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Qu Q, Liu N, Su Q, Liu X, Jia H, Liu Y, Sun M, Cao Z, Dong J. MicroRNAs involved in the trans-kingdom gene regulation in the interaction of maize kernels and Fusarium verticillioides. Int J Biol Macromol 2023:125046. [PMID: 37245767 DOI: 10.1016/j.ijbiomac.2023.125046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 05/19/2023] [Accepted: 05/22/2023] [Indexed: 05/30/2023]
Abstract
Maize ear rot is a widespread disease and the main pathogen is Fusarium verticillioides. Plant microRNAs (miRNAs) have great effects on disease resistance and it has been reported that maize miRNA participates in defense responses in maize ear rot. However, the trans-kingdom regulation of miRNAs between maize and F. verticillioides remains uncharacterized. In this study, the relationship between miRNA-like RNAs (milRNAs) of F. verticillioides and pathogenicity was investigated, followed by sRNA analysis and degradome sequencing of miRNA profiles and the target genes of maize and F. verticillioides after inoculation. It was found that the milRNA biogenesis positively regulated the pathogenicity of F. verticillioides by knocking out the gene FvDicer2-encoded Dicer-like protein in F. verticillioides. Following inoculation with F. verticillioides, 284 known and 6571 novel miRNAs were obtained in maize, including 28 miRNAs differentially expressed at multiple time points. The target genes of maize differentially expressed miRNAs in F. verticillioides mediated multiple pathways, including autophagy and MAPK signaling pathway. Fifty-one novel F. verticillioides milRNAs were predicted to target 333 genes in maize involved in MAPK signaling pathways, plant hormone signaling transduction and plant-pathogen interaction pathways. Additionally, the miR528b-5p in maize targeted the mRNA of FvTTP which encoded a twice transmembrane protein in F. verticillioides. The FvTTP-knockout mutants displayed decreased pathogenicity and reduced synthesis of fumonisins. Thus, by interfering with the translation of FvTTP, the miR528b-5p inhibited F. verticillioides infection. These findings suggested a novel function of miR528 in resisting F. verticillioides infection. The miRNAs identified in this research and their putative target genes can be used to further elucidate the trans-kingdom functions of microRNAs in plant pathogen interaction.
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Affiliation(s)
- Qing Qu
- Plant Pathogenic Mycotoxin and Molecular Plant Pathology Laboratory, Hebei Key Laboratory of Plant Physiology and Molecular Pathology, Hebei Agriculture University, Baoding 071001, China; State Key Laboratory of North China Crop Improvement and Regulation, Hebei Agriculture University, Baoding 071001, China
| | - Ning Liu
- Plant Pathogenic Mycotoxin and Molecular Plant Pathology Laboratory, Hebei Key Laboratory of Plant Physiology and Molecular Pathology, Hebei Agriculture University, Baoding 071001, China; State Key Laboratory of North China Crop Improvement and Regulation, Hebei Agriculture University, Baoding 071001, China
| | - Qianfu Su
- Jilin Academy of Agricultural Sciences, Jilin 130033, China
| | - Xinfang Liu
- Corn Research Institute, Liaoning Academy of Agricultural Sciences, Shenyang 110161, China
| | - Hui Jia
- Plant Pathogenic Mycotoxin and Molecular Plant Pathology Laboratory, Hebei Key Laboratory of Plant Physiology and Molecular Pathology, Hebei Agriculture University, Baoding 071001, China; State Key Laboratory of North China Crop Improvement and Regulation, Hebei Agriculture University, Baoding 071001, China
| | - Yuwei Liu
- Plant Pathogenic Mycotoxin and Molecular Plant Pathology Laboratory, Hebei Key Laboratory of Plant Physiology and Molecular Pathology, Hebei Agriculture University, Baoding 071001, China
| | - Manli Sun
- Plant Pathogenic Mycotoxin and Molecular Plant Pathology Laboratory, Hebei Key Laboratory of Plant Physiology and Molecular Pathology, Hebei Agriculture University, Baoding 071001, China; State Key Laboratory of North China Crop Improvement and Regulation, Hebei Agriculture University, Baoding 071001, China
| | - Zhiyan Cao
- Plant Pathogenic Mycotoxin and Molecular Plant Pathology Laboratory, Hebei Key Laboratory of Plant Physiology and Molecular Pathology, Hebei Agriculture University, Baoding 071001, China; State Key Laboratory of North China Crop Improvement and Regulation, Hebei Agriculture University, Baoding 071001, China.
| | - Jingao Dong
- Plant Pathogenic Mycotoxin and Molecular Plant Pathology Laboratory, Hebei Key Laboratory of Plant Physiology and Molecular Pathology, Hebei Agriculture University, Baoding 071001, China; State Key Laboratory of North China Crop Improvement and Regulation, Hebei Agriculture University, Baoding 071001, China.
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Xie L, Wu Y, Duan X, Li T, Jiang Y. Proteomic and physiological analysis provides an elucidation of Fusarium proliferatum infection causing crown rot on banana fruit. Microbiol Res 2021; 256:126952. [PMID: 34968824 DOI: 10.1016/j.micres.2021.126952] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 08/10/2021] [Accepted: 12/19/2021] [Indexed: 11/30/2022]
Abstract
Fusarium proliferatum causes the crown rot of harvested banana fruit but the underling infection mechanism remains unclear. Here, proteomic changes of the banana peel with and without inoculation of F. proliferatum were evaluated. In addition, we investigated the effects of F. proliferatum infection on cell structure, hormone content, primary metabolites and defense-related enzyme activities in the banana peel. Our results showed that F. proliferatum infection mainly affects cell wall components and inhibits the activities of polyphenoloxidase, peroxidase, and chitinase. Gel free quantitative proteomic analysis showed 92 down-regulated and 29 up-regulated proteins of banana peel after F. proliferatum infection. These proteins were mainly related to defense response to biotic stress, chloroplast structure and function, JA signaling pathway, and primary metabolism. Although jasmonic acid (JA) content and JA signaling component coronatine-insensitive (COI) protein were induced by F. proliferatum infection, JA-responsible defense genes/proteins were downregulated. In contrast, expression of senescence-related genes was induced by F. proliferatum, indicating that F. proliferatum modulated the JA signaling to accelerate the senescence of banana fruit. Additionally, salicylic acid (SA) content and SA signaling for resistance acquisition were inhibited by F. proliferatum. Taken together, these results suggest that F. proliferatum depolymerizes the cell wall barrier, impairs the defense system in banana fruit, and activates non-defensive JA-signaling pathway accelerated the senescence of banana fruit. This study provided the elucidation of the prominent pathways disturbed by F. proliferatum in banana fruit, which will facilitate the development of a new strategy to control crown rot of banana fruit and improvement of banana cultivars.
