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Westrick NM, Dominguez EG, Bondy M, Hull CM, Smith DL, Kabbage M. A single laccase acts as a key component of environmental sensing in a broad host range fungal pathogen. Commun Biol 2024; 7:348. [PMID: 38514801 PMCID: PMC10957995 DOI: 10.1038/s42003-024-06034-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Accepted: 03/11/2024] [Indexed: 03/23/2024] Open
Abstract
Secreted laccases are important enzymes on a broad ecological scale for their role in mediating plant-microbe interactions, but within ascomycete fungi these enzymes have been primarily associated with melanin biosynthesis. In this study, a putatively secreted laccase, Sslac2, was characterized from the broad-host-range plant pathogen Sclerotinia sclerotiorum, which is largely unpigmented and is not dependent on melanogenesis for plant infection. Gene knockouts of Sslac2 demonstrate wide ranging developmental phenotypes and are functionally non-pathogenic. These mutants also displayed indiscriminate growth behaviors and enhanced biomass formation, seemingly as a result of their inability to respond to canonical environmental growth cues, a phenomenon further confirmed through chemical stress, physiological, and transcriptomic analyses. Transmission and scanning electron microscopy demonstrate apparent differences in extracellular matrix structure between WT and mutant strains that likely explain the inability of the mutants to respond to their environment. Targeting Sslac2 using host-induced gene silencing significantly improved resistance to S. sclerotiorum, suggesting that fungal laccases could be a valuable target of disease control. Collectively, we identified a laccase critical to the development and virulence of the broad-host-range pathogen S. sclerotiorum and propose a potentially novel role for fungal laccases in modulating environmental sensing.
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Affiliation(s)
- Nathaniel M Westrick
- Valley Laboratory, Connecticut Agricultural Experiment Station, Windsor, CT, USA
| | - Eddie G Dominguez
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, USA
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, USA
| | - Madeline Bondy
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, USA
| | - Christina M Hull
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, USA
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, USA
| | - Damon L Smith
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, USA
| | - Mehdi Kabbage
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, USA.
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Abstract
Fungi have been used to better the lives of everyday people and unravel the mysteries of higher eukaryotic organisms for decades. However, comparing progress and development stemming from fungal research to that of human, plant, and bacterial research, fungi remain largely understudied and underutilized. Recent commercial ventures have begun to gain popularity in society, providing a new surge of interest in fungi, mycelia, and potential new applications of these organisms to various aspects of research. Biotechnological advancements in fungal research cannot occur without intensive amounts of time, investments, and research tool development. In this review, we highlight past breakthroughs in fungal biotechnology, discuss requirements to advance fungal biotechnology even further, and touch on the horizon of new breakthroughs with the highest potential to positively impact both research and society.
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Affiliation(s)
- Mitchell G. Roth
- Department of Plant Pathology, The Ohio State University, Wooster, OH, United States
| | - Nathaniel M. Westrick
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, United States
| | - Thomas T. Baldwin
- Department of Plant Pathology, North Dakota State University, Fargo, ND, United States
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Westrick NM, Park SC, Keller NP, Smith DL, Kabbage M. A broadly conserved fungal alcohol oxidase (AOX) facilitates fungal invasion of plants. Mol Plant Pathol 2023; 24:28-43. [PMID: 36251755 PMCID: PMC9742500 DOI: 10.1111/mpp.13274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 09/13/2022] [Accepted: 09/15/2022] [Indexed: 06/16/2023]
Abstract
Alcohol oxidases (AOXs) are ecologically important enzymes that facilitate a number of plant-fungal interactions. Within Ascomycota they are primarily associated with methylotrophy, as a peroxisomal AOX catalysing the conversion of methanol to formaldehyde in methylotrophic yeast. In this study we demonstrate that AOX orthologues are phylogenetically conserved proteins that are common in the genomes of nonmethylotrophic, plant-associating fungi. Additionally, AOX orthologues are highly expressed during infection in a range of diverse pathosystems. To study the role of AOX in plant colonization, AOX knockout mutants were generated in the broad host range pathogen Sclerotinia sclerotiorum. Disease assays in soybean showed that these mutants had a significant virulence defect as evidenced by markedly reduced stem lesions and mortality rates. Chemical genomics suggested that SsAOX may function as an aromatic AOX, and growth assays demonstrated that ΔSsAOX is incapable of properly utilizing plant extract as a nutrient source. Profiling of known aromatic alcohols pointed towards the monolignol coniferyl alcohol (CA) as a possible substrate for SsAOX. As CA and other monolignols are ubiquitous among land plants, the presence of highly conserved AOX orthologues throughout Ascomycota implies that this is a broadly conserved protein used by ascomycete fungi during plant colonization.
