1
|
Morikawa S, Verdonk C, John E, Lenzo L, Sbaraini N, Turo C, Li H, Jiang D, Chooi YH, Tan KC. The Velvet transcription factor PnVeA regulates necrotrophic effectors and secondary metabolism in the wheat pathogen Parastagonospora nodorum. BMC Microbiol 2024; 24:299. [PMID: 39127645 PMCID: PMC11316297 DOI: 10.1186/s12866-024-03454-7] [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: 02/05/2024] [Accepted: 08/05/2024] [Indexed: 08/12/2024] Open
Abstract
The fungus Parastagonospora nodorum causes septoria nodorum blotch on wheat. The role of the fungal Velvet-family transcription factor VeA in P. nodorum development and virulence was investigated here. Deletion of the P. nodorum VeA ortholog, PnVeA, resulted in growth abnormalities including pigmentation, abolished asexual sporulation and highly reduced virulence on wheat. Comparative RNA-Seq and RT-PCR analyses revealed that the deletion of PnVeA also decoupled the expression of major necrotrophic effector genes. In addition, the deletion of PnVeA resulted in an up-regulation of four predicted secondary metabolite (SM) gene clusters. Using liquid-chromatography mass-spectrometry, it was observed that one of the SM gene clusters led to an accumulation of the mycotoxin alternariol. PnVeA is essential for asexual sporulation, full virulence, secondary metabolism and necrotrophic effector regulation.
Collapse
Affiliation(s)
- Shota Morikawa
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, Australia
| | - Callum Verdonk
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, Australia
| | - Evan John
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, Australia
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 115201, Taiwan
| | - Leon Lenzo
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, Australia
| | - Nicolau Sbaraini
- School of Molecular Sciences, University of Western Australia, Perth, Australia
| | - Chala Turo
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, Australia
| | - Hang Li
- School of Molecular Sciences, University of Western Australia, Perth, Australia
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - David Jiang
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, Australia
| | - Yit-Heng Chooi
- School of Molecular Sciences, University of Western Australia, Perth, Australia
| | - Kar-Chun Tan
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, Australia.
| |
Collapse
|
2
|
Nuzhnaya TV, Sorokan AV, Burkhanova GF, Maksimov IV, Veselova SV. The Role of Cytokinins and Abscisic Acid in the Growth, Development and Virulence of the Pathogenic Fungus Stagonospora nodorum (Berk.). Biomolecules 2024; 14:517. [PMID: 38785924 PMCID: PMC11117529 DOI: 10.3390/biom14050517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 04/16/2024] [Accepted: 04/22/2024] [Indexed: 05/25/2024] Open
Abstract
Cytokinins (CKs) and abscisic acid (ABA) play an important role in the life of both plants and pathogenic fungi. However, the role of CKs and ABA in the regulation of fungal growth, development and virulence has not been sufficiently studied. We compared the ability of two virulent isolates (SnB and Sn9MN-3A) and one avirulent isolate (Sn4VD) of the pathogenic fungus Stagonospora nodorum Berk. to synthesize three groups of hormones (CKs, ABA and auxins) and studied the effect of exogenous ABA and zeatin on the growth, sporulation and gene expression of necrotrophic effectors (NEs) and transcription factors (TFs) in them. Various isolates of S. nodorum synthesized different amounts of CKs, ABA and indoleacetic acid. Using exogenous ABA and zeatin, we proved that the effect of these hormones on the growth and sporulation of S. nodorum isolates can be opposite, depends on both the genotype of the isolate and on the concentration of the hormone and is carried out through the regulation of carbohydrate metabolism. ABA and zeatin regulated the expression of fungal TF and NE genes, but correlation analysis of these parameters showed that this effect depended on the genotype of the isolate. This study will contribute to our understanding of the role of the hormones ABA and CKs in the biology of the fungal pathogen S. nodorum.
Collapse
Affiliation(s)
- Tatyana V. Nuzhnaya
- Institute of Biochemistry and Genetics, Ufa Federal Research Centre, Russian Academy of Sciences, Prospekt Oktyabrya, 71, 450054 Ufa, Russia; (T.V.N.); (A.V.S.); (G.F.B.); (I.V.M.)
