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Formela-Luboińska M, Remlein-Starosta D, Waśkiewicz A, Karolewski Z, Bocianowski J, Stępień Ł, Labudda M, Jeandet P, Morkunas I. The Role of Saccharides in the Mechanisms of Pathogenicity of Fusarium oxysporum f. sp. lupini in Yellow Lupine ( Lupinus luteus L.). Int J Mol Sci 2020; 21:ijms21197258. [PMID: 33019571 PMCID: PMC7582877 DOI: 10.3390/ijms21197258] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 09/21/2020] [Accepted: 09/29/2020] [Indexed: 12/15/2022] Open
Abstract
The primary aim of this study was to determine the relationship between soluble sugar levels (sucrose, glucose, or fructose) in yellow lupine embryo axes and the pathogenicity of the hemibiotrophic fungus Fusarium oxysporum f. sp. Schlecht lupini. The first step of this study was to determine the effect of exogenous saccharides on the growth and sporulation of F. oxysporum. The second one focused on estimating the levels of ergosterol as a fungal growth indicator in infected embryo axes cultured in vitro on sugar containing-medium or without it. The third aim of this study was to record the levels of the mycotoxin moniliformin as the most characteristic secondary metabolite of F. oxysporum in the infected embryo axes with the high sugar medium and without it. Additionally, morphometric measurements, i.e., the length and fresh weight of embryo axes, were done. The levels of ergosterol were the highest in infected embryo axes with a sugar deficit. At the same time, significant accumulation of the mycotoxin moniliformin was recorded in those tissues. Furthermore, it was found that the presence of sugars in water agar medium inhibited the sporulation of the pathogenic fungus F. oxysporum in relation to the control (sporulation of the pathogen on medium without sugar), the strongest inhibiting effect was observed in the case of glucose. Infection caused by F. oxysporum significantly limited the growth of embryo axes, but this effect was more visible on infected axes cultured under sugar deficiency than on the ones cultured with soluble sugars. The obtained results thus showed that high sugar levels may lead to reduced production of mycotoxins by F. oxysporum, limiting infection development and fusariosis.
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Affiliation(s)
- Magda Formela-Luboińska
- Department of Plant Physiology, Poznań University of Life Sciences, Wołyńska 35, 60-637 Poznań, Poland;
| | - Dorota Remlein-Starosta
- Department of Ecology and Environmental Protection, Institute of Plant Protection—National Research Institute, Władysława Węgorka 20, 60-318 Poznań, Poland
| | - Agnieszka Waśkiewicz
- Department of Chemistry, Poznań University of Life Sciences, Wojska Polskiego 75, 60-625 Poznań, Poland;
| | - Zbigniew Karolewski
- Department of Phytopathology, Seed Science and Technology, Poznań University of Life Sciences, Dąbrowskiego 159, 60-594 Poznań, Poland;
| | - Jan Bocianowski
- Department of Mathematical and Statistical Methods, Poznań University of Life Sciences, Wojska Polskiego 28, 60-637 Poznań, Poland;
| | - Łukasz Stępień
- Department of Pathogen Genetics and Plant Resistance, Institute of Plant Genetics, Polish Academy of Sciences, Strzeszyńska 34, 60-479 Poznań, Poland;
| | - Mateusz Labudda
- Department of Biochemistry and Microbiology, Institute of Biology, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland;
| | - Philippe Jeandet
- Research Unit “Induced Resistance and Plant Bioprotection”, UPRES EA 4707, Department of Biology and Biochemistry, Faculty of Sciences, University of Reims, P.O. Box 1039, CEDEX 02, 51687 Reims, France;
| | - Iwona Morkunas
- Department of Plant Physiology, Poznań University of Life Sciences, Wołyńska 35, 60-637 Poznań, Poland;
- Correspondence: or ; Tel.: +48-61-8466040
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Rodríguez-Pires S, Espeso EA, Baró-Montel N, Torres R, Melgarejo P, De Cal A. Labeling of Monilinia fructicola with GFP and Its Validation for Studies on Host-Pathogen Interactions in Stone and Pome Fruit. Genes (Basel) 2019; 10:E1033. [PMID: 31835779 PMCID: PMC6947648 DOI: 10.3390/genes10121033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 11/28/2019] [Accepted: 12/05/2019] [Indexed: 11/16/2022] Open
Abstract
