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Paiva DS, Fernandes L, Portugal A, Trovão J. First Genome Sequence of the Microcolonial Black Fungus Saxispiralis lemnorum MUM 23.14: Insights into the Unique Genomic Traits of the Aeminiaceae Family. Microorganisms 2024; 12:104. [PMID: 38257931 PMCID: PMC10820743 DOI: 10.3390/microorganisms12010104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/15/2023] [Accepted: 01/02/2024] [Indexed: 01/24/2024] Open
Abstract
Saxispiralis lemnorum MUM 23.14 is an extremotolerant microcolonial black fungus, originally isolated from a biodeteriorated limestone artwork in Portugal. This recently introduced species belongs to the Aeminiaceae family, representing the second member of this monophyletic clade. This fungus exhibits a unique set of characteristics, including xerophily, cold tolerance, high UV radiation tolerance, and an exceptional ability to thrive in NaCl concentrations of up to 30% while also enduring pH levels ranging from 5 to 11. To gain insights into its genomic traits associated with stress resistance mechanisms, specialization, and their potential implications in stone biodeterioration, we conducted a comprehensive genome sequencing and analysis. This draft genome not only marks the first for the Saxispiralis genus but also the second for the Aeminiaceae family. Furthermore, we performed two comparative genomic analyses: one focusing on the closest relative within the Aeminiaceae family, Aeminium ludgeri, and another encompassing the genome of different extremotolerant black fungi. In this study, we successfully achieved high genome completeness for S. lemnorum and confirmed its close phylogenetic relationship to A. ludgeri. Our findings revealed traits contributing to its extremophilic nature and provided insights into potential mechanisms contributing to stone biodeterioration. Many traits are common to both Aeminiaceae species and are shared with other black fungi, while numerous unique traits may be attributed to species-specific characteristics.
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Affiliation(s)
- Diana S. Paiva
- Centre for Functional Ecology (CFE)—Science for People & the Planet, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal (J.T.)
| | - Luís Fernandes
- Centre for Functional Ecology (CFE)—Science for People & the Planet, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal (J.T.)
| | - António Portugal
- Centre for Functional Ecology (CFE)—Science for People & the Planet, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal (J.T.)
- FitoLab—Laboratory for Phytopathology, Instituto Pedro Nunes (IPN), Rua Pedro Nunes, 3030-199 Coimbra, Portugal
- TERRA—Associate Laboratory for Sustainable Land Use and Ecosystem Services, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal
| | - João Trovão
- Centre for Functional Ecology (CFE)—Science for People & the Planet, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal (J.T.)
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Li Z, dos Santos RF, Gao L, Chang P, Wang X. Current status and future prospects of grapevine anthracnose caused by Elsinoe ampelina: An important disease in humid grape-growing regions. MOLECULAR PLANT PATHOLOGY 2021; 22:899-910. [PMID: 34096145 PMCID: PMC8295512 DOI: 10.1111/mpp.13076] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 03/21/2021] [Accepted: 04/28/2021] [Indexed: 05/20/2023]
Abstract
UNLABELLED Anthracnose, caused by Elsinoe ampelina, is one of the most destructive diseases of grapevines worldwide, especially in humid areas. E. ampelina mainly infects young tissues starting from shoots to berries and affects vine vigour and berry yield. The occurrence and the role of the sexual stage in the disease cycle and the grapevine-E. ampelina interaction remain poorly understood. However, the recent genome sequence data of E. ampelina provides the basis for further studies to understand its evolution, pathogenicity mechanisms, and effector repertoire. New studies on E. ampelina have been conducted in recent years. In this pathogen profile, we present a comprehensive literature review of E. ampelina to summarize the findings on its aetiology, infection mechanisms, genome, pathogenicity, and host resistance. TAXONOMY Elsinoe ampelina Shear; Kingdom Fungi; Phylum Ascomycota; Subphylum Pezizomycotina; Class Dothideomycetes; Subclass Dothideomycetidae; Order Myriangiales Starbäck; Family Elsinoaceae Höhnel; Genus Elsinoe Racib. HOST RANGE E. ampelina only infects Vitis species and hybrids. DISTRIBUTION The grapevine anthracnose is distributed worldwide but is most prevalent in Argentina, Australia, Brazil, Canada, China, India, Japan, Korea, New Zealand, South Africa, Thailand, USA, and Uruguay. DISEASE SYMPTOMS E. ampelina causes slightly abundant depressed spots on young leaves, petioles, stems, tendrils, rachises, and berries. Under severe infection conditions, early defoliation, berry dropping, and delayed berry development and ripening may occur. GENOME The genomes of two E. ampelina isolates, YL-1 and CECT 20119, are publicly released with 8,057 and 10,207 predicted genes, respectively.
