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Chen Y, Cao Y, Jiao C, Sun X, Gai Y, Zhu Z, Li H. The Alternaria alternata StuA transcription factor interacting with the pH-responsive regulator PacC for the biosynthesis of host-selective toxin and virulence in citrus. Microbiol Spectr 2023; 11:e0233523. [PMID: 37812002 PMCID: PMC10715145 DOI: 10.1128/spectrum.02335-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 08/19/2023] [Indexed: 10/10/2023] Open
Abstract
IMPORTANCE In this study, we used Alternaria alternata as a biological model to report the role of StuA in phytopathogenic fungi. Our findings indicated that StuA is required for Alternaria citri toxin (ACT) biosynthesis and fungal virulence. In addition, StuA physically interacts with PacC. Disruption of stuA or pacC led to decreased expression of seven toxin biosynthetic genes (ACCT) and toxin production. PacC could recognize and bind to the promoter regions of ACTT6 and ACTTR. Our results revealed a previously unrecognized (StuA-PacC)→ACTTR module for the biosynthesis of ACT in A. alternata, which also provides a framework for the study of StuA in other fungi.
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Affiliation(s)
- Yanan Chen
- The Key Laboratory of Molecular Biology of Crop Pathogens and Insects of Ministry of Agriculture, The Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- Collaborative Innovation Center for Efficient and Green Production of Agriculture in Mountainous Areas of Zhejiang Province, College of Horticulture Science, Zhejiang Agriculture & Forestry University, Hangzhou, China
| | - Yingzi Cao
- The Key Laboratory of Molecular Biology of Crop Pathogens and Insects of Ministry of Agriculture, The Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Chen Jiao
- The Key Laboratory of Molecular Biology of Crop Pathogens and Insects of Ministry of Agriculture, The Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Xuepeng Sun
- Collaborative Innovation Center for Efficient and Green Production of Agriculture in Mountainous Areas of Zhejiang Province, College of Horticulture Science, Zhejiang Agriculture & Forestry University, Hangzhou, China
| | - Yunpeng Gai
- The Key Laboratory of Molecular Biology of Crop Pathogens and Insects of Ministry of Agriculture, The Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Zengrong Zhu
- The Key Laboratory of Molecular Biology of Crop Pathogens and Insects of Ministry of Agriculture, The Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- Hainan Institute, Zhejiang University, Sanya, China
| | - Hongye Li
- The Key Laboratory of Molecular Biology of Crop Pathogens and Insects of Ministry of Agriculture, The Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou, China
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Liu L, Li X, Guo W, Shi J, Chen W, Lei Y, Ma Y, Dai H. MdWRKY120 Enhance Apple Susceptibility to Alternaria alternata. PLANTS (BASEL, SWITZERLAND) 2022; 11:3389. [PMID: 36501429 PMCID: PMC10004717 DOI: 10.3390/plants11233389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 12/01/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Alternaria alternata (A. alternata) is a common pathogen that greatly influences apples' quantity and quality. However, chemical treatments produce increased health risks along with decreased food and environmental safety. Advancements in plant molecular biology, such as transgenic technology, have increased apple trees' resistance to pathogens and have therefore attracted widespread attention. WRKY transcription factors are involved in abiotic and biotic stress regulation; however, their biological role in non-model plants such as apple, is still unknown. In this investigation, MdWRKY120 was isolated from the 'GL-3' apple to determine its function during Alternaria alternate infection. The MdWRKY120-GFP fusion protein was located in the nucleus. MdWRKY120 in yeast cells exhibited activating transcriptional activity, meaning it is a transcription activator. MdWRKY120 overexpression transgenic plants were more sensitive to A. alternata, while RNAi transgenic plants showed increased resistance to A. alternata. This investigation demonstrates that MdWRKY120 enhances the susceptibility of apples to A. alternata.
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Affiliation(s)
- Lifu Liu
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
- School of Horticulture, Liaoning Vocational College of Ecological Engineering, Shenyang 110101, China
| | - Xiaoming Li
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Wei Guo
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Jiajun Shi
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Wenjun Chen
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Yingying Lei
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Yue Ma
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Hongyan Dai
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
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3
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Noriler S, Navarro-Muñoz JC, Glienke C, Collemare J. Evolutionary relationships of adenylation domains in fungi. Genomics 2022; 114:110525. [PMID: 36423773 DOI: 10.1016/j.ygeno.2022.110525] [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: 09/26/2022] [Revised: 11/11/2022] [Accepted: 11/20/2022] [Indexed: 11/23/2022]
Abstract
Non-ribosomal peptide synthetases (NRPSs) and NRPS-like enzymes are abundant in microbes as they are involved in the production of primary and secondary metabolites. In contrast to the well-studied NRPSs, known to produce non-ribosomal peptides, NRPS-like enzymes exhibit more diverse activities and their evolutionary relationships are unclear. Here, we present the first in-depth phylogenetic analysis of fungal NRPS-like A domains from functionally characterized pathways, and their relationships to characterized A domains found in fungal NRPSs. This study clearly differentiated amino acid reductases, including NRPSs, from CoA/AMP ligases, which could be divided into 10 distinct phylogenetic clades that reflect their conserved domain organization, substrate specificity and enzymatic activity. In particular, evolutionary relationships of adenylate forming reductases could be refined and explained the substrate specificity difference. Consistent with their phylogeny, the deduced amino acid code of A domains differentiated amino acid reductases from other enzymes. However, a diagnostic code was found for α-keto acid reductases and clade 7 CoA/AMP ligases only. Comparative genomics of loci containing these enzymes revealed that they can be independently recruited as tailoring genes in diverse secondary metabolite pathways. Based on these results, we propose a refined and clear phylogeny-based classification of A domain-containing enzymes, which will provide a robust framework for future functional analyses and engineering of these enzymes to produce new bioactive molecules.