To compare in vivo the infection process of Monilinia fructicola on nectarines and apples using confocal microscopy it is necessary to transform a pathogenic strain with a construct expressing a fluorescent chromophore such as GFP. Thus, germinated conidia of the pathogen were transformed with Agrobacterium tumefaciens carrying the plasmid pPK2-hphgfp that allowed the expression of a fluorescent Hph-GFP chimera. The transformants were selected according to their resistance to hygromycin B, provided by the constitutive expression of the hph-gfp gene driven by the glyceraldehyde 3P dehydrogenase promoter of Aspergillus nidulans. The presence of T-DNA construct in the genomic DNA was confirmed by PCR using a range of specific primers. Subsequent PCR-mediated analyses proved integration of the transgene at a different genomic location in each transformant and the existence of structural reorganizations at these insertion points. The expression of Hph-GFP in three independent M. fructicola transformants was monitored by immunodetection and epifluorescence and confocal microscopy. The Atd9-M. fructicola transformant displayed no morphological defects and showed growth and pathogenic characteristics similar to the wild type. Microscopy analysis of the Atd9 transformant evidenced that nectarine infection by M. fructicola was at least three times faster than on apples.
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Affiliation(s)
- Silvia Rodríguez-Pires
- Department of Plant Protection, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Ctra. de La Coruña Km. 7, 28040 Madrid, Spain; (S.R.-P.); (P.M.)
| | - Eduardo Antonio Espeso
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040 Madrid, Spain;
| | - Nuria Baró-Montel
- IRTA, XaRTA-Postharvest, Edifici Fruitcentre, Parc Científic i Tecnologic Agroalimentari de Lleida, 25003 Lleida, Spain; (N.B.-M.); (R.T.)
| | - Rosario Torres
- IRTA, XaRTA-Postharvest, Edifici Fruitcentre, Parc Científic i Tecnologic Agroalimentari de Lleida, 25003 Lleida, Spain; (N.B.-M.); (R.T.)
| | - Paloma Melgarejo
- Department of Plant Protection, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Ctra. de La Coruña Km. 7, 28040 Madrid, Spain; (S.R.-P.); (P.M.)
| | - Antonieta De Cal
- Department of Plant Protection, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Ctra. de La Coruña Km. 7, 28040 Madrid, Spain; (S.R.-P.); (P.M.)
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Meena M, Gupta SK, Swapnil P, Zehra A, Dubey MK, Upadhyay RS. Alternaria Toxins: Potential Virulence Factors and Genes Related to Pathogenesis. Front Microbiol 2017; 8:1451. [PMID: 28848500 PMCID: PMC5550700 DOI: 10.3389/fmicb.2017.01451] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 07/18/2017] [Indexed: 01/04/2023] Open
Abstract
Alternaria is an important fungus to study due to their different life style from saprophytes to endophytes and a very successful fungal pathogen that causes diseases to a number of economically important crops. Alternaria species have been well-characterized for the production of different host-specific toxins (HSTs) and non-host specific toxins (nHSTs) which depend upon their physiological and morphological stages. The pathogenicity of Alternaria species depends on host susceptibility or resistance as well as quantitative production of HSTs and nHSTs. These toxins are chemically low molecular weight secondary metabolites (SMs). The effects of toxins are mainly on different parts of cells like mitochondria, chloroplast, plasma membrane, Golgi complex, nucleus, etc. Alternaria species produce several nHSTs such as brefeldin A, tenuazonic acid, tentoxin, and zinniol. HSTs that act in very low concentrations affect only certain plant varieties or genotype and play a role in determining the host range of specificity of plant pathogens. The commonly known HSTs are AAL-, AK-, AM-, AF-, ACR-, and ACT-toxins which are named by their host specificity and these toxins are classified into different family groups. The HSTs are differentiated on the basis of bio-statistical and other molecular analyses. All these toxins have different mode of action, biochemical reactions and signaling mechanisms to cause diseases. Different species of Alternaria produced toxins which reveal its biochemical and genetic effects on itself as well as on its host cells tissues. The genes responsible for the production of HSTs are found on the conditionally dispensable chromosomes (CDCs) which have been well characterized. Different bio-statistical methods like basic local alignment search tool (BLAST) data analysis used for the annotation of gene prediction, pathogenicity-related genes may provide surprising knowledge in present and future.
