10) ◽

pp. 718

Author(s):

Qi Deng ◽

Hanxiang Wu ◽

Qin Gu ◽

Guangfei Tang ◽

Wende Liu

Keyword(s):

High Performance ◽

Fusarium Verticillioides ◽

Animal Health ◽

Fumonisin B1 ◽

Fungal Growth ◽

Wall Stress ◽

Ear Rot ◽

Stalk Rot ◽

Chromatography Analysis

Fusarium verticillioides is the major maize pathogen associated with ear rot and stalk rot worldwide. Fumonisin B1 (FB1) produced by F. verticillioides, poses a serious threat to human and animal health. However, our understanding of FB1 synthesis and virulence mechanism in this fungus is still very limited. Glycosylation catalyzed by glycosyltransferases (GTs) has been identified as contributing to fungal infection and secondary metabolism synthesis. In this study, a family 2 glycosyltransferase, FvCpsA, was identified and characterized in F. verticillioides. ΔFvcpsA exhibited significant defects in vegetative growth. Moreover, ΔFvcpsA also increased resistance to osmotic and cell wall stress agents. In addition, expression levels of FUM genes involved in FB1 production were greatly up-regulated in ΔFvcpsA. HPLC (high performance liquid chromatography) analysis revealed that ΔFvcpsA significantly increased FB1 production. Interestingly, we found that the deletion of FvCPSA showed penetration defects on cellophane membrane, and thus led to obvious defects in pathogenicity. Characterization of FvCpsA domain experiments showed that conserved DXD and QXXRW domains were vital for the biological functions of FvCpsA. Taken together, our results indicate that FvCpsA is critical for fungal growth, FB1 biosynthesis and virulence in F. verticillioides.

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Morphological and molecular identification of Fusarium spp. isolated from maize kernels in Java and Lombok, Indonesia

Biodiversitas Journal of Biological Diversity ◽

10.13057/biodiv/d210650 ◽

2020 ◽

Vol 21 (6) ◽

Author(s):

Ani Widiastuti ◽

Monica Lucky Karlina ◽

Kurnia Ritma Dhanti ◽

Yufita Dwi Chinta ◽

Tri Joko ◽

...

Keyword(s):

Molecular Identification ◽

Fusarium Verticillioides ◽

Animal Health ◽

Morphological Characteristics ◽

Morphological Identification ◽

Fusarium Spp ◽

Single Spore ◽

Central Java ◽

Species Specific ◽

Maize Kernels

Abstract. Widiastuti A, Karlina ML, Dhanti KR, Chinta YD, Joko T, Suryanti, Wibowo A. 2020. Morphological and molecular identification of Fusarium spp. isolated from maize kernels in Java and Lombok, Indonesia. Biodiversitas 21: 2741-2750. Fungal contamination of maize is a serious problem in Indonesia. Fusarium spp. infect maize in the field will be continuing to contaminate in the post-harvest period even though disease symptoms are not always emerged. Some Fusarium spp. produced mycotoxins which are harmful to human and animal health. Aims of this research were to reveal the presence of Fusarium spp. from both symptomatic and unsymptomatic maize, and to identify them based on morphological characteristics and molecular analysis. Samples of maize were collected from maize cultivation areas in East Java (EJ), Central Java (CJ), West Java (WJ), Yogyakarta Special Province (DIY), and Lombok, West Nusa Tenggara. Fusarium spp. were isolated in a single spore method and cultured in potato dextrose agar (PDA) medium for morphological identification of macro-and microconidia. Molecular identification was conducted by PCR assay using species-specific primers. Furthermore, unidentified species were analyzed by DNA sequence. This research found four species of mycotoxigenic Fusarium isolated from maize-based on molecular identification, which were Fusarium verticillioides (15 isolates), F. proliferatum (6 isolates), F. graminearum (1 isolate) and F. asiaticum (1 isolate). This research showed a novel report of F. asiaticum infection on maize kernel in Indonesia.

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