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Wang M, Dean RA. Host induced gene silencing of Magnaporthe oryzae by targeting pathogenicity and development genes to control rice blast disease. FRONTIERS IN PLANT SCIENCE 2022; 13:959641. [PMID: 36035704 PMCID: PMC9403838 DOI: 10.3389/fpls.2022.959641] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Rice blast disease caused by the hemi-biotrophic fungus Magnaporthe oryzae is the most destructive disease of rice world-wide. Traditional disease resistance strategies for the control of rice blast disease have not proved durable. HIGS (host induced gene silencing) is being developed as an alternative strategy. Six genes (CRZ1, PMC1, MAGB, LHS1, CYP51A, CYP51B) that play important roles in pathogenicity and development of M. oryzae were chosen for HIGS. HIGS vectors were transformed into rice calli through Agrobacterium-mediated transformation and T0, T1 and T2 generations of transgenic rice plants were generated. Except for PMC1 and LHS1, HIGS transgenic rice plants challenged with M. oryzae showed significantly reduced disease compared with non-silenced control plants. Following infection with M. oryzae of HIGS transgenic plants, expression levels of target genes were reduced as demonstrated by Quantitative RT-PCR. In addition, treating M. oryzae with small RNA derived from the target genes inhibited fungal growth. These findings suggest RNA silencing signals can be transferred from host to an invasive fungus and that HIGS has potential to generate resistant rice against M. oryzae.
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OUP accepted manuscript. FEMS Microbiol Lett 2022; 369:6544667. [DOI: 10.1093/femsle/fnab162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 03/04/2022] [Indexed: 11/13/2022] Open
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Abstract
This introductory chapter describes the life cycle of Magnaporthe oryzae, the causal agent of rice blast disease. During plant infection, M. oryzae forms a specialized infection structure called an appressorium, which generates enormous turgor, applied as a mechanical force to breach the rice cuticle. Appressoria form in response to physical cues from the hydrophobic rice leaf cuticle and nutrient availability. The signaling pathways involved in perception of surface signals are described and the mechanism by which appressoria function is also introduced. Re-polarization of the appressorium requires a septin complex to organize a toroidal F-actin network at the base of the cell. Septin aggregation requires a turgor-dependent sensor kinase, Sln1, necessary for re-polarization of the appressorium and development of a rigid penetration hypha to rupture the leaf cuticle. Once inside the plant, the fungus undergoes secretion of a large set of effector proteins, many of which are directed into plant cells using a specific secretory pathway. Here they suppress plant immunity, but can also be perceived by rice immune receptors, triggering resistances. M. oryzae then manipulates pit field sites, containing plasmodesmata, to facilitate rapid spread from cell to cell in plant tissue, leading to disease symptom development.
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Wang Y, Wei X, Bian Z, Wei J, Xu JR. Coregulation of dimorphism and symbiosis by cyclic AMP signaling in the lichenized fungus Umbilicaria muhlenbergii. Proc Natl Acad Sci U S A 2020; 117:23847-23858. [PMID: 32873646 PMCID: PMC7519320 DOI: 10.1073/pnas.2005109117] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Umbilicaria muhlenbergii is the only known dimorphic lichenized fungus that grows in the hyphal form in lichen thalli but as yeast cells in axenic cultures. However, the regulation of yeast-to-hypha transition and its relationship to the establishment of symbiosis are not clear. In this study, we show that nutrient limitation and hyperosmotic stress trigger the dimorphic change in U. muhlenbergii Contact with algal cells of its photobiont Trebouxia jamesii induced pseudohyphal growth. Treatments with the cAMP diphosphoesterase inhibitor IBMX (3-isobutyl-1-methylxanthine) induced pseudohyphal/hyphal growth and resulted in the differentiation of heavily melanized, lichen cortex-like structures in culture, indicating the role of cAMP signaling in regulating dimorphism. To confirm this observation, we identified and characterized two Gα subunits UmGPA2 and UmGPA3 Whereas deletion of UmGPA2 had only a minor effect on pseudohyphal growth, the ΔUmgpa3 mutant was defective in yeast-to-pseudohypha transition induced by hyperosmotic stress or T. jamesii cells. IBMX treatment suppressed the defect of ΔUmgpa3 in pseudohyphal growth. Transformants expressing the UmGPA3G45V or UmGPA3Q208L dominant active allele were enhanced in the yeast-to-pseudohypha transition and developed pseudohyphae under conditions noninducible to the wild type. Interestingly, T. jamesii cells in close contact with pseudohyphae of UmGPA3G45V and UmGPA3Q208L transformants often collapsed and died after coincubation for over 72 h, indicating that improperly regulated pseudohyphal growth due to dominant active mutations may disrupt the initial establishment of symbiotic interaction between the photobiont and mycobiont. Taken together, these results show that the cAMP-PKA pathway plays a critical role in regulating dimorphism and symbiosis in U. muhlenbergii.
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Affiliation(s)
- Yanyan Wang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907
| | - Xinli Wei
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China
| | - Zhuyun Bian
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907
| | - Jiangchun Wei
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China
| | - Jin-Rong Xu
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907
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Singh P, Mazumdar P, Harikrishna JA, Babu S. Sheath blight of rice: a review and identification of priorities for future research. PLANTA 2019; 250:1387-1407. [PMID: 31346804 DOI: 10.1007/s00425-019-03246-8] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 07/20/2019] [Indexed: 05/04/2023]
Abstract
Rice sheath blight research should prioritise optimising biological control approaches, identification of resistance gene mechanisms and application in genetic improvement and smart farming for early disease detection. Rice sheath blight, caused by Rhizoctonia solani AG1-1A, is one of the most devasting diseases of the crop. To move forward with effective crop protection against sheath blight, it is important to review the published information related to pathogenicity and disease management and to determine areas of research that require deeper study. While progress has been made in the identification of pathogenesis-related genes both in rice and in the pathogen, the mechanisms remain unclear. Research related to disease management practices has addressed the use of agronomic practices, chemical control, biological control and genetic improvement: Optimising nitrogen fertiliser use in conjunction with plant spacing can reduce spread of infection while smart agriculture technologies such as crop monitoring with Unmanned Aerial Systems assist in early detection and management of sheath blight disease. Replacing older fungicides with natural fungicides and use of biological agents can provide effective sheath blight control, also minimising environmental impact. Genetic approaches that show promise for the control of sheath blight include treatment with exogenous dsRNA to silence pathogen gene expression, genome editing to develop rice lines with lower susceptibility to sheath blight and development of transgenic rice lines overexpressing or silencing pathogenesis related genes. The main challenges that were identified for effective crop protection against sheath blight are the adaptive flexibility of the pathogen, lack of resistant rice varieties, abscence of single resistance genes for use in breeding and low access of farmers to awareness programmes for optimal management practices.
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Affiliation(s)
- Pooja Singh
- Centre for Research in Biotechnology for Agriculture, University of Malaya, 50603, Kuala Lumpur, Malaysia.
| | - Purabi Mazumdar
- Centre for Research in Biotechnology for Agriculture, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Jennifer Ann Harikrishna
- Centre for Research in Biotechnology for Agriculture, University of Malaya, 50603, Kuala Lumpur, Malaysia
- Faculty of Science, Institute of Biological Sciences, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Subramanian Babu
- VIT School of Agricultural Innovations and Advanced Learning, VIT University, Vellore, Tamil Nadu, 632014, India
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Selvaraj P, Shen Q, Yang F, Naqvi NI. Cpk2, a Catalytic Subunit of Cyclic AMP-PKA, Regulates Growth and Pathogenesis in Rice Blast. Front Microbiol 2017; 8:2289. [PMID: 29209297 PMCID: PMC5702331 DOI: 10.3389/fmicb.2017.02289] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 11/06/2017] [Indexed: 12/11/2022] Open
Abstract
The cAMP-Protein Kinase A signaling, anchored on CpkA, is necessary for appressorium development and host penetration, but indispensable for infectious growth in Magnaporthe oryzae. In this study, we identified and characterized the gene encoding the second catalytic subunit, CPK2, whose expression was found to be lower compared to CPKA at various stages of pathogenic growth in M. oryzae. Deletion of CPK2 caused no alterations in vegetative growth, conidiation, appressorium formation, or pathogenicity. Surprisingly, the cpkAΔcpk2Δ double deletion strain displayed significant reduction in growth rate and conidiation compared to the single deletion mutants. Interestingly, loss of CPKA and CPK2 resulted in morphogenetic defects in germ tubes (with curled/wavy and serpentine growth pattern) on hydrophobic surfaces, and a complete failure to produce appressoria therein, thus suggesting an important role for CPK2-mediated cAMP-PKA in surface sensing and response pathway. CPKA promoter-driven expression of CPK2 partially suppressed the defects in host penetration and pathogenicity in the cpkAΔ. Such ectopic CPK2 expressing strain successfully penetrated the rice leaves, but was unable to produce proper secondary invasive hyphae, thus underscoring the importance of CpkA in growth and differentiation in planta. The Cpk2-GFP localized to the nuclei and cytoplasmic vesicles in conidia and germ tubes. The Cpk2-GFP colocalized with CpkA-mCherry on vesicles in the cytosol, but such overlap was not evident in the nuclei. Our studies indicate that CpkA and Cpk2 share overlapping functions, but also play distinct roles during pathogenesis-associated signaling and morphogenesis in the rice blast fungus.
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Affiliation(s)
- Poonguzhali Selvaraj
- Temasek Life Sciences Laboratory and Department of Biological Sciences, 1 Research Link, National University of Singapore, Singapore, Singapore
| | - Qing Shen
- Temasek Life Sciences Laboratory and Department of Biological Sciences, 1 Research Link, National University of Singapore, Singapore, Singapore
| | - Fan Yang
- Temasek Life Sciences Laboratory and Department of Biological Sciences, 1 Research Link, National University of Singapore, Singapore, Singapore
| | - Naweed I Naqvi
- Temasek Life Sciences Laboratory and Department of Biological Sciences, 1 Research Link, National University of Singapore, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
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Sun X, Li Z, Liu H, Yang J, Liang W, Peng YL, Huang J. Large-scale identification of lysine acetylated proteins in vegetative hyphae of the rice blast fungus. Sci Rep 2017; 7:15316. [PMID: 29127393 PMCID: PMC5681509 DOI: 10.1038/s41598-017-15655-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 10/30/2017] [Indexed: 12/30/2022] Open
Abstract
Lysine acetylation is a major post-translational modification that plays important regulatory roles in diverse biological processes to perform various cellular functions in both eukaryotes and prokaryotes. However, roles of lysine acetylation in plant fungal pathogens were less studied. Here, we provided the first lysine acetylome of vegetative hyphae of the rice blast fungus Magnaporthe oryzae through a combination of highly sensitive immune-affinity purification and high-resolution LC-MS/MS. This lysine acetylome had 2,720 acetylation sites in 1,269 proteins. The lysine acetylated proteins were involved indiverse cellular functions, and located in 820 nodes and 7,709 edges among the protein-protein interaction network. Several amino acid residues nearby the lysine acetylation sites were conserved, including KacR, KacK, and KacH. Importantly, dozens of lysine acetylated proteins are found to be important to vegetative hyphal growth and fungal pathogenicity. Taken together, our results provided the first comprehensive view of lysine acetylome of M.oryzae and suggested protein lysine acetylation played important roles to fungal development and pathogenicity.