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Affiliation(s)
- Zhi Li
- State Key Laboratory of Crop Stress Biology in Arid AreasCollege of HorticultureNorthwest A&F UniversityYanglingChina
- Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest ChinaMinistry of AgricultureNorthwest A&F UniversityYanglingChina
| | - Ricardo Feliciano dos Santos
- Departament of Plant Pathology and NematologyLuiz de Queiroz College of AgricultureUniversidade de São PauloPiracicaba, São PauloBrazil
| | - Linlin Gao
- State Key Laboratory of Crop Stress Biology in Arid AreasCollege of HorticultureNorthwest A&F UniversityYanglingChina
| | - Pingping Chang
- State Key Laboratory of Crop Stress Biology in Arid AreasCollege of HorticultureNorthwest A&F UniversityYanglingChina
| | - Xiping Wang
- State Key Laboratory of Crop Stress Biology in Arid AreasCollege of HorticultureNorthwest A&F UniversityYanglingChina
- Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest ChinaMinistry of AgricultureNorthwest A&F UniversityYanglingChina
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Global identification of alternative splicing in Shiraia bambusicola and analysis of its regulation in hypocrellin biosynthesis. Appl Microbiol Biotechnol 2019; 104:211-223. [PMID: 31768612 DOI: 10.1007/s00253-019-10189-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/21/2019] [Accepted: 10/03/2019] [Indexed: 01/24/2023]
Abstract
Hypocrellins, as natural pigments from Shiraia bambusicola, have extensive applications in the agricultural, cosmetic, food, and feed industries, and play a vital role in photodynamic therapy for anticancer and antiviral treatments. However, environmental stresses are always the bottlenecks for increasing hypocrellin yield during the process of fermentation. Pre-mRNA alternative splicing (AS) is an essential mechanism in the defense of abiotic stresses in the animal and plant kingdom, but is seldom involved in fungi. In this study, AS from genome-wide sequencing and RNA-seq data for S. bambusicola was analyzed for the first time. Interestingly, the proportion of AS in S. bambusicola was 38.44% (most of them participated in metabolic processes, covering pigmentation and response to stimulus), a much higher ratio than seen in that of other fungal species (1.3-18%). Here, we identified the relationship of AS and secondary metabolic (SM) biosynthesis under a series of abiotic stresses. Suitable fungicides suppressed hypocrellin production significantly, and AS occurred in key functional genes (sbFLO, sbMFS, sbPKS) of hypocrellin biosynthesis. In contrast, H2O2 improved the yield of hypocrellins, but AS were not found in the corresponding gene cluster. A further study showed that overexpressing an isoform of sbPKS (sbPKSa) in Shiraia bambusicola could dramatically down-regulate the expression of the original gene sbPKS and nearly inhibit the production of hypocrellins. Altogether, our study strongly supported the hypothesis that AS had a vital role in the regulation of hypocrellin biosynthesis under stresses, and initially explored whether SM functional genes were relevant for fungi.