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Affiliation(s)
- Nathaniel M. Westrick
- Department of Plant PathologyUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
- United States Department of Agriculture–Agricultural Research ServiceMadisonWisconsinUSA
| | - Sung Chul Park
- Department of Medical Microbiology and ImmunologyUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Nancy P. Keller
- Department of Plant PathologyUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
- Department of Medical Microbiology and ImmunologyUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Damon L. Smith
- Department of Plant PathologyUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Mehdi Kabbage
- Department of Plant PathologyUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
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Gebreegziabher Amare M, Westrick NM, Keller NP, Kabbage M. The conservation of IAP-like proteins in fungi, and their potential role in fungal programmed cell death. Fungal Genet Biol 2022; 162:103730. [PMID: 35998750 DOI: 10.1016/j.fgb.2022.103730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 08/07/2022] [Indexed: 11/30/2022]
Abstract
Programmed cell death (PCD) is a tightly regulated process which is required for survival and proper development of all cellular life. Despite this ubiquity, the precise molecular underpinnings of PCD have been primarily characterized in animals. Attempts to expand our understanding of this process in fungi have proven difficult as core regulators of animal PCD are apparently absent in fungal genomes, with the notable exception of a class of proteins referred to as inhibitors of apoptosis proteins (IAPs). These proteins are characterized by the conservation of a distinct Baculovirus IAP Repeat (BIR) domain and animal IAPs are known to regulate a number of processes, including cellular death, development, organogenesis, immune system maturation, host-pathogen interactions and more. IAP homologs are broadly conserved throughout the fungal kingdom, but our understanding of both their mechanism and role in fungal development/virulence is still unclear. In this review, we provide a broad and comparative overview of IAP function across taxa, with a particular focus on fungal processes regulated by IAPs. Furthermore, their putative modes of action in the absence of canonical interactors will be discussed.
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Affiliation(s)
| | - Nathaniel M Westrick
- Department of Plant Pathology, University of Wisconsin - Madison, Madison, WI, USA
| | - Nancy P Keller
- Department of Plant Pathology, University of Wisconsin - Madison, Madison, WI, USA
| | - Mehdi Kabbage
- Department of Plant Pathology, University of Wisconsin - Madison, Madison, WI, USA.
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Westrick NM, Smith DL, Kabbage M. Disarming the Host: Detoxification of Plant Defense Compounds During Fungal Necrotrophy. Front Plant Sci 2021; 12:651716. [PMID: 33995447 PMCID: PMC8120277 DOI: 10.3389/fpls.2021.651716] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 03/26/2021] [Indexed: 05/02/2023]
Abstract
While fungal biotrophs are dependent on successfully suppressing/subverting host defenses during their interaction with live cells, necrotrophs, due to their lifestyle are often confronted with a suite of toxic metabolites. These include an assortment of plant defense compounds (PDCs) which can demonstrate broad antifungal activity. These PDCs can be either constitutively present in plant tissue or induced in response to infection, but are nevertheless an important obstacle which needs to be overcome for successful pathogenesis. Fungal necrotrophs have developed a number of strategies to achieve this goal, from the direct detoxification of these compounds through enzymatic catalysis and modification, to the active transport of various PDCs to achieve toxin sequestration and efflux. Studies have shown across multiple pathogens that the efficient detoxification of host PDCs is both critical for successful infection and often a determinant factor in pathogen host range. Here, we provide a broad and comparative overview of the various mechanisms for PDC detoxification which have been identified in both fungal necrotrophs and fungal pathogens which depend on detoxification during a necrotrophic phase of infection. Furthermore, the effect that these mechanisms have on fungal host range, metabolism, and disease control will be discussed.
