1
|
Scanlan JL, Mitchell AC, Marcroft SJ, Forsyth LM, Idnurm A, Van de Wouw AP. Deep amplicon sequencing reveals extensive allelic diversity in the erg11/CYP51 promoter and allows multi-population DMI fungicide resistance monitoring in the canola pathogen Leptosphaeria maculans. Fungal Genet Biol 2023; 168:103814. [PMID: 37343617 DOI: 10.1016/j.fgb.2023.103814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 04/29/2023] [Accepted: 06/12/2023] [Indexed: 06/23/2023]
Abstract
Continued use of fungicides provides a strong selection pressure towards strains with mutations to render these chemicals less effective. Previous research has shown that resistance to the demethylation inhibitor (DMI) fungicides, which target ergosterol synthesis, in the canola pathogen Leptosphaeria maculans has emerged in Australia and Europe. The change in fungicide sensitivity of individual isolates was found to be due to DNA insertions into the promoter of the erg11/CYP51 DMI target gene. Whether or not these were the only types of mutations and how prevalent they were in Australian populations was explored in the current study. New isolates with reduced DMI sensitivity were obtained from screens on DMI-treated plants, revealing eight independent insertions in the erg11 promoter. A novel deep amplicon sequencing approach applied to populations of ascospores fired from stubble identified an additional undetected insertion allele and quantified the frequencies of all known insertions, suggesting that, at least in the samples processed, the combined frequency of resistant alleles is between 0.0376% and 32.6%. Combined insertion allele frequencies positively correlated with population-level measures of in planta resistance to four different DMI treatments. Additionally, there was no evidence for erg11 coding mutations playing a role in conferring resistance in Australian populations. This research provides a key method for assessing fungicide resistance frequency in stubble-borne populations of plant pathogens and a baseline from which additional surveillance can be conducted in L. maculans. Whether or not the observed resistance allele frequencies are associated with loss of effective disease control in the field remains to be established.
Collapse
Affiliation(s)
- Jack L Scanlan
- School of BioSciences, The University of Melbourne, VIC 3010, Australia
| | - Angela C Mitchell
- School of BioSciences, The University of Melbourne, VIC 3010, Australia
| | | | | | - Alexander Idnurm
- School of BioSciences, The University of Melbourne, VIC 3010, Australia
| | | |
Collapse
|
2
|
Komluski J, Habig M, Stukenbrock EH. Repeat-Induced Point Mutation and Gene Conversion Coinciding with Heterochromatin Shape the Genome of a Plant-Pathogenic Fungus. mBio 2023:e0329022. [PMID: 37093087 DOI: 10.1128/mbio.03290-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023] Open
Abstract
Meiosis is associated with genetic changes in the genome-via recombination, gene conversion, and mutations. The occurrence of gene conversion and mutations during meiosis may further be influenced by the chromatin conformation, similar to the effect of the chromatin conformation on the mitotic mutation rate. To date, however, the exact distribution and type of meiosis-associated changes and the role of the chromatin conformation in this context are largely unexplored. Here, we determine recombination, gene conversion, and de novo mutations using whole-genome sequencing of all meiotic products of 23 individual meioses in Zymoseptoria tritici, an important pathogen of wheat. We confirm a high genome-wide recombination rate of 65 centimorgan (cM)/Mb and see higher recombination rates on the accessory compared to core chromosomes. A substantial fraction of 0.16% of all polymorphic markers was affected by gene conversions, showing a weak GC-bias and occurring at higher frequency in regions of constitutive heterochromatin, indicated by the histone modification H3K9me3. The de novo mutation rate associated with meiosis was approximately three orders of magnitude higher than the corresponding mitotic mutation rate. Importantly, repeat-induced point mutation (RIP), a fungal defense mechanism against duplicated sequences, is active in Z. tritici and responsible for the majority of these de novo meiotic mutations. Our results indicate that the genetic changes associated with meiosis are a major source of variability in the genome of an important plant pathogen and shape its evolutionary trajectory. IMPORTANCE The impact of meiosis on the genome composition via gene conversion and mutations is mostly poorly understood, in particular, for non-model species. Here, we sequenced all four meiotic products for 23 individual meioses and determined the genetic changes caused by meiosis for the important fungal wheat pathogen Zymoseptoria tritici. We found a high rate of gene conversions and an effect of the chromatin conformation on gene conversion rates. Higher conversion rates were found in regions enriched with the H3K9me3-a mark for constitutive heterochromatin. Most importantly, meiosis was associated with a much higher frequency of de novo mutations than mitosis; 78% of the meiotic mutations were caused by repeat-induced point mutations-a fungal defense mechanism against duplicated sequences. In conclusion, the genetic changes associated with meiosis are therefore a major factor shaping the genome of this fungal pathogen.