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Affiliation(s)
- Xiaomei Sun
- College of Animation and Communication, Qingdao Agricultural University, Qingdao, 266109, China
| | - Zhigang Li
- State Key Laboratory of Agrobiotechnology, and Ministry of Agriculture Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Hang Liu
- State Key Laboratory of Agrobiotechnology, and Ministry of Agriculture Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Jun Yang
- State Key Laboratory of Agrobiotechnology, and Ministry of Agriculture Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Wenxing Liang
- The Key Laboratory of Integrated Crop Pest Management of Shandong Province, College of Plant Health and Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - You-Liang Peng
- State Key Laboratory of Agrobiotechnology, and Ministry of Agriculture Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Jinguang Huang
- The Key Laboratory of Integrated Crop Pest Management of Shandong Province, College of Plant Health and Medicine, Qingdao Agricultural University, Qingdao, 266109, China.
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Selvaraj P, Tham HF, Ramanujam R, Naqvi NI. Subcellular compartmentation, interdependency and dynamics of the cyclic AMP-dependent PKA subunits during pathogenic differentiation in rice blast. Mol Microbiol 2017; 105:484-504. [PMID: 28544028 DOI: 10.1111/mmi.13713] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2017] [Indexed: 02/03/2023]
Abstract
The cAMP-dependent PKA signalling plays a central role in growth, asexual development and pathogenesis in fungal pathogens. Here, we functionally characterised RPKA, the regulatory subunit of cAMP/PKA and studied the dynamics and organisation of the PKA subunits in the rice blast pathogen Magnaporthe oryzae. The RPKA subunit was essential for proper vegetative growth, asexual sporulation and surface hydrophobicity in M. oryzae. A spontaneous suppressor mutation, SMR19, that restored growth and conidiation in the RPKA deletion mutant was isolated and characterised. SMR19 enhanced conidiation and appressorium formation but failed to suppress the pathogenesis defects in rpkAΔ. The PKA activity was undetectable in the mycelial extracts of SMR19, which showed a single mutation (val242leu) in the highly conserved active site of the catalytic subunit (CPKA) of cAMP/PKA. The two subunits of cAMP/PKA showed different subcellular localisation patterns with RpkA being predominantly nucleocytoplasmic in conidia, while CpkA was largely cytosolic and/or vesicular. The CpkA anchored RpkA in cytoplasmic vesicles, and localisation of PKA in the cytoplasm was governed by CpkA in a cAMP-dependant or independent manner. We show that there exists a tight regulation of PKA subunits at the level of transcription, and the cAMP signalling is differentially compartmentalised in a stage-specific manner in rice blast.
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Affiliation(s)
- Poonguzhali Selvaraj
- Temasek Life Sciences Laboratory and Department of Biological Sciences, 1 Research Link, National University of Singapore, Singapore
| | - Hong Fai Tham
- School of Applied Science, Temasek Polytechnic, Singapore
| | - Ravikrishna Ramanujam
- Temasek Life Sciences Laboratory and Department of Biological Sciences, 1 Research Link, National University of Singapore, Singapore
| | - Naweed I Naqvi
- Temasek Life Sciences Laboratory and Department of Biological Sciences, 1 Research Link, National University of Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore
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Kou Y, Naqvi NI. Surface sensing and signaling networks in plant pathogenic fungi. Semin Cell Dev Biol 2016; 57:84-92. [DOI: 10.1016/j.semcdb.2016.04.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 04/21/2016] [Accepted: 04/26/2016] [Indexed: 11/29/2022]
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Zhang Z, Wang J, Chai R, Qiu H, Jiang H, Mao X, Wang Y, Liu F, Sun G. An S-(hydroxymethyl)glutathione dehydrogenase is involved in conidiation and full virulence in the rice blast fungus Magnaporthe oryzae. PLoS One 2015; 10:e0120627. [PMID: 25793615 PMCID: PMC4368689 DOI: 10.1371/journal.pone.0120627] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 01/24/2015] [Indexed: 11/25/2022] Open
Abstract
Magnaporthe oryzae is a hemibiotrophic fungal pathogen that causes rice blast disease. A compatible interaction requires overcoming plant defense responses to initiate colonization during the early infection process. Nitric oxide (NO) plays important roles in defense responses during host-pathogen interactions. Microbes generally protect themselves against NO-induced damage by using enzymes. Here, we characterized an S-(hydroxymethyl)-glutathione dehydrogenase gene in M. oryzae, MoSFA1, the homologs of which are involved in NO metabolism by specifically catalyzing the reduction of S-nitrosoglutathione (GSNO) in yeasts and plants. As expected from the activities of S-(hydroxymethyl)glutathione dehydrogenase in formaldehyde detoxification and GSNO reduction, MoSFA1 deletion mutants were lethal in formaldehyde containing medium, sensitive to exogenous NO and exhibited a higher level of S-nitrosothiols (SNOs) than that of the wild type. Notably, the mutants showed severe reduction of conidiation and appressoria turgor pressure, as well as significantly attenuated the virulence on rice cultivar CO-39. However, the virulence of MoSFA1 deletion mutants on wounded rice leaf was not affected. An infection assay on barley leaf further revealed that MoSFA1 deletion mutants exhibited a lower infection rate, and growth of infectious hyphae of the mutants was retarded not only in primary infected cells but also in expansion from cell to cell. Furthermore, barley leaf cell infected by MoSFA1 deletion mutants exhibited a stronger accumulation of H2O2 at 24 and 36 hpi. MoSFA1 deletion mutants displayed hypersensitivity to different oxidants, reduced activities of superoxide dismutases and peroxidases, and lower glutathione content in cells, compared with the wild type. These results imply that MoSFA1-mediated NO metabolism is important in redox homeostasis in response to development and host infection of M. oryzae. Taken together, this work identifies that MoSFA1 is required for conidiation and contributes to virulence in the penetration and biotrophic phases in M. oryzae.
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Affiliation(s)
- Zhen Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Jiaoyu Wang
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Rongyao Chai
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Haiping Qiu
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Hua Jiang
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Xueqin Mao
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Yanli Wang
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Fengquan Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Guochang Sun
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
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Zhou X, Zhao X, Xue C, Dai Y, Xu JR. Bypassing both surface attachment and surface recognition requirements for appressorium formation by overactive ras signaling in Magnaporthe oryzae. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:996-1004. [PMID: 24835254 DOI: 10.1094/mpmi-02-14-0052-r] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Magnaporthe oryzae forms a highly specialized infection structure called an appressorium for plant penetration. In M. oryzae and many other plant-pathogenic fungi, surface attachment and surface recognition are two essential requirements for appressorium formation. Development of appressoria in the air has not been reported. In this study, we found that expression of a dominant active MoRAS2(G18V) allele in M. oryzae resulted in the formation of morphologically abnormal appressoria on nonconducive surfaces, in liquid suspensions, and on aerial hyphae without attachment to hard surfaces. Both the Pmk1 mitogen-activated protein kinase cascade and cAMP signaling pathways that regulate surface recognition and appressorium morphogenesis in M. oryzae were overactivated in the MoRAS2(G18V) transformant. In mutants deleted of PMK1 or CPKA, expression of MoRAS2(G18V) had no significant effects on appressorium morphogenesis. Furthermore, expression of dominant MoRAS2 in Colletotrichum graminicola and C. gloeosporioides also caused the formation of appressorium-like structures in aerial hyphae. Overall, our data indicate that MoRas2 functions upstream from both the cAMP-PKA and Pmk1 pathways and overactive Ras signaling leads to improper activation of these two pathways and appressorium formation without surface attachment in appressorium-forming pathogens.
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Fernandez J, Wilson RA. Cells in cells: morphogenetic and metabolic strategies conditioning rice infection by the blast fungus Magnaporthe oryzae. PROTOPLASMA 2014; 251:37-47. [PMID: 23990109 DOI: 10.1007/s00709-013-0541-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Accepted: 08/13/2013] [Indexed: 06/02/2023]
Abstract
The rice blast fungus Magnaporthe oryzae is a global food security threat due to its destruction of cultivated rice. Of the world's rice harvest, 10-30 % is lost each year to this pathogen, and changing climates are likely to favor its spread into new areas. Insights into how the fungus might be contained could come from the wealth of molecular and cellular studies that have been undertaken in order to shed light on the biological underpinnings of blast disease, aspects of which we review herein. Infection begins when a three-celled spore lands on the surface of a leaf, germinates, and develops the specialized infection structure called the appressorium. The mature appressorium develops a high internal turgor that acts on a thin penetration peg, forcing it through the rice cuticle and into the underlying epidermal cells. Primary then invasive hyphae (IH) elaborate from the peg and grow asymptomatically from one living rice cell to another for the first few days of infection before host cells begin to die and characteristic necrotic lesions form on the surface of the leaf, from which spores are produced to continue the life cycle. To gain new insights into the biology of rice blast disease, we argue that, conceptually, the infection process can be viewed as two discrete phases occurring in markedly different environments and requiring distinct biochemical pathways and morphogenetic regulation: outside the host cell, where the appressorium develops in a nutrient-free environment, and inside the host cell, where filamentous growth occurs in a glucose-rich, nitrogen-poor environment, at least from the perspective of the fungus. Here, we review the physiological and metabolic changes that occur in M. oryzae as it transitions from the surface to the interior of the host, thus enabling us to draw lessons about the strategies that allow M. oryzae cells to thrive in rice cells.