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Affiliation(s)
- Lihong Xie
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement/Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China; University of Chinese Academy of Sciences, Beijing 100039, China
| | - Yanfei Wu
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement/Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China; University of Chinese Academy of Sciences, Beijing 100039, China
| | - Xuewu Duan
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement/Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Taotao Li
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement/Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
| | - Yueming Jiang
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement/Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
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Castano-Duque L, Gilbert MK, Mack BM, Lebar MD, Carter-Wientjes CH, Sickler CM, Cary JW, Rajasekaran K. Flavonoids Modulate the Accumulation of Toxins From Aspergillus flavus in Maize Kernels. FRONTIERS IN PLANT SCIENCE 2021; 12:761446. [PMID: 34899785 PMCID: PMC8662736 DOI: 10.3389/fpls.2021.761446] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 10/15/2021] [Indexed: 06/14/2023]
Abstract
Aspergillus flavus is an opportunistic fungal pathogen capable of producing aflatoxins, potent carcinogenic toxins that accumulate in maize kernels after infection. To better understand the molecular mechanisms of maize resistance to A. flavus growth and aflatoxin accumulation, we performed a high-throughput transcriptomic study in situ using maize kernels infected with A. flavus strain 3357. Three maize lines were evaluated: aflatoxin-contamination resistant line TZAR102, semi-resistant MI82, and susceptible line Va35. A modified genotype-environment association method (GEA) used to detect loci under selection via redundancy analysis (RDA) was used with the transcriptomic data to detect genes significantly influenced by maize line, fungal treatment, and duration of infection. Gene ontology enrichment analysis of genes highly expressed in infected kernels identified molecular pathways associated with defense responses to fungi and other microbes such as production of pathogenesis-related (PR) proteins and lipid bilayer formation. To further identify novel genes of interest, we incorporated genomic and phenotypic field data from a genome wide association analysis with gene expression data, allowing us to detect significantly expressed quantitative trait loci (eQTL). These results identified significant association between flavonoid biosynthetic pathway genes and infection by A. flavus. In planta fungal infections showed that the resistant line, TZAR102, has a higher fold increase of the metabolites naringenin and luteolin than the susceptible line, Va35, when comparing untreated and fungal infected plants. These results suggest flavonoids contribute to plant resistance mechanisms against aflatoxin contamination through modulation of toxin accumulation in maize kernels.
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Fusarium verticillioides and Aspergillus flavus Co-Occurrence Influences Plant and Fungal Transcriptional Profiles in Maize Kernels and In Vitro. Toxins (Basel) 2021; 13:toxins13100680. [PMID: 34678972 PMCID: PMC8537323 DOI: 10.3390/toxins13100680] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 09/09/2021] [Accepted: 09/17/2021] [Indexed: 12/26/2022] Open
Abstract
Climate change will increase the co-occurrence of Fusarium verticillioides and Aspergillus flavus, along with their mycotoxins, in European maize. In this study, the expression profiles of two pathogenesis-related (PR) genes and four mycotoxin biosynthetic genes, FUM1 and FUM13, fumonisin pathway, and aflR and aflD, aflatoxin pathway, as well as mycotoxin production, were examined in kernels and in artificial medium after a single inoculation with F. verticillioides or A. flavus or with the two fungi in combination. Different temperature regimes (20, 25 and 30 °C) over a time-course of 21 days were also considered. In maize kernels, PR genes showed the strongest induction at 25 °C in the earlier days post inoculation (dpi)with both fungi inoculated singularly. A similar behaviour was maintained with fungi co-occurrence, but with enhanced defence response at 9 dpi under 20 °C. Regarding FUM genes, in the kernels inoculated with F. verticillioides the maximal transcript levels occurred at 6 dpi at 25 °C. At this temperature regime, expression values decreased with the co-occurrence of A. flavus, where the highest gene induction was detected at 20 °C. Similar results were observed in fungi grown in vitro, whilst A. flavus presence determined lower levels of expression along the entire time-course. As concerns afl genes, considering both A. flavus alone and in combination, the most elevated transcript accumulation occurred at 30 °C during all time-course both in infected kernels and in fungi grown in vitro. Regarding mycotoxin production, no significant differences were found among temperatures for kernel contamination, whereas in vitro the highest production was registered at 25 °C for aflatoxin B1 and at 20 °C for fumonisins in the case of single inoculation. In fungal co-occurrence, both mycotoxins resulted reduced at all the temperatures considered compared to the amount produced with single inoculation.
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Bai H, Si H, Zang J, Pang X, Yu L, Cao H, Xing J, Zhang K, Dong J. Comparative Proteomic Analysis of the Defense Response to Gibberella Stalk Rot in Maize and Reveals That ZmWRKY83 Is Involved in Plant Disease Resistance. FRONTIERS IN PLANT SCIENCE 2021; 12:694973. [PMID: 34489999 PMCID: PMC8417113 DOI: 10.3389/fpls.2021.694973] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 07/21/2021] [Indexed: 05/12/2023]
Abstract
Fusarium graminearum is the causal agent of Gibberella stalk rot in maize stem, resulting in maize lodging, yield, quality, and mechanical harvesting capacity. To date, little is known about the maize stem defense mechanism in response to the invasion of F. graminearum. This study represents a global proteomic approach to document the infection by F. graminearum. A total of 1,894 differentially expressed proteins (DEPs) were identified in maize stem with F. graminearum inoculation. Functional categorization analysis indicated that proteins involved in plant-pathogen interaction were inducible at the early stages of infection. We also found that the expression of proteins involved in phenylpropanoid, flavonoid, and terpenoid biosynthesis were upregulated in response to F. graminearum infection, which may reflect that these secondary metabolism pathways were important in the protection against the fungal attack in maize stem. In continuously upregulated proteins after F. graminearum infection, we identified a WRKY transcription factor, ZmWRKY83, which could improve the resistance to plant pathogens. Together, the results show that the defense response of corn stalks against F. graminearum infection was multifaceted, involving the induction of proteins from various immune-related pathways, which had a directive significance for molecular genetic breeding of maize disease-resistant varieties.