Collapse
Affiliation(s)
- Jovan Komluski
- Environmental Genomics, Christian-Albrechts University of Kiel, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Michael Habig
- Environmental Genomics, Christian-Albrechts University of Kiel, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Eva H Stukenbrock
- Environmental Genomics, Christian-Albrechts University of Kiel, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| |
Collapse
|
3
|
Xu M, Ashley NA, Vaghefi N, Wilkinson I, Idnurm A. Isolation of strains and their genome sequencing to analyze the mating system of Ophiocordyceps robertsii. PLoS One 2023; 18:e0284978. [PMID: 37130139 PMCID: PMC10153710 DOI: 10.1371/journal.pone.0284978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 04/13/2023] [Indexed: 05/03/2023] Open
Abstract
The fungal genus Ophiocordyceps contains a number of insect pathogens. One of the best known of these is Ophiocordyceps sinensis, which is used in Chinese medicine and its overharvesting threatens sustainability; hence, alternative species are being sought. Ophiocordyceps robertsii, found in Australia and New Zealand, has been proposed to be a close relative to O. sinensis, but little is known about this species despite being also of historical significance. Here, O. robertsii strains were isolated into culture and high coverage draft genome sequences obtained and analyzed. This species has a large genome expansion, as also occurred in O. sinensis. The mating type locus was characterized, indicating a heterothallic arrangement whereby each strain has an idiomorphic region of two (MAT1-2-1, MAT1-2-2) or three (MAT1-1-1, MAT1-1-2, MAT1-1-3) genes flanked by the conserved APN2 and SLA2 genes. These resources provide a new opportunity for understanding the evolution of the expanded genome in the homothallic species O. sinensis, as well as capabilities to explore the pharmaceutical potential in a species endemic to Australia and New Zealand.
Collapse
Affiliation(s)
- Melvin Xu
- School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
| | | | - Niloofar Vaghefi
- Centre for Crop Health, University of Southern Queensland, Darling Heights, Queensland, Australia
- School of Agriculture and Food, The University of Melbourne, Parkville, Victoria, Australia
| | - Ian Wilkinson
- GhostMothLabs, 20 Lynch Drive, Echuca, Victoria, Australia
| | - Alexander Idnurm
- School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
| |
Collapse
|
4
|
Van de Wouw AP, Sheedy EM, Ware AH, Marcroft S, Idnurm A. Independent breakdown events of the Brassica napus Rlm7 resistance gene including via the off-target impact of a dual-specificity avirulence interaction. MOLECULAR PLANT PATHOLOGY 2022; 23:997-1010. [PMID: 35249259 PMCID: PMC9190981 DOI: 10.1111/mpp.13204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 02/01/2022] [Accepted: 02/15/2022] [Indexed: 05/08/2023]
Abstract
Protection of many crops is achieved through the use of genetic resistance. Leptosphaeria maculans, the causal agent of blackleg disease of Brassica napus, has emerged as a model for understanding gene-for-gene interactions that occur between plants and pathogens. Whilst many of the characterized avirulence effector genes interact with a single resistance gene in the host, the AvrLm4-7 avirulence gene is recognized by two resistance genes, Rlm4 and Rlm7. Here, we report the "breakdown" of the Rlm7 resistance gene in Australia, under two different field conditions. The first, and more typical, breakdown probably resulted from widescale use of Rlm7-containing cultivars whereby selection has led to an increase of individuals in the L. maculans population that have undergone repeat-induced point (RIP) mutations at the AvrLm4-7 locus. This has rendered the AvrLm4-7 gene ineffective and therefore these isolates have become virulent towards both Rlm4 and Rlm7. The second, more atypical, situation was the widescale use of Rlm4 cultivars. Whilst a single-nucleotide polymorphism is the more common mechanism of virulence towards Rlm4, in this field situation, RIP mutations have been selected leading to the breakdown of resistance for both Rlm4 and Rlm7. This is an example of a resistance gene being rendered ineffective without having grown cultivars with the corresponding resistance gene due to the dual specificity of the avirulence gene. These findings highlight the value of pathogen surveillance in the context of expanded knowledge about potential complexities for Avr-R interactions for the deployment of appropriate resistance gene strategies.