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Affiliation(s)
- Jessie Fernandez
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA
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Functional analyses of regulators of G protein signaling in Gibberella zeae. Fungal Genet Biol 2012; 49:511-20. [PMID: 22634273 DOI: 10.1016/j.fgb.2012.05.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 05/08/2012] [Accepted: 05/09/2012] [Indexed: 11/20/2022]
Abstract
Regulators of G protein signaling (RGS) proteins make up a highly diverse and multifunctional protein family that plays a critical role in controlling heterotrimeric G protein signaling. In this study, seven RGS genes (FgFlbA, FgFlbB, FgRgsA, FgRgsB, FgRgsB2, FgRgsC, and FgGprK) were functionally characterized in the plant pathogenic fungus, Gibberella zeae. Mutant phenotypes were observed for deletion mutants of FgRgsA and FgRgsB in vegetative growth, FgFlbB and FgRgsB in conidia morphology, FgFlbA in conidia production, FgFlbA, FgRgsB, and FgRgsC in sexual development, FgFlbA and FgRgsA in spore germination and mycotoxin production, and FgFlbA, FgRgsA, and FgRgsB in virulence. Furthermore, FgFlbA, FgRgsA, and FgRgsB acted pleiotropically, while FgFlbB and FgRgsC deletion mutants exhibited a specific defect in conidia morphology and sexual development, respectively. Amino acid substitutions in Gα subunits and overexpression of the FgFlbA gene revealed that deletion of FgFlbA and dominant active GzGPA2 mutant, gzgpa2(Q207L), had similar phenotypes in cell wall integrity, perithecia formation, mycotoxin production, and virulence, suggesting that FgFlbA may regulate asexual/sexual development, mycotoxin biosynthesis, and virulence through GzGPA2-dependent signaling in G. zeae.
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Bosch DE, Willard FS, Ramanujam R, Kimple AJ, Willard MD, Naqvi NI, Siderovski DP. A P-loop mutation in Gα subunits prevents transition to the active state: implications for G-protein signaling in fungal pathogenesis. PLoS Pathog 2012; 8:e1002553. [PMID: 22383884 PMCID: PMC3285607 DOI: 10.1371/journal.ppat.1002553] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 01/12/2012] [Indexed: 11/26/2022] Open
Abstract
Heterotrimeric G-proteins are molecular switches integral to a panoply of different physiological responses that many organisms make to environmental cues. The switch from inactive to active Gαβγ heterotrimer relies on nucleotide cycling by the Gα subunit: exchange of GTP for GDP activates Gα, whereas its intrinsic enzymatic activity catalyzes GTP hydrolysis to GDP and inorganic phosphate, thereby reverting Gα to its inactive state. In several genetic studies of filamentous fungi, such as the rice blast fungus Magnaporthe oryzae, a G42R mutation in the phosphate-binding loop of Gα subunits is assumed to be GTPase-deficient and thus constitutively active. Here, we demonstrate that Gα(G42R) mutants are not GTPase deficient, but rather incapable of achieving the activated conformation. Two crystal structure models suggest that Arg-42 prevents a typical switch region conformational change upon Gαi1(G42R) binding to GDP·AlF4− or GTP, but rotameric flexibility at this locus allows for unperturbed GTP hydrolysis. Gα(G42R) mutants do not engage the active state-selective peptide KB-1753 nor RGS domains with high affinity, but instead favor interaction with Gβγ and GoLoco motifs in any nucleotide state. The corresponding Gαq(G48R) mutant is not constitutively active in cells and responds poorly to aluminum tetrafluoride activation. Comparative analyses of M. oryzae strains harboring either G42R or GTPase-deficient Q/L mutations in the Gα subunits MagA or MagB illustrate functional differences in environmental cue processing and intracellular signaling outcomes between these two Gα mutants, thus demonstrating the in vivo functional divergence of G42R and activating G-protein mutants. Heterotrimeric G-proteins function as molecular switches to convey cellular signals. When a G-protein coupled receptor encounters its ligand at the cellular membrane, it catalyzes guanine nucleotide exchange on the Gα subunit, resulting in a shift from an inactive to an active conformation. G-protein signaling pathways are conserved from mammals to plants and fungi, including the rice blast fungus Magnaporthe oryzae. A mutation in the Gα subunit (G42R), previously thought to eliminate its GTPase activity, leading to constitutive activation, has been utilized to investigate roles of heterotrimeric G-protein signaling pathways in multiple species of filamentous fungi. Here, we demonstrate through structural, biochemical, and cellular approaches that G42R mutants are neither GTPase deficient nor constitutively active, but rather are unable to transition to the activated conformation. A direct comparison of M. oryzae fungal strains harboring either G42R or truly constitutively activating mutations in two Gα subunits, MagA and MagB, revealed markedly different phenotypes. Our results suggest that activation of MagB is critical for pathogenic development of M. oryzae in response to hydrophobic surfaces, such as plant leaves. Furthermore, the lack of constitutive activity by Gα(G42R) mutants prompts a re-evaluation of its use in previous genetic experiments in multiple fungal species.
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Affiliation(s)
- Dustin E. Bosch
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Francis S. Willard
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail: (FSW); (DPS)
| | - Ravikrishna Ramanujam
- Fungal Patho-Biology Group, Temasek Life Sciences Laboratory, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Adam J. Kimple
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Melinda D. Willard
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Naweed I. Naqvi
- Fungal Patho-Biology Group, Temasek Life Sciences Laboratory, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore
| | - David P. Siderovski
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- UNC Neuroscience Center and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail: (FSW); (DPS)
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Zhang H, Tang W, Liu K, Huang Q, Zhang X, Yan X, Chen Y, Wang J, Qi Z, Wang Z, Zheng X, Wang P, Zhang Z. Eight RGS and RGS-like proteins orchestrate growth, differentiation, and pathogenicity of Magnaporthe oryzae. PLoS Pathog 2011; 7:e1002450. [PMID: 22241981 PMCID: PMC3248559 DOI: 10.1371/journal.ppat.1002450] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 11/05/2011] [Indexed: 11/18/2022] Open
Abstract
A previous study identified MoRgs1 as an RGS protein that negative regulates G-protein signaling to control developmental processes such as conidiation and appressorium formation in Magnaporthe oryzae. Here, we characterized additional seven RGS and RGS-like proteins (MoRgs2 through MoRgs8). We found that MoRgs1 and MoRgs4 positively regulate surface hydrophobicity, conidiation, and mating. Indifference to MoRgs1, MoRgs4 has a role in regulating laccase and peroxidase activities. MoRgs1, MoRgs2, MoRgs3, MoRgs4, MoRgs6, and MoRgs7 are important for germ tube growth and appressorium formation. Interestingly, MoRgs7 and MoRgs8 exhibit a unique domain structure in which the RGS domain is linked to a seven-transmembrane motif, a hallmark of G-protein coupled receptors (GPCRs). We have also shown that MoRgs1 regulates mating through negative regulation of Gα MoMagB and is involved in the maintenance of cell wall integrity. While all proteins appear to be involved in the control of intracellular cAMP levels, only MoRgs1, MoRgs3, MoRgs4, and MoRgs7 are required for full virulence. Taking together, in addition to MoRgs1 functions as a prominent RGS protein in M. oryzae, MoRgs4 and other RGS and RGS-like proteins are also involved in a complex process governing asexual/sexual development, appressorium formation, and pathogenicity.
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Affiliation(s)
- Haifeng Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Wei Tang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Kaiyue Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Qian Huang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Xin Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Xia Yan
- State Key Laboratory for Rice Biology, Biotechnology Institute, Zhejiang University, Huajiachi Campus, Hangzhou, China
| | - Yue Chen
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Jiansheng Wang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Zhongqiang Qi
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Zhengyi Wang
- State Key Laboratory for Rice Biology, Biotechnology Institute, Zhejiang University, Huajiachi Campus, Hangzhou, China
| | - Xiaobo Zheng
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Ping Wang
- Department of Pediatrics and the Research Institute for Children, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Zhengguang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- * E-mail:
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17
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Yan X, Li Y, Yue X, Wang C, Que Y, Kong D, Ma Z, Talbot NJ, Wang Z. Two novel transcriptional regulators are essential for infection-related morphogenesis and pathogenicity of the rice blast fungus Magnaporthe oryzae. PLoS Pathog 2011; 7:e1002385. [PMID: 22144889 PMCID: PMC3228794 DOI: 10.1371/journal.ppat.1002385] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2011] [Accepted: 10/02/2011] [Indexed: 11/24/2022] Open
Abstract
The cyclic AMP-dependent protein kinase A signaling pathway plays a major role in regulating plant infection by the rice blast fungus Magnaporthe oryzae. Here, we report the identification of two novel genes, MoSOM1 and MoCDTF1, which were discovered in an insertional mutagenesis screen for non-pathogenic mutants of M. oryzae. MoSOM1 or MoCDTF1 are both necessary for development of spores and appressoria by M. oryzae and play roles in cell wall differentiation, regulating melanin pigmentation and cell surface hydrophobicity during spore formation. MoSom1 strongly interacts with MoStu1 (Mstu1), an APSES transcription factor protein, and with MoCdtf1, while also interacting more weakly with the catalytic subunit of protein kinase A (CpkA) in yeast two hybrid assays. Furthermore, the expression levels of MoSOM1 and MoCDTF1 were significantly reduced in both Δmac1 and ΔcpkA mutants, consistent with regulation by the cAMP/PKA signaling pathway. MoSom1-GFP and MoCdtf1-GFP fusion proteins localized to the nucleus of fungal cells. Site-directed mutagenesis confirmed that nuclear localization signal sequences in MoSom1 and MoCdtf1 are essential for their sub-cellular localization and biological functions. Transcriptional profiling revealed major changes in gene expression associated with loss of MoSOM1 during infection-related development. We conclude that MoSom1 and MoCdtf1 functions downstream of the cAMP/PKA signaling pathway and are novel transcriptional regulators associated with cellular differentiation during plant infection by the rice blast fungus. Magnaporthe oryzae, the causal agent of rice blast disease, is an important model fungal pathogen for understanding the molecular basis of plant-fungus interactions. In M. oryzae, the conserved cAMP/PKA signaling pathway has been demonstrated to be crucial for regulating infection-related morphogenesis and pathogenicity, including the control of sporulation and appressorium formation. In this study, we report the identification of two novel pathogenicity-related genes, MoSOM1 and MoCDTF1, by T-DNA insertional mutagenesis. Our results show that MoSOM1 or MoCDTF1 are essential for sporulation, appressorium formatiom and pathogenicity, and also play a key role in hyphal growth, melanin pigmentation and cell surface hydrophobicity. Nuclear localization sequences and conserved domains of the MoSom1 and MoCdtf1 proteins are crucial for their biological function. MoSom1 interacts physically with the transcription factors MoCdtf1 and MoStu1. We also show evidence that MoSom1 has the capacity to interact with CpkA, suggesting that MoSom1 may act downstream of the cAMP/PKA signaling pathway to regulate infection-related morphogenesis and pathogenicity in M. oryzae. Our studies extend the current understanding of downstream components of the conserved cAMP/PKA pathway and its precise role in regulating infection-related development and cellular differentiation by M. oryzae.