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Affiliation(s)
- Hua Bai
- State Key Laboratory of North China Crop Improvement and Regulation, Hebei Agricultural University, Baoding, China
- College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Helong Si
- Hebei Key Laboratory of Plant Physiology and Molecular Pathology, Hebei Agricultural University, Baoding, China
- College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Jinping Zang
- Hebei Key Laboratory of Plant Physiology and Molecular Pathology, Hebei Agricultural University, Baoding, China
- College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Xi Pang
- College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Lu Yu
- College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Hongzhe Cao
- Hebei Key Laboratory of Plant Physiology and Molecular Pathology, Hebei Agricultural University, Baoding, China
- College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Jihong Xing
- State Key Laboratory of North China Crop Improvement and Regulation, Hebei Agricultural University, Baoding, China
- Hebei Key Laboratory of Plant Physiology and Molecular Pathology, Hebei Agricultural University, Baoding, China
- College of Life Sciences, Hebei Agricultural University, Baoding, China
- *Correspondence: Jihong Xing,
| | - Kang Zhang
- State Key Laboratory of North China Crop Improvement and Regulation, Hebei Agricultural University, Baoding, China
- Hebei Key Laboratory of Plant Physiology and Molecular Pathology, Hebei Agricultural University, Baoding, China
- College of Life Sciences, Hebei Agricultural University, Baoding, China
- Kang Zhang,
| | - Jingao Dong
- State Key Laboratory of North China Crop Improvement and Regulation, Hebei Agricultural University, Baoding, China
- Hebei Key Laboratory of Plant Physiology and Molecular Pathology, Hebei Agricultural University, Baoding, China
- College of Plant Protection, Hebei Agricultural University, Baoding, China
- Jingao Dong,
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Aoun M, Stafstrom W, Priest P, Fuchs J, Windham GL, Williams WP, Nelson RJ. Low-cost grain sorting technologies to reduce mycotoxin contamination in maize and groundnut. Food Control 2020; 118:107363. [PMID: 33273755 PMCID: PMC7439795 DOI: 10.1016/j.foodcont.2020.107363] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The widespread contamination of foods by mycotoxins continues to be a public health hazard in sub-Saharan Africa, with maize and groundnut being major sources of contamination. This study was undertaken to assess the hypothesis that grain sorting can be used to reduce mycotoxin contamination in grain lots by removing toxic kernels. We tested a set of sorting principles and methods for reducing mycotoxin levels in maize and groundnut from a variety of genotypes and environments. We found that kernel bulk density (KBD) and 100-kernel weight (HKW) were associated with the levels of aflatoxins (AF) and fumonisins (FUM) in maize grain. A low-cost sorter prototype (the ‘DropSort’ device) that separated maize grain based on KBD and HKW was more effective in reducing FUM than AF. We then evaluated the effectiveness of DropSorting when combined with either size or visual sorting. Size sorting followed by DropSorting was the fastest method for reducing FUM to under 2 ppm, but was not effective in reducing AF levels in maize grain to under 20 ppb, especially for heavily AF-contaminated grain. Analysis of individual kernels showed that high -AF maize kernels had lower weight, volume, density, length, and width and higher sphericity than those with low AF. Single kernel weight was the most significant predictor of AF concentration. The DropSort excluded kernels with lower single kernel weight, volume, width, depth, and sphericity. We also found that visual sorting and bright greenish-yellow fluorescence sorting of maize single kernels were successful in separating kernels based on AF levels. For groundnut, the DropSort grouped grain based on HKW and did not significantly reduce AF concentrations, whereas size sorting and visual sorting were much more effective. The DropSort prototype was more effective in reducing fumonisins than aflatoxins. DropSorting following size sorting was effective in reducing fumonisins below 2 ppm. Visual sorting was more effective in reducing fumonisins than aflatoxins in maize. Size and visual sorting separated groundnut grain based on aflatoxin levels. Single kernel mass is the most significant determinant of AF levels.
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Affiliation(s)
- Meriem Aoun
- School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
| | - William Stafstrom
- School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
| | - Paige Priest
- Masters of Public Health Program, Cornell University, Ithaca, NY, 14853, USA
| | - John Fuchs
- The Widget Factory, Ithaca, NY, 14850, USA
| | - Gary L Windham
- USDA, Agricultural Research Service, Corn Host Plant Resistance Research Unit, Mississippi State, MS, 39762, USA
| | - W Paul Williams
- USDA, Agricultural Research Service, Corn Host Plant Resistance Research Unit, Mississippi State, MS, 39762, USA
| | - Rebecca J Nelson
- School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
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Chalivendra S, Huang F, Busman M, Williams WP, Ham JH. Low Aflatoxin Levels in Aspergillus flavus-Resistant Maize Are Correlated With Increased Corn Earworm Damage and Enhanced Seed Fumonisin. FRONTIERS IN PLANT SCIENCE 2020; 11:565323. [PMID: 33101334 PMCID: PMC7546873 DOI: 10.3389/fpls.2020.565323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 08/19/2020] [Indexed: 06/11/2023]
Abstract
Preharvest mycotoxin contamination of field-grown crops is influenced not only by the host genotype, but also by inoculum load, insect pressure and their confounding interactions with seasonal weather. In two different field trials, we observed a preference in the natural infestation of corn earworm (CEW; Helicoverpa zea Boddie) to specific maize (Zea mays L.) genotypes and investigated this observation. The field trials involved four maize lines with contrasting levels of resistance to Aspergillus flavus. The resistant lines had 7 to 14-fold greater infested ears than the susceptible lines. Seed aflatoxin B1 (AF) levels, in mock- and A. flavus-inoculated ears were consistent with genotype resistance to A. flavus, in that the resistant lines showed low levels of AF (<30 ppb), whereas the susceptible lines had up to 500 ppb. On the other hand, CEW infestation showed a positive correlation with seed fumonisins (FUM) contamination by native Fusarium verticillioides strains. We inferred that the inverse trend in the correlation of AF and FUM with H. zea infestation may be due to a differential sensitivity of CEW to the two mycotoxins. This hypothesis was tested by toxin-feeding studies. H. zea larvae showed decreasing mass with increasing AF in the diet and incurred >30% lethality at 250 ppb. In contrast, CEW was tolerant to fumonisin with no significant loss in larval mass even at 100 ppm, implicating the low seed aflatoxin content as a predominant factor for the prevalence of CEW infestation and the associated fumonisin contamination in A. flavus resistant maize lines. Further, delayed flowering of the two resistant maize lines might have contributed to the pervasive H. zea damage of these lines by providing young silk for egg-laying. These results highlight the need for integrated strategies targeting mycotoxigenic fungi as well as their insect vectors for enhanced food safety.
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Affiliation(s)
- Subbaiah Chalivendra
- Department of Plant Pathology and Crop Physiology, Louisiana State University AgCenter, Baton Rouge, LA, United States
| | - Fangneng Huang
- Department of Entomology, Louisiana State University AgCenter, Baton Rouge, LA, United States
| | - Mark Busman
- Bacterial Foodborne Pathogens and Mycology Research Unit, USDA-ARS-NCAUR, Peoria, IL, United States
| | - W. Paul Williams
- Corn Host Plant Resistance Research Unit, USDA-ARS, Mississippi State, MS, United States
| | - Jong Hyun Ham
- Department of Plant Pathology and Crop Physiology, Louisiana State University AgCenter, Baton Rouge, LA, United States
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Pfliegler WP, Pócsi I, Győri Z, Pusztahelyi T. The Aspergilli and Their Mycotoxins: Metabolic Interactions With Plants and the Soil Biota. Front Microbiol 2020; 10:2921. [PMID: 32117074 PMCID: PMC7029702 DOI: 10.3389/fmicb.2019.02921] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 12/04/2019] [Indexed: 01/06/2023] Open
Abstract
Species of the highly diverse fungal genus Aspergillus are well-known agricultural pests, and, most importantly, producers of various mycotoxins threatening food safety worldwide. Mycotoxins are studied predominantly from the perspectives of human and livestock health. Meanwhile, their roles are far less known in nature. However, to understand the factors behind mycotoxin production, the roles of the toxins of Aspergilli must be understood from a complex ecological perspective, taking mold-plant, mold-microbe, and mold-animal interactions into account. The Aspergilli may switch between saprophytic and pathogenic lifestyles, and the production of secondary metabolites, such as mycotoxins, may vary according to these fungal ways of life. Recent studies highlighted the complex ecological network of soil microbiotas determining the niches that Aspergilli can fill in. Interactions with the soil microbiota and soil macro-organisms determine the role of secondary metabolite production to a great extent. While, upon infection of plants, metabolic communication including fungal secondary metabolites like aflatoxins, gliotoxin, patulin, cyclopiazonic acid, and ochratoxin, influences the fate of both the invader and the host. In this review, the role of mycotoxin producing Aspergillus species and their interactions in the ecosystem are discussed. We intend to highlight the complexity of the roles of the main toxic secondary metabolites as well as their fate in natural environments and agriculture, a field that still has important knowledge gaps.