Collapse
Affiliation(s)
| | | | | | | | - Alexander Idnurm
- School of BioSciencesUniversity of MelbourneParkvilleVictoriaAustralia
| |
Collapse
|
5
|
Fouché S, Oggenfuss U, Chanclud E, Croll D. A devil's bargain with transposable elements in plant pathogens. Trends Genet 2021; 38:222-230. [PMID: 34489138 DOI: 10.1016/j.tig.2021.08.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 08/03/2021] [Accepted: 08/04/2021] [Indexed: 02/08/2023]
Abstract
Transposable elements (TEs) spread in genomes through self-copying mechanisms and are a major cause of genome expansions. Plant pathogens have finely tuned the expression of virulence factors to rely on epigenetic control targeted at nearby TEs. Stress experienced during the plant infection process leads to derepression of TEs and concurrently allows the expression of virulence factors. We argue that the derepression of TEs elements causes an evolutionary conflict by favoring TEs that can be reactivated. Active TEs and recent genome size expansions indicate that plant pathogens could face long-term consequences from the short-term benefit of fine-tuning the infection process. Hence, encoding key virulence factors close to TEs under epigenetic control constitutes a devil's bargain for pathogens.
Collapse
Affiliation(s)
- Simone Fouché
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland; Department of Organismal Biology - Systematic Biology, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden
| | - Ursula Oggenfuss
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Emilie Chanclud
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland.
| |
Collapse
|
6
|
Pereira D, Oggenfuss U, McDonald BA, Croll D. Population genomics of transposable element activation in the highly repressive genome of an agricultural pathogen. Microb Genom 2021; 7:000540. [PMID: 34424154 PMCID: PMC8549362 DOI: 10.1099/mgen.0.000540] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 02/03/2021] [Indexed: 12/13/2022] Open
Abstract
The activity of transposable elements (TEs) can be an important driver of genetic diversity with TE-mediated mutations having a wide range of fitness consequences. To avoid deleterious effects of TE activity, some fungi have evolved highly sophisticated genomic defences to reduce TE proliferation across the genome. Repeat-induced point mutation (RIP) is a fungal-specific TE defence mechanism efficiently targeting duplicated sequences. The rapid accumulation of RIPs is expected to deactivate TEs over the course of a few generations. The evolutionary dynamics of TEs at the population level in a species with highly repressive genome defences is poorly understood. Here, we analyse 366 whole-genome sequences of Parastagonospora nodorum, a fungal pathogen of wheat with efficient RIP. A global population genomics analysis revealed high levels of genetic diversity and signs of frequent sexual recombination. Contrary to expectations for a species with RIP, we identified recent TE activity in multiple populations. The TE composition and copy numbers showed little divergence among global populations regardless of the demographic history. Miniature inverted-repeat transposable elements (MITEs) and terminal repeat retrotransposons in miniature (TRIMs) were largely underlying recent intra-species TE expansions. We inferred RIP footprints in individual TE families and found that recently active, high-copy TEs have possibly evaded genomic defences. We find no evidence that recent positive selection acted on TE-mediated mutations rather that purifying selection maintained new TE insertions at low insertion frequencies in populations. Our findings highlight the complex evolutionary equilibria established by the joint action of TE activity, selection and genomic repression.