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Affiliation(s)
- Mukesh Meena
- Department of Botany, Institute of Science, Banaras Hindu UniversityVaranasi, India
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Gabriel MF, Uriel N, Teifoori F, Postigo I, Suñén E, Martínez J. The major Alternaria alternata allergen, Alt a 1: A reliable and specific marker of fungal contamination in citrus fruits. Int J Food Microbiol 2017. [PMID: 28633053 DOI: 10.1016/j.ijfoodmicro.2017.06.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The ubiquitously present spores of Alternaria alternata can spoil a wide variety of foodstuffs, including a variety of fruits belonging to the Citrus genus. The major allergenic protein of A. alternata, Alt a 1, is a species-specific molecular marker that has been strongly associated with allergenicity and phytopathogenicity of this fungal species. This study aimed to evaluate the potential of the detection of Alt a 1 as a reliable indicator of A. alternata contamination in citrus fruits. To accomplish this aim, sixty oranges were artificially infected with a spore suspension of A. alternata. Internal fruit material was collected at different incubation times (one, two and three weeks after the fungal inoculation) and used for both total RNA extraction and protein extraction. Alt a 1 detection was then performed by polymerase chain reaction (PCR) amplification using Alt a 1 specific primers and by enzyme-linked immunosorbent assay (ELISA). The experimental model presented in this work was effective to simulate the typical Alternaria black rot phenotype and its progression. Although both PCR and ELISA techniques have been successfully carried out for detecting Alt a 1 allergen in A. alternata infected oranges, the PCR method was found to be more sensitive than ELISA. Nevertheless, ELISA results were highly valuable to demonstrate that considerable amounts of Alt a 1 are produced during A. alternata fruit infection process, corroborating the recently proposed hypothesis that this protein plays a role in the pathogenicity and virulence of Alternaria species. Such evidence suggests that the detection of Alt a 1 by PCR-based assay may be used as a specific indicator of the presence of pathogenic and allergenic fungal species, A. alternata, in fruits. This knowledge can be employed to control the fungal infection and mitigate agricultural losses as well as human exposure to A. alternata allergens and toxins.
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Affiliation(s)
- M F Gabriel
- Department of Immunology, Microbiology and Parasitology, Faculty of Pharmacy, Laboratory of Parasitology and Allergy, Lascaray Research Centre, University of the Basque Country, Vitoria, Spain
| | - N Uriel
- Department of Immunology, Microbiology and Parasitology, Faculty of Pharmacy, Laboratory of Parasitology and Allergy, Lascaray Research Centre, University of the Basque Country, Vitoria, Spain
| | - F Teifoori
- Department of Immunology, Microbiology and Parasitology, Faculty of Pharmacy, Laboratory of Parasitology and Allergy, Lascaray Research Centre, University of the Basque Country, Vitoria, Spain
| | - I Postigo
- Department of Immunology, Microbiology and Parasitology, Faculty of Pharmacy, Laboratory of Parasitology and Allergy, Lascaray Research Centre, University of the Basque Country, Vitoria, Spain
| | - E Suñén
- Department of Immunology, Microbiology and Parasitology, Faculty of Pharmacy, Laboratory of Parasitology and Allergy, Lascaray Research Centre, University of the Basque Country, Vitoria, Spain
| | - J Martínez
- Department of Immunology, Microbiology and Parasitology, Faculty of Pharmacy, Laboratory of Parasitology and Allergy, Lascaray Research Centre, University of the Basque Country, Vitoria, Spain.