- Ufa Institute of Biology, Ufa Federal Research Centre, Russian Academy of Sciences, Prospekt Oktyabrya, 69, 450054 Ufa, Russia
| | - Antonina V. Sorokan
- Institute of Biochemistry and Genetics, Ufa Federal Research Centre, Russian Academy of Sciences, Prospekt Oktyabrya, 71, 450054 Ufa, Russia; (T.V.N.); (A.V.S.); (G.F.B.); (I.V.M.)
| | - Guzel F. Burkhanova
- Institute of Biochemistry and Genetics, Ufa Federal Research Centre, Russian Academy of Sciences, Prospekt Oktyabrya, 71, 450054 Ufa, Russia; (T.V.N.); (A.V.S.); (G.F.B.); (I.V.M.)
| | - Igor V. Maksimov
- Institute of Biochemistry and Genetics, Ufa Federal Research Centre, Russian Academy of Sciences, Prospekt Oktyabrya, 71, 450054 Ufa, Russia; (T.V.N.); (A.V.S.); (G.F.B.); (I.V.M.)
| | - Svetlana V. Veselova
- Institute of Biochemistry and Genetics, Ufa Federal Research Centre, Russian Academy of Sciences, Prospekt Oktyabrya, 71, 450054 Ufa, Russia; (T.V.N.); (A.V.S.); (G.F.B.); (I.V.M.)
| |
Collapse
|
3
|
Chen S, Li P, Abubakar YS, Lü P, Li Y, Mao X, Zhang C, Zheng W, Wang Z, Lu GD, Zheng H. A feedback regulation of FgHtf1-FgCon7 loop in conidiogenesis and development of Fusarium graminearum. Int J Biol Macromol 2024; 261:129841. [PMID: 38309401 DOI: 10.1016/j.ijbiomac.2024.129841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 01/15/2024] [Accepted: 01/27/2024] [Indexed: 02/05/2024]
Abstract
The transcription factor FgHtf1 is important for conidiogenesis in Fusarium graminearum and it positively regulates the expression of the sporulation-related gene FgCON7. However, the regulatory mechanism underlying its functions is still unclear. The present study intends to uncover the functional mechanism of FgHtf1 in relation to FgCon7 in F. graminearum. We demonstrated that FgCON7 serves as a target gene for FgHtf1. Interestingly, FgCon7 also binds the promoter region of FgHTF1 to negatively regulate its expression, thus forming a negative-feedback loop. We demonstrated that FgHtf1 and FgCon7 have functional redundancy in fungal development. FgCon7 localizes in the nucleus and has transcriptional activation activity. Deletion of FgCON7 significantly reduces conidia production. 4444 genes were regulated by FgCon7 in ChIP-Seq, and RNA-Seq revealed 4430 differentially expressed genes in FgCON7 deletion mutant, with CCAAT serving as a consensus binding motif of FgCon7 to the target genes. FgCon7 directly binds the promoter regions of FgMSN2, FgABAA, FgVEA and FgSMT3 genes and regulates their expression. These genes were found to be important for conidiogenesis. To our knowledge, this is the first study that unveiled the mutual regulatory functions of FgCON7 and FgHTF1 to form a negative-feedback loop, and how the loop mediates sporulation in F. graminearum.
Collapse
Affiliation(s)
- Shuang Chen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China; Fujian Key Laboratory on Conservation and Sustainable Utilization of Marine Biodiversity, Fuzhou Institute of Oceanography, College of Geography and Oceanography, Minjiang University, Fuzhou 350108, China
| | - Pengfang Li
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Yakubu Saddeeq Abubakar
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China; Department of Biochemistry, Faculty of Life Sciences, Ahmadu Bello University, Zaria 810281, Nigeria
| | - Peitao Lü
- College of Horticulture, Center for Plant Metabolomics, Haixia lnstitute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yulong Li
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China; Fujian Key Laboratory on Conservation and Sustainable Utilization of Marine Biodiversity, Fuzhou Institute of Oceanography, College of Geography and Oceanography, Minjiang University, Fuzhou 350108, China
| | - Xuzhao Mao
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China; Fujian Key Laboratory on Conservation and Sustainable Utilization of Marine Biodiversity, Fuzhou Institute of Oceanography, College of Geography and Oceanography, Minjiang University, Fuzhou 350108, China
| | - Chengkang Zhang
- College of Life Science, Ningde Normal University, Ningde 352100, China
| | - Wenhui Zheng
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Zonghua Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China; Fujian Key Laboratory on Conservation and Sustainable Utilization of Marine Biodiversity, Fuzhou Institute of Oceanography, College of Geography and Oceanography, Minjiang University, Fuzhou 350108, China
| | - Guo-Dong Lu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China.
| | - Huawei Zheng
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China; Fujian Key Laboratory on Conservation and Sustainable Utilization of Marine Biodiversity, Fuzhou Institute of Oceanography, College of Geography and Oceanography, Minjiang University, Fuzhou 350108, China.