Collapse
Affiliation(s)
- Danilo Pereira
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
- Present address: Max Planck Institute for Evolutionary Biology, August-Thienemann-Straße 2, D-24306 Plön, Germany
| | - Ursula Oggenfuss
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Bruce A. McDonald
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| |
Collapse
|
7
|
Elfstrand M, Chen J, Cleary M, Halecker S, Ihrmark K, Karlsson M, Davydenko K, Stenlid J, Stadler M, Durling MB. Comparative analyses of the Hymenoscyphus fraxineus and Hymenoscyphus albidus genomes reveals potentially adaptive differences in secondary metabolite and transposable element repertoires. BMC Genomics 2021; 22:503. [PMID: 34217229 PMCID: PMC8254937 DOI: 10.1186/s12864-021-07837-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 06/24/2021] [Indexed: 11/29/2022] Open
Abstract
Background The dieback epidemic decimating common ash (Fraxinus excelsior) in Europe is caused by the invasive fungus Hymenoscyphus fraxineus. In this study we analyzed the genomes of H. fraxineus and H. albidus, its native but, now essentially displaced, non-pathogenic sister species, and compared them with several other members of Helotiales. The focus of the analyses was to identify signals in the genome that may explain the rapid establishment of H. fraxineus and displacement of H. albidus. Results The genomes of H. fraxineus and H. albidus showed a high level of synteny and identity. The assembly of H. fraxineus is 13 Mb longer than that of H. albidus’, most of this difference can be attributed to higher dispersed repeat content (i.e. transposable elements [TEs]) in H. fraxineus. In general, TE families in H. fraxineus showed more signals of repeat-induced point mutations (RIP) than in H. albidus, especially in Long-terminal repeat (LTR)/Copia and LTR/Gypsy elements. Comparing gene family expansions and 1:1 orthologs, relatively few genes show signs of positive selection between species. However, several of those did appeared to be associated with secondary metabolite genes families, including gene families containing two of the genes in the H. fraxineus-specific, hymenosetin biosynthetic gene cluster (BGC). Conclusion The genomes of H. fraxineus and H. albidus show a high degree of synteny, and are rich in both TEs and BGCs, but the genomic signatures also indicated that H. albidus may be less well equipped to adapt and maintain its ecological niche in a rapidly changing environment. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07837-2.
Collapse
Affiliation(s)
- Malin Elfstrand
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7026, SE-750 07, Uppsala, Sweden.
| | - Jun Chen
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7026, SE-750 07, Uppsala, Sweden.,Systematic & Evolutionary Botany and Biodiversity group, MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Michelle Cleary
- Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Sundsvägen 3, Box 49, SE-230 53, Alnarp, Sweden
| | - Sandra Halecker
- Dept. Microbial Drugs, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, D-38124, Braunschweig, Germany
| | - Katarina Ihrmark
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7026, SE-750 07, Uppsala, Sweden
| | - Magnus Karlsson
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7026, SE-750 07, Uppsala, Sweden
| | - Kateryna Davydenko
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7026, SE-750 07, Uppsala, Sweden.,Ukrainian research Institute of Forestry and Forest Melioration, 62458, Kharkov, Ukraine
| | - Jan Stenlid
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7026, SE-750 07, Uppsala, Sweden
| | - Marc Stadler
- Dept. Microbial Drugs, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, D-38124, Braunschweig, Germany
| | - Mikael Brandström Durling
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7026, SE-750 07, Uppsala, Sweden
| |
Collapse
|
8
|
van Wyk S, Wingfield BD, De Vos L, van der Merwe NA, Steenkamp ET. Genome-Wide Analyses of Repeat-Induced Point Mutations in the Ascomycota. Front Microbiol 2021; 11:622368. [PMID: 33597932 PMCID: PMC7882544 DOI: 10.3389/fmicb.2020.622368] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 12/29/2020] [Indexed: 11/17/2022] Open
Abstract
The Repeat-Induced Point (RIP) mutation pathway is a fungus-specific genome defense mechanism that mitigates the deleterious consequences of repeated genomic regions and transposable elements (TEs). RIP mutates targeted sequences by introducing cytosine to thymine transitions. We investigated the genome-wide occurrence and extent of RIP with a sliding-window approach. Using genome-wide RIP data and two sets of control groups, the association between RIP, TEs, and GC content were contrasted in organisms capable and incapable of RIP. Based on these data, we then set out to determine the extent and occurrence of RIP in 58 representatives of the Ascomycota. The findings were summarized by placing each of the fungi investigated in one of six categories based on the extent of genome-wide RIP. In silico RIP analyses, using a sliding-window approach with stringent RIP parameters, implemented simultaneously within the same genetic context, on high quality genome assemblies, yielded superior results in determining the genome-wide RIP among the Ascomycota. Most Ascomycota had RIP and these mutations were particularly widespread among classes of the Pezizomycotina, including the early diverging Orbiliomycetes and the Pezizomycetes. The most extreme cases of RIP were limited to representatives of the Dothideomycetes and Sordariomycetes. By contrast, the genomes of the Taphrinomycotina and Saccharomycotina contained no detectable evidence of RIP. Also, recent losses in RIP combined with controlled TE proliferation in the Pezizomycotina subphyla may promote substantial genome enlargement as well as the formation of sub-genomic compartments. These findings have broadened our understanding of the taxonomic range and extent of RIP in Ascomycota and how this pathway affects the genomes of fungi harboring it.