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Li T, Hou CL, Shen XY. Efficient agrobacterium-mediated transformation of Shiraia bambusicola and activation of a specific transcription factor for hypocrellin production. BIOTECHNOL BIOTEC EQ 2019. [DOI: 10.1080/13102818.2019.1667874] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Affiliation(s)
- Tong Li
- College of Life Science, Capital Normal University, Beijing, PR China
| | - Cheng-Lin Hou
- College of Life Science, Capital Normal University, Beijing, PR China
| | - Xiao-Ye Shen
- College of Life Science, Capital Normal University, Beijing, PR China
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One stop shop II: taxonomic update with molecular phylogeny for important phytopathogenic genera: 26–50 (2019). FUNGAL DIVERS 2019. [DOI: 10.1007/s13225-019-00418-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Chooi Y, Zhang G, Hu J, Muria‐Gonzalez MJ, Tran PN, Pettitt A, Maier AG, Barrow RA, Solomon PS. Functional genomics‐guided discovery of a light‐activated phytotoxin in the wheat pathogen
Parastagonospora nodorum
via pathway activation. Environ Microbiol 2017; 19:1975-1986. [DOI: 10.1111/1462-2920.13711] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 02/23/2017] [Indexed: 12/17/2022]
Affiliation(s)
- Yit‐Heng Chooi
- School of Molecular SciencesUniversity of Western AustraliaPerth WA6009 Australia
- Research School of BiologyAustralian National UniversityCanberra ACT2601 Australia
| | - Guozhi Zhang
- Research School of BiologyAustralian National UniversityCanberra ACT2601 Australia
| | - Jinyu Hu
- School of Molecular SciencesUniversity of Western AustraliaPerth WA6009 Australia
| | | | - Phuong N. Tran
- Research School of BiologyAustralian National UniversityCanberra ACT2601 Australia
| | - Amber Pettitt
- School of Molecular SciencesUniversity of Western AustraliaPerth WA6009 Australia
| | - Alexander G. Maier
- Research School of BiologyAustralian National UniversityCanberra ACT2601 Australia
| | - Russell A. Barrow
- Research School of ChemistryAustralian National UniversityCanberra ACT2601 Australia
| | - Peter S. Solomon
- Research School of BiologyAustralian National UniversityCanberra ACT2601 Australia
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Yu PL, Chen LH, Chung KR. How the Pathogenic Fungus Alternaria alternata Copes with Stress via the Response Regulators SSK1 and SHO1. PLoS One 2016; 11:e0149153. [PMID: 26863027 PMCID: PMC4749125 DOI: 10.1371/journal.pone.0149153] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 01/27/2016] [Indexed: 01/06/2023] Open
Abstract
The tangerine pathotype of Alternaria alternata is a necrotrophic fungal pathogen causing brown spot disease on a number of citrus cultivars. To better understand the dynamics of signal regulation leading to oxidative and osmotic stress response and fungal infection on citrus, phenotypic characterization of the yeast SSK1 response regulator homolog was performed. It was determined that SSK1 responds to diverse environmental stimuli and plays a critical role in fungal pathogenesis. Experiments to determine the phenotypes resulting from the loss of SSK1 reveal that the SSK1 gene product may be fulfilling similar regulatory roles in signaling pathways involving a HOG1 MAP kinase during ROS resistance, osmotic resistance, fungicide sensitivity and fungal virulence. The SSK1 mutants display elevated sensitivity to oxidants, fail to detoxify H2O2 effectively, induce minor necrosis on susceptible citrus leaves, and displays resistance to dicarboximide and phenylpyrrole fungicides. Unlike the SKN7 response regulator, SSK1 and HOG1 confer resistance to salt-induced osmotic stress via an unknown kinase sensor rather than the “two component” histidine kinase HSK1. SSK1 and HOG1 play a moderate role in sugar-induced osmotic stress. We also show that SSK1 mutants are impaired in their ability to produce germ tubes from conidia, indicating a role for the gene product in cell differentiation. SSK1 also is involved in multi-drug resistance. However, deletion of the yeast SHO1 (synthetic high osmolarity) homolog resulted in no noticeable phenotypes. Nonetheless, our results show that A. alternata can sense and react to different types of stress via SSK1, HOG1 and SKN7 in a cooperative manner leading to proper physiological and pathological functions.
