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Ashton GD, Sang F, Blythe M, Zadik D, Holmes N, Malla S, Camps SMT, Wright V, Melchers WJG, Verweij PE, Dyer PS. Use of Bulk Segregant Analysis for Determining the Genetic Basis of Azole Resistance in the Opportunistic Pathogen Aspergillus fumigatus. Front Cell Infect Microbiol 2022; 12:841138. [PMID: 35531335 PMCID: PMC9069965 DOI: 10.3389/fcimb.2022.841138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 03/03/2022] [Indexed: 12/19/2022] Open
Abstract
A sexual cycle was described in 2009 for the opportunistic fungal pathogen Aspergillus fumigatus, opening up for the first time the possibility of using techniques reliant on sexual crossing for genetic analysis. The present study was undertaken to evaluate whether the technique 'bulk segregant analysis' (BSA), which involves detection of differences between pools of progeny varying in a particular trait, could be applied in conjunction with next-generation sequencing to investigate the underlying basis of monogenic traits in A. fumigatus. Resistance to the azole antifungal itraconazole was chosen as a model, with a dedicated bioinformatic pipeline developed to allow identification of SNPs that differed between the resistant progeny pool and resistant parent compared to the sensitive progeny pool and parent. A clinical isolate exhibiting monogenic resistance to itraconazole of unknown basis was crossed to a sensitive parent and F1 progeny used in BSA. In addition, the use of backcrossing and increasing the number in progeny pools was evaluated as ways to enhance the efficiency of BSA. Use of F1 pools of 40 progeny led to the identification of 123 candidate genes with SNPs distributed over several contigs when aligned to an A1163 reference genome. Successive rounds of backcrossing enhanced the ability to identify specific genes and a genomic region, with BSA of progeny (using 40 per pool) from a third backcross identifying 46 genes with SNPs, and BSA of progeny from a sixth backcross identifying 20 genes with SNPs in a single 292 kb region of the genome. The use of an increased number of 80 progeny per pool also increased the resolution of BSA, with 29 genes demonstrating SNPs between the different sensitive and resistant groupings detected using progeny from just the second backcross with the majority of variants located on the same 292 kb region. Further bioinformatic analysis of the 292 kb region identified the presence of a cyp51A gene variant resulting in a methionine to lysine (M220K) change in the CYP51A protein, which was concluded to be the causal basis of the observed resistance to itraconazole. The future use of BSA in genetic analysis of A. fumigatus is discussed.
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Affiliation(s)
- George D. Ashton
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Fei Sang
- DeepSeq, Centre for Genetics and Genomics, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Martin Blythe
- DeepSeq, Centre for Genetics and Genomics, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Daniel Zadik
- DeepSeq, Centre for Genetics and Genomics, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Nadine Holmes
- DeepSeq, Centre for Genetics and Genomics, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Sunir Malla
- DeepSeq, Centre for Genetics and Genomics, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Simone M. T. Camps
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Victoria Wright
- DeepSeq, Centre for Genetics and Genomics, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Willem J. G. Melchers
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Paul E. Verweij
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Paul S. Dyer
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
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Wiles ET, Mumford CC, McNaught KJ, Tanizawa H, Selker EU. The ACF chromatin-remodeling complex is essential for Polycomb repression. eLife 2022; 11:e77595. [PMID: 35257662 PMCID: PMC9038196 DOI: 10.7554/elife.77595] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 03/03/2022] [Indexed: 11/13/2022] Open
Abstract
Establishing and maintaining appropriate gene repression is critical for the health and development of multicellular organisms. Histone H3 lysine 27 (H3K27) methylation is a chromatin modification associated with repressed facultative heterochromatin, but the mechanism of this repression remains unclear. We used a forward genetic approach to identify genes involved in transcriptional silencing of H3K27-methylated chromatin in the filamentous fungus Neurospora crassa. We found that the N. crassa homologs of ISWI (NCU03875) and ACF1 (NCU00164) are required for repression of a subset of H3K27-methylated genes and that they form an ACF chromatin-remodeling complex. This ACF complex interacts with chromatin throughout the genome, yet association with facultative heterochromatin is specifically promoted by the H3K27 methyltransferase, SET-7. H3K27-methylated genes that are upregulated when iswi or acf1 are deleted show a downstream shift of the +1 nucleosome, suggesting that proper nucleosome positioning is critical for repression of facultative heterochromatin. Our findings support a direct role of the ACF complex in Polycomb repression.