| |
Collapse
|
4
|
Qiu M, Qiu L, Deng Q, Fang Z, Sun L, Wang Y, Gooneratne R, Zhao J. L-Cysteine hydrochloride inhibits Aspergillus flavus growth and AFB 1 synthesis by disrupting cell structure and antioxidant system balance. JOURNAL OF HAZARDOUS MATERIALS 2023; 459:132218. [PMID: 37552922 DOI: 10.1016/j.jhazmat.2023.132218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 07/26/2023] [Accepted: 08/02/2023] [Indexed: 08/10/2023]
Abstract
Aflatoxin B1 (AFB1) is the most potent known naturally occurring carcinogen and pose an immense threat to food safety and human health. L-Cysteine hydrochloride (L-CH) is a food additive often used as a fruit and vegetable preservative and also to approved bread consistency. In this study, we investigated the effects and mechanisms of L-CH as an antimicrobial on the growth of Aspergillus flavus (A. flavus) and AFB1 biosynthesis. L-CH significantly inhibited A. flavus mycelial growth, affected mycelial morphology and AFB1 synthesis. Furthermore, L-CH induced glutathione (GSH) synthesis which scavenged intracellular reactive oxygen species (ROS). RNA-Seq indicated that L-CH inhibited hyphal branching, and spore and sclerotia formation by controlling cell wall and spore development-related genes. Activation of the GSH metabolic pathway eliminated intracellular ROS, leading to hyphal dwarfing. L-CH treatment downregulated most of the Aflatoxin (AF) cluster genes and aflS, aflR, AFLA_091090 transcription factors. This study provides new insights into the molecular mechanism of L-CH control of A. flavus and AFB1 foundation. We believe that L-CH could be used as a food additive to control AFB1 in foods and also in the environment.
Collapse
Affiliation(s)
- Mei Qiu
- College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Zhanjiang 524088, China
| | - Lihong Qiu
- Department of Clinical Laboratory, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Qi Deng
- College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Zhanjiang 524088, China.
| | - Zhijia Fang
- College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Zhanjiang 524088, China
| | - Lijun Sun
- College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Zhanjiang 524088, China
| | - Yaling Wang
- College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Zhanjiang 524088, China
| | - Ravi Gooneratne
- Department of Wine, Food and Molecular Biosciences, Faculty of Agriculture and Life Sciences, Lincoln University, Lincoln 7647, New Zealand
| | - Jian Zhao
- School of Chemical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia
| |
Collapse
|
5
|
Peters Haugrud AR, Zhang Z, Friesen TL, Faris JD. Genetics of resistance to septoria nodorum blotch in wheat. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2022; 135:3685-3707. [PMID: 35050394 DOI: 10.1007/s00122-022-04036-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 12/23/2021] [Indexed: 05/12/2023]
Abstract
Septoria nodorum blotch (SNB) is a foliar disease of wheat caused by the necrotrophic fungal pathogen Parastagonospora nodorum. Research over the last two decades has shown that the wheat-P. nodorum pathosystem mostly follows an inverse gene-for-gene model. The fungus produces necrotrophic effectors (NEs) that interact with specific host gene products encoded by dominant sensitivity (S) genes. When a compatible interaction occurs, a 'defense response' in the host leads to programmed cell death thereby provided dead/dying cells from which the pathogen, being a necrotroph, can acquire nutrients allowing it to grow and sporulate. To date, nine S gene-NE interactions have been characterized in this pathosystem. Five NE-encoding genes, SnTox1, SnTox3, SnToxA, SnTox5, and SnTox267, have been cloned along with three host S genes, Tsn1, Snn1, and Snn3-D1. Studies have shown that P. nodorum hijacks multiple and diverse host targets to cause disease. SNB resistance is often quantitative in nature because multiple compatible interactions usually occur concomitantly. NE gene expression plays a key role in disease severity, and the effect of each compatible interaction can vary depending on the other existing compatible interactions. Numerous SNB-resistance QTL have been identified in addition to the known S genes, and more research is needed to understand the nature of these resistance loci. Marker-assisted elimination of S genes through conventional breeding practices and disruption of S genes using gene editing techniques are both effective strategies for the development of SNB-resistant wheat cultivars, which will become necessary as the global demand for sustenance grows.