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Affiliation(s)
- Xia Yan
- State Key Laboratory for Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, People's Republic of China
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18
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Che YZ, Li YR, Zou HS, Zou LF, Zhang B, Chen GY. A novel antimicrobial protein for plant protection consisting of a Xanthomonas oryzae harpin and active domains of cecropin A and melittin. Microb Biotechnol 2011; 4:777-93. [PMID: 21895994 PMCID: PMC3815413 DOI: 10.1111/j.1751-7915.2011.00281.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Discoveries about antimicrobial peptides and plant defence activators have made possible the de novo and rational design of novel peptides for use in crop protection. Here we report a novel chimeric protein, Hcm1, which was made by linking the active domains of cecropin A and melittin to the hypersensitive response (HR)‐elicitor Hpa1 of Xanthomonas oryzae pv. oryzicola, the causal agent of rice bacterial leaf streak. The resulting chimeric protein maintained not only the HR‐inducing property of the harpin, but also the antimicrobial activity of the cecropin A‐melittin hybrid. Hcm1 was purified from engineered Escherichia coli and evaluated in terms of the minimal inhibitory concentration (MIC) and the 50% effective dose (ED50) against important plant pathogenic bacteria and fungi. Importantly, the protein acted as a potential pesticide by inducing disease resistance for viral, bacterial and fungal pathogens. This designed drug can be considered as a lead compound for use in plant protection, either for the development of new broad‐spectrum pesticides or for expression in transgenic plants.
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Affiliation(s)
- Yi-Zhou Che
- Department of Plant Pathology, Nanjing Agricultural University/Key Laboratory of Monitoring and Management for Plant Diseases and Insects, Ministry of Agriculture of China, Nanjing 210095, China
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19
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Zhang H, Liu K, Zhang X, Tang W, Wang J, Guo M, Zhao Q, Zheng X, Wang P, Zhang Z. Two phosphodiesterase genes, PDEL and PDEH, regulate development and pathogenicity by modulating intracellular cyclic AMP levels in Magnaporthe oryzae. PLoS One 2011; 6:e17241. [PMID: 21386978 PMCID: PMC3046207 DOI: 10.1371/journal.pone.0017241] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Accepted: 01/22/2011] [Indexed: 01/02/2023] Open
Abstract
Cyclic AMP (cAMP) signaling plays an important role in regulating multiple cellular responses, such as growth, morphogenesis, and/or pathogenicity of eukaryotic organisms such as fungi. As a second messenger, cAMP is important in the activation of downstream effector molecules. The balance of intracellular cAMP levels depends on biosynthesis by adenylyl cyclases (ACs) and hydrolysis by cAMP phosphodiesterases (PDEases). The rice blast fungus Magnaporthe oryzae contains a high-affinity (PdeH/Pde2) and a low-affinity (PdeL/Pde1) PDEases, and a previous study showed that PdeH has a major role in asexual differentiation and pathogenicity. Here, we show that PdeL is required for asexual development and conidial morphology, and it also plays a minor role in regulating cAMP signaling. This is in contrast to PdeH whose mutation resulted in major defects in conidial morphology, cell wall integrity, and surface hydrophobicity, as well as a significant reduction in pathogenicity. Consistent with both PdeH and PdeL functioning in cAMP signaling, disruption of PDEH only partially rescued the mutant phenotype of ΔmagB and Δpka1. Further studies suggest that PdeH might function through a feedback mechanism to regulate the expression of pathogenicity factor Mpg1 during surface hydrophobicity and pathogenic development. Moreover, microarray data revealed new insights into the underlying cAMP regulatory mechanisms that may help to identify potential pathogenicity factors for the development of new disease management strategies.
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Affiliation(s)
- Haifeng Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Kaiyue Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Xing Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Wei Tang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Jiansheng Wang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Min Guo
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Qian Zhao
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Xiaobo Zheng
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Ping Wang
- Department of Pediatrics and the Research Institute for Children, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Zhengguang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
- * E-mail:
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20
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Zhou X, Liu W, Wang C, Xu Q, Wang Y, Ding S, Xu JR. A MADS-box transcription factor MoMcm1 is required for male fertility, microconidium production and virulence in Magnaporthe oryzae. Mol Microbiol 2011; 80:33-53. [PMID: 21276092 DOI: 10.1111/j.1365-2958.2011.07556.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Appressorium formation is a key step in the infection cycle of Magnaporthe oryzae. Mst12 is a transcription factor essential for appressorium penetration and invasive growth. In this study we used the affinity purification approach to identify proteins that physically associate with Mst12. One of the Mst12-interacting genes identified was MoMCM1, which encodes a MADS-box protein orthologous to yeast Mcm1. MoMcm1 interacted with both Mst12 and Mata-1 in yeast two-hybrid assays. Deletion of MoMCM1 resulted in the loss of male fertility and microconidium production. The Momcm1 mutant was defective in appressorium penetration and formed narrower invasive hyphae, which may be responsible for its reduced virulence. In transformants expressing MoMCM1-eGFP fusion, GFP signals were observed in the nucleus. We also generated the Momcm1 mst12 double mutant, which was defective in penetration and non-pathogenic. On hydrophilic surfaces, germ tubes produced by the double mutant were severely curved, and 20% of them formed appressoria. In contrast, the Momcm1 or mst12 mutant did not form appressoria on hydrophilic surfaces. These results suggest that MoMCM1 and MST12 have overlapping functions to suppress appressorium formation under non-conducive conditions. MoMcm1 may interact with Mst12 and MatA-1 to regulate germ tube identity and male fertility respectively.
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Affiliation(s)
- Xiaoying Zhou
- Purdue-NWAFU Joint Research Center, Department Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA
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21
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Pérez-Sánchez L, González E, Colón-Lorenzo EE, González-Velázquez W, González-Méndez R, Rodríguez-del Valle N. Interaction of the heterotrimeric G protein alpha subunit SSG-1 of Sporothrix schenckii with proteins related to stress response and fungal pathogenicity using a yeast two-hybrid assay. BMC Microbiol 2010; 10:317. [PMID: 21143936 PMCID: PMC3018405 DOI: 10.1186/1471-2180-10-317] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 12/09/2010] [Indexed: 11/15/2022] Open
Abstract
Background Important biological processes require selective and orderly protein-protein interactions at every level of the signalling cascades. G proteins are a family of heterotrimeric GTPases that effect eukaryotic signal transduction through the coupling of cell surface receptors to cytoplasmic effector proteins. They have been associated with growth and pathogenicity in many fungi through gene knock-out studies. In Sporothrix schenckii, a pathogenic, dimorphic fungus, we previously identified a pertussis sensitive G alpha subunit, SSG-1. In this work we inquire into its interactions with other proteins. Results Using the yeast two-hybrid technique, we identified protein-protein interactions between SSG-1 and other important cellular proteins. The interactions were corroborated using co-immuneprecipitation. Using these techniques we identified a Fe/Mn superoxide dismutase (SOD), a glyceraldehyde-3-P dehydrogenase (GAPDH) and two ion transport proteins, a siderophore-iron transporter belonging to the Major Facilitator Superfamily (MFS) and a divalent-cation transporter of the Nramp (natural resistance-associated macrophage protein) family as interacting with SSG-1. The cDNA's encoding these proteins were sequenced and bioinformatic macromolecular sequence analyses were used for the correct classification and functional assignment. Conclusions This study constitutes the first report of the interaction of a fungal G alpha inhibitory subunit with SOD, GAPDH, and two metal ion transporters. The identification of such important proteins as partners of a G alpha subunit in this fungus suggests possible mechanisms through which this G protein can affect pathogenicity and survival under conditions of environmental stress or inside the human host. The two ion transporters identified in this work are the first to be reported in S. schenckii and the first time they are identified as interacting with fungal G protein alpha subunits. The association of G protein alpha subunits to transport molecules reinforces the role of G proteins in the response to environmental signals and also highlights the involvement of fungal G protein alpha subunits in nutrient sensing in S. schenckii. These interactions suggest that these permeases could function as transceptors for G proteins in fungi.
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Affiliation(s)
- Lizaida Pérez-Sánchez
- Department of Microbiology and Medical Zoology, Medical Sciences Campus, University of Puerto Rico, PO Box 365067, San Juan, PR 00936-5067, USA
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Guo M, Guo W, Chen Y, Dong S, Zhang X, Zhang H, Song W, Wang W, Wang Q, Lv R, Zhang Z, Wang Y, Zheng X. The basic leucine zipper transcription factor Moatf1 mediates oxidative stress responses and is necessary for full virulence of the rice blast fungus Magnaporthe oryzae. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1053-1068. [PMID: 20615116 DOI: 10.1094/mpmi-23-8-1053] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Magnaporthe oryzae is the causal agent of rice blast disease, leading to enormous losses of rice production. Here, we characterized a basic leucine zipper (bZIP) transcription factor, Moatf1, in M. oryzae, a homolog of Schizosaccharomyces pombe ATF/CREB that regulates the oxidative stress response. Moatf1 deletion caused retarded vegetative growth of mycelia, and the Moatf1 mutant exhibited higher sensitivity to hydrogen peroxide (H(2)O(2)) than did the wild-type strain. The mutant showed severely reduced activity of extracellular enzymes and transcription level of laccases and peroxidases and exhibited significantly reduced virulence on rice cultivar CO-39. On rice leaf sheath, most of the infectious hyphae of the mutant became swollen and displayed restricted growth in primary infected cells. Defense response was strongly activated in plants infected by the mutant. Diamino benzidine staining revealed an accumulation of H(2)O(2) around Moatf1 mutant appressoria and rice cells with Moatf1 hyphae that was absent in the wild type. Inhibition of the plant NADPH oxidase by diphenyleneiodonium prevented host-derived H(2)O(2) accumulation and restored infectious hyphal growth of the mutant in rice cells. Thus, we conclude that Moatf1 is necessary for full virulence of M. oryzae by regulating the transcription of laccases and peroxidases to impair reactive oxygen species-mediated plant defense.