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Fruits and Vegetables. Food Microbiol 2014. [DOI: 10.1128/9781555818463.ch8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Castruita-Domínguez JP, González-Hernández SE, Polaina J, Flores-Villavicencio LL, Alvarez-Vargas A, Flores-Martínez A, Ponce-Noyola P, Leal-Morales CA. Analysis of a polygalacturonase gene of Ustilago maydis and characterization of the encoded enzyme. J Basic Microbiol 2013; 54:340-9. [PMID: 23686704 DOI: 10.1002/jobm.201200606] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 12/20/2012] [Indexed: 11/07/2022]
Abstract
Ustilago maydis is a pathogenic fungus that produces the corn smut. It is a biotrophic parasite that depends on living plant tissues for its proliferation and development. Polygalacturonases are secreted by pathogens to solubilize the plant cell-wall and are required for pathogen virulence. In this paper, we report the isolation of a U. maydis polygalacturonase gene (Pgu1) and the functional and structural characterization of the encoded enzyme. The U. maydis Pgu1 gene is expressed when the fungus is grown in liquid culture media containing different carbon sources. In plant tissue, the expression increased as a function of incubation time. Pgu1 gene expression was detected during plant infection around 10 days post-infection with U. maydis FB-D12 strain in combination with teliospore formation. Synthesis and secretion of active recombinant PGU1 were achieved using Pichia pastoris, the purified enzyme had a optimum temperature of 34 °C, optimum pH of 4.5, a Km of 57.84 g/L for polygalacturonic acid, and a Vmax of 28.9 µg/min mg. Structural models of PGU1 based on homologous enzymes yielded a typical right-handed β-helix fold of pectinolytic enzymes classified in the glycosyl hydrolases family 28, and the U. maydis PGU1 is related with endo rather than exo polygalacturonases.
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Affiliation(s)
- José P Castruita-Domínguez
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato. Noria Alta s/n, Guanajuato, Gto., México
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Buron-Moles G, López-Pérez M, González-Candelas L, Viñas I, Teixidó N, Usall J, Torres R. Use of GFP-tagged strains of Penicillium digitatum and Penicillium expansum to study host-pathogen interactions in oranges and apples. Int J Food Microbiol 2012. [PMID: 23177056 DOI: 10.1016/j.ijfoodmicro.2012.10.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Penicillium digitatum and Penicillium expansum are responsible for green and blue molds in citrus and pome fruits, respectively, which result in major monetary losses worldwide. In order to study their infection process in fruits, we successfully introduced a green fluorescent protein (GFP) encoding gene into wild type P. digitatum and P. expansum isolates, using Agrobacterium tumefaciens-mediated transformation (ATMT), with hygromycin B resistance as the selectable marker. To our knowledge, this is the first report describing the transformation of these two important postharvest pathogens with GFP and the use of transformed strains to study compatible and non-host pathogen interactions. Transformation did not affect the pathogenicity or the ecophysiology of either species compared to their respective wild type strains. The GFP-tagged strains were used for in situ analysis of compatible and non-host pathogen interactions on oranges and apples. Knowledge of the infection process of apples and oranges by these pathogens will facilitate the design of novel strategies to control these postharvest diseases and the use of the GFP-tagged strains will help to determine the response of P. digitatum and P. expansum on/in plant surface and tissues to different postharvest treatments.