Collapse
Affiliation(s)
| | - Zengcui Zhang
- USDA-ARS Cereal Crops Research Unit, Edward T. Schafer Agricultural Research Center, Fargo, ND, 58102, USA
| | - Timothy L Friesen
- USDA-ARS Cereal Crops Research Unit, Edward T. Schafer Agricultural Research Center, Fargo, ND, 58102, USA
| | - Justin D Faris
- USDA-ARS Cereal Crops Research Unit, Edward T. Schafer Agricultural Research Center, Fargo, ND, 58102, USA.
| |
Collapse
|
6
|
John E, Singh KB, Oliver RP, Tan K. Transcription factor control of virulence in phytopathogenic fungi. MOLECULAR PLANT PATHOLOGY 2021; 22:858-881. [PMID: 33973705 PMCID: PMC8232033 DOI: 10.1111/mpp.13056] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 03/02/2021] [Accepted: 03/04/2021] [Indexed: 05/12/2023]
Abstract
Plant-pathogenic fungi are a significant threat to economic and food security worldwide. Novel protection strategies are required and therefore it is critical we understand the mechanisms by which these pathogens cause disease. Virulence factors and pathogenicity genes have been identified, but in many cases their roles remain elusive. It is becoming increasingly clear that gene regulation is vital to enable plant infection and transcription factors play an essential role. Efforts to determine their regulatory functions in plant-pathogenic fungi have expanded since the annotation of fungal genomes revealed the ubiquity of transcription factors from a broad range of families. This review establishes the significance of transcription factors as regulatory elements in plant-pathogenic fungi and provides a systematic overview of those that have been functionally characterized. Detailed analysis is provided on regulators from well-characterized families controlling various aspects of fungal metabolism, development, stress tolerance, and the production of virulence factors such as effectors and secondary metabolites. This covers conserved transcription factors with either specialized or nonspecialized roles, as well as recently identified regulators targeting key virulence pathways. Fundamental knowledge of transcription factor regulation in plant-pathogenic fungi provides avenues to identify novel virulence factors and improve our understanding of the regulatory networks linked to pathogen evolution, while transcription factors can themselves be specifically targeted for disease control. Areas requiring further insight regarding the molecular mechanisms and/or specific classes of transcription factors are identified, and direction for future investigation is presented.
Collapse
Affiliation(s)
- Evan John
- Centre for Crop and Disease ManagementCurtin UniversityBentleyWestern AustraliaAustralia
- School of Molecular and Life SciencesCurtin UniversityBentleyWestern AustraliaAustralia
| | - Karam B. Singh
- Agriculture and FoodCommonwealth Scientific and Industrial Research OrganisationFloreatWestern AustraliaAustralia
| | - Richard P. Oliver
- School of Molecular and Life SciencesCurtin UniversityBentleyWestern AustraliaAustralia
| | - Kar‐Chun Tan
- Centre for Crop and Disease ManagementCurtin UniversityBentleyWestern AustraliaAustralia
- School of Molecular and Life SciencesCurtin UniversityBentleyWestern AustraliaAustralia
| |
Collapse
|
7
|
Wang C, Milgate AW, Solomon PS, McDonald MC. The identification of a transposon affecting the asexual reproduction of the wheat pathogen Zymoseptoria tritici. MOLECULAR PLANT PATHOLOGY 2021; 22:800-816. [PMID: 33949756 PMCID: PMC8232023 DOI: 10.1111/mpp.13064] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 03/15/2021] [Accepted: 03/16/2021] [Indexed: 05/13/2023]
Abstract
Zymoseptoria tritici, the causal agent of Septoria tritici blotch, is a fungal wheat pathogen that causes significant global yield losses. Within Z. tritici populations, quantitative differences in virulence among different isolates are commonly observed; however, the genetic components that underpin these differences remain elusive. In this study, intraspecific comparative transcriptomic analysis was used to identify candidate genes that contribute to differences in virulence on the wheat cultivar WW2449. This led to the identification of a multicopy gene that was not expressed in the high-virulence isolate when compared to the medium- and low-virulence isolates. Further investigation suggested this gene resides in a 7.9-kb transposon. Subsequent long-read sequencing of the isolates used in the transcriptomic analysis confirmed that this gene did reside in an active Class II transposon, which is composed of four genes named REP9-1 to -4. Silencing and overexpression of REP9-1 in two distinct genetic backgrounds demonstrated that its expression alone reduces the number of pycnidia produced by Z. tritici during infection. The REP9-1 gene identified within a Class II transposon is the first discovery of a gene in a transposable element that influences the virulence of Z. tritici. This discovery adds further complexity to genetic loci that contribute to quantitative virulence in this important pathogen.