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Affiliation(s)
- Sandriele Noriler
- Postgraduate Program of Microbiology, Parasitology and Pathology, Department of Pathology, Universidade Federal do Parana, Av. Coronel Francisco Heráclito dos Santos, 210, CEP: 81531-970, Curitiba, PR, Brazil
| | - Jorge C Navarro-Muñoz
- Westerdijk Fungal Biodiversity Institute, Uppsalalaan 8, 3584, CT, Utrecht, the Netherlands
| | - Chirlei Glienke
- Postgraduate Program of Microbiology, Parasitology and Pathology, Department of Pathology, Universidade Federal do Parana, Av. Coronel Francisco Heráclito dos Santos, 210, CEP: 81531-970, Curitiba, PR, Brazil; Postgraduate Program of Genetics, Department of Genetics, Universidade Federal do Parana, Av. Coronel Francisco Heráclito dos Santos, 210, CEP: 81531-970, Curitiba, PR, Brazil
| | - Jérôme Collemare
- Westerdijk Fungal Biodiversity Institute, Uppsalalaan 8, 3584, CT, Utrecht, the Netherlands.
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Loop-Mediated Isothermal Amplification (LAMP) for the Rapid and Sensitive Detection of Alternaria alternata (Fr.) Keissl in Apple Alternaria Blotch Disease with Aapg-1 Encoding the Endopolygalacturonase. Pathogens 2022; 11:pathogens11111221. [PMID: 36364972 PMCID: PMC9697310 DOI: 10.3390/pathogens11111221] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/18/2022] [Accepted: 10/19/2022] [Indexed: 01/11/2023] Open
Abstract
Apple Alternaria blotch disease, caused by Alternaria alternata (Fr.) Keissl, is one of the most famous leaf diseases. When the disease is prevalent, it causes leaf abscission and influences the formation of flower buds and photosynthesis. Therefore, a simple, rapid, high-specificity and sensitivity method for monitoring infected leaves at early developmental stages is urgently needed, so that the occurrence and expansion of A. alternata can be controlled in time. In our research, a rapid, specific and efficient loop-mediated isothermal amplification (LAMP) method was developed to detect A. alternata within 60 min. Six primers of LAMP detection can only specifically amplify the aapg-1 gene in A. alternata but not in four other important fungi in apples. The aapg-1 gene encodes endopolygalacturonase in A. alternata, and there are significant differences among different species. Thus, it was applied as the target for LAMP primers. Compared to conventional PCR detection, our LAMP method had the same sensitivity as that of detecting as little as 1 fg of pure genomic DNA of A. alternata. When leaves were inoculated with A. alternata conidia, LAMP detected 1 × 102 conidia/mL as the minimum concentration. However, the traditional tissue isolation and identification method only isolated A. alternata from leaves inoculated with 1 × 105 and 1 × 106 conidia/mL, indicating that the LAMP method was more sensitive than the traditional tissue isolation and identification method for A. alternata before symptoms. Further tests also indicated that LAMP detection was more accurate and sensitive than the traditional tissue isolation and identification method for A. alternata in leaves with the Alternaria blotch symptom collected from the field. Our results showed that the LAMP-targeting the aapg-1 gene has the advantages of high sensitivity, specificity and simplicity and can be used for rapid detection and early monitoring of A. alternata in the field. LAMP is instructive for us to effectively prevent and control apple Alternaria blotch disease.
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Wang H, Guo Y, Luo Z, Gao L, Li R, Zhang Y, Kalaji HM, Qiang S, Chen S. Recent Advances in Alternaria Phytotoxins: A Review of Their Occurrence, Structure, Bioactivity and Biosynthesis. J Fungi (Basel) 2022; 8:jof8020168. [PMID: 35205922 PMCID: PMC8878860 DOI: 10.3390/jof8020168] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/06/2022] [Accepted: 02/07/2022] [Indexed: 12/04/2022] Open
Abstract
Alternaria is a ubiquitous fungal genus in many ecosystems, consisting of species and strains that can be saprophytic, endophytic, or pathogenic to plants or animals, including humans. Alternaria species can produce a variety of secondary metabolites (SMs), especially low molecular weight toxins. Based on the characteristics of host plant susceptibility or resistance to the toxin, Alternaria phytotoxins are classified into host-selective toxins (HSTs) and non-host-selective toxins (NHSTs). These Alternaria toxins exhibit a variety of biological activities such as phytotoxic, cytotoxic, and antimicrobial properties. Generally, HSTs are toxic to host plants and can cause severe economic losses. Some NHSTs such as alternariol, altenariol methyl-ether, and altertoxins also show high cytotoxic and mutagenic activities in the exposed human or other vertebrate species. Thus, Alternaria toxins are meaningful for drug and pesticide development. For example, AAL-toxin, maculosin, tentoxin, and tenuazonic acid have potential to be developed as bioherbicides due to their excellent herbicidal activity. Like altersolanol A, bostrycin, and brefeldin A, they exhibit anticancer activity, and ATX V shows high activity to inhibit the HIV-1 virus. This review focuses on the classification, chemical structure, occurrence, bioactivity, and biosynthesis of the major Alternaria phytotoxins, including 30 HSTs and 50 NHSTs discovered to date.