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Affiliation(s)
- G Buron-Moles
- University of Lleida, XaRTA-Postharvest, Rovira Roure 191, 25198 Lleida, Spain
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Miyamoto Y, Masunaka A, Tsuge T, Yamamoto M, Ohtani K, Fukumoto T, Gomi K, Peever TL, Tada Y, Ichimura K, Akimitsu K. ACTTS3 encoding a polyketide synthase is essential for the biosynthesis of ACT-toxin and pathogenicity in the tangerine pathotype of Alternaria alternata. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:406-414. [PMID: 20192828 DOI: 10.1094/mpmi-23-4-0406] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The tangerine pathotype of Alternaria alternata produces host-selective ACT-toxin and causes Alternaria brown spot disease of tangerine and tangerine hybrids. Sequence analysis of a genomic BAC clone identified part of the ACT-toxin TOX (ACTT) gene cluster, and knockout experiments have implicated several open reading frames (ORF) contained within the cluster in the biosynthesis of ACT-toxin. One of the ORF, designated ACTTS3, encoding a putative polyketide synthase, was isolated by rapid amplification of cDNA ends and genomic/reverse transcription-polymerase chain reactions using the specific primers designed from the BAC sequences. The 7,374-bp ORF encodes a polyketide synthase with putative beta-ketoacyl synthase, acyltransferase, methyltransferase, beta-ketoacyl reductase, and phosphopantetheine attachment site domains. Genomic Southern blots demonstrated that ACTTS3 is present on the smallest chromosome in the tangerine pathotype of A. alternata, and the presence of ACTTS3 is highly correlated with ACT-toxin production and pathogenicity. Targeted gene disruption of two copies of ACTTS3 led to a complete loss of ACT-toxin production and pathogenicity. These results indicate that ACTTS3 is an essential gene for ACT-toxin biosynthesis in the tangerine pathotype of A. alternata and is required for pathogenicity of this fungus.
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Affiliation(s)
- Y Miyamoto
- Faculty of Agriculture and Gene Research Center, Kagawa University, Miki, Kagawa, Japan
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Morán-Diez E, Hermosa R, Ambrosino P, Cardoza RE, Gutiérrez S, Lorito M, Monte E. The ThPG1 endopolygalacturonase is required for the trichoderma harzianum-plant beneficial interaction. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:1021-31. [PMID: 19589077 DOI: 10.1094/mpmi-22-8-1021] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Considering the complexity of the in vivo interactions established by a mycoparasitic biocontrol agent at the plant rhizosphere, proteomic, genomic, and transcriptomic approaches were used to study a novel Trichoderma gene coding for a plant cell wall (PCW)-degrading enzyme. A proteome analysis, using a three-component (Trichoderma spp.-tomato plantlets-pathogen) system, allowed us to identify a differentially expressed Trichoderma harzianum endopolygalacturonase (endoPG). Spot 0303 remarkably increased only in the presence of the soilborne pathogens Rhizoctonia solani and Pythium ultimum, and corresponded to an expressed sequence tag from a T. harzianum T34 cDNA library that was constructed in the presence of PCW polymers and used to isolate the Thpg1 gene. Compared with the wild-type strain, Thpg1-silenced transformants showed lower PG activity, less growth on pectin medium, and reduced capability to colonize tomato roots. These results were combined with microarray comparative data from the transcriptome of Arabidopsis plants inoculated with the wild type or a Thpg1-silenced transformant (ePG5). The endoPG-encoding gene was found to be required for active root colonization and plant defense induction by T. harzianum T34. In vivo assays showed that Botrytis cinerea leaf necrotic lesions were slightly smaller in plants colonized by ePG5, although no statistically significant differences were observed.