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Affiliation(s)
- Walter P. Pfliegler
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - István Pócsi
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Zoltán Győri
- Institute of Nutrition, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Debrecen, Hungary
| | - Tünde Pusztahelyi
- Central Laboratory of Agricultural and Food Products, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Debrecen, Hungary
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Stagnati L, Lanubile A, Samayoa LF, Bragalanti M, Giorni P, Busconi M, Holland JB, Marocco A. A Genome Wide Association Study Reveals Markers and Genes Associated with Resistance to Fusarium verticillioides Infection of Seedlings in a Maize Diversity Panel. G3 (BETHESDA, MD.) 2019; 9:571-579. [PMID: 30567831 PMCID: PMC6385986 DOI: 10.1534/g3.118.200916] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 12/18/2018] [Indexed: 12/12/2022]
Abstract
Fusarium verticillioides infects maize, causing ear rot, yield loss and contamination by fumonisin mycotoxins. The fungus can be transmitted via kernels and cause systemic infection in maize. Maize resistance to the fungus may occur at different developmental stages, from seedling to maturity. Resistance during kernel germination is part of the plant-pathogen interaction and so far this aspect has not been investigated. In the present study, a genome wide association study (GWAS) of resistance to Fusarium during the seedling developmental stage was conducted in a maize diversity panel using 226,446 SNP markers. Seedling germination and disease phenotypes were scored on artificially inoculated kernels using the rolled towel assay. GWAS identified 164 SNPs significantly associated with the traits examined. Four SNPs were associated with disease severity score after inoculation, 153 were associated with severity in asymptomatic kernels and 7 with the difference between the severity ratings in inoculated and non-inoculated seeds. A set of genes containing or physically near the significant SNPs were identified as candidates for Fusarium resistance at the seedling stage. Functional analysis revealed that many of these genes are directly involved in plant defense against pathogens and stress responses, including transcription factors, chitinase, cytochrome P450, and ubiquitination proteins. In addition, 25 genes were found in high linkage disequilibrium with the associated SNPs identified by GWAS and four of them directly involved in disease resistance. These findings contribute to understanding the complex system of maize-F. verticillioides and may improve genomic selection for Fusarium resistance at the seedling stage.
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Affiliation(s)
- Lorenzo Stagnati
- Dipartimento di Scienze delle Produzioni Vegetali Sostenibili, Università Cattolica del Sacro Cuore, via Emilia Parmense 84, 29122 Piacenza (Italy)
| | - Alessandra Lanubile
- Dipartimento di Scienze delle Produzioni Vegetali Sostenibili, Università Cattolica del Sacro Cuore, via Emilia Parmense 84, 29122 Piacenza (Italy)
| | - Luis F Samayoa
- Department of Crop & Soil Sciences, North Carolina State University, Raleigh, North Carolina 27695
| | - Mario Bragalanti
- Dipartimento di Scienze delle Produzioni Vegetali Sostenibili, Università Cattolica del Sacro Cuore, via Emilia Parmense 84, 29122 Piacenza (Italy)
| | - Paola Giorni
- Dipartimento di Scienze delle Produzioni Vegetali Sostenibili, Università Cattolica del Sacro Cuore, via Emilia Parmense 84, 29122 Piacenza (Italy)
| | - Matteo Busconi
- Dipartimento di Scienze delle Produzioni Vegetali Sostenibili, Università Cattolica del Sacro Cuore, via Emilia Parmense 84, 29122 Piacenza (Italy)
| | - James B Holland
- Department of Crop & Soil Sciences, North Carolina State University, Raleigh, North Carolina 27695
- U.S. Department of Agriculture-Agricultural Research Service, Plant Science Research Unit, Raleigh, North Carolina 27695
| | - Adriano Marocco
- Dipartimento di Scienze delle Produzioni Vegetali Sostenibili, Università Cattolica del Sacro Cuore, via Emilia Parmense 84, 29122 Piacenza (Italy)
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10
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Majumdar R, Minocha R, Lebar MD, Rajasekaran K, Long S, Carter-Wientjes C, Minocha S, Cary JW. Contribution of Maize Polyamine and Amino Acid Metabolism Toward Resistance Against Aspergillus flavus Infection and Aflatoxin Production. FRONTIERS IN PLANT SCIENCE 2019; 10:692. [PMID: 31178889 PMCID: PMC6543017 DOI: 10.3389/fpls.2019.00692] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 05/08/2019] [Indexed: 05/05/2023]
Abstract
Polyamines (PAs) are ubiquitous polycations found in plants and other organisms that are essential for growth, development, and resistance against abiotic and biotic stresses. The role of PAs in plant disease resistance depends on the relative abundance of higher PAs [spermidine (Spd), spermine (Spm)] vs. the diamine putrescine (Put) and PA catabolism. With respect to the pathogen, PAs are required to achieve successful pathogenesis of the host. Maize is an important food and feed crop, which is highly susceptible to Aspergillus flavus infection. Upon infection, the fungus produces carcinogenic aflatoxins and numerous other toxic secondary metabolites that adversely affect human health and crop value worldwide. To evaluate the role of PAs in aflatoxin resistance in maize, in vitro kernel infection assays were performed using maize lines that are susceptible (SC212) or resistant (TZAR102, MI82) to aflatoxin production. Results indicated significant induction of both PA biosynthetic and catabolic genes upon A. flavus infection. As compared to the susceptible line, the resistant maize lines showed higher basal expression of PA metabolism genes in mock-inoculated kernels that increased upon fungal infection. In general, increased biosynthesis and conversion of Put to Spd and Spm along with their increased catabolism was evident in the resistant lines vs. the susceptible line SC212. There were higher concentrations of amino acids such as glutamate (Glu), glutamine (Gln) and γ-aminobutyric acid (GABA) in SC212. The resistant lines were significantly lower in fungal load and aflatoxin production as compared to the susceptible line. The data presented here demonstrate an important role of PA metabolism in the resistance of maize to A. flavus colonization and aflatoxin contamination. These results provide future direction for the manipulation of PA metabolism in susceptible maize genotypes to improve aflatoxin resistance and overall stress tolerance.