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Affiliation(s)
- Min Guo
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China
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Ding SL, Liu W, Iliuk A, Ribot C, Vallet J, Tao A, Wang Y, Lebrun MH, Xu JR. The tig1 histone deacetylase complex regulates infectious growth in the rice blast fungus Magnaporthe oryzae. THE PLANT CELL 2010; 22:2495-508. [PMID: 20675574 PMCID: PMC2929099 DOI: 10.1105/tpc.110.074302] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Magnaporthe oryzae is the most damaging fungal pathogen of rice (Oryza sativa). In this study, we characterized the TIG1 transducin beta-like gene required for infectious growth and its interacting genes that are required for plant infection in this model phytopathogenic fungus. Tig1 homologs in yeast and mammalian cells are part of a conserved histone deacetylase (HDAC) transcriptional corepressor complex. The tig1 deletion mutant was nonpathogenic and defective in conidiogenesis. It had an increased sensitivity to oxidative stress and failed to develop invasive hyphae in plant cells. Using affinity purification and coimmunoprecipitation assays, we identified several Tig1-associated proteins, including two HDACs that are homologous to components of the yeast Set3 complex. Functional analyses revealed that TIG1, SET3, SNT1, and HOS2 were core components of the Tig1 complex in M. oryzae. The set3, snt1, and hos2 deletion mutants displayed similar defects as those observed in the tig1 mutant, but deletion of HST1 or HOS4 had no detectable phenotypes. Deletion of any of these core components of the Tig1 complex resulted in a significant reduction in HDAC activities. Our results showed that TIG1, like its putative yeast and mammalian orthologs, is one component of a conserved HDAC complex that is required for infectious growth and conidiogenesis in M. oryzae and highlighted that chromatin modification is an essential regulatory mechanism during plant infection.
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Affiliation(s)
- Sheng-Li Ding
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
| | - Wende Liu
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
| | - Anton Iliuk
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
| | - Cecile Ribot
- Université Lyon-1, Centre National de la Recherche Scientifique, Bayer CropScience, 69263 Lyon Cedex 09, France
| | - Julie Vallet
- Université Lyon-1, Centre National de la Recherche Scientifique, Bayer CropScience, 69263 Lyon Cedex 09, France
| | - Andy Tao
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
| | - Yang Wang
- College of Plant Protection and Shaanxi Key Laboratory of Molecular Biology for Agriculture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Marc-Henri Lebrun
- Université Lyon-1, Centre National de la Recherche Scientifique, Bayer CropScience, 69263 Lyon Cedex 09, France
- Institut National de la Recherche Agronomique, 78850 Thiverval-Grignon, France
| | - Jin-Rong Xu
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
- College of Plant Protection and Shaanxi Key Laboratory of Molecular Biology for Agriculture, Northwest A&F University, Yangling, Shaanxi 712100, China
- Address correspondence to
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Liu W, Xie S, Zhao X, Chen X, Zheng W, Lu G, Xu JR, Wang Z. A homeobox gene is essential for conidiogenesis of the rice blast fungus Magnaporthe oryzae. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:366-75. [PMID: 20192824 DOI: 10.1094/mpmi-23-4-0366] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Magnaporthe oryzae starts its infection by the attachment of pyriform conidia on rice tissues, and severity of the disease epidemic is proportional to the quantity of conidia produced in the rice blast lesions. However, the mechanism of conidial production is not well understood. Homeodomain proteins play critical roles in regulating various growth and developmental processes in fungi and other eukaryotes. Through targeted gene replacement, we find that deletion of HTF1, one of seven homeobox genes in the fungal genome, does not affect mycelial growth but causes total defect of conidial production. Further observation revealed that the Deltahtf1 mutant produces significantly more conidiophores, which curve slightly near the tip but could not develop sterigmata-like structures. Although the Deltahtf1 mutant fails to form conidia, it could still develop melanized appressoria from hyphal tips and infect plants. The expression level of HTF1 is significantly reduced in the Deltamgb1 G-beta and DeltacpkA deletion mutant, and the ACR1 but not CON7 gene that encodes transcription factor required for normal conidiogenesis is significantly downregulated in the Deltahtf1 mutant. These data suggest that the HTF1 gene is essential for conidiogenesis, and may be functionally related to the trimeric G-protein signaling and other transcriptional regulators that are known to be important for conidiation in M. oryzae.
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Affiliation(s)
- Wende Liu
- Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
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Li Y, Yan X, Wang H, Liang S, Ma WB, Fang MY, Talbot NJ, Wang ZY. MoRic8 Is a novel component of G-protein signaling during plant infection by the rice blast fungus Magnaporthe oryzae. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:317-331. [PMID: 20121453 DOI: 10.1094/mpmi-23-3-0317] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
An insertional mutagenesis screen was used to investigate the biology of plant infection by the devastating rice blast pathogen, Magnaporthe oryzae. Here, we report the identification of a new mutant, LY-130, which is defective in multiple steps during infection-related morphogenesis and pathogenicity. Analysis of the mutation confirmed an insertion into gene MoRIC8, which encodes a 480-amino-acid protein that is a putative homologue of the Ric8 regulator of GTP-binding protein (G-protein) signaling, previously described in animals. Targeted gene deletion mutants of MoRIC8 were nonpathogenic and impaired in cellular differentiation associated with sporulation, sexual development, and plant infection. MoRic8 physically interacts with the Galpha subunit MagB in yeast two-hybrid assays and appears to act upstream of the cyclic AMP response pathway that is necessary for appressorium morphogenesis. Taken together, our results indicate that MoRic8 may act as a novel regulator of the G-protein signaling during infection-related development of rice blast fungus M. oryzae.
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Affiliation(s)
- Ya Li
- State Key Laboratory For Rice Biology, Biotechnology Institute, Zhejian University, Huajiachi Campus, Hangzhou, China
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Casey T, Solomon PS, Bringans S, Tan KC, Oliver RP, Lipscombe R. Quantitative proteomic analysis of G-protein signalling inStagonospora nodorumusing isobaric tags for relative and absolute quantification. Proteomics 2010; 10:38-47. [DOI: 10.1002/pmic.200900474] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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García-Rico RO, Fierro F, Martín JF. Heterotrimeric Galpha protein Pga1 of Penicillium chrysogenum controls conidiation mainly by a cAMP-independent mechanism. Biochem Cell Biol 2009; 86:57-69. [PMID: 18364746 DOI: 10.1139/o07-148] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Fungal heterotrimeric G proteins regulate different processes related to development, such as colony growth and asexual sporulation, the main mechanism of propagation in filamentous fungi. To gain insight into the mechanisms controlling growth and differentiation in the industrial penicillin producer Penicillioum chrysogenum, we investigated the role of the heterotrimeric Galpha subunit Pga1 in conidiogenesis. A pga1 deleted strain (Deltapga1) and transformants with constitutively activated (pga1G42R) and inactivated (pga1G203R) Pga1 alpha subunits were obtained. They showed phenotypes that clearly implicate Pga1 as an important negative regulator of conidiogenesis. Pga1 positively affected the level of intracellular cAMP, which acts as secondary messenger of Pga1-mediated signalling. Although cAMP has some inhibitory effect on conidiation, the regulation of asexual development by Pga1 is exerted mainly via cAMP-independent pathways. The regulation of conidiation by Pga1 is mediated by repression of the brlA and wetA genes. The Deltapga1 strain and transformants with the constitutively inactive Pga1G203R subunit developed a sporulation microcycle in submerged cultures triggered by the expression of brlA and wetA genes, which are deregulated in the absence of active Pga1. Our results indicate that although basic mechanisms for regulating conidiation are similar in most filamentous fungi, there are differences in the degree of involvement of specific pathways, such as the cAMP-mediated pathway, in the regulation of this process.
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Affiliation(s)
- Ramón Ovidio García-Rico
- Instituto de Biotecnologia de Leon, INBIOTEC, Parque Cientifico de Leon, Avenida Real 1, Leon, Spain
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Seibel C, Gremel G, do Nascimento Silva R, Schuster A, Kubicek CP, Schmoll M. Light-dependent roles of the G-protein alpha subunit GNA1 of Hypocrea jecorina (anamorph Trichoderma reesei). BMC Biol 2009; 7:58. [PMID: 19728862 PMCID: PMC2749820 DOI: 10.1186/1741-7007-7-58] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 09/03/2009] [Indexed: 02/02/2023] Open
Abstract
Background The filamentous ascomycete Hypocrea jecorina (anamorph Trichoderma reesei) is primarily known for its efficient enzymatic machinery that it utilizes to decompose cellulosic substrates. Nevertheless, the nature and transmission of the signals initiating and modulating this machinery are largely unknown. Heterotrimeric G-protein signaling represents one of the best studied signal transduction pathways in fungi. Results Analysis of the regulatory targets of the G-protein α subunit GNA1 in H. jecorina revealed a carbon source and light-dependent role in signal transduction. Deletion of gna1 led to significantly decreased biomass formation in darkness in submersed culture but had only minor effects on morphology and hyphal apical extension rates on solid medium. Cellulase gene transcription was abolished in Δgna1 on cellulose in light and enhanced in darkness. However, analysis of strains expressing a constitutively activated GNA1 revealed that GNA1 does not transmit the essential inducing signal. Instead, it relates a modulating signal with light-dependent significance, since induction still required the presence of an inducer. We show that regulation of transcription and activity of GNA1 involves a carbon source-dependent feedback cycle. Additionally we found a function of GNA1 in hydrophobin regulation as well as effects on conidiation and tolerance of osmotic and oxidative stress. Conclusion We conclude that GNA1 transmits a signal the physiological relevance of which is dependent on both the carbon source as well as the light status. The widespread consequences of mutations in GNA1 indicate a broad function of this Gα subunit in appropriation of intracellular resources to environmental (especially nutritional) conditions.
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Affiliation(s)
- Christian Seibel
- Research Area Gene Technology and Applied Biochemistry, Institute of Chemical Engineering, Vienna University of Technology, Wien, Austria.
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Fujikawa T, Kuga Y, Yano S, Yoshimi A, Tachiki T, Abe K, Nishimura M. Dynamics of cell wall components of Magnaporthe grisea during infectious structure development. Mol Microbiol 2009; 73:553-70. [PMID: 19602150 DOI: 10.1111/j.1365-2958.2009.06786.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Oligosaccharides derived from cell wall of fungal pathogens induce host primary immune responses. To understand fungal strategies circumventing the host plant immune responses, cell wall polysaccharide localization was investigated using fluorescent labels during infectious structure differentiation in the rice blast fungus Magnaporthe grisea. alpha-1,3-glucan was labelled only on appressoria developing on plastic surfaces, whereas it was detected on both germ tubes and appressoria on plant surfaces. Chitin, chitosan and beta-1,3-glucan were detected on germ tubes and appressoria regardless of the substrate. Major polysaccharides labelled at accessible surface of infectious hyphae were alpha-1,3-glucan and chitosan, but after enzymatic digestion of alpha-1,3-glucan, beta-1,3-glucan and chitin became detectable. Immunoelectron microscopic analysis showed alpha-1,3-glucan and beta-1,3-glucan intermixed in the cell wall of infectious hyphae; however, alpha-1,3-glucan tended to be distributed farther from the fungal cell membrane. The fungal cell wall became more tolerant to chitinase digestion upon accumulation of alpha-1,3-glucan. Accumulation of alpha-1,3-glucan was dependent on the Mps1 MAP kinase pathway, which was activated by a plant wax derivative, 1,16-hexadecanediol. Taken together, alpha-1,3-glucan spatially and functionally masks beta-1,3-glucan and chitin in the cell wall of infectious hyphae. Thus, a dynamic change of composition of cell wall polysaccharides occurs during plant infection in M. grisea.