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Affiliation(s)
- Eugenia Morán-Diez
- Centro Hispano-Luso de Investigaciones Agrarias (CIALE). Departamento de Microbiología y Genética, Universidad de Salamanca, Campus de Villamayor, C/ Duero 12. 37185 Salamanca, Spain
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Miyamoto Y, Ishii Y, Honda A, Masunaka A, Tsuge T, Yamamoto M, Ohtani K, Fukumoto T, Gomi K, Peever TL, Akimitsu K. Function of genes encoding acyl-CoA synthetase and enoyl-CoA hydratase for host-selective act-toxin biosynthesis in the tangerine pathotype of Alternaria alternata. PHYTOPATHOLOGY 2009; 99:369-377. [PMID: 19271978 DOI: 10.1094/phyto-99-4-0369] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The tangerine pathotype of Alternaria alternata produces host-selective ACT-toxin and causes Alternaria brown spot disease. Sequence analysis of a genomic cosmid clone identified a part of the ACTT gene cluster and implicated two genes, ACTT5 encoding an acyl-CoA synthetase and ACTT6 encoding an enoyl-CoA hydratase, in the biosynthesis of ACT-toxin. Genomic Southern blots demonstrated that both genes were present in tangerine pathotype isolates producing ACT-toxin and also in Japanese pear pathotype isolates producing AK-toxin and strawberry pathotype isolates producing AF-toxin. ACT-, AK-, and AF-toxins from these three pathotypes share a common 9,10-epoxy-8-hydroxy-9-methyl-decatrienoic acid moiety. Targeted gene disruption of two copies of ACTT5 significantly reduced ACT-toxin production and virulence. Targeted gene disruption of two copies of ACTT6 led to complete loss of ACT-toxin production and pathogenicity and a putative decatrienoic acid intermediate in ACT-toxin biosynthesis accumulated in mycelial mats. These results indicate that ACTT5 and ACTT6 are essential genes in ACT-toxin biosynthesis in the tangerine pathotype of A. alternata and both are required for full virulence of this fungus.
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Affiliation(s)
- Y Miyamoto
- United Graduate School and Faculty of Agriculture, Kagawa University, Miki, Kagawa 761-0795 Japan
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Miyamoto Y, Masunaka A, Tsuge T, Yamamoto M, Ohtani K, Fukumoto T, Gomi K, Peever TL, Akimitsu K. Functional analysis of a multicopy host-selective ACT-toxin biosynthesis gene in the tangerine pathotype of Alternaria alternata using RNA silencing. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2008; 21:1591-1599. [PMID: 18986255 DOI: 10.1094/mpmi-21-12-1591] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Alternaria brown spot, caused by the tangerine pathotype of Alternaria alternata, is a serious disease of commercially important tangerines and their hybrids. The pathogen produces host-selective ACT toxin, and several genes (named ACTT) responsible for ACT-toxin biosynthesis have been identified. These genes have many paralogs, which are clustered on a small, conditionally dispensable chromosome, making it difficult to disrupt entire functional copies of ACTT genes using homologous recombination-mediated gene disruption. To overcome this problem, we attempted to use RNA silencing, which has never been employed in Alternaria spp., to knock down the functional copies of one ACTT gene with a single silencing event. ACTT2, which encodes a putative hydrolase and is present in multiple copies in the genome, was silenced by transforming the fungus with a plasmid construct expressing hairpin ACTT2 RNAs. The ACTT2 RNA-silenced transformant (S-7-24-2) completely lost ACTT2 transcripts and ACT-toxin production as well as pathogenicity. These results indicated that RNA silencing may be a useful technique for studying the role of ACTT genes responsible for host-selective toxin biosynthesis in A. alternata. Further, this technique may be broadly applicable to the analysis of many genes present in multiple copies in fungal genomes that are difficult to analyze using recombination-mediated knockdowns.
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Affiliation(s)
- Y Miyamoto
- United Graduate School and Faculty of Agriculture, Kagawa University, Miki, Kagawa 761-0795, Japan
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Katoh H, Ohtani K, Yamamoto H, Akimitsu K. Overexpression of a Gene Encoding a Catabolite Repression Element in Alternaria citri Causes Severe Symptoms of Black Rot in Citrus Fruit. PHYTOPATHOLOGY 2007; 97:557-63. [PMID: 18943574 DOI: 10.1094/phyto-97-5-0557] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
ABSTRACT A gene (AcCreA) encoding a catabolite repression element (CreA) with (two zinc fingers of the Cys(2)His(2) type was isolated from the postharvest fungal pathogen Alternaria citri. The AcCreA overexpression mutant AcOEC2 of A. citri showed normal growth on pectin medium and on segments of peel or the juice sac area from citrus fruit. Production of endopolygalacturonase, an essential virulence factor of this pathogen, was similar in AcOEC2 and the wild type in pectin-containing media. However, addition of glucose to the medium showed that carbon catabolite repression of endopolygalacturonase gene (Acpg1) expression, as well as endopolygalacturonase production, was lost in AcOEC2. The wild-type strain of A. citri causes rot mainly in the central axis of citrus fruit without development of rotting in the juice sac area; however, AcOEC2 caused severe black rot symptoms in both the central axis and juice sac areas. These results indicate that AcCreA-mediated catabolite repression controls the virulence or infection of this pathogen, and that the wild-type A. citri does not cause symptoms in the juice sac area due to carbon catabolite repression by sugars in the juice of the juice sac area.