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Affiliation(s)
- Rajtilak Majumdar
- Food and Feed Safety Research Unit, Southern Regional Research Center, United States Department of Agriculture, Agricultural Research Service, New Orleans, LA, United States
| | - Rakesh Minocha
- United States Department of Agriculture Forest Service, Northern Research Station, Durham, NH, United States
| | - Matthew D. Lebar
- Food and Feed Safety Research Unit, Southern Regional Research Center, United States Department of Agriculture, Agricultural Research Service, New Orleans, LA, United States
| | - Kanniah Rajasekaran
- Food and Feed Safety Research Unit, Southern Regional Research Center, United States Department of Agriculture, Agricultural Research Service, New Orleans, LA, United States
| | - Stephanie Long
- United States Department of Agriculture Forest Service, Northern Research Station, Durham, NH, United States
| | - Carol Carter-Wientjes
- Food and Feed Safety Research Unit, Southern Regional Research Center, United States Department of Agriculture, Agricultural Research Service, New Orleans, LA, United States
| | - Subhash Minocha
- Department of Biological Sciences, University of New Hampshire, Durham, NH, United States
| | - Jeffrey W. Cary
- Food and Feed Safety Research Unit, Southern Regional Research Center, United States Department of Agriculture, Agricultural Research Service, New Orleans, LA, United States
- *Correspondence: Jeffrey W. Cary,
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11
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Ojiambo PS, Battilani P, Cary JW, Blum BH, Carbone I. Cultural and Genetic Approaches to Manage Aflatoxin Contamination: Recent Insights Provide Opportunities for Improved Control. PHYTOPATHOLOGY 2018; 108:1024-1037. [PMID: 29869954 DOI: 10.1094/phyto-04-18-0134-rvw] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Aspergillus flavus is a morphologically complex species that can produce the group of polyketide derived carcinogenic and mutagenic secondary metabolites, aflatoxins, as well as other secondary metabolites such as cyclopiazonic acid and aflatrem. Aflatoxin causes aflatoxicosis when aflatoxins are ingested through contaminated food and feed. In addition, aflatoxin contamination is a major problem, from both an economic and health aspect, in developing countries, especially Asia and Africa, where cereals and peanuts are important food crops. Earlier measures for control of A. flavus infection and consequent aflatoxin contamination centered on creating unfavorable environments for the pathogen and destroying contaminated products. While development of atoxigenic (nonaflatoxin producing) strains of A. flavus as viable commercial biocontrol agents has marked a unique advance for control of aflatoxin contamination, particularly in Africa, new insights into the biology and sexuality of A. flavus are now providing opportunities to design improved atoxigenic strains for sustainable biological control of aflatoxin. Further, progress in the use of molecular technologies such as incorporation of antifungal genes in the host and host-induced gene silencing, is providing knowledge that could be harnessed to develop germplasm that is resistant to infection by A. flavus and aflatoxin contamination. This review summarizes the substantial progress that has been made to understand the biology of A. flavus and mitigate aflatoxin contamination with emphasis on maize. Concepts developed to date can provide a basis for future research efforts on the sustainable management of aflatoxin contamination.
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Affiliation(s)
- Peter S Ojiambo
- First and fifth authors: Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh 27695; second author: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29122 Piacenza, Italy; third author: U.S. Department of Agriculture-Agriculture Research Service, SRRC, New Orleans, LA 70124; and fourth author: Department of Plant Pathology, University of Arkansas, Fayetteville 72701
| | - Paola Battilani
- First and fifth authors: Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh 27695; second author: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29122 Piacenza, Italy; third author: U.S. Department of Agriculture-Agriculture Research Service, SRRC, New Orleans, LA 70124; and fourth author: Department of Plant Pathology, University of Arkansas, Fayetteville 72701
| | - Jeffrey W Cary
- First and fifth authors: Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh 27695; second author: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29122 Piacenza, Italy; third author: U.S. Department of Agriculture-Agriculture Research Service, SRRC, New Orleans, LA 70124; and fourth author: Department of Plant Pathology, University of Arkansas, Fayetteville 72701
| | - Burt H Blum
- First and fifth authors: Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh 27695; second author: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29122 Piacenza, Italy; third author: U.S. Department of Agriculture-Agriculture Research Service, SRRC, New Orleans, LA 70124; and fourth author: Department of Plant Pathology, University of Arkansas, Fayetteville 72701
| | - Ignazio Carbone
- First and fifth authors: Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh 27695; second author: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29122 Piacenza, Italy; third author: U.S. Department of Agriculture-Agriculture Research Service, SRRC, New Orleans, LA 70124; and fourth author: Department of Plant Pathology, University of Arkansas, Fayetteville 72701
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12
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Rajasekaran K, Sayler RJ, Sickler CM, Majumdar R, Jaynes JM, Cary JW. Control of Aspergillus flavus growth and aflatoxin production in transgenic maize kernels expressing a tachyplesin-derived synthetic peptide, AGM182. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2018; 270:150-156. [PMID: 29576068 DOI: 10.1016/j.plantsci.2018.02.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 01/28/2018] [Accepted: 02/07/2018] [Indexed: 06/08/2023]
Abstract
Aspergillus flavus is an opportunistic, saprophytic fungus that infects maize and other fatty acid-rich food and feed crops and produces toxic and carcinogenic secondary metabolites known as aflatoxins. Contamination of maize with aflatoxin poses a serious threat to human health in addition to reducing the crop value leading to a substantial economic loss. Here we report designing a tachyplesin1-derived synthetic peptide AGM182 and testing its antifungal activity both in vitro and in planta. In vitro studies showed a five-fold increase in antifungal activity of AGM182 (vs. tachyplesin1) against A. flavus. Transgenic maize plants expressing AGM182 under maize Ubiquitin-1 promoter were produced through Agrobacterium-mediated transformation. PCR products confirmed integration of the AGM182 gene, while RT-PCR of maize RNA confirmed the presence of AGM182 transcripts. Maize kernel screening assay using a highly aflatoxigenic A. flavus strain (AF70) showed up to 72% reduction in fungal growth in the transgenic AGM182 seeds compared to isogenic negative control seeds. Reduced fungal growth in the AGM182 transgenic seeds resulted in a significant reduction in aflatoxin levels (76-98%). The results presented here show the power of computational and synthetic biology to rationally design and synthesize an antimicrobial peptide against A. flavus that is effective in reducing fungal growth and aflatoxin contamination in an economically important food and feed crop such as maize.