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Affiliation(s)
- Takashi Fujikawa
- National Institute of Agrobiological Sciences, Tsukuba 305-8602, Japan
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Cytosolic phospholipase A2: a member of the signalling pathway of a new G protein alpha subunit in Sporothrix schenckii. BMC Microbiol 2009; 9:100. [PMID: 19454031 PMCID: PMC2694196 DOI: 10.1186/1471-2180-9-100] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 05/19/2009] [Indexed: 11/25/2022] Open
Abstract
Background Sporothrix schenckii is a pathogenic dimorphic fungus, the etiological agent of sporotrichosis, a lymphocutaneous disease that can remain localized or can disseminate, involving joints, lungs, and the central nervous system. Pathogenic fungi use signal transduction pathways to rapidly adapt to changing environmental conditions and S. schenckii is no exception. S. schenckii yeast cells, either proliferate (yeast cell cycle) or engage in a developmental program that includes proliferation accompanied by morphogenesis (yeast to mycelium transition) depending on the environmental conditions. The principal intracellular receptors of environmental signals are the heterotrimeric G proteins, suggesting their involvement in fungal dimorphism and pathogenicity. Identifying these G proteins in fungi and their involvement in protein-protein interactions will help determine their role in signal transduction pathways. Results In this work we describe a new G protein α subunit gene in S. schenckii, ssg-2. The cDNA sequence of ssg-2 revealed a predicted open reading frame of 1,065 nucleotides encoding a 355 amino acids protein with a molecular weight of 40.9 kDa. When used as bait in a yeast two-hybrid assay, a cytoplasmic phospholipase A2 catalytic subunit was identified as interacting with SSG-2. The sspla2 gene, revealed an open reading frame of 2538 bp and encoded an 846 amino acid protein with a calculated molecular weight of 92.62 kDa. The principal features that characterize cPLA2 were identified in this enzyme such as a phospholipase catalytic domain and the characteristic invariable arginine and serine residues. A role for SSPLA2 in the control of dimorphism in S. schenckii is suggested by observing the effects of inhibitors of the enzyme on the yeast cell cycle and the yeast to mycelium transition in this fungus. Phospholipase A2 inhibitors such as AACOCF3 (an analogue of archidonic acid) and isotetrandrine (an inhibitor of G protein PLA2 interactions) were found to inhibit budding by yeasts induced to re-enter the yeast cell cycle and to stimulate the yeast to mycelium transition showing that this enzyme is necessary for the yeast cell cycle. Conclusion A new G protein α subunit gene was characterized in S. schenckii and protein-protein interactions studies revealed this G protein alpha subunit interacts with a cPLA2 homologue. The PLA2 homologue reported here is the first phospholipase identified in S. schenckii and the first time a PLA2 homologue is identified as interacting with a G protein α subunit in a pathogenic dimorphic fungus, establishing a relationship between these G proteins and the pathogenic potential of fungi. This cPLA2 homologue is known to play a role in signal transduction and fungal pathogenesis. Using cPLA2 inhibitors, this enzyme was found to affect dimorphism in S. schenckii and was found to be necessary for the development of the yeast or pathogenic form of the fungus.
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Molecular mechanisms of mechanosensing and their roles in fungal contact sensing. Nat Rev Microbiol 2009; 6:667-73. [PMID: 18679170 DOI: 10.1038/nrmicro1960] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Numerous fungal species respond to contact with a surface by undergoing differentiation. Contact between plant pathogenic fungi and a surface results in the elaboration of the complex structures that enable invasion of the host plant, and for the opportunistic human pathogen Candida albicans, contact with a semi-solid surface results in invasive growth into the subjacent material. The ability to sense contact with an appropriate surface therefore contributes to the ability of these fungi to cause disease in their respective hosts. This Review discusses molecular mechanisms of mechanosensitivity, the proteins involved, such as mechanosensitive ion channels, G-protein-coupled receptors and integrins, and their putative roles in fungal contact sensing.
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Wilson RA, Talbot NJ. Under pressure: investigating the biology of plant infection by Magnaporthe oryzae. Nat Rev Microbiol 2009; 7:185-95. [PMID: 19219052 DOI: 10.1038/nrmicro2032] [Citation(s) in RCA: 606] [Impact Index Per Article: 40.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The filamentous fungus Magnaporthe oryzae causes rice blast, the most serious disease of cultivated rice. Cellular differentiation of M. oryzae forms an infection structure called the appressorium, which generates enormous cellular turgor that is sufficient to rupture the plant cuticle. Here, we show how functional genomics approaches are providing new insight into the genetic control of plant infection by M. oryzae. We also look ahead to the key questions that need to be addressed to provide a better understanding of the molecular processes that lead to plant disease and the prospects for sustainable control of rice blast.
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Affiliation(s)
- Richard A Wilson
- School of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, United Kingdom
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Tan KC, Heazlewood JL, Millar AH, Thomson G, Oliver RP, Solomon PS. A signaling-regulated, short-chain dehydrogenase of Stagonospora nodorum regulates asexual development. EUKARYOTIC CELL 2008; 7:1916-29. [PMID: 18776038 PMCID: PMC2583533 DOI: 10.1128/ec.00237-08] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Accepted: 08/22/2008] [Indexed: 11/20/2022]
Abstract
The fungus Stagonospora nodorum is a causal agent of leaf and glume blotch disease of wheat. It has been previously shown that inactivation of heterotrimeric G protein signaling in Stagonospora nodorum caused development defects and reduced pathogenicity [P. S. Solomon et al., Mol. Plant-Microbe Interact. 17:456-466, 2004]. In this study, we sought to identify targets of the signaling pathway that may have contributed to phenotypic defects of the signaling mutants. A comparative analysis of Stagonospora nodorum wild-type and Galpha-defective mutant (gna1) intracellular proteomes was performed via two-dimensional polyacrylamide gel electrophoresis. Several proteins showed significantly altered abundances when comparing the two strains. One such protein, the short-chain dehydrogenase Sch1, was 18-fold less abundant in the gna1 strain, implying that it is positively regulated by Galpha signaling. Gene expression and transcriptional enhanced green fluorescent protein fusion analyses of Sch1 indicates strong expression during asexual development. Mutant strains of Stagonospora nodorum lacking Sch1 demonstrated poor growth on minimal media and exhibited a significant reduction in asexual sporulation on all growth media examined. Detailed histological experiments on sch1 pycnidia revealed that the gene is required for the differentiation of the subparietal layers of asexual pycnidia resulting in a significant reduction in both pycnidiospore size and numbers.
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Affiliation(s)
- Kar-Chun Tan
- Australian Centre for Necrotrophic Fungal Pathogens, Murdoch University, South Street, Murdoch 6150, Australia
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Oh Y, Donofrio N, Pan H, Coughlan S, Brown DE, Meng S, Mitchell T, Dean RA. Transcriptome analysis reveals new insight into appressorium formation and function in the rice blast fungus Magnaporthe oryzae. Genome Biol 2008; 9:R85. [PMID: 18492280 PMCID: PMC2441471 DOI: 10.1186/gb-2008-9-5-r85] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 03/18/2008] [Accepted: 05/20/2008] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Rice blast disease is caused by the filamentous Ascomycetous fungus Magnaporthe oryzae and results in significant annual rice yield losses worldwide. Infection by this and many other fungal plant pathogens requires the development of a specialized infection cell called an appressorium. The molecular processes regulating appressorium formation are incompletely understood. RESULTS We analyzed genome-wide gene expression changes during spore germination and appressorium formation on a hydrophobic surface compared to induction by cAMP. During spore germination, 2,154 (approximately 21%) genes showed differential expression, with the majority being up-regulated. During appressorium formation, 357 genes were differentially expressed in response to both stimuli. These genes, which we refer to as appressorium consensus genes, were functionally grouped into Gene Ontology categories. Overall, we found a significant decrease in expression of genes involved in protein synthesis. Conversely, expression of genes associated with protein and amino acid degradation, lipid metabolism, secondary metabolism and cellular transportation exhibited a dramatic increase. We functionally characterized several differentially regulated genes, including a subtilisin protease (SPM1) and a NAD specific glutamate dehydrogenase (Mgd1), by targeted gene disruption. These studies revealed hitherto unknown findings that protein degradation and amino acid metabolism are essential for appressorium formation and subsequent infection. CONCLUSION We present the first comprehensive genome-wide transcript profile study and functional analysis of infection structure formation by a fungal plant pathogen. Our data provide novel insight into the underlying molecular mechanisms that will directly benefit efforts to identify fungal pathogenicity factors and aid the development of new disease management strategies.
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Affiliation(s)
- Yeonyee Oh
- North Carolina State University, Center for Integrated Fungal Research, Raleigh, NC 27695-7251, USA
| | - Nicole Donofrio
- North Carolina State University, Center for Integrated Fungal Research, Raleigh, NC 27695-7251, USA
- Current address: University of Delaware, Department of Plant and Soil Science, Newark, DE 19716, USA
| | - Huaqin Pan
- North Carolina State University, Center for Integrated Fungal Research, Raleigh, NC 27695-7251, USA
- Current address: RTI international, Research Triangle Park, NC 27709-2194, USA
| | - Sean Coughlan
- Agilent Technologies, Little Falls, DE 19808-1644, USA
| | - Douglas E Brown
- North Carolina State University, Center for Integrated Fungal Research, Raleigh, NC 27695-7251, USA
| | - Shaowu Meng
- North Carolina State University, Center for Integrated Fungal Research, Raleigh, NC 27695-7251, USA
| | - Thomas Mitchell
- North Carolina State University, Center for Integrated Fungal Research, Raleigh, NC 27695-7251, USA
- Current address: Ohio State University, Department of Plant Pathology, Columbus, OH 43210, USA
| | - Ralph A Dean
- North Carolina State University, Center for Integrated Fungal Research, Raleigh, NC 27695-7251, USA
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Münch S, Lingner U, Floss DS, Ludwig N, Sauer N, Deising HB. The hemibiotrophic lifestyle of Colletotrichum species. JOURNAL OF PLANT PHYSIOLOGY 2008; 165:41-51. [PMID: 17765357 DOI: 10.1016/j.jplph.2007.06.008] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Revised: 05/30/2007] [Accepted: 06/03/2007] [Indexed: 05/08/2023]
Abstract
Colletotrichum species infect several economically important crop plants. To establish a compatible parasitic interaction, a specialized infection cell, the melanized appressorium, is differentiated on the cuticle of the host. After penetration, an infection vesicle and primary hyphae are formed. These structures do not kill the host cell and show some similarities with haustoria formed by powdery mildews and rust fungi. Therefore, this stage of infection is called biotrophic. Later in the infection process, necrotrophic secondary hyphae spread within and kill the host tissue. The lifestyle of Colletotrichum species is called hemibiotrophic, as biotrophic and necrotrophic developmental stages are sequentially established. As most Colletotrichum species are accessible to molecular techniques, genes can be identified and functionally characterized. Here we demonstrate that Agrobacterium tumefaciens-mediated transformation is a well-suited method for tagging of genes mediating compatibility in the Colletotrichum graminicola-maize interaction.