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Katoh H, Nalumpang S, Yamamoto H, Akimitsu K. Overexpression of citrus polygalacturonase-inhibiting protein in citrus black rot pathogen Alternaria citri. JOURNAL OF PLANT PHYSIOLOGY 2007; 164:527-35. [PMID: 17223223 DOI: 10.1016/j.jplph.2006.10.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Revised: 10/05/2006] [Accepted: 10/06/2006] [Indexed: 05/13/2023]
Abstract
The rough lemon (Citrus jambhiri) gene encoding polygalacturonase-inhibiting protein (RlemPGIPA) was overexpressed in the pathogenic fungus Alternaria citri. The overexpression mutant AcOPI6 retained the ability to utilize pectin as a sole carbon source, and the overexpression of polygalacturonase-inhibiting protein did not have any effect on the growth of AcOPI6 in potato dextrose and pectin medium. The pathogenicity of AcOPI6 to cause a black rot symptom in citrus fruits was also unchanged. Polygalacturonase-inhibiting protein was secreted together with endopolygalacturonase into culture filtrates of AcOPI6, and oligogalacturonides were digested from polygalacturonic acid by both proteins in the culture filtrates. The reaction mixture containing oligogalacturonides possessed activity for induction of defense-related gene, RlemLOX, in rough lemon leaves.
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Affiliation(s)
- Hiroshi Katoh
- Laboratory of Plant Pathology, United Graduate School and Faculty of Agriculture, Kagawa University, Miki, Kagawa 761-0795 Japan
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Katoh H, Isshiki A, Masunaka A, Yamamoto H, Akimitsu K. A Virulence-Reducing Mutation in the Postharvest Citrus Pathogen Alternaria citri. PHYTOPATHOLOGY 2006; 96:934-940. [PMID: 18944048 DOI: 10.1094/phyto-96-0934] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
ABSTRACT Alternaria citri causes Alternaria black rot, a postharvest fruit disease, on a broad range of citrus cultivars. We previously described that an endopolygalacturonase minus mutant of A. citri caused significantly less black rot in citrus fruit. To search for other essential factors causing symptoms in addition to endopolygalacturonase, a random mutation analysis of pathogenicity was performed using restriction enzyme-mediated integration. Three isolates among 1,694 transformants of A. citri had a loss in pathogenicity in a citrus peel assay, and one of these three mutants was a histidine auxotroph. Gene AcIGPD that encodes imidazole glycerol phosphate dehydratase, the sixth enzyme in the histidine biosynthetic pathway, was cloned, and the mutant containing the disrupted target gene, AcIGPD, caused less black rot.