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Affiliation(s)
- He Wang
- Weed Research Laboratory, College of Life Science, Nanjing Agricultural University, Nanjing 210095, China; (H.W.); (Y.G.); (Z.L.); (L.G.); (Y.Z.); (S.Q.)
| | - Yanjing Guo
- Weed Research Laboratory, College of Life Science, Nanjing Agricultural University, Nanjing 210095, China; (H.W.); (Y.G.); (Z.L.); (L.G.); (Y.Z.); (S.Q.)
| | - Zhi Luo
- Weed Research Laboratory, College of Life Science, Nanjing Agricultural University, Nanjing 210095, China; (H.W.); (Y.G.); (Z.L.); (L.G.); (Y.Z.); (S.Q.)
| | - Liwen Gao
- Weed Research Laboratory, College of Life Science, Nanjing Agricultural University, Nanjing 210095, China; (H.W.); (Y.G.); (Z.L.); (L.G.); (Y.Z.); (S.Q.)
| | - Rui Li
- Agricultural and Animal Husbandry Ecology and Resource Protection Center, Ordos Agriculture and Animal Husbandry Bureau, Ordos 017010, China;
| | - Yaxin Zhang
- Weed Research Laboratory, College of Life Science, Nanjing Agricultural University, Nanjing 210095, China; (H.W.); (Y.G.); (Z.L.); (L.G.); (Y.Z.); (S.Q.)
| | - Hazem M. Kalaji
- Department of Plant Physiology, Institute of Biology, Warsaw University of Life Sciences SGGW, 159 Nowoursynowska 159, 02-776 Warsaw, Poland;
- Institute of Technology and Life Sciences—National Research Institute, Falenty, Al. Hrabska 3, 05-090 Raszyn, Poland
| | - Sheng Qiang
- Weed Research Laboratory, College of Life Science, Nanjing Agricultural University, Nanjing 210095, China; (H.W.); (Y.G.); (Z.L.); (L.G.); (Y.Z.); (S.Q.)
| | - Shiguo Chen
- Weed Research Laboratory, College of Life Science, Nanjing Agricultural University, Nanjing 210095, China; (H.W.); (Y.G.); (Z.L.); (L.G.); (Y.Z.); (S.Q.)
- Correspondence: ; Tel.: +86-25-84395117
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Ma H, Li L, Gai Y, Zhang X, Chen Y, Zhuo X, Cao Y, Jiao C, Gmitter FG, Li H. Histone Acetyltransferases and Deacetylases Are Required for Virulence, Conidiation, DNA Damage Repair, and Multiple Stresses Resistance of Alternaria alternata. Front Microbiol 2021; 12:783633. [PMID: 34880849 PMCID: PMC8645686 DOI: 10.3389/fmicb.2021.783633] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 11/02/2021] [Indexed: 01/16/2023] Open
Abstract
Histone acetylation, which is critical for transcriptional regulation and various biological processes in eukaryotes, is a reversible dynamic process regulated by HATs and HDACs. This study determined the function of 6 histone acetyltransferases (HATs) (Gcn5, RTT109, Elp3, Sas3, Sas2, Nat3) and 6 histone deacetylases (HDACs) (Hos2, Rpd3, Hda1, Hos3, Hst2, Sir2) in the phytopathogenic fungus Alternaria alternata by analyzing targeted gene deletion mutants. Our data provide evidence that HATs and HDACs are both required for mycelium growth, cell development and pathogenicity as many gene deletion mutants (ΔGcn5, ΔRTT109, ΔElp3, ΔSas3, ΔNat3, ΔHos2, and ΔRpd3) displayed reduced growth, conidiation or virulence at varying degrees. In addition, HATs and HDACs are involved in the resistance to multiple stresses such as oxidative stress (Sas3, Gcn5, Elp3, RTT109, Hos2), osmotic stress (Sas3, Gcn5, RTT109, Hos2), cell wall-targeting agents (Sas3, Gcn5, Hos2), and fungicide (Gcn5, Hos2). ΔGcn5, ΔSas3, and ΔHos2 displayed severe growth defects on sole carbon source medium suggesting a vital role of HATs and HDACs in carbon source utilization. More SNPs were generated in ΔGcn5 in comparison to wild-type when they were exposed to ultraviolet ray. Moreover, ΔRTT109, ΔGcn5, and ΔHos2 showed severe defects in resistance to DNA-damaging agents, indicating the critical role of HATs and HDACs in DNA damage repair. These phenotypes correlated well with the differentially expressed genes in ΔGcn5 and ΔHos2 that are essential for carbon sources metabolism, DNA damage repair, ROS detoxification, and asexual development. Furthermore, Gcn5 is required for the acetylation of H3K4. Overall, our study provides genetic evidence to define the central role of HATs and HDACs in the pathological and biological functions of A. alternata.
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Affiliation(s)
- Haijie Ma
- Collaborative Innovation Center for Efficient and Green Production of Agriculture in Mountainous Areas of Zhejiang Province, College of Horticulture Science, Zhejiang A&F University, Hangzhou, China.,Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China.,Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
| | - Lei Li
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Yunpeng Gai
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Xiaoyan Zhang
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Yanan Chen
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Xiaokang Zhuo
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
| | - Yingzi Cao
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Chen Jiao
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Fred G Gmitter
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
| | - Hongye Li
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China
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7
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Witte TE, Villeneuve N, Boddy CN, Overy DP. Accessory Chromosome-Acquired Secondary Metabolism in Plant Pathogenic Fungi: The Evolution of Biotrophs Into Host-Specific Pathogens. Front Microbiol 2021; 12:664276. [PMID: 33968000 PMCID: PMC8102738 DOI: 10.3389/fmicb.2021.664276] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 03/09/2021] [Indexed: 11/25/2022] Open
Abstract
Accessory chromosomes are strain- or pathotype-specific chromosomes that exist in addition to the core chromosomes of a species and are generally not considered essential to the survival of the organism. Among pathogenic fungal species, accessory chromosomes harbor pathogenicity or virulence factor genes, several of which are known to encode for secondary metabolites that are involved in plant tissue invasion. Accessory chromosomes are of particular interest due to their capacity for horizontal transfer between strains and their dynamic "crosstalk" with core chromosomes. This review focuses exclusively on secondary metabolism (including mycotoxin biosynthesis) associated with accessory chromosomes in filamentous fungi and the role accessory chromosomes play in the evolution of secondary metabolite gene clusters. Untargeted metabolomics profiling in conjunction with genome sequencing provides an effective means of linking secondary metabolite products with their respective biosynthetic gene clusters that reside on accessory chromosomes. While the majority of literature describing accessory chromosome-associated toxin biosynthesis comes from studies of Alternaria pathotypes, the recent discovery of accessory chromosome-associated biosynthetic genes in Fusarium species offer fresh insights into the evolution of biosynthetic enzymes such as non-ribosomal peptide synthetases (NRPSs), polyketide synthases (PKSs) and regulatory mechanisms governing their expression.