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Affiliation(s)
- Steffen Münch
- Martin-Luther-University Halle-Wittenberg, Phytopathology and Plant Protection, Ludwig-Wucherer-Str. 2, 06108 Halle (Saale), Germany
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Charoensopharat K, Aukkanit N, Thanonkeo S, Saksirirat W, Thanonkeo P, Akiyama K. Targeted disruption of a G protein α subunit gene results in reduced growth and pathogenicity in Rhizoctonia solani. World J Microbiol Biotechnol 2007. [DOI: 10.1007/s11274-007-9476-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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García-Rico RO, Martín JF, Fierro F. The pga1 gene of Penicillium chrysogenum NRRL 1951 encodes a heterotrimeric G protein alpha subunit that controls growth and development. Res Microbiol 2007; 158:437-46. [PMID: 17467244 DOI: 10.1016/j.resmic.2007.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Revised: 03/08/2007] [Accepted: 03/08/2007] [Indexed: 10/23/2022]
Abstract
The pga1 gene of Penicillium chrysogenum NRRL 1951 has been cloned and shown to participate in the developmental program of this fungus. It encodes a protein showing a high degree of identity to group I alpha subunits of fungal heterotrimeric G proteins, presenting in its sequence all the distinctive characteristics of this group. Northern analysis revealed that pga1 is highly expressed in a constitutive manner in submerged cultures, while its expression changes during development on solid media cultures; it is higher during vegetative growth and decreases significantly at the time of conidiogenesis. Attenuation of pga1 gene expression by antisense RNA, and mutations of pga1 resulting in a constitutively activated (pga1G42R allele) or constitutively inactivated (pga1G203R allele) Pga1 alpha subunit were used to study the function of Pga1 in P. chrysogenum. The phenotype of transformants expressing the antisense construction and the mutant alleles showed substantial morphological differences in colony diameter and conidiation, indicating that Pga1 controls apical extension and negatively regulates conidiogenesis on solid medium, but has no effect on submerged cultures. Pga1 is also functional in Penicillium roqueforti, controlling the same processes.
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Affiliation(s)
- Ramón O García-Rico
- Area de Microbiología, Fac. CC. Biológicas y Ambientales, Dpto. De Biologia Molecular, Universidad de León, Campus de Vegazana, s/n, 24071 León, Spain
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Liu H, Suresh A, Willard FS, Siderovski DP, Lu S, Naqvi NI. Rgs1 regulates multiple Galpha subunits in Magnaporthe pathogenesis, asexual growth and thigmotropism. EMBO J 2007; 26:690-700. [PMID: 17255942 PMCID: PMC1794393 DOI: 10.1038/sj.emboj.7601536] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Accepted: 12/11/2006] [Indexed: 11/09/2022] Open
Abstract
Regulators of G-protein signaling (RGS proteins) negatively regulate heterotrimeric G-protein cascades that enable eukaryotic cells to perceive and respond to external stimuli. The rice-blast fungus Magnaporthe grisea forms specialized infection structures called appressoria in response to inductive surface cues. We isolated Magnaporthe RGS1 in a screen for mutants that form precocious appressoria on non-inductive surfaces. We report that a thigmotropic cue is necessary for initiating appressoria and for accumulating cAMP. Similar to an RGS1-deletion strain, magA(G187S) (RGS-insensitive Galpha(s)) and magA(Q208L) (GTPase-dead) mutants accumulated excessive cAMP and elaborated appressoria on non-inductive surfaces, suggesting that Rgs1 regulates MagA during pathogenesis. Rgs1 was also found to negatively regulate the Galpha(i) subunit MagB during asexual development. Deficiency of MAGB suppressed the hyper-conidiation defect in RGS1-deletion strain, whereas magB(G183S) and magB(Q204L) mutants produced more conidia, similar to the RGS1-deletion strain. Rgs1 physically interacted with GDP.AlF(4)(-)-activated forms of MagA, MagB and MagC (a Galpha(II) subunit). Thus, Rgs1 serves as a negative regulator of all Galpha subunits in Magnaporthe and controls important developmental events during asexual and pathogenic development.
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Affiliation(s)
- Hao Liu
- Fungal Patho-Biology Group, Temasek Life Sciences Laboratory, National University of Singapore, Singapore
| | - Angayarkanni Suresh
- Fungal Patho-Biology Group, Temasek Life Sciences Laboratory, National University of Singapore, Singapore
| | - Francis S Willard
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA
| | - David P Siderovski
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA
| | - Shen Lu
- Institute of Materials Research and Engineering, Singapore
| | - Naweed I Naqvi
- Fungal Patho-Biology Group, Temasek Life Sciences Laboratory, National University of Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore
- Fungal Patho-Biology Group, Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604, Singapore. Tel.: +65 6872 7493; Fax: +65 6872 7007; E-mail:
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Xu JR, Zhao X, Dean RA. From genes to genomes: a new paradigm for studying fungal pathogenesis in Magnaporthe oryzae. ADVANCES IN GENETICS 2007; 57:175-218. [PMID: 17352905 DOI: 10.1016/s0065-2660(06)57005-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Magnaporthe oryzae is the most destructive fungal pathogen of rice worldwide and because of its amenability to classical and molecular genetic manipulation, availability of a genome sequence, and other resources it has emerged as a leading model system to study host-pathogen interactions. This chapter reviews recent progress toward elucidation of the molecular basis of infection-related morphogenesis, host penetration, invasive growth, and host-pathogen interactions. Related information on genome analysis and genomic studies of plant infection processes is summarized under specific topics where appropriate. Particular emphasis is placed on the role of MAP kinase and cAMP signal transduction pathways and unique features in the genome such as repetitive sequences and expanded gene families. Emerging developments in functional genome analysis through large-scale insertional mutagenesis and gene expression profiling are detailed. The chapter concludes with new prospects in the area of systems biology, such as protein expression profiling, and highlighting remaining crucial information needed to fully appreciate host-pathogen interactions.
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Affiliation(s)
- Jin-Rong Xu
- Department of Botany and Plant Pathology, Purdue University West Lafayette, Indiana 47907, USA
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Segers GC, Regier JC, Nuss DL. Evidence for a role of the regulator of G-protein signaling protein CPRGS-1 in Galpha subunit CPG-1-mediated regulation of fungal virulence, conidiation, and hydrophobin synthesis in the chestnut blight fungus Cryphonectria parasitica. EUKARYOTIC CELL 2005; 3:1454-63. [PMID: 15590820 PMCID: PMC539028 DOI: 10.1128/ec.3.6.1454-1463.2004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We previously reported that the chestnut blight fungus Cryphonectria parasitica expresses at least three G-protein alpha subunits and that Galpha subunit CPG-1 is essential for regulated growth, pigmentation, sporulation, and virulence. We now report the cloning and characterization of a C. parasitica regulator of G-protein signaling (RGS) protein, CPRGS-1. The phylogenetic relationship of CPRGS-1 to orthologs from other fungi was inferred and found to be generally concordant with species relationships based on 18S ribosomal sequences and on morphology. However, Hemiascomycotine RGS branch lengths in particular were longer than for their 18S sequence counterparts, which correlates with functional diversification in the signaling pathway. Deletion of cprgs-1 resulted in reduced growth, sparse aerial mycelium, and loss of pigmentation, sporulation, and virulence. Disruption of cprgs-1 was also accompanied by a severe posttranscriptional reduction in accumulation of CPG-1 and Gbeta subunit CPGB-1 and severely reduced expression of the hydrophobin-encoding gene cryparin. The changes in phenotype, cryparin expression, and CPGB-1 accumulation resulting from cprgs-1 gene deletion were also observed in a strain containing a mutationally activated copy of CPG-1 but not in strains containing constitutively activated mutant alleles of the other two identified Galpha subunits, CPG-2 and CPG-3. Furthermore, cprgs-1 transcript levels were increased in the activated CPG-1 strain but were unaltered in activated CPG-2 and CPG-3 strains. The results strongly suggest that CPRGS-1 is involved in regulation of Galpha subunit CPG-1-mediated signaling and establish a role for a RGS protein in the modulation of virulence, conidiation, and hydrophobin synthesis in a plant pathogenic fungus.
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Affiliation(s)
- Gerrit C. Segers
- Center for Biosystems Research, University of Maryland Biotechnology Institute, College Park, Maryland
| | - Jerome C. Regier
- Center for Biosystems Research, University of Maryland Biotechnology Institute, College Park, Maryland
| | - Donald. L. Nuss
- Center for Biosystems Research, University of Maryland Biotechnology Institute, College Park, Maryland
- Corresponding author. Mailing address: Center for Biosystems Research, University of Maryland Biotechnology Institute, 5115 Plant Sciences Bldg., College Park, MD 20742. Phone: (301) 405-0334. Fax: (301) 314-9075. E-mail:
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41
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Jain S, Akiyama K, Takata R, Ohguchi T. Signaling via the G protein alpha subunit FGA2 is necessary for pathogenesis in Fusarium oxysporum. FEMS Microbiol Lett 2005; 243:165-72. [PMID: 15668015 DOI: 10.1016/j.femsle.2004.12.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2004] [Revised: 11/15/2004] [Accepted: 12/01/2004] [Indexed: 10/26/2022] Open
Abstract
Cloning and disruption of fga1, the gene encoding the G protein alpha subunit FGA1 in phytopathogenic fungus Fusarium oxysporum, has been reported previously, and the fga1 disruptants showed altered colony morphology, increased heat resistance, reduced conidiation and pathogenicity. To further evaluate the role of G protein signaling in this fungus, cloning of fga2, which encodes the second Galpha protein FGA2, was performed by PCR methods. The deduced primary structure of FGA2 (355 amino acid residues) showed high identity with other Galpha proteins, which belong to class III of fungal Galpha proteins. Disruption of fga2 led to higher heat resistance, similar to the fga1 disruptants, but pathogenicity was completely lost, unlike the fga1 disruptants. Alteration of colony morphology and conidiation, which was observed in the fga1 disruptants, was not observed in the fga2 disruptants. The fga1/fga2 double disruptants showed phenotypic alterations similar to the fga1 or fga2 single disruptants, but increase of heat resistance was much more pronounced than in each single disruptant.