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Affiliation(s)
- Kanniah Rajasekaran
- Food and Feed Safety Research Unit, USDA-ARS, Southern Regional Research Center, New Orleans, LA 70124, United States.
| | - Ronald J Sayler
- Department of Plant Pathology, University of Arkansas, Fayetteville, AR 72701, United States
| | - Christine M Sickler
- Food and Feed Safety Research Unit, USDA-ARS, Southern Regional Research Center, New Orleans, LA 70124, United States
| | - Rajtilak Majumdar
- Food and Feed Safety Research Unit, USDA-ARS, Southern Regional Research Center, New Orleans, LA 70124, United States
| | - Jesse M Jaynes
- College of Agriculture, Environment and Nutrition Sciences, Tuskegee University, Tuskegee, AL 36088, United States
| | - Jeffrey W Cary
- Food and Feed Safety Research Unit, USDA-ARS, Southern Regional Research Center, New Orleans, LA 70124, United States
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13
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Windham GL, Williams WP, Mylroie JE, Reid CX, Womack ED. A Histological Study of Aspergillus flavus Colonization of Wound Inoculated Maize Kernels of Resistant and Susceptible Maize Hybrids in the Field. Front Microbiol 2018; 9:799. [PMID: 29740423 PMCID: PMC5928334 DOI: 10.3389/fmicb.2018.00799] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 04/10/2018] [Indexed: 11/13/2022] Open
Abstract
Aspergillus flavus colonization in developing kernels of maize single-cross hybrids resistant (Mp313E × Mp717) and susceptible (GA209 × T173) to aflatoxin accumulation was determined in the field over three growing seasons (2012-2014). Plants were hand pollinated, and individual kernels were inoculated with a needle dipped in a suspension of A. flavus conidia 21 days after pollination. Kernels were harvested at 1- to 2-day intervals from 1 to 21 days after inoculation (DAI). Kernels were placed in FAA fixative, dehydrated, embedded in paraffin, sectioned, and stained with toluidine blue. Kernels were also collected additional kernels for aflatoxin analyses in 2013 and 2014. At 2 DAI, A. flavus hyphae were observed among endosperm cells in the susceptible hybrid, but colonization of the endosperm in the resistant hybrid was limited to the wound site of the resistant hybrid. Sections of the scutellum of the susceptible hybrid were colonized by A. flavus by 5 DAI. Fungal growth was slower in the resistant hybrid compared to the susceptible hybrid. By 10 DAI, A. flavus had colonized a large section of the embryo in the susceptible hybrid; whereas in the resistant hybrid, approximately half of the endosperm had been colonized and very few cells in the embryo were colonized. Fungal colonization in some of the kernels of the resistant hybrid was slowed in the aleurone layer or at the endosperm-scutellum interface. In wounded kernels with intact aleurone layers, the fungus spread around the kernel between the pericarp and aleurone layer with minimal colonization of the endosperm. Aflatoxin B1 was first detected in susceptible kernel tissues 8 DAI in 2013 (14 μg/kg) and 2014 (18 μg/kg). The resistant hybrid had significantly lower levels of aflatoxin accumulation compared to the susceptible hybrid at harvests 10, 21, and 28 DAI in 2013, and 20 and 24 DAI in 2014. Our study found differential A. flavus colonization of susceptible and resistant kernel tissues, and that the aleurone and the outer layer of the scutellum slowed the rate of colonization by A. flavus.
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Affiliation(s)
- Gary L. Windham
- Corn Host Plant Resistance Research Unit, United States Department of Agriculture-Agricultural Research Service, Mississippi State, MS, United States
| | - William P. Williams
- Corn Host Plant Resistance Research Unit, United States Department of Agriculture-Agricultural Research Service, Mississippi State, MS, United States
| | - J. E. Mylroie
- Corn Host Plant Resistance Research Unit, United States Department of Agriculture-Agricultural Research Service, Mississippi State, MS, United States
| | - Cedric X. Reid
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS, United States
| | - Erika D. Womack
- Corn Host Plant Resistance Research Unit, United States Department of Agriculture-Agricultural Research Service, Mississippi State, MS, United States
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14
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Majumdar R, Lebar M, Mack B, Minocha R, Minocha S, Carter-Wientjes C, Sickler C, Rajasekaran K, Cary JW. The Aspergillus flavus Spermidine Synthase ( spds) Gene, Is Required for Normal Development, Aflatoxin Production, and Pathogenesis During Infection of Maize Kernels. FRONTIERS IN PLANT SCIENCE 2018; 9:317. [PMID: 29616053 PMCID: PMC5870473 DOI: 10.3389/fpls.2018.00317] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 02/27/2018] [Indexed: 05/10/2023]
Abstract
Aspergillus flavus is a soil-borne saprophyte and an opportunistic pathogen of both humans and plants. This fungus not only causes disease in important food and feed crops such as maize, peanut, cottonseed, and tree nuts but also produces the toxic and carcinogenic secondary metabolites (SMs) known as aflatoxins. Polyamines (PAs) are ubiquitous polycations that influence normal growth, development, and stress responses in living organisms and have been shown to play a significant role in fungal pathogenesis. Biosynthesis of spermidine (Spd) is critical for cell growth as it is required for hypusination-mediated activation of eukaryotic translation initiation factor 5A (eIF5A), and other biochemical functions. The tri-amine Spd is synthesized from the diamine putrescine (Put) by the enzyme spermidine synthase (Spds). Inactivation of spds resulted in a total loss of growth and sporulation in vitro which could be partially restored by addition of exogenous Spd. Complementation of the Δspds mutant with a wild type (WT) A. flavus spds gene restored the WT phenotype. In WT A. flavus, exogenous supply of Spd (in vitro) significantly increased the production of sclerotia and SMs. Infection of maize kernels with the Δspds mutant resulted in a significant reduction in fungal growth, sporulation, and aflatoxin production compared to controls. Quantitative PCR of Δspds mutant infected seeds showed down-regulation of aflatoxin biosynthetic genes in the mutant compared to WT A. flavus infected seeds. Expression analyses of PA metabolism/transport genes during A. flavus-maize interaction showed significant increase in the expression of arginine decarboxylase (Adc) and S-adenosylmethionine decarboxylase (Samdc) genes in the maize host and PA uptake transporters in the fungus. The results presented here demonstrate that Spd biosynthesis is critical for normal development and pathogenesis of A. flavus and pre-treatment of a Δspds mutant with Spd or Spd uptake from the host plant, are insufficient to restore WT levels of pathogenesis and aflatoxin production during seed infection. The data presented here suggest that future studies targeting spermidine biosynthesis in A. flavus, using RNA interference-based host-induced gene silencing approaches, may be an effective strategy to reduce aflatoxin contamination in maize and possibly in other susceptible crops.