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Affiliation(s)
- Thomas E. Witte
- Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, Ottawa, ON, Canada
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Nicolas Villeneuve
- Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, Ottawa, ON, Canada
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Christopher N. Boddy
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, Canada
| | - David P. Overy
- Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, Ottawa, ON, Canada
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Li L, Ma H, Zheng F, Chen Y, Wang M, Jiao C, Li H, Gai Y. The transcription regulator ACTR controls ACT-toxin biosynthesis and pathogenicity in the tangerine pathotype of Alternaria alternata. Microbiol Res 2021; 248:126747. [PMID: 33740671 DOI: 10.1016/j.micres.2021.126747] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/27/2021] [Accepted: 03/08/2021] [Indexed: 10/21/2022]
Abstract
The host-selective ACT toxin is essential for the pathogenesis of the citrus fungal pathogen Alternaria alternata. However, the mechanism of ACT-toxin gene clusters ACT-toxin biosynthesis regulated by is still poorly understood. The biosynthesis of ACT toxin is mainly regulated by multiple ACT toxin genes located in the secondary metabolite gene cluster. In this study, we reported a transcription regulator ACTR contributes ACT toxin biosynthesis through mediating ACT toxin synthesis gene ACTS4 in Alternaria alternata. We generated ACTR-disrupted and -silenced mutants in the tangerine pathotype of A. alternata. Phenotype analysis showed that the ACTR mutants displayed a significant loss of ACT toxin production and a decreased virulence on citrus leaves whereas the vegetative growth and sporulation were not affected, indicating an essential role of ACTR in both ACT toxin biosynthesis and pathogenicity. To elucidate the transcription network of ACTR, we performed RNA-Seq experiments on wild-type and ACTR null mutant and identified genes that were differentially expressed between two genotypes. Transcriptome profiling and RT-qPCR analysis demonstrated that the ACT toxin biosynthetic gene ACTS4 is down-regulated in ACTR mutant. We generated ACTS4 knock-down mutant and found that the pathogenicity of ACTS4 mutant was severely impaired. Interestingly, both ACTR and ACTS4 are not involved in the response to different abiotic stresses including oxidative stress, salt stress, cell-wall disrupting regents, and metal ion stress, indicating the function of these two genes is highly specific. In conclusion, our results highlight the important regulatory role of ACTR in ACT toxin biosynthesis through mediating ACT toxin synthesis gene ACTS4 and underline the essential role of in the tangerine pathotype of A. alternata.
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Affiliation(s)
- Lei Li
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China; College of Plant Protection, Shanxi Agricultural University, Taigu, 030801, China
| | - Haijie Ma
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China; School of Agriculture and Food Sciences, Zhejiang Agriculture & Forestry University, Hangzhou, 311300, China
| | - Fang Zheng
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Yanan Chen
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Meiqin Wang
- College of Plant Protection, Shanxi Agricultural University, Taigu, 030801, China
| | - Chen Jiao
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China; Boyce Thompson Institute, Ithaca, NY, USA
| | - Hongye Li
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.
| | - Yunpeng Gai
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.
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Armitage AD, Cockerton HM, Sreenivasaprasad S, Woodhall J, Lane CR, Harrison RJ, Clarkson JP. Genomics Evolutionary History and Diagnostics of the Alternaria alternata Species Group Including Apple and Asian Pear Pathotypes. Front Microbiol 2020; 10:3124. [PMID: 32038562 PMCID: PMC6989435 DOI: 10.3389/fmicb.2019.03124] [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: 03/28/2019] [Accepted: 12/24/2019] [Indexed: 02/04/2023] Open
Abstract
The Alternaria section alternaria (Alternaria alternata species group) represents a diverse group of saprotroph, human allergens, and plant pathogens. Alternaria taxonomy has benefited from recent phylogenetic revision but the basis of differentiation between major phylogenetic clades within the group is not yet understood. Furthermore, genomic resources have been limited for the study of host-specific pathotypes. We report near complete genomes of the apple and Asian pear pathotypes as well as draft assemblies for a further 10 isolates representing Alternaria tenuissima and Alternaria arborescens lineages. These assemblies provide the first insights into differentiation of these taxa as well as allowing the description of effector and non-effector profiles of apple and pear conditionally dispensable chromosomes (CDCs). We define the phylogenetic relationship between the isolates sequenced in this study and a further 23 Alternaria spp. based on available genomes. We determine which of these genomes represent MAT1-1-1 or MAT1-2-1 idiomorphs and designate host-specific pathotypes. We show for the first time that the apple pathotype is polyphyletic, present in both the A. arborescens and A. tenuissima lineages. Furthermore, we profile a wider set of 89 isolates for both mating type idiomorphs and toxin gene markers. Mating-type distribution indicated that gene flow has occurred since the formation of A. tenuissima and A. arborescens lineages. We also developed primers designed to AMT14, a gene from the apple pathotype toxin gene cluster with homologs in all tested pathotypes. These primers allow identification and differentiation of apple, pear, and strawberry pathotypes, providing new tools for pathogen diagnostics.