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Mehli L, Schaart JG, Kjellsen TD, Tran DH, Salentijn EMJ, Schouten HJ, Iversen TH. A gene encoding a polygalacturonase-inhibiting protein (PGIP) shows developmental regulation and pathogen-induced expression in strawberry. THE NEW PHYTOLOGIST 2004; 163:99-110. [PMID: 33873779 DOI: 10.1111/j.1469-8137.2004.01088.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
• Polygalacturonase-inhibiting proteins (PGIPs) have been demonstrated to play a role in host defence in several plants. • The PGIP now cloned from strawberry (Fragaria × ananassa) showed a high degree of homology to other fruit PGIPs. The gene expression of strawberry PGIP was monitored in healthy leaves, flowers and fruit at different maturity stages. PGIP transcript levels were also analysed following fruit inoculation with the fungal pathogen Botrytis cinerea in strawberry cultivars displaying variation in susceptibility. • Healthy mature berries showed the highest constitutive PGIP gene expression levels compared with leaves, flowers and immature fruit, indicating that the gene is developmentally regulated. Among the cultivars studied ('Elsanta', 'Korona', 'Polka', 'Senga sengana', 'Tenira'), 'Polka' had the highest constitutive expression level of PGIP. After inoculation with B. cinerea, all five cultivars displayed a significant induction of PGIP gene expression, but the differences between them were not statistically significant. • The high induction of the PGIP gene after inoculation with B. cinerea indicates that PGIP has a role in defence of strawberry.
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Affiliation(s)
- Lisbeth Mehli
- Plantebiosenteret, Department of Biology, NTNU, 7491 Trondheim, Norway
- Present address: Sør-Trøndelag University College, Department of Food Science, Trondheim, Norway
| | - Jan G Schaart
- Plant Research International, Business Unit Biodiversity and Breeding, Post box 16, 6700 AA Wageningen, The Netherlands
| | - Trygve D Kjellsen
- Plantebiosenteret, Department of Biology, NTNU, 7491 Trondheim, Norway
| | - Diem Hong Tran
- Plant Research International, Business Unit Biodiversity and Breeding, Post box 16, 6700 AA Wageningen, The Netherlands
| | - Elma M J Salentijn
- Plant Research International, Business Unit Biodiversity and Breeding, Post box 16, 6700 AA Wageningen, The Netherlands
| | - Henk J Schouten
- Plant Research International, Business Unit Biodiversity and Breeding, Post box 16, 6700 AA Wageningen, The Netherlands
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Elliott CE, Howlett BJ. Approaches for identification of fungal genes essential for plant disease. GENETIC ENGINEERING 2004; 26:85-103. [PMID: 15387294 DOI: 10.1007/978-0-306-48573-2_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
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Akimitsu K, Peever TL, Timmer LW. Molecular, ecological and evolutionary approaches to understanding Alternaria diseases of citrus. MOLECULAR PLANT PATHOLOGY 2003; 4:435-446. [PMID: 20569403 DOI: 10.1046/j.1364-3703.2003.00189.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
SUMMARY Alternaria fungi cause four different diseases of citrus: Alternaria brown spot of tangerines, Alternaria leaf spot of rough lemon, Alternaria black rot of several citrus fruits and Mancha foliar of Mexican lime. The first three diseases are caused by the small-spored species, Alternaria alternata and the causal agents can only be differentiated using pathogenicity tests, toxin assays or genetic markers. Mancha foliar is caused by the morphologically distinct, large-spored species A. limicola. Substantial progress has been made in understanding the biology, ecology, population biology, systematics, molecular biology and biochemistry of the interactions between these pathogens and citrus. Epidemiological studies have focused on brown spot of tangerines and their hybrids and have contributed to the development of a model of disease development which has improved control and reduced fungicide use. Studies of the population genetics, host specificity and ecology of A. alternata from different ecological niches on citrus have revealed host specific forms of the pathogen which cause disease on different citrus species, the existence of three phylogenetic lineages of the fungus which cause brown spot world-wide, and closely related non-pathogenic isolates which colonize healthy citrus tissue. The role of host-specific toxins in Alternaria diseases of citrus has been extensively studied for over 20 years, and these pathosystems have become model systems for host-pathogen interactions. Recent molecular research has started to unravel the genetic basis of toxin production and the host susceptibility to toxin, and the role of extracellular, degradative enzymes in disease.
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Affiliation(s)
- Kazuya Akimitsu
- Laboratory of Plant Pathology, Department of Life Sciences, Faculty of Agriculture, Kagawa University, Miki, Kagawa 761-0795, Japan
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