Collapse
Affiliation(s)
| | | | | | | | - Emma T. Steenkamp
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa
| |
Collapse
|
9
|
Gardiner DM, Rusu A, Barrett L, Hunter GC, Kazan K. Can natural gene drives be part of future fungal pathogen control strategies in plants? THE NEW PHYTOLOGIST 2020; 228:1431-1439. [PMID: 32593207 DOI: 10.1111/nph.16779] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 06/15/2020] [Indexed: 06/11/2023]
Abstract
Globally, fungal pathogens cause enormous crop losses and current control practices are not always effective, economical or environmentally sustainable. Tools enabling genetic management of wild pathogen populations could potentially solve many problems associated with plant diseases. A natural gene drive from a heterologous species can be used in the globally important cereal pathogen Fusarium graminearum to remove pathogenic traits from contained populations of the fungus. The gene drive element became fixed in a freely crossing population in only three generations. Repeat-induced point mutation (RIP), a natural genome defence mechanism in fungi that causes C to T mutations during meiosis in highly similar sequences, may be useful to recall the gene drive following release, should a failsafe mechanism be required. We propose that gene drive technology is a potential tool to control plant pathogens once its efficacy is demonstrated under natural settings.
Collapse
Affiliation(s)
- Donald M Gardiner
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation (CSIRO), 306 Carmody Road, St Lucia, Queensland, 4067, Australia
| | - Anca Rusu
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation (CSIRO), 306 Carmody Road, St Lucia, Queensland, 4067, Australia
| | - Luke Barrett
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Clunies Ross Street, Acton, ACT, 2601, Australia
| | - Gavin C Hunter
- Health and Biosecurity, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Clunies Ross Street, Acton, ACT, 2601, Australia
| | - Kemal Kazan
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation (CSIRO), 306 Carmody Road, St Lucia, Queensland, 4067, Australia
| |
Collapse
|
10
|
Yang Y, Marcoft SJ, Forsyth LM, Zhao J, Li Z, Van de Wouw AP, Idnurm A. Sterol Demethylation Inhibitor Fungicide Resistance in Leptosphaeria maculans is Caused by Modifications in the Regulatory Region of ERG11. PLANT DISEASE 2020; 104:1280-1290. [PMID: 32202465 DOI: 10.1094/pdis-10-19-2088-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Blackleg is a worldwide disease of canola (Brassica napus), caused by a complex of fungal species in the genus Leptosphaeria, that impacts canola production and seed quality. Demethylation inhibitor (DMI) fungicides that target sterol 14α-demethylase are an integral part of disease control. Here, we report six DMI-resistant isolates of Leptosphaeria maculans and two different types of genetic modification related to the resistance. Analysis of the regulatory region of the DMI target gene ERG11 (also known as CYP51) revealed a 275-bp insertion in two of the isolates and three long terminal repeat retrotransposons (5,263, 5,267, and 5,248 bp) inserted in the promoter region of three resistant isolates. Genetic approaches confirmed that these elements are responsible for DMI resistance in L. maculans and crosses show segregation consistent with a single locus. Reverse-transcription quantitative PCR assays demonstrated that the 275-bp insertion increases ERG11 gene expression, conferring DMI fungicide resistance both in vitro and in planta. Moreover, transformation of a susceptible isolate of L. maculans with ERG11 driven by a promoter containing the 275-bp insertion increased resistance to tebuconazole. A minimal shift of the values of concentration whereby 50% of the mycelial growth is inhibited in vitro was observed in resistant isolates containing long terminal repeat retrotransposons; nevertheless, these isolates were able to develop significant lesions on cotyledons from fungicide-treated seedlings. This is the first report of genetic modifications in L. maculans relating to DMI fungicide resistance.