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Affiliation(s)
- Elizabeth T Wiles
- Institute of Molecular Biology, University of OregonEugeneUnited States
| | - Colleen C Mumford
- Institute of Molecular Biology, University of OregonEugeneUnited States
| | - Kevin J McNaught
- Institute of Molecular Biology, University of OregonEugeneUnited States
| | - Hideki Tanizawa
- Institute of Molecular Biology, University of OregonEugeneUnited States
| | - Eric U Selker
- Institute of Molecular Biology, University of OregonEugeneUnited States
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Acosta Morel W, Anta Fernández F, Baroncelli R, Becerra S, Thon MR, van Kan JAL, Díaz-Mínguez JM, Benito EP. A Major Effect Gene Controlling Development and Pathogenicity in Botrytis cinerea Identified Through Genetic Analysis of Natural Mycelial Non-pathogenic Isolates. FRONTIERS IN PLANT SCIENCE 2021; 12:663870. [PMID: 33936154 PMCID: PMC8079791 DOI: 10.3389/fpls.2021.663870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 03/22/2021] [Indexed: 06/12/2023]
Abstract
Botrytis cinerea is a necrotrophic plant pathogenic fungus with a wide host range. Its natural populations are phenotypically and genetically very diverse. A survey of B. cinerea isolates causing gray mold in the vineyards of Castilla y León, Spain, was carried out and as a result eight non-pathogenic natural variants were identified. Phenotypically these isolates belong to two groups. The first group consists of seven isolates displaying a characteristic mycelial morphotype, which do not sporulate and is unable to produce sclerotia. The second group includes one isolate, which sporulates profusely and does not produce sclerotia. All of them are unresponsive to light. Crosses between a representative mycelial non-pathogenic isolate and a highly aggressive field isolate revealed that the phenotypic differences regarding pathogenicity, sporulation and production of sclerotia cosegregated in the progeny and are determined by a single genetic locus. By applying a bulked segregant analysis strategy based on the comparison of the two parental genomes the locus was mapped to a 110 kb region in chromosome 4. Subcloning and transformation experiments revealed that the polymorphism is an SNP affecting gene Bcin04g03490 in the reference genome of B. cinerea. Genetic complementation analysis and sequencing of the Bcin04g03490 alleles demonstrated that the mutations in the mycelial isolates are allelic and informed about the nature of the alterations causing the phenotypes observed. Integration of the allele of the pathogenic isolate into the non-pathogenic isolate fully restored the ability to infect, to sporulate and to produce sclerotia. Therefore, it is concluded that a major effect gene controlling differentiation and developmental processes as well as pathogenicity has been identified in B. cinerea. It encodes a protein with a GAL4-like Zn(II)2Cys6 binuclear cluster DNA binding domain and an acetyltransferase domain, suggesting a role in regulation of gene expression through a mechanism involving acetylation of specific substrates.