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Affiliation(s)
- Sona Jain
- Faculty of Agriculture, Ehime University, Matsuyama, 790-8566, Japan
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Hooley P, Fincham DA, Whitehead MP, Clipson NJ. Fungal osmotolerance. ADVANCES IN APPLIED MICROBIOLOGY 2004; 53:177-211. [PMID: 14696319 DOI: 10.1016/s0065-2164(03)53005-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- P Hooley
- School of Applied Sciences, University of Wolverhampton, Wolverhampton, WV1 1SB, UK
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Nishimura M, Park G, Xu JR. The G-beta subunit MGB1 is involved in regulating multiple steps of infection-related morphogenesis in Magnaporthe grisea. Mol Microbiol 2003; 50:231-43. [PMID: 14507377 DOI: 10.1046/j.1365-2958.2003.03676.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Trimeric G-proteins transmit extracellular signals to various downstream effectors (e.g. MAP kinases) in eukaryotes. In the rice blast fungus Magnaporthe grisea, the Pmk1 MAP kinase is essential for appressorium formation and infectious growth. The pmk1 deletion mutant fails to form appressoria but still responds to exogenous cAMP for tip deformation. Since gene disruption mutants of three Galpha subunits still form appressoria and are phenotypically different from pmk1 mutants, it is likely that the Pmk1 pathway is activated by Gbeta in M. grisea. In this study, we isolated and characterized the MGB1 gene that encodes the G subunit in M. grisea. Mutants disrupted in MGB1 were reduced in conidiation. Conidia from mgb1 mutants were defective in appressorium formation and failed to penetrate or grow invasively on rice leaves. Exogenous cAMP induced appressorium formation in mgb1 mutants, but these appressoria were abnormal in shape and could not penetrate. The intracellular cAMP level was reduced in mgb1 mutants and the defects in conidiation and hyphal growth were partially suppressed with 1 mM cAMP. Transformants expressing multiple copies of MGB1 were able to form appressoria on hydrophilic surfaces. Our results suggest that MGB1 may be involved in the cAMP signalling for regulating conidiation, surface recognition and appressorium formation. The Pmk1 pathway may be the downstream target of MGB1 for regulating penetration and infectious hyphae growth in M. grisea.
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Affiliation(s)
- Marie Nishimura
- National Institute of Agrobiological Sciences, 2-1-2, Kan' non dai, Tsukuba, Ibaraki, 305-8602, Japan
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Abstract
The blast fungus Magnaporthe grisea causes a serious disease on a wide variety of grasses including rice, wheat, and barley. Rice blast is the most serious disease of cultivated rice and therefore poses a threat to the world's most important food security crop. Here, I review recent progress toward understanding the molecular biology of plant infection by M. grisea, which involves development of a specialized cell, the appressorium. This dome-shaped cell generates enormous turgor pressure and physical force, allowing the fungus to breach the host cuticle and invade plant tissue. The review also considers the role of avirulence genes in M. grisea and the mechanisms by which resistant rice cultivars are able to perceive the fungus and defend themselves. Finally, the likely mechanisms that promote genetic diversity in M. grisea and our current understanding of the population structure of the blast fungus are evaluated.
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Affiliation(s)
- Nicholas J Talbot
- School of Biological Sciences, University of Exeter, Washington Singer Laboratories, Perry Road, Exeter EX4 4QG, United Kingdom.
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Lee N, D'Souza CA, Kronstad JW. Of smuts, blasts, mildews, and blights: cAMP signaling in phytopathogenic fungi. ANNUAL REVIEW OF PHYTOPATHOLOGY 2003; 41:399-427. [PMID: 12651963 DOI: 10.1146/annurev.phyto.41.052002.095728] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
cAMP regulates morphogenesis and virulence in a wide variety of fungi including the plant pathogens. In saprophytic yeasts such as Saccharomyces cerevisiae, cAMP signaling plays an important role in nutrient sensing. In filamentous saprophytes, the cAMP pathway appears to play an integral role in vegetative growth and sporulation, with possible connections to mating. Infection-related morphogenesis includes sporulation (conidia and teliospores), formation of appressoria, infection hyphae, and sclerotia. Here, we review studies of cAMP signaling in a variety of plant fungal pathogens. The primary fungi to be considered include Ustilago maydis, Magnaporthe grisea, Cryphonectria parasitica, Colletotrichum and Fusarium species, and Erisyphe graminis. We also include related information on Trichoderma species that act as mycoparasites and biocontrol agents of phytopathogenic fungi. We point out similarities in infection mechanisms, conservation of signaling components, as well as instances of cross-talk with other signaling pathways.
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Affiliation(s)
- Nancy Lee
- Biotechnology Laboratory, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z3;
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Segers GC, Nuss DL. Constitutively activated Galpha negatively regulates virulence, reproduction and hydrophobin gene expression in the chestnut blight fungus Cryphonectria parasitica. Fungal Genet Biol 2003; 38:198-208. [PMID: 12620256 DOI: 10.1016/s1087-1845(02)00534-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Disruption of the gene encoding Galpha subunit cpg-1 in the chestnut blight fungus Cryphonectria parasitica reduces growth and pigmentation and abolishes reproduction and virulence. We now report the consequences of mutations designed to constitutively activate (Q204-L and R178-C) CPG-1-mediated signaling. Introduction of cpg-1-QL or cpg-1-RC into wild type, Deltacpg-1 and Deltacpgb-1 (Gbeta) mutant strains resulted in a dominant phenotype characterized by a complete absence of aerial hyphae, pigmentation, conidia production and virulence. Opposing responses of Deltacpg-1 and activated mutant strains to chronic heat, hyperosmolarity and oxidative stress suggested that CPG-1 plays a role in mediating stress response. Growth of the cpg-1 mutant strains proceeded at wild-type level in rich liquid medium, but was severely curtailed on solid medium and absent in chestnut tissue, indicating the importance of CPG-1 mediated signaling under these harsher conditions. Both cpg-1 deletion and activating CPG-1 mutations resulted in post-transcriptional alterations in the accumulation of CPG-1 and/or CPGB-1, providing evidence for extensive post-transcriptional regulation of G-protein subunit accumulation in C. parasitica. Finally, the absence of aerial hyphae and the easily wettable phenotype exhibited by the QL and RC mutants correlated with reduced expression of the gene encoding cryparin, suggesting G-protein-mediated regulation of a fungal hydrophobin.
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Affiliation(s)
- Gert C Segers
- Center for Biosystems Research, University of Maryland, Biotechnology Institute, Plant Sciences Building, Room 5115, College Park, MD 20742-4450, USA
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Bastmeyer M, Deising HB, Bechinger C. Force exertion in fungal infection. ANNUAL REVIEW OF BIOPHYSICS AND BIOMOLECULAR STRUCTURE 2002; 31:321-41. [PMID: 11988473 DOI: 10.1146/annurev.biophys.31.091701.170951] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Fungal pathogens of plants or animals invade their hosts either by secretion of lytic enzymes, exerting force, or by a combination of both. Although many fungi are thought to rely mostly on lysis of the host tissue, some plant pathogenic fungi differentiate complex infection cells that develop enormous turgor pressure, which in turn is translated into force used for invasion. In order to understand mechanisms of fungal infection in detail, methods have been developed that indirectly or directly measure turgor pressure and force. In this article, these methods are described and critically discussed, and their importance in analysis of fungal infection are outlined.
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Affiliation(s)
- Martin Bastmeyer
- Department of Biology, University of Konstanz, Fach M626, Universitätsstrasse 10, D-77457 Konstanz, Germany.
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48
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Zuber S, Hynes MJ, Andrianopoulos A. G-protein signaling mediates asexual development at 25 degrees C but has no effect on yeast-like growth at 37 degrees C in the dimorphic fungus Penicillium mameffei. EUKARYOTIC CELL 2002; 1:440-7. [PMID: 12455992 PMCID: PMC118015 DOI: 10.1128/ec.1.3.440-447.2002] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ascomycete Penicillium marneffei is an opportunistic human pathogen exhibiting a temperature-dependent dimorphic switch. At 25 degrees C, P. marneffei grows as filamentous multinucleate hyphae and undergoes asexual development, producing uninucleate spores. At 37 degrees C, it forms uninucleate yeast cells which divide by fission. We have cloned a gene encoding a G alpha subunit of a heterotrimeric G protein from P. marneffei named gasA with high similarity to fadA in Aspergillus nidulans. Through the characterization of a delta gasA strain and mutants carrying a dominant activating or a dominant interfering gasA allele, we show that GasA is a key regulator of asexual development but seems to play no role in the regulation of growth. A dominant activating gasA mutant whose mutation results in a G42-to-R change (gasA(G42R)) does not express brlA, the conidiation-specific regulatory gene, and is locked in vegetative growth, while a dominant interfering gasA(G203R) mutant shows inappropriate brlA expression and conidiation. Interestingly, the gasA mutants have no apparent defect in dimorphic switching or yeast-like growth at 37 degrees C. Growth tests on dibutyryl cyclic AMP (dbcAMP) and theophylline suggest that a cAMP-protein kinase A cascade may be involved in the GasA signaling pathway.
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Affiliation(s)
- Sophie Zuber
- Department of Genetics, University of Melbourne, 3010 Victoria, Australia
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Memmott SD, Ha YS, Dickman MB. Proline reverses the abnormal phenotypes of Colletotrichum trifolii associated with expression of endogenous constitutively active Ras. Appl Environ Microbiol 2002; 68:1647-51. [PMID: 11916680 PMCID: PMC123849 DOI: 10.1128/aem.68.4.1647-1651.2002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Colletotrichum trifolii is the causative organism of alfalfa anthracnose. We previously cloned and characterized the small prototypical G protein, Ras, of C. trifolii, which is involved in the signaling pathways that mediate interaction between the pathogen and its host. Transformants expressing constitutively active forms of Ras have growth medium-dependent phenotypes. In nutrient-rich media (e.g., yeast extract and peptone), the phenotype of the transformants was indistinguishable from that of the wild type. However, during nutrient starvation, the transformants lose polarity, have distended hyphae, and fail to sporulate and produce appressoria. Since peptone caused the phenotype to revert, amino acids were tested singly and in combination to identify the responsible amino acid(s). We found that 1.6 mM proline in the medium reverses the constitutively active Ras phenotype.
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Affiliation(s)
- Stephen D Memmott
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722, USA
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