Collapse
Affiliation(s)
- Yongqing Yang
- School of Life Sciences, Inner Mongolia University, Hohhot 010020, China
- School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia
- Inner Mongolia Academy of Agricultural & Animal Husbandry Sciences, Hohhot 010031, China
| | - Stephen J Marcoft
- Marcroft Grains Pathology, Grains Innovation Park, Horsham, Victoria 3400, Australia
| | | | - Ji Zhao
- School of Life Sciences, Inner Mongolia University, Hohhot 010020, China
| | - Ziqin Li
- Inner Mongolia Academy of Agricultural & Animal Husbandry Sciences, Hohhot 010031, China
| | - Angela P Van de Wouw
- School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Alexander Idnurm
- School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia
| |
Collapse
|
11
|
|
12
|
Urquhart AS, Mondo SJ, Mäkelä MR, Hane JK, Wiebenga A, He G, Mihaltcheva S, Pangilinan J, Lipzen A, Barry K, de Vries RP, Grigoriev IV, Idnurm A. Genomic and Genetic Insights Into a Cosmopolitan Fungus, Paecilomyces variotii (Eurotiales). Front Microbiol 2018; 9:3058. [PMID: 30619145 PMCID: PMC6300479 DOI: 10.3389/fmicb.2018.03058] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 11/27/2018] [Indexed: 02/02/2023] Open
Abstract
Species in the genus Paecilomyces, a member of the fungal order Eurotiales, are ubiquitous in nature and impact a variety of human endeavors. Here, the biology of one common species, Paecilomyces variotii, was explored using genomics and functional genetics. Sequencing the genome of two isolates revealed key genome and gene features in this species. A striking feature of the genome was the two-part nature, featuring large stretches of DNA with normal GC content separated by AT-rich regions, a hallmark of many plant-pathogenic fungal genomes. These AT-rich regions appeared to have been mutated by repeat-induced point (RIP) mutations. We developed methods for genetic transformation of P. variotii, including forward and reverse genetics as well as crossing techniques. Using transformation and crossing, RIP activity was identified, demonstrating for the first time that RIP is an active process within the order Eurotiales. A consequence of RIP is likely reflected by a reduction in numbers of genes within gene families, such as in cell wall degradation, and reflected by growth limitations on P. variotii on diverse carbon sources. Furthermore, using these transformation tools we characterized a conserved protein containing a domain of unknown function (DUF1212) and discovered it is involved in pigmentation.
Collapse
Affiliation(s)
- Andrew S Urquhart
- School of BioSciences, University of Melbourne, Melbourne, VIC, Australia
| | - Stephen J Mondo
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA, United States
| | - Miia R Mäkelä
- Department of Microbiology, Faculty of Agriculture and Forestry, Viikki Biocenter 1, University of Helsinki, Helsinki, Finland
| | - James K Hane
- CCDM Bioinformatics, Centre for Crop and Disease Management, Curtin University, Bentley, WA, Australia.,Curtin Institute for Computation, Curtin University, Bentley, WA, Australia
| | - Ad Wiebenga
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute and Fungal Molecular Physiology, Utrecht University, Utrecht, Netherlands
| | - Guifen He
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA, United States
| | - Sirma Mihaltcheva
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA, United States
| | - Jasmyn Pangilinan
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA, United States
| | - Anna Lipzen
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA, United States
| | - Kerrie Barry
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA, United States
| | - Ronald P de Vries
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute and Fungal Molecular Physiology, Utrecht University, Utrecht, Netherlands
| | - Igor V Grigoriev
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA, United States
| | - Alexander Idnurm
- School of BioSciences, University of Melbourne, Melbourne, VIC, Australia
| |
Collapse
|