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Affiliation(s)
- Pei-Ling Yu
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung-Hsing University, Taichung, Taiwan
| | - Li-Hung Chen
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung-Hsing University, Taichung, Taiwan
| | - Kuang-Ren Chung
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung-Hsing University, Taichung, Taiwan
- * E-mail:
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Yang SL, Yu PL, Chung KR. The glutathione peroxidase-mediated reactive oxygen species resistance, fungicide sensitivity and cell wall construction in the citrus fungal pathogen Alternaria alternata. Environ Microbiol 2016; 18:923-35. [PMID: 26567914 DOI: 10.1111/1462-2920.13125] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 11/04/2015] [Accepted: 11/05/2015] [Indexed: 12/18/2022]
Abstract
The ability to detoxify reactive oxygen species (ROS) is critical for pathogenicity in the necrotrophic fungus Alternaria alternata. We report a glutathione peroxidase 3 (AaGPx3) involved in the complex signalling network that is essential for the detoxification of cellular stresses induced by ROS and for A. alternata pathogenesis in citrus. AaGPx3 deletion mutants displayed increased sensitivity to H2 O2 and many ROS-generating compounds. AaGPx3 is required for correct fungal development as the AaGPx3 mutant strains showed a severe reduction in conidiation. AaGPx3 mutants accumulated higher chitin content than the wild-type and were less sensitive to the cell wall-targeting compounds calcofluor white and Congo red, as well as the fungicides fludioxonil and vinclozolin, suggesting a role of the glutathione systems in fungal cell wall construction. Virulence assays revealed that AaGPx3 is required for full virulence. The expression of AaGPx3 was downregulated in fungal strains carrying defective NADPH oxidase (Nox) or the oxidative stress responsive regulators YAP1 and HOG1, all implicated in ROS resistance. These results further support the important role of ROS detoxification during A. alternata pathogenesis in citrus. Overall, our study provides genetic evidence to define the central role of AaGPx3 in the biological and pathological functions of A. alternata.
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Affiliation(s)
- Siwy Ling Yang
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, USA
| | - Pei-Ling Yu
- Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung-Hsing University, Taichung, Taiwan
| | - Kuang-Ren Chung
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, USA.,Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung-Hsing University, Taichung, Taiwan
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Daub ME, Herrero S, Chung KR. Reactive oxygen species in plant pathogenesis: the role of perylenequinone photosensitizers. Antioxid Redox Signal 2013; 19:970-89. [PMID: 23259634 DOI: 10.1089/ars.2012.5080] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
SIGNIFICANCE Reactive oxygen species (ROS) play multiple roles in interactions between plants and microbes, both as host defense mechanisms and as mediators of pathogenic and symbiotic associations. One source of ROS in these interactions are photoactivated, ROS-generating perylenequinone pigments produced via polyketide metabolic pathways in plant-associated fungi. These natural products, including cercosporin, elsinochromes, hypocrellins, and calphostin C, are being utilized as medicinal agents, enzyme inhibitors, and in tumor therapy, but in nature, they play a role in the establishment of pathogenic associations between fungi and their plant hosts. RECENT ADVANCES Photoactivated perylenequinones are photosensitizers that use light energy to form singlet oxygen (¹O₂) and free radical oxygen species which damage cellular components based on localization of the perylenequinone molecule. Production of perylenequinones during infection commonly results in lipid peroxidation and membrane damage, leading to leakage of nutrients from cells into the intercellular spaces colonized by the pathogen. Perylenequinones show almost universal toxicity against organisms, including plants, mice, bacteria, and most fungi. The producing fungi are resistant, however, and serve as models for understanding resistance mechanisms. CRITICAL ISSUES Studies of resistance mechanisms by perylenequinone-producing fungi such as Cercospora species are leading to an understanding of cellular resistance to ¹O₂ and oxidative stress. Recent studies show commonalities between resistance mechanisms in these fungi with extensive studies of ¹O₂ and oxidative stress responses in photosynthetic organisms. FUTURE DIRECTIONS Such studies hold promise both for improved medical use and for engineering crop plants for disease resistance.
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Affiliation(s)
- Margaret E Daub
- Department of Plant Biology, North Carolina State University, Raleigh, NC 27695, USA.