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Affiliation(s)
- Andrew D. Armitage
- NIAB EMR, East Malling, United Kingdom
- Natural Resources Institute, University of Greenwich, Chatham Maritime, London, United Kingdom
| | | | | | - James Woodhall
- Parma Research and Extension Center, University of Idaho, Parma, ID, United States
| | | | | | - John P. Clarkson
- Warwick Crop Centre, University of Warwick, Warwick, United Kingdom
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10
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Wang M, Fu H, Shen X, Ruan R, Rokas A, Li H. Genomic features and evolution of the conditionally dispensable chromosome in the tangerine pathotype of Alternaria alternata. MOLECULAR PLANT PATHOLOGY 2019; 20:1425-1438. [PMID: 31297970 PMCID: PMC6792136 DOI: 10.1111/mpp.12848] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The tangerine pathotype of the ascomycete fungus Alternaria alternata is the causal agent of citrus brown spot, which can result in significant losses of both yield and marketability for tangerines worldwide. A conditionally dispensable chromosome (CDC), which harbours the host-selective ACT toxin gene cluster, is required for tangerine pathogenicity of A. alternata. To understand the genetic makeup and evolution of the tangerine pathotype CDC, we isolated and sequenced the CDCs of the A. alternata Z7 strain and analysed the function and evolution of their genes. The A. alternata Z7 strain has two CDCs (~1.1 and ~0.8 Mb, respectively), and the longer Z7 CDC contains all but one contig of the shorter one. Z7 CDCs contain 254 predicted protein-coding genes, which are enriched in functional categories associated with 'metabolic process' (55 genes, P = 0.037). Relatively few of the CDC genes can be classified as carbohydrate-active enzymes (CAZymes) (4) and transporters (19) and none as kinases. Evolutionary analysis of the 254 CDC proteins showed that their evolutionary conservation tends to be restricted within the genus Alternaria and that the CDC genes evolve faster than genes in the essential chromosomes, likely due to fewer selective constraints. Interestingly, phylogenetic analysis suggested that four of the 25 genes responsible for the ACT toxin production were likely transferred from Colletotrichum (Sordariomycetes). Functional experiments showed that two of them are essential for the virulence of the tangerine pathotype of A. alternata. These results provide new insights into the function and evolution of CDC genes in Alternaria.
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Affiliation(s)
- Mingshuang Wang
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of BiotechnologyZhejiang UniversityHangzhou310058China
- Department of Biological SciencesVanderbilt UniversityNashvilleTN37235USA
- College of Life and Environmental SciencesHangzhou Normal UniversityHangzhou310036China
| | - Huilan Fu
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of BiotechnologyZhejiang UniversityHangzhou310058China
| | - Xing‐Xing Shen
- Department of Biological SciencesVanderbilt UniversityNashvilleTN37235USA
| | - Ruoxin Ruan
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of BiotechnologyZhejiang UniversityHangzhou310058China
- Hangzhou Academy of Agricultural SciencesHangzhou310024China
| | - Antonis Rokas
- Department of Biological SciencesVanderbilt UniversityNashvilleTN37235USA
| | - Hongye Li
- Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of BiotechnologyZhejiang UniversityHangzhou310058China
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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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Hao L, Johnson K, Cursino L, Mowery P, Burr TJ. Characterization of the Xylella fastidiosa PD1311 gene mutant and its suppression of Pierce's disease on grapevines. MOLECULAR PLANT PATHOLOGY 2017; 18:684-694. [PMID: 27388152 PMCID: PMC6638296 DOI: 10.1111/mpp.12428] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 04/17/2016] [Accepted: 05/13/2016] [Indexed: 05/25/2023]
Abstract
Xylella fastidiosa causes Pierce's disease (PD) on grapevines, leading to significant economic losses in grape and wine production. To further our understanding of X. fastidiosa virulence on grapevines, we examined the PD1311 gene, which encodes a putative acyl-coenzyme A (acyl-CoA) synthetase, and is highly conserved across Xylella species. It was determined that PD1311 is required for virulence, as the deletion mutant, ΔPD1311, was unable to cause disease on grapevines. The ΔPD1311 strain was impaired in behaviours known to be associated with PD development, including motility, aggregation and biofilm formation. ΔPD1311 also expressed enhanced sensitivity to H2 O2 and polymyxin B, and showed reduced survival in grapevine sap, when compared with wild-type X. fastidiosa Temecula 1 (TM1). Following inoculation, ΔPD1311 could not be detected in grape shoots, which may be related to its altered growth and sensitivity phenotypes. Inoculation with ΔPD1311 2 weeks prior to TM1 prevented the development of PD in a significant fraction of vines and eliminated detectable levels of TM1. In contrast, vines inoculated simultaneously with TM1 and ΔPD1311 developed disease at the same level as TM1 alone. In these vines, TM1 populations were distributed similarly to populations in TM1-only inoculated plants. These findings suggest that, through an indirect mechanism, pretreatment of vines with ΔPD1311 suppresses pathogen population and disease.