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Affiliation(s)
- Rajtilak Majumdar
- Food and Feed Safety Research Unit, United States Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
| | - Matt Lebar
- Food and Feed Safety Research Unit, United States Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
| | - Brian Mack
- Food and Feed Safety Research Unit, United States Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
| | - Rakesh Minocha
- United States Department of Agriculture Forest Service, Northern Research Station, Durham, NH, United States
| | - Subhash Minocha
- Department of Biological Sciences, University of New Hampshire, Durham, NH, United States
| | - Carol Carter-Wientjes
- Food and Feed Safety Research Unit, United States Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
| | - Christine Sickler
- Food and Feed Safety Research Unit, United States Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
| | - Kanniah Rajasekaran
- Food and Feed Safety Research Unit, United States Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
| | - Jeffrey W. Cary
- Food and Feed Safety Research Unit, United States Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
- *Correspondence: Jeffrey W. Cary,
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15
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Assessing Genotype-By-Environment Interactions in Aspergillus Ear Rot and Pre-Harvest Aflatoxin Accumulation in Maize Inbred Lines. AGRONOMY-BASEL 2017. [DOI: 10.3390/agronomy7040086] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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16
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Majumdar R, Rajasekaran K, Sickler C, Lebar M, Musungu BM, Fakhoury AM, Payne GA, Geisler M, Carter-Wientjes C, Wei Q, Bhatnagar D, Cary JW. The Pathogenesis-Related Maize Seed ( PRms) Gene Plays a Role in Resistance to Aspergillus flavus Infection and Aflatoxin Contamination. FRONTIERS IN PLANT SCIENCE 2017; 8:1758. [PMID: 29089952 PMCID: PMC5651032 DOI: 10.3389/fpls.2017.01758] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 09/25/2017] [Indexed: 05/26/2023]
Abstract
Aspergillus flavus is an opportunistic plant pathogen that colonizes and produces the toxic and carcinogenic secondary metabolites, aflatoxins, in oil-rich crops such as maize (Zea mays ssp. mays L.). Pathogenesis-related (PR) proteins serve as an important defense mechanism against invading pathogens by conferring systemic acquired resistance in plants. Among these, production of the PR maize seed protein, ZmPRms (AC205274.3_FG001), has been speculated to be involved in resistance to infection by A. flavus and other pathogens. To better understand the relative contribution of ZmPRms to A. flavus resistance and aflatoxin production, a seed-specific RNA interference (RNAi)-based gene silencing approach was used to develop transgenic maize lines expressing hairpin RNAs to target ZmPRms. Downregulation of ZmPRms in transgenic kernels resulted in a ∼250-350% increase in A. flavus infection accompanied by a ∼4.5-7.5-fold higher accumulation of aflatoxins than control plants. Gene co-expression network analysis of RNA-seq data during the A. flavus-maize interaction identified ZmPRms as a network hub possibly responsible for regulating several downstream candidate genes associated with disease resistance and other biochemical functions. Expression analysis of these candidate genes in the ZmPRms-RNAi lines demonstrated downregulation (vs. control) of a majority of these ZmPRms-regulated genes during A. flavus infection. These results are consistent with a key role of ZmPRms in resistance to A. flavus infection and aflatoxin accumulation in maize kernels.
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Affiliation(s)
- Rajtilak Majumdar
- Food and Feed Safety Research Unit, United States Department of Agriculture – Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
| | - Kanniah Rajasekaran
- Food and Feed Safety Research Unit, United States Department of Agriculture – Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
| | - Christine Sickler
- Food and Feed Safety Research Unit, United States Department of Agriculture – Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
| | - Matthew Lebar
- Food and Feed Safety Research Unit, United States Department of Agriculture – Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
| | - Bryan M. Musungu
- Department of Plant Biology, Southern Illinois University, Carbondale, IL, United States
- Warm Water Aquaculture Unit, United States Department of Agriculture – Agricultural Research Service, Stoneville, MS, United States
| | - Ahmad M. Fakhoury
- Department of Plant, Soil and Agriculture Systems, Southern Illinois University, Carbondale, IL, United States
| | - Gary A. Payne
- Department of Plant Pathology, North Carolina State University, Raleigh, NC, United States
| | - Matt Geisler
- Department of Plant Biology, Southern Illinois University, Carbondale, IL, United States
| | - Carol Carter-Wientjes
- Food and Feed Safety Research Unit, United States Department of Agriculture – Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
| | - Qijian Wei
- Food and Feed Safety Research Unit, United States Department of Agriculture – Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
| | - Deepak Bhatnagar
- Food and Feed Safety Research Unit, United States Department of Agriculture – Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
| | - Jeffrey W. Cary
- Food and Feed Safety Research Unit, United States Department of Agriculture – Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, United States
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17
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Dhakal R, Chai C, Karan R, Windham GL, Williams WP, Subudhi PK. Expression Profiling Coupled with In-silico Mapping Identifies Candidate Genes for Reducing Aflatoxin Accumulation in Maize. FRONTIERS IN PLANT SCIENCE 2017; 8:503. [PMID: 28428796 PMCID: PMC5382453 DOI: 10.3389/fpls.2017.00503] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Accepted: 03/22/2017] [Indexed: 05/31/2023]
Abstract
Aflatoxin, produced by Aspergillus flavus, is hazardous to health of humans and livestock. The lack of information about large effect QTL for resistance to aflatoxin accumulation is a major obstacle to employ marker-assisted selection for maize improvement. The understanding of resistance mechanisms of the host plant and the associated genes is necessary for improving resistance to A. flavus infection. A suppression subtraction hybridization (SSH) cDNA library was made using the developing kernels of Mp715 (resistant inbred) and B73 (susceptible inbred) and 480 randomly selected cDNA clones were sequenced to identify differentially expressed genes (DEGs) in response to A. flavus infection and map these clones onto the corn genome by in-silico mapping. A total of 267 unigenes were identified and majority of genes were related to metabolism, stress response, and disease resistance. Based on the reverse northern hybridization experiment, 26 DEGs were selected for semi-quantitative RT-PCR analysis in seven inbreds with variable resistance to aflatoxin accumulation at two time points after A. flavus inoculation. Most of these genes were highly expressed in resistant inbreds. Quantitative RT-PCR analysis validated upregulation of PR-4, DEAD-box RNA helicase, and leucine rich repeat family protein in resistant inbreds. Fifty-six unigenes, which were placed on linkage map through in-silico mapping, overlapped the QTL regions for resistance to aflatoxin accumulation identified in a mapping population derived from the cross between B73 and Mp715. Since majority of these mapped genes were related to disease resistance, stress response, and metabolism, these should be ideal candidates to investigate host pathogen interaction and to reduce aflatoxin accumulation in maize.