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Tsai HC, Yang SL, Chung KR. Cyclic AMP-dependent protein kinase A negatively regulates conidia formation by the tangerine pathotype of Alternaria alternata. World J Microbiol Biotechnol 2012; 29:289-300. [PMID: 23054702 DOI: 10.1007/s11274-012-1182-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 09/24/2012] [Indexed: 01/24/2023]
Abstract
The necrotrophic fungal pathogen Alternaria alternata causes brown spot diseases in many citrus cultivars. The FUS3 and SLT2 mitogen-activated protein kinases (MAPK)-mediated signaling pathways have been shown to be required for conidiation. Exogenous application of cAMP to this fungal pathogen decreased conidia formation considerably. This study determined whether a cAMP-activated protein kinase A (PKA) is required for conidiation. Using loss-of-function mutations in PKA catalytic and regulatory subunit-coding genes, we demonstrated that PKA negatively regulates conidiation. Fungal mutants lacking PKA catalytic subunit gene (PKA ( cat )) reduced growth, lacked detectable PKA activity, and produced higher amounts of conidia compared to wild-type. Introduction of a functional copy of PKA ( cat ) into a null mutant partially restored PKA activity and produced wild-type level of conidia. In contrast, fungi lacking PKA regulatory subunit gene (PKA ( reg )) produced detectable PKA activity, exhibited severe growth reduction, formed swelling hyphal segments, and produced no mature conidia. Introduction of the PKA ( reg ) gene to a regulatory subunit mutant restored all phenotypes to wild type. PKA ( reg )-null mutants induced fewer necrotic lesions on citrus compared to wild-type, whereas PKA ( cat ) mutant displayed wild-type virulence. Overall, our studies indicate that PKA and FUS3-mediated signaling pathways apparently have very different roles in the regulation of conidia production and A. alternata pathogenesis in citrus.
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Affiliation(s)
- Hsieh-Chin Tsai
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences (IFAS), University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, USA
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Stergiopoulos I, Collemare J, Mehrabi R, De Wit PJGM. Phytotoxic secondary metabolites and peptides produced by plant pathogenic Dothideomycete fungi. FEMS Microbiol Rev 2012; 37:67-93. [PMID: 22931103 DOI: 10.1111/j.1574-6976.2012.00349.x] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/01/2012] [Accepted: 07/19/2012] [Indexed: 01/25/2023] Open
Abstract
Many necrotrophic plant pathogenic fungi belonging to the class of Dothideomycetes produce phytotoxic metabolites and peptides that are usually required for pathogenicity. Phytotoxins that affect a broad range of plant species are known as non-host-specific toxins (non-HSTs), whereas HSTs affect only a particular plant species or more often genotypes of that species. For pathogens producing HSTs, pathogenicity and host specificity are largely defined by the ability to produce the toxin, while plant susceptibility is dependent on the presence of the toxin target. Non-HSTs are not the main determinants of pathogenicity but contribute to virulence of the producing pathogen. Dothideomycetes are remarkable for the production of toxins, particularly HSTs because they are the only fungal species known so far to produce them. The synthesis, regulation, and mechanisms of action of the most important HSTs and non-HSTs will be discussed. Studies on the mode of action of HSTs have highlighted the induction of programed cell death (PCD) as an important mechanism. We discuss HST-induced PCD and the plant hypersensitive response upon recognition of avirulence factors that share common pathways. In this respect, although nucleotide-binding-site-leucine-rich repeat types of resistance proteins mediate resistance against biotrophs, they can also contribute to susceptibility toward necrotrophs.
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Yago JI, Lin CH, Chung KR. The SLT2 mitogen-activated protein kinase-mediated signalling pathway governs conidiation, morphogenesis, fungal virulence and production of toxin and melanin in the tangerine pathotype of Alternaria alternata. MOLECULAR PLANT PATHOLOGY 2011; 12:653-65. [PMID: 21726368 PMCID: PMC6640243 DOI: 10.1111/j.1364-3703.2010.00701.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Fungi respond and adapt to different environmental stimuli via signal transduction systems. We determined the function of a yeast SLT2 mitogen-activated protein (MAP) kinase homologue (AaSLT2) in Alternaria alternata, the fungal pathogen of citrus. Analysis of the loss-of-function mutant indicated that AaSLT2 is required for the production of a host-selective toxin, and is crucial for fungal pathogenicity. Moreover, the A. alternata slt2 mutants displayed hypersensitivity to cell wall-degrading enzymes and chemicals such as Calcofluor white and Congo red. This implicates an important role of AaSLT2 in the maintenance of cell wall integrity in A. alternata. The A. alternata slt2 mutants were also hypersensitive to a heteroaromatic compound, 2-chloro-5-hydroxypyridine, and a plant growth regulator, 2,3,5-triiodobenzoic acid. Developmentally, the AaSLT2 gene product was shown to be critical for conidial formation and hyphal elongation. Compared with the wild-type, the mutants produced fewer but slightly larger conidia with less transverse septae. The mutants also accumulated lower levels of melanin and chitin. Unlike the wild-type progenitor, the A. alternata slt2 mutants produced globose, swollen hyphae that did not elongate in a straight radial direction. All defective phenotypes in the mutant were restored by transformation and expression of a wild-type copy of AaSLT2 under the control of its endogenous promoter. This study highlights an important role of the AaSLT2 MAP kinase-mediated signalling pathway, regulating diverse physiological, developmental and pathological functions, in the tangerine pathotype of A. alternata.