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Affiliation(s)
- Lingyun Hao
- Department of Plant Pathology and Plant–Microbe BiologyCornell University‐New York State Agricultural Experiment StationGenevaNY14456USA
| | - Kameka Johnson
- Department of Plant Pathology and Plant–Microbe BiologyCornell University‐New York State Agricultural Experiment StationGenevaNY14456USA
| | - Luciana Cursino
- Department of BiologyHobart and William Smith CollegesGenevaNY14456USA
- Present address:
Division of Natural SciencesKeuka CollegeKeuka ParkNY14478USA
| | - Patricia Mowery
- Department of BiologyHobart and William Smith CollegesGenevaNY14456USA
| | - Thomas J. Burr
- Department of Plant Pathology and Plant–Microbe BiologyCornell University‐New York State Agricultural Experiment StationGenevaNY14456USA
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Genomic and transcriptomic analyses of the tangerine pathotype of Alternaria alternata in response to oxidative stress. Sci Rep 2016; 6:32437. [PMID: 27582273 PMCID: PMC5007530 DOI: 10.1038/srep32437] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 08/09/2016] [Indexed: 12/19/2022] Open
Abstract
The tangerine pathotype of Alternaria alternata produces the A. citri toxin (ACT) and is the causal agent of citrus brown spot that results in significant yield losses worldwide. Both the production of ACT and the ability to detoxify reactive oxygen species (ROS) are required for A. alternata pathogenicity in citrus. In this study, we report the 34.41 Mb genome sequence of strain Z7 of the tangerine pathotype of A. alternata. The host selective ACT gene cluster in strain Z7 was identified, which included 25 genes with 19 of them not reported previously. Of these, 10 genes were present only in the tangerine pathotype, representing the most likely candidate genes for this pathotype specialization. A transcriptome analysis of the global effects of H2O2 on gene expression revealed 1108 up-regulated and 498 down-regulated genes. Expressions of those genes encoding catalase, peroxiredoxin, thioredoxin and glutathione were highly induced. Genes encoding several protein families including kinases, transcription factors, transporters, cytochrome P450, ubiquitin and heat shock proteins were found associated with adaptation to oxidative stress. Our data not only revealed the molecular basis of ACT biosynthesis but also provided new insights into the potential pathways that the phytopathogen A. alternata copes with oxidative stress.
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Vleeshouwers VGAA, Oliver RP. Effectors as Tools in Disease Resistance Breeding Against Biotrophic, Hemibiotrophic, and Necrotrophic Plant Pathogens. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 2015:40-50. [PMID: 27839074 DOI: 10.1094/mpmi-10-13-0313-ta.testissue] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
One of most important challenges in plant breeding is improving resistance to the plethora of pathogens that threaten our crops. The ever-growing world population, changing pathogen populations, and fungicide resistance issues have increased the urgency of this task. In addition to a vital inflow of novel resistance sources into breeding programs, the functional characterization and deployment of resistance also needs improvement. Therefore, plant breeders need to adopt new strategies and techniques. In modern resistance breeding, effectors are emerging as tools to accelerate and improve the identification, functional characterization, and deployment of resistance genes. Since genome-wide catalogues of effectors have become available for various pathogens, including biotrophs as well as necrotrophs, effector-assisted breeding has been shown to be successful for various crops. "Effectoromics" has contributed to classical resistance breeding as well as for genetically modified approaches. Here, we present an overview of how effector-assisted breeding and deployment is being exploited for various pathosystems.
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Affiliation(s)
- Vivianne G A A Vleeshouwers
- 1 Wageningen UR Plant Breeding, Wageningen University and Research Centre, P.O. Box 386, 6700 AJ, Wageningen, The Netherlands
| | - Richard P Oliver
- 2 Australian Centre for Necrotrophic Fungal Pathogens, Curtin University, Perth WA 6845, Australia
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Vleeshouwers VGAA, Oliver RP. Effectors as Tools in Disease Resistance Breeding Against Biotrophic, Hemibiotrophic, and Necrotrophic Plant Pathogens. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 2015:17-27. [PMID: 27839075 DOI: 10.1094/mpmi-10-13-0313-cr.testissue] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
One of most important challenges in plant breeding is improving resistance to the plethora of pathogens that threaten our crops. The ever-growing world population, changing pathogen populations, and fungicide resistance issues have increased the urgency of this task. In addition to a vital inflow of novel resistance sources into breeding programs, the functional characterization and deployment of resistance also needs improvement. Therefore, plant breeders need to adopt new strategies and techniques. In modern resistance breeding, effectors are emerging as tools to accelerate and improve the identification, functional characterization, and deployment of resistance genes. Since genome-wide catalogues of effectors have become available for various pathogens, including biotrophs as well as necrotrophs, effector-assisted breeding has been shown to be successful for various crops. "Effectoromics" has contributed to classical resistance breeding as well as for genetically modified approaches. Here, we present an overview of how effector-assisted breeding and deployment is being exploited for various pathosystems.
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Affiliation(s)
- Vivianne G A A Vleeshouwers
- 1 Wageningen UR Plant Breeding, Wageningen University and Research Centre, P.O. Box 386, 6700 AJ, Wageningen, The Netherlands
| | - Richard P Oliver
- 2 Australian Centre for Necrotrophic Fungal Pathogens, Curtin University, Perth WA 6845, Australia
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Vega B, Dewdney MM. QoI-Resistance Stability in Relation to Pathogenic and Saprophytic Fitness Components of Alternaria alternata from Citrus. PLANT DISEASE 2014; 98:1371-1378. [PMID: 30703928 DOI: 10.1094/pdis-01-14-0078-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The phenotypic stability, fitness components, and ability to cause disease of isolates of the Alternaria alternata tangerine pathotype resistant to quinone-outside inhibitors (QoIs) were studied. Stability of resistance to azoxystrobin (AZ) and pyraclostrobin (PYR) was determined after consecutive transfers on potato dextrose agar (PDA). The sensitivity to QoIs did not change significantly after 10 transfers on PDA compared with the initial sensitivity of all isolates tested. Fitness components evaluated in vitro were mycelial growth, conidial germination, and conidial production. Incubation period, number of lesions per leaf area, and virulence were determined with detached leaf assays using four cultivars: Dancy, Minneola, Murcott, and Sunburst. Variability in fitness components was observed among isolates within the same sensitivity group. As a group, no significant differences in the mean values of these fitness components were observed between resistant and sensitive phenotypes, except for virulence. Resistant isolates were significantly (P < 0.05) more virulent than the sensitive isolates on Dancy, Minneola, and Sunburst but not on Murcott (P = 0.3506). There was no significant correlation between individual fitness components and the level of sensitivity to AZ and PYR. Preventive applications of Abound (commercial formulation of AZ) at full field rates failed to control disease caused by QoI-resistant isolates under greenhouse conditions. Our results suggest that QoI resistance in A. alternata tangerine pathotype is stable in the absence of QoI selection pressure and that resistance development did not affect the fitness of resistant isolates.