Collapse
Affiliation(s)
- Chen Wang
- Division of Plant SciencesResearch School of BiologyThe Australian National UniversityCanberraACTAustralia
| | - Andrew W. Milgate
- NSW Department of Primary IndustriesWagga Wagga Agricultural InstituteWagga WaggaNSWAustralia
| | - Peter S. Solomon
- Division of Plant SciencesResearch School of BiologyThe Australian National UniversityCanberraACTAustralia
| | - Megan C. McDonald
- Division of Plant SciencesResearch School of BiologyThe Australian National UniversityCanberraACTAustralia
- School of BiosciencesUniversity of BirminghamEdgbastonBirminghamUK
| |
Collapse
|
8
|
Zhu J, Jeong JS, Khang CH. Tandem DNA repeats contain cis-regulatory sequences that activate biotrophy-specific expression of Magnaporthe effector gene PWL2. MOLECULAR PLANT PATHOLOGY 2021; 22:508-521. [PMID: 33694285 PMCID: PMC8035637 DOI: 10.1111/mpp.13038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 12/18/2020] [Accepted: 12/18/2020] [Indexed: 06/12/2023]
Abstract
During plant infection, fungi secrete effector proteins in coordination with distinct infection stages. Thus, the success of plant infection is determined by precise control of effector gene expression. We analysed the PWL2 effector gene of the rice blast fungus Magnaporthe oryzae to understand how effector genes are activated specifically during the early biotrophic stages of rice infection. Here, we used confocal live-cell imaging of M. oryzae transformants with various PWL2 promoter fragments fused to sensitive green fluorescent protein reporter genes to determine the expression patterns of PWL2 at the cellular level, together with quantitative reverse transcription PCR analyses at the tissue level. We found PWL2 expression was coupled with sequential biotrophic invasion of rice cells. PWL2 expression was induced in the appressorium upon penetration into a living rice cell but greatly declined in the highly branched hyphae when the first-invaded rice cell was dead. PWL2 expression then increased again as the hyphae penetrate into living adjacent cells. The expression of PWL2 required fungal penetration into living plant cells of either host rice or nonhost onion. Deletion and mutagenesis experiments further revealed that the tandem repeats in the PWL2 promoter contain 12-base pair sequences required for expression. We conclude that PWL2 expression is (a) activated by an unknown signal commonly present in living plant cells, (b) specific to biotrophic stages of fungal infection, and (c) requires 12-base pair cis-regulatory sequences in the promoter.
Collapse
Affiliation(s)
- Jie Zhu
- Department of Plant BiologyUniversity of GeorgiaAthensGeorgiaUSA
- Present address:
Department of Plant PathologyUniversity of CaliforniaDavisCaliforniaUSA
| | - Jun Seop Jeong
- Department of BiologyNorth Carolina A&T State UniversityGreensboroNorth CarolinaUSA
| | - Chang Hyun Khang
- Department of Plant BiologyUniversity of GeorgiaAthensGeorgiaUSA
| |
Collapse
|
9
|
A specific fungal transcription factor controls effector gene expression and orchestrates the establishment of the necrotrophic pathogen lifestyle on wheat. Sci Rep 2019; 9:15884. [PMID: 31685928 PMCID: PMC6828707 DOI: 10.1038/s41598-019-52444-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 10/17/2019] [Indexed: 12/14/2022] Open
Abstract
The fungus Parastagonospora nodorum infects wheat through the use of necrotrophic effector (NE) proteins that cause host-specific tissue necrosis. The Zn2Cys6 transcription factor PnPf2 positively regulates NE gene expression and is required for virulence on wheat. Little is known about other downstream targets of PnPf2. We compared the transcriptomes of the P. nodorum wildtype and a strain deleted in PnPf2 (pf2-69) during in vitro growth and host infection to further elucidate targets of PnPf2 signalling. Gene ontology enrichment analysis of the differentially expressed (DE) genes revealed that genes associated with plant cell wall degradation and proteolysis were enriched in down-regulated DE gene sets in pf2-69 compared to SN15. In contrast, genes associated with redox control, nutrient and ion transport were up-regulated in the mutant. Further analysis of the DE gene set revealed that PnPf2 positively regulates twelve genes that encode effector-like proteins. Two of these genes encode proteins with homology to previously characterised effectors in other fungal phytopathogens. In addition to modulating effector gene expression, PnPf2 may play a broader role in the establishment of a necrotrophic lifestyle by orchestrating the expression of genes associated with plant cell wall degradation and nutrient assimilation.
Collapse
|