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Affiliation(s)
- Wilson Acosta Morel
- Spanish-Portuguese Institute for Agricultural Research (CIALE), Department of Microbiology and Genetics, University of Salamanca, Salamanca, Spain
| | - Francisco Anta Fernández
- Spanish-Portuguese Institute for Agricultural Research (CIALE), Department of Microbiology and Genetics, University of Salamanca, Salamanca, Spain
| | - Riccardo Baroncelli
- Spanish-Portuguese Institute for Agricultural Research (CIALE), Department of Microbiology and Genetics, University of Salamanca, Salamanca, Spain
| | - Sioly Becerra
- Spanish-Portuguese Institute for Agricultural Research (CIALE), Department of Microbiology and Genetics, University of Salamanca, Salamanca, Spain
| | - Michael R. Thon
- Spanish-Portuguese Institute for Agricultural Research (CIALE), Department of Microbiology and Genetics, University of Salamanca, Salamanca, Spain
| | - Jan A. L. van Kan
- Laboratory of Phytopathology, Wageningen University, Wageningen, Netherlands
| | - José María Díaz-Mínguez
- Spanish-Portuguese Institute for Agricultural Research (CIALE), Department of Microbiology and Genetics, University of Salamanca, Salamanca, Spain
| | - Ernesto Pérez Benito
- Spanish-Portuguese Institute for Agricultural Research (CIALE), Department of Microbiology and Genetics, University of Salamanca, Salamanca, Spain
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Gladieux P, De Bellis F, Hann-Soden C, Svedberg J, Johannesson H, Taylor JW. Neurospora from Natural Populations: Population Genomics Insights into the Life History of a Model Microbial Eukaryote. Methods Mol Biol 2021; 2090:313-336. [PMID: 31975173 DOI: 10.1007/978-1-0716-0199-0_13] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The ascomycete filamentous fungus Neurospora crassa played a historic role in experimental biology and became a model system for genetic research. Stimulated by a systematic effort to collect wild strains initiated by Stanford geneticist David Perkins, the genus Neurospora has also become a basic model for the study of evolutionary processes, speciation, and population biology. In this chapter, we will first trace the history that brought Neurospora into the era of population genomics. We will then cover the major contributions of population genomic investigations using Neurospora to our understanding of microbial biogeography and speciation, and review recent work using population genomics and genome-wide association mapping that illustrates the unique potential of Neurospora as a model for identifying the genetic basis of (potentially adaptive) phenotypes in filamentous fungi. The advent of population genomics has contributed to firmly establish Neurospora as a complete model system and we hope our review will entice biologists to include Neurospora in their research.
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Affiliation(s)
- Pierre Gladieux
- UMR BGPI, Univ Montpellier, CIRAD, INRA, Montpellier SupAgro, Montpellier, France.
| | - Fabien De Bellis
- UMR AGAP, Univ Montpellier, CIRAD, INRA, Montpellier SupAgro, Montpellier, France
| | - Christopher Hann-Soden
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Jesper Svedberg
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden
| | - Hanna Johannesson
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden
| | - John W Taylor
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, USA
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Klocko AD, Summers CA, Glover ML, Parrish R, Storck WK, McNaught KJ, Moss ND, Gotting K, Stewart A, Morrison AM, Payne L, Hatakeyama S, Selker EU. Selection and Characterization of Mutants Defective in DNA Methylation in Neurospora crassa. Genetics 2020; 216:671-688. [PMID: 32873602 PMCID: PMC7648584 DOI: 10.1534/genetics.120.303471] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 08/25/2020] [Indexed: 01/05/2023] Open
Abstract
DNA methylation, a prototypical epigenetic modification implicated in gene silencing, occurs in many eukaryotes and plays a significant role in the etiology of diseases such as cancer. The filamentous fungus Neurospora crassa places DNA methylation at regions of constitutive heterochromatin such as in centromeres and in other A:T-rich regions of the genome, but this modification is dispensable for normal growth and development. This and other features render N. crassa an excellent model to genetically dissect elements of the DNA methylation pathway. We implemented a forward genetic selection on a massive scale, utilizing two engineered antibiotic-resistance genes silenced by DNA methylation, to isolate mutants d efective i n m ethylation (dim). Hundreds of potential mutants were characterized, yielding a rich collection of informative alleles of 11 genes important for DNA methylation, most of which were already reported. In parallel, we characterized the pairwise interactions in nuclei of the DCDC, the only histone H3 lysine 9 methyltransferase complex in Neurospora, including those between the DIM-5 catalytic subunit and other complex members. We also dissected the N- and C-termini of the key protein DIM-7, required for DIM-5 histone methyltransferase localization and activation. Lastly, we identified two alleles of a novel gene, dim-10 - a homolog of Clr5 in Schizosaccharomyces pombe - that is not essential for DNA methylation, but is necessary for repression of the antibiotic-resistance genes used in the selection