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Affiliation(s)
- Byron Vega
- Citrus Research and Education Center, University of Florida, Lake Alfred
| | - Megan M Dewdney
- Citrus Research and Education Center, University of Florida, Lake Alfred
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Takaoka S, Kurata M, Harimoto Y, Hatta R, Yamamoto M, Akimitsu K, Tsuge T. Complex regulation of secondary metabolism controlling pathogenicity in the phytopathogenic fungus Alternaria alternata. THE NEW PHYTOLOGIST 2014; 202:1297-1309. [PMID: 24611558 DOI: 10.1111/nph.12754] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 02/03/2014] [Indexed: 05/10/2023]
Abstract
The filamentous fungus Alternaria alternata includes seven pathogenic variants (pathotypes), which produce different host-selective toxins and cause disease on different plants. The Japanese pear, strawberry and tangerine pathotypes produce AK-toxin, AF-toxin and ACT-toxin, respectively, which have a common structural moiety, 9,10-epoxy-8-hydroxy-9-methyl-decatrienoic acid (EDA). Here, we identified a new gene, AKT7 (AK-toxin biosynthetic gene 7), from the Japanese pear pathotype, which encodes a cytochrome P450 monooxygenase and functions to limit AK-toxin production. AKT7 homologs were found in the strawberry pathotype, but not the tangerine pathotype. However, the strawberry pathotype homolog appeared to include a premature stop codon. Although the Japanese pear pathotype strain has multiple copies of AKT7, a single-copy disruption resulted in mutants with increased production of AK-toxin and EDA. AKT7 overexpression in the three pathotypes caused marked reductions of toxin and EDA production, suggesting that Akt7 catalyzes a side reaction of EDA or its precursor. AKT7 overexpression caused reduced virulence in these pathotypes. We also found that AKT7 transcripts predominantly include misspliced mRNAs, which have premature stop codons. Our observations suggest that the AK-toxin production required for full virulence is regulated in a complex way by the copy number and intron information content of AKT7.
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Affiliation(s)
- Shinya Takaoka
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, 464-8601, Japan
| | - Mariko Kurata
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, 464-8601, Japan
| | - Yoshiaki Harimoto
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, 464-8601, Japan
| | - Rieko Hatta
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, 464-8601, Japan
| | - Mikihiro Yamamoto
- Graduate School of Environmental and Life Science, Okayama University, Okayama, 700-8530, Japan
| | - Kazuya Akimitsu
- Faculty of Agriculture, Kagawa University, Miki, Kagawa, 761-0795, Japan
| | - Takashi Tsuge
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, 464-8601, Japan
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Vleeshouwers VGAA, Oliver RP. Effectors as tools in disease resistance breeding against biotrophic, hemibiotrophic, and necrotrophic plant pathogens. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:196-206. [PMID: 24405032 DOI: 10.1094/mpmi-10-13-0313-ia] [Citation(s) in RCA: 204] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
One of most important challenges in plant breeding is improving resistance to the plethora of pathogens that threaten our crops. The ever-growing world population, changing pathogen populations, and fungicide resistance issues have increased the urgency of this task. In addition to a vital inflow of novel resistance sources into breeding programs, the functional characterization and deployment of resistance also needs improvement. Therefore, plant breeders need to adopt new strategies and techniques. In modern resistance breeding, effectors are emerging as tools to accelerate and improve the identification, functional characterization, and deployment of resistance genes. Since genome-wide catalogues of effectors have become available for various pathogens, including biotrophs as well as necrotrophs, effector-assisted breeding has been shown to be successful for various crops. "Effectoromics" has contributed to classical resistance breeding as well as for genetically modified approaches. Here, we present an overview of how effector-assisted breeding and deployment is being exploited for various pathosystems.
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Tsuge T, Harimoto Y, Akimitsu K, Ohtani K, Kodama M, Akagi Y, Egusa M, Yamamoto M, Otani H. Host-selective toxins produced by the plant pathogenic fungusAlternaria alternata. FEMS Microbiol Rev 2013; 37:44-66. [DOI: 10.1111/j.1574-6976.2012.00350.x] [Citation(s) in RCA: 247] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 06/14/2012] [Accepted: 07/19/2012] [Indexed: 12/19/2022] Open
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Izumi Y, Ohtani K, Miyamoto Y, Masunaka A, Fukumoto T, Gomi K, Tada Y, Ichimura K, Peever TL, Akimitsu K. A polyketide synthase gene, ACRTS2, is responsible for biosynthesis of host-selective ACR-toxin in the rough lemon pathotype of Alternaria alternata. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:1419-1429. [PMID: 22835272 DOI: 10.1094/mpmi-06-12-0155-r] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The rough lemon pathotype of Alternaria alternata produces host-selective ACR-toxin and causes Alternaria leaf spot disease of rough lemon (Citrus jambhiri). The structure of ACR-toxin I (MW = 496) consists of a polyketide with an α-dihydropyrone ring in a 19-carbon polyalcohol. Genes responsible for toxin production were localized to a 1.5-Mb chromosome in the genome of the rough lemon pathotype. Sequence analysis of this chromosome revealed an 8,338-bp open reading frame, ACRTS2, that was present only in the genomes of ACR-toxin-producing isolates. ACRTS2 is predicted to encode a putative polyketide synthase of 2,513 amino acids and belongs to the fungal reducing type I polyketide synthases. Typical polyketide functional domains were identified in the predicted amino acid sequence, including β-ketoacyl synthase, acyl transferase, methyl transferase, dehydratase, β-ketoreductase, and phosphopantetheine attachment site domains. Combined use of homologous recombination-mediated gene disruption and RNA silencing allowed examination of the functional role of multiple paralogs in ACR-toxin production. ACRTS2 was found to be essential for ACR-toxin production and pathogenicity of the rough lemon pathotype of A. alternata.