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Ranjan A, Westrick NM, Jain S, Piotrowski JS, Ranjan M, Kessens R, Stiegman L, Grau CR, Conley SP, Smith DL, Kabbage M. Resistance against Sclerotinia sclerotiorum in soybean involves a reprogramming of the phenylpropanoid pathway and up-regulation of antifungal activity targeting ergosterol biosynthesis. Plant Biotechnol J 2019; 17:1567-1581. [PMID: 30672092 PMCID: PMC6662107 DOI: 10.1111/pbi.13082] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 01/11/2019] [Accepted: 01/19/2019] [Indexed: 05/18/2023]
Abstract
Sclerotinia sclerotiorum, a predominately necrotrophic fungal pathogen with a broad host range, causes a significant yield-limiting disease of soybean called Sclerotinia stem rot. Resistance mechanisms against this pathogen in soybean are poorly understood, thus hindering the commercial deployment of resistant varieties. We used a multiomic approach utilizing RNA-sequencing, gas chromatography-mass spectrometry-based metabolomics and chemical genomics in yeast to decipher the molecular mechanisms governing resistance to S. sclerotiorum in soybean. Transcripts and metabolites of two soybean recombinant inbred lines, one resistant and one susceptible to S. sclerotiorum were analysed in a time course experiment. The combined results show that resistance to S. sclerotiorum in soybean is associated in part with an early accumulation of JA-Ile ((+)-7-iso-jasmonoyl-L-isoleucine), a bioactive jasmonate, increased ability to scavenge reactive oxygen species, and importantly, a reprogramming of the phenylpropanoid pathway leading to increased antifungal activities. Indeed, we noted that phenylpropanoid pathway intermediates, such as 4-hydroxybenzoate, cinnamic acid, ferulic acid and caffeic acid, were highly accumulated in the resistant line. In vitro assays show that these metabolites and total stem extracts from the resistant line clearly affect S. sclerotiorum growth and development. Using chemical genomics in yeast, we further show that this antifungal activity targets ergosterol biosynthesis in the fungus, by disrupting enzymes involved in lipid and sterol biosynthesis. Overall, our results are consistent with a model where resistance to S. sclerotiorum in soybean coincides with an early recognition of the pathogen, leading to the modulation of the redox capacity of the host and the production of antifungal metabolites.
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Affiliation(s)
- Ashish Ranjan
- Department of Plant PathologyUniversity of Wisconsin‐MadisonMadisonWIUSA
| | | | - Sachin Jain
- Department of Plant PathologyUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Jeff S. Piotrowski
- The Great Lakes Bioenergy Research CenterUniversity of Wisconsin‐MadisonMadisonWIUSA
- Present address:
Yumanity TherapeuticsCambridgeMAUSA
| | - Manish Ranjan
- School of Computational and Integrative SciencesJawaharlal Nehru UniversityNew DelhiIndia
| | - Ryan Kessens
- Department of Plant PathologyUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Logan Stiegman
- Department of Plant PathologyUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Craig R. Grau
- Department of Plant PathologyUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Shawn P. Conley
- Department of AgronomyUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Damon L. Smith
- Department of Plant PathologyUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Mehdi Kabbage
- Department of Plant PathologyUniversity of Wisconsin‐MadisonMadisonWIUSA
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Westrick NM, Ranjan A, Jain S, Grau CR, Smith DL, Kabbage M. Gene regulation of Sclerotinia sclerotiorum during infection of Glycine max: on the road to pathogenesis. BMC Genomics 2019; 20:157. [PMID: 30808300 PMCID: PMC6390599 DOI: 10.1186/s12864-019-5517-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 02/07/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Sclerotinia sclerotiorum is a broad-host range necrotrophic pathogen which is the causative agent of Sclerotinia stem rot (SSR), and a major disease of soybean (Glycine max). A time course transcriptomic analysis was performed in both compatible and incompatible soybean lines to identify pathogenicity and developmental factors utilized by S. sclerotiorum to achieve pathogenic success. RESULTS A comparison of genes expressed during early infection identified the potential importance of toxin efflux and nitrogen metabolism during the early stages of disease establishment. The later stages of infection were characterized by an apparent shift to survival structure formation. Analysis of genes highly upregulated in-planta revealed a temporal regulation of hydrolytic and detoxification enzymes, putative secreted effectors, and secondary metabolite synthesis genes. Redox regulation also appears to play a key role during the course of infection, as suggested by the high expression of genes involved in reactive oxygen species production and scavenging. Finally, distinct differences in early gene expression were noted based on the comparison of S. sclerotiorum infection of resistant and susceptible soybean lines. CONCLUSIONS Although many potential virulence factors have been noted in the S. sclerotiorum pathosystem, this study serves to highlight soybean specific processes most likely to be critical in successful infection. Functional studies of genes identified in this work are needed to confirm their importance to disease development, and may constitute valuable targets of RNAi approaches to improve resistance to SSR.