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Affiliation(s)
- Jonar Ingan Yago
- Citrus Research and Education Center and Department of Plant Pathology, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850, USA
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Chung KR. Elsinoë fawcettii and Elsinoë australis: the fungal pathogens causing citrus scab. MOLECULAR PLANT PATHOLOGY 2011; 12:123-35. [PMID: 21199563 PMCID: PMC6640467 DOI: 10.1111/j.1364-3703.2010.00663.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
UNLABELLED Elsinoë fawcettii and E. australis are important pathogens of citrus. Both species are known to produce red or orange pigments, called elsinochrome. Elsinochrome is a nonhost-selective phytotoxin and is required for full fungal virulence and lesion formation. This article discusses the taxonomy, epidemiology, genetics and pathology of the pathogens. It also provides a perspective on the cellular toxicity, biosynthetic regulation and pathological role of elsinochrome phytotoxin. TAXONOMY Elsinoë fawcettii (anamorph: Sphaceloma fawcettii) and E. australis (anamorph: S. australis) are classified in the Phylum Ascomycota, Class Dothideomycetes, Order Myriangiales and Family Elsinoaceae. HOST RANGE Elsinoë fawcettii causes citrus scab (formerly sour orange scab and common scab) on various species and hybrids in the Rutaceae family worldwide, whereas E. australis causes sweet orange scab, primarily on sweet orange and some mandarins, and has a limited geographical distribution. DISEASE SYMPTOMS Citrus tissues infested with Elsinoë often display erumpent scab pustules with a warty appearance. TOXIN PRODUCTION: Elsinochrome and many perylenequinone-containing phytotoxins of fungal origin are grouped as photosensitizing compounds that are able to absorb light energy, react with oxygen molecules and produce reactive oxygen species, such as superoxide and singlet oxygen. Elsinochrome has been documented to cause peroxidation of cell membranes and to induce rapid electrolyte leakage from citrus tissues. Elsinochrome biosynthesis and conidiation are coordinately regulated in E. fawcettii, and the environmental and physiological inducers commonly involved in both processes have begun to be elucidated.
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Affiliation(s)
- Kuang-Ren Chung
- Citrus Research and Education Center, and Department of Plant Pathology, Institute of Food and Agricultural Sciences (IFAS), University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, USA.
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Jaulneau V, Cazaux M, Wong Sak Hoi J, Fournier S, Esquerré-Tugayé MT, Jacquet C, Dumas B. Host and nonhost resistance in Medicago-Colletotrichum interactions. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1107-17. [PMID: 20687801 DOI: 10.1094/mpmi-23-9-1107] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Medicago truncatula lines resistant (A17) or susceptible (F83005.5) to the alfalfa pathogen Colletotrichum trifolii were used to compare defense reactions induced upon inoculation with C. trifolii or with the nonadapted pathogens C. lindemuthianum and C. higginsianum. Nonadapted Colletotrichum spp. induced a hypersensitive response (HR)-like reaction similar to the one induced during the host-incompatible interaction. Molecular analyses indicated an induction of PR10 and chalcone synthase genes in host and nonhost interactions but delayed responses were observed in the F83005.5 line. The clste12 penetration-deficient C. lindemuthianum mutant induced an HR and defense gene expression, showing that perception of nonadapted strains occurs before penetration of epidermal cells. Cytological and transcriptomic analyses performed upon inoculation of near-isogenic M. truncatula lines, differing only at the C. trifolii resistance locus, Ct1, with the nonadapted Colletotrichum strain, showed that nonhost responses are similar in the two lines. These included a localized oxidative burst, accumulation of fluorescent compounds, and transient expression of a small number of genes. Host interactions were characterized by a group of defense and signaling-related genes induced at 3 days postinoculation, associated with an accumulation of salicylic acid. Together, these results show that M. truncatula displays a rapid and transient response to nonadapted Colletotrichum strains and that this response is not linked to the C. trifolii resistance locus.
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