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Affiliation(s)
- Ramesh Dhakal
- School of Plant, Environmental, and Soil Sciences, Louisiana State University Agricultural CenterBaton Rouge, LA, USA
| | - Chenglin Chai
- School of Plant, Environmental, and Soil Sciences, Louisiana State University Agricultural CenterBaton Rouge, LA, USA
| | - Ratna Karan
- Department of Agronomy, University of FloridaGainesville, FL, USA
| | - Gary L. Windham
- USDA-ARS Corn Host Plant Resistance Research UnitMississippi State, MS, USA
| | | | - Prasanta K. Subudhi
- School of Plant, Environmental, and Soil Sciences, Louisiana State University Agricultural CenterBaton Rouge, LA, USA
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18
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Orina I, Manley M, Williams PJ. Use of High-Resolution X-Ray Micro-Computed Tomography for the Analysis of Internal Structural Changes in Maize Infected with Fusarium verticillioides. FOOD ANAL METHOD 2017. [DOI: 10.1007/s12161-017-0831-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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19
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Shu X, Livingston DP, Woloshuk CP, Payne GA. Comparative Histological and Transcriptional Analysis of Maize Kernels Infected with Aspergillus flavus and Fusarium verticillioides. FRONTIERS IN PLANT SCIENCE 2017; 8:2075. [PMID: 29270183 PMCID: PMC5723656 DOI: 10.3389/fpls.2017.02075] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 11/20/2017] [Indexed: 05/04/2023]
Abstract
Aspergillus flavus and Fusarium verticillioides infect maize kernels and contaminate them with the mycotoxins aflatoxin, and fumonisin, respectively. Genetic resistance in maize to these fungi and to mycotoxin contamination has been difficult to achieve due to lack of identified resistance genes. The objective of this study was to identify new candidate resistance genes by characterizing their temporal expression in response to infection and comparing expression of these genes with genes known to be associated with plant defense. Fungal colonization and transcriptional changes in kernels inoculated with each fungus were monitored at 4, 12, 24, 48, and 72 h post inoculation (hpi). Maize kernels responded by differential gene expression to each fungus within 4 hpi, before the fungi could be observed visually, but more genes were differentially expressed between 48 and 72 hpi, when fungal colonization was more extensive. Two-way hierarchal clustering analysis grouped the temporal expression profiles of the 5,863 differentially expressed maize genes over all time points into 12 clusters. Many clusters were enriched for genes previously associated with defense responses to either A. flavus or F. verticillioides. Also within these expression clusters were genes that lacked either annotation or assignment to functional categories. This study provided a comprehensive analysis of gene expression of each A. flavus and F. verticillioides during infection of maize kernels, it identified genes expressed early and late in the infection process, and it provided a grouping of genes of unknown function with similarly expressed defense related genes that could inform selection of new genes as targets in breeding strategies.
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Affiliation(s)
- Xiaomei Shu
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, United States
| | - David P. Livingston
- Department of Crop Science, North Carolina State University, Raleigh, NC, United States
| | - Charles P. Woloshuk
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, United States
| | - Gary A. Payne
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, United States
- *Correspondence: Gary A. Payne, ;
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20
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Musungu BM, Bhatnagar D, Brown RL, Payne GA, OBrian G, Fakhoury AM, Geisler M. A Network Approach of Gene Co-expression in the Zea mays/ Aspergillus flavus Pathosystem to Map Host/Pathogen Interaction Pathways. Front Genet 2016; 7:206. [PMID: 27917194 PMCID: PMC5116468 DOI: 10.3389/fgene.2016.00206] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 11/04/2016] [Indexed: 12/27/2022] Open
Abstract
A gene co-expression network (GEN) was generated using a dual RNA-seq study with the fungal pathogen Aspergillus flavus and its plant host Zea mays during the initial 3 days of infection. The analysis deciphered novel pathways and mapped genes of interest in both organisms during the infection. This network revealed a high degree of connectivity in many of the previously recognized pathways in Z. mays such as jasmonic acid, ethylene, and reactive oxygen species (ROS). For the pathogen A. flavus, a link between aflatoxin production and vesicular transport was identified within the network. There was significant interspecies correlation of expression between Z. mays and A. flavus for a subset of 104 Z. mays, and 1942 A. flavus genes. This resulted in an interspecies subnetwork enriched in multiple Z. mays genes involved in the production of ROS. In addition to the ROS from Z. mays, there was enrichment in the vesicular transport pathways and the aflatoxin pathway for A. flavus. Included in these genes, a key aflatoxin cluster regulator, AflS, was found to be co-regulated with multiple Z. mays ROS producing genes within the network, suggesting AflS may be monitoring host ROS levels. The entire GEN for both host and pathogen, and the subset of interspecies correlations, is presented as a tool for hypothesis generation and discovery for events in the early stages of fungal infection of Z. mays by A. flavus.
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Affiliation(s)
- Bryan M Musungu
- Department of Plant Biology, Southern Illinois University, CarbondaleIL, USA; Southern Regional Research Center, United States Department of Agriculture - Agricultural Research Service, New OrleansLA, USA
| | - Deepak Bhatnagar
- Southern Regional Research Center, United States Department of Agriculture - Agricultural Research Service, New Orleans LA, USA
| | - Robert L Brown
- Southern Regional Research Center, United States Department of Agriculture - Agricultural Research Service, New Orleans LA, USA
| | - Gary A Payne
- Department of Plant Pathology, North Carolina State University, Raleigh NC, USA
| | - Greg OBrian
- Department of Plant Pathology, North Carolina State University, Raleigh NC, USA
| | - Ahmad M Fakhoury
- Department of Plant Soil and Agriculture Systems, Southern Illinois University, Carbondale IL, USA
| | - Matt Geisler
- Department of Plant Biology, Southern Illinois University, Carbondale IL, USA
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Maschietto V, Lanubile A, Leonardis SD, Marocco A, Paciolla C. Constitutive expression of pathogenesis-related proteins and antioxydant enzyme activities triggers maize resistance towards Fusarium verticillioides. JOURNAL OF PLANT PHYSIOLOGY 2016; 200:53-61. [PMID: 27340858 DOI: 10.1016/j.jplph.2016.06.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 05/10/2016] [Accepted: 06/11/2016] [Indexed: 05/21/2023]
Abstract
Fusarium verticillioides is a fungal pathogen of maize that causes ear rot and contaminates the grains with fumonisin mycotoxins. Breeding for resistance to Fusarium emerged as the most economic and environmentally safe strategy; therefore the discovery of resistant sources and effective molecular markers are a priority. Ears of resistant (CO441 and CO433) and susceptible (CO354 and CO389) maize lines were inoculated with F. verticillioides and the expression of pathogenesis-related (PR) genes (PR1, PR5, PRm3, PRm6) and genes that protect from oxidative stress (peroxidase, catalase, superoxide dismutase and ascorbate peroxidase) were evaluated in the kernels at 72h post inoculation. In addition, the oxidation level and the enzymatic activity of ascorbate-glutathione cycle, catalase, superoxide dismutase and cytosolic and wall peroxidases were investigated. The uninoculated kernels of the resistant lines showed higher gene expression and enzymatic activities, highlighting the key role of constitutive resistance in limiting pathogen attack. In contrast, the susceptible lines activated defensive genes only after pathogen inoculation, resulting in increased levels of H2O2 and lipid peroxidation, as well as lower enzymatic activities. The constitutive defenses observed in this study from seed could be profitably exploited to develop markers to speed up conventional breeding programs in the selection of resistant genotypes.
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Affiliation(s)
- Valentina Maschietto
- Dipartimento di Scienze delle Produzioni Vegetali Sostenibili, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, Piacenza 29122, Italy.
| | - Alessandra Lanubile
- Dipartimento di Scienze delle Produzioni Vegetali Sostenibili, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, Piacenza 29122, Italy.
| | - Silvana De Leonardis
- Dipartimento di Biologia, Università di Bari "Aldo Moro", via E. Orabona 4, Bari 70125, Italy.
| | - Adriano Marocco
- Dipartimento di Scienze delle Produzioni Vegetali Sostenibili, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, Piacenza 29122, Italy.
| | - Costantino Paciolla
- Dipartimento di Biologia, Università di Bari "Aldo Moro", via E. Orabona 4, Bari 70125, Italy.
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