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Affiliation(s)
| | - Ashish Ranjan
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI USA
| | - Sachin Jain
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI USA
| | - Craig R. Grau
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI USA
| | - Damon L. Smith
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI USA
| | - Mehdi Kabbage
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI USA
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Abstract
Increased use of metagenomics for routine virus diagnosis has led to the characterization of several genus level geminiviruses from tree fruit long thought to exclusively host RNA viruses. In this study, the identification and molecular characterization of a novel geminivirus is reported for the first time in Prunus spp. The virus, provisionally named Prunus geminivirus A (PrGVA), was identified by Illumina sequencing from an asymptomatic plum tree. PrGVA was subsequently confirmed by rolling cycle amplification, cloning, and Sanger sequencing of its complete genome (3,174 to 3,176 nucleotides) from an additional 18 (9 apricot and 9 plum) field isolates. Apart from the nonanucleotide motif TAATATT↓AC present in its virion strand origin of replication, other conserved motifs of PrGVA support its geminiviral origin. PrGVA shared highest complete genome (73 to 74%), coat protein amino acid (83 to 85%) and rep-associated amino acid (74%) identities with Grapevine red blotch virus (GRBV). PrGVA was graft but not mechanically transmissible. Quantitative polymerase chain reaction screening of Prunus spp. in the National Clonal Germplasm Repository collection using newly designed primers and probes revealed 69.4% (apricot), 55.8% (plum), and 8.3% (cherry) incidences of PrGVA. PrGVA is proposed as a novel member of the genus Grablovirus based on its close genome and phylogenetic relationship with GRBV.
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Affiliation(s)
- Maher Al Rwahnih
- Department of Plant Pathology, University of California, Davis, 95616
| | - Olufemi J Alabi
- Department of Plant Pathology & Microbiology, Texas A&M AgriLife Research and Extension Center, Weslaco 78596
| | | | - Deborah Golino
- Department of Plant Pathology, University of California, Davis
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Al Rwahnih M, Alabi OJ, Westrick NM, Golino D, Rowhani A. Description of a Novel Monopartite Geminivirus and Its Defective Subviral Genome in Grapevine. Phytopathology 2017; 107:240-251. [PMID: 27670772 DOI: 10.1094/phyto-07-16-0282-r] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A novel virus was detected in grapevines by Illumina sequencing during the screening of two table grape (Vitis vinifera) accessions, cultivars Black Beet and Nagano Purple, from South Korea. The monopartite circular ssDNA genome sequence was subsequently confirmed by rolling cycle amplification, cloning and Sanger sequencing. The complete viral genomic sequence from both accessions ranged from 2,903 to 2,907 nucleotides in length and contained the conserved nonanucleotide sequence TAATATT↓AC and other sequence features typical of the family Geminiviridae, including two predicted sense and four complementary-sense open reading frames. Phylogenetic analysis placed the novel virus in a unique taxon within the family Geminiviridae. A naturally occurring defective subviral DNA was also discovered. This defective DNA molecule carried a deletion of approximately 46% of the full-length genome. Both the genomic and defective DNA molecules were graft-transmissible although no disease is yet correlated with their occurrence in Vitis spp. The tentative names Grapevine geminivirus A (GGVA) and GGVA defective DNA (GGVA D-DNA) are proposed. PCR assays developed using primers designed in the coat protein gene led to the detection of GGVA in 1.74% of 1,262 vines derived from 15 grapevine cultivars from six countries across three continents.
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Affiliation(s)
- Maher Al Rwahnih
- First, third, fourth, and fifth authors: Department of Plant Pathology, University of California, Davis, 95616; and second author: Department of Plant Pathology & Microbiology, Texas A&M AgriLife Research and Extension Center, Weslaco 78596
| | - Olufemi J Alabi
- First, third, fourth, and fifth authors: Department of Plant Pathology, University of California, Davis, 95616; and second author: Department of Plant Pathology & Microbiology, Texas A&M AgriLife Research and Extension Center, Weslaco 78596
| | - Nathaniel M Westrick
- First, third, fourth, and fifth authors: Department of Plant Pathology, University of California, Davis, 95616; and second author: Department of Plant Pathology & Microbiology, Texas A&M AgriLife Research and Extension Center, Weslaco 78596
| | - Deborah Golino
- First, third, fourth, and fifth authors: Department of Plant Pathology, University of California, Davis, 95616; and second author: Department of Plant Pathology & Microbiology, Texas A&M AgriLife Research and Extension Center, Weslaco 78596
| | - Adib Rowhani
- First, third, fourth, and fifth authors: Department of Plant Pathology, University of California, Davis, 95616; and second author: Department of Plant Pathology & Microbiology, Texas A&M AgriLife Research and Extension Center, Weslaco 78596
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