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Affiliation(s)
- Y Izumi
- Kagawa University, Kagawa, Japan
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Izumi Y, Kamei E, Miyamoto Y, Ohtani K, Masunaka A, Fukumoto T, Gomi K, Tada Y, Ichimura K, Peever TL, Akimitsu K. Role of the pathotype-specific ACRTS1 gene encoding a hydroxylase involved in the biosynthesis of host-selective ACR-toxin in the rough lemon pathotype of Alternaria alternata. PHYTOPATHOLOGY 2012; 102:741-748. [PMID: 22779742 DOI: 10.1094/phyto-02-12-0021-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The rough lemon pathotype of Alternaria alternata produces host-selective ACR-toxin and causes Alternaria leaf spot disease of the rootstock species rough lemon (Citrus jambhiri) and Rangpur lime (C. limonia). Genes controlling toxin production were localized to a 1.5-Mb chromosome carrying the ACR-toxin biosynthesis gene cluster (ACRT) in the genome of the rough lemon pathotype. A genomic BAC clone containing a portion of the ACRT cluster was sequenced which allowed identification of three open reading frames present only in the genomes of ACR-toxin producing isolates. We studied the functional role of one of these open reading frames, ACRTS1 encoding a putative hydroxylase, in ACR-toxin production by homologous recombination-mediated gene disruption. There are at least three copies of ACRTS1 gene in the genome and disruption of two copies of this gene significantly reduced ACR-toxin production as well as pathogenicity; however, transcription of ACRTS1 and production of ACR-toxin were not completely eliminated due to remaining functional copies of the gene. RNA-silencing was used to knock down the remaining ACRTS1 transcripts to levels undetectable by reverse transcription-polymerase chain reaction. The silenced transformants did not produce detectable ACR-toxin and were not pathogenic. These results indicate that ACRTS1 is an essential gene in ACR-toxin biosynthesis in the rough lemon pathotype of A. alternata and is required for full virulence of this fungus.
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Affiliation(s)
- Yuriko Izumi
- Faculty of Agriculture, Kagawa University, Miki, Kagawa, Japan
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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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Contribution of peroxisomes to secondary metabolism and pathogenicity in the fungal plant pathogen Alternaria alternata. EUKARYOTIC CELL 2010; 9:682-94. [PMID: 20348386 DOI: 10.1128/ec.00369-09] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The filamentous fungus Alternaria alternata includes seven pathogenic variants (pathotypes) which produce different host-selective toxins and cause diseases on different plants. The Japanese pear pathotype produces the host-selective AK-toxin, an epoxy-decatrienoic acid ester, and causes black spot of Japanese pear. Previously, we identified four genes, AKT1, AKT2, AKT3, and AKTR, involved in AK toxin biosynthesis. AKT1, AKT2, and AKT3 encode enzyme proteins with peroxisomal targeting signal type 1 (PTS1)-like tripeptides, SKI, SKL, and PKL, respectively, at the C-terminal ends. In this study, we verified the peroxisome localization of Akt1, Akt2, and Akt3 by using strains expressing N-terminal green fluorescent protein (GFP)-tagged versions of the proteins. To assess the role of peroxisome function in AK-toxin production, we isolated AaPEX6, which encodes a peroxin protein essential for peroxisome biogenesis, from the Japanese pear pathotype and made AaPEX6 disruption-containing transformants from a GFP-Akt1-expressing strain. The DeltaAaPEX6 mutant strains did not grow on fatty acid media because of a defect in fatty acid beta oxidation. The import of GFP-Akt1 into peroxisomes was impaired in the DeltaAaPEX6 mutant strains. These strains completely lost AK toxin production and pathogenicity on susceptible pear leaves. These data show that peroxisomes are essential for AK-toxin biosynthesis. The DeltaAaPEX6 mutant strains showed a marked reduction in the ability to cause lesions on leaves of a resistant pear cultivar with defense responses compromised by heat shock. This result suggests that peroxisome function is also required for plant invasion and tissue colonization in A. alternata. We also observed that mutation of AaPEX6 caused a marked reduction of conidiation.
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Ajiro N, Miyamoto Y, Masunaka A, Tsuge T, Yamamoto M, Ohtani K, Fukumoto T, Gomi K, Peever TL, Izumi Y, Tada Y, Akimitsu K. Role of the host-selective ACT-toxin synthesis gene ACTTS2 encoding an enoyl-reductase in pathogenicity of the tangerine pathotype of Alternaria alternata. PHYTOPATHOLOGY 2010; 100:120-126. [PMID: 20055645 DOI: 10.1094/phyto-100-2-0120] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
ABSTRACT The tangerine pathotype of Alternaria alternata produces host-selective ACT-toxin and causes Alternaria brown spot disease of tangerines and tangerine hybrids. Sequence analysis of a genomic BAC clone identified a previously uncharacterized portion of the ACT-toxin biosynthesis gene cluster (ACTT). A 1,034-bp gene encoding a putative enoyl-reductase was identified by using rapid amplification of cDNA ends and polymerase chain reaction and designated ACTTS2. Genomic Southern blots demonstrated that ACTTS2 is present only in ACT-toxin producers and is carried on a 1.9 Mb conditionally dispensable chromosome by the tangerine pathotype. Targeted gene disruption of ACTTS2 led to a reduction in ACT-toxin production and pathogenicity, and transcriptional knockdown of ACTTS2 using RNA silencing resulted in complete loss of ACT-toxin production and pathogenicity. These results indicate that ACTTS2 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)
- Naoya Ajiro
- Faculty of Agriculture and Gene Research Center, Kagawa University, Miki, Kagawa 761-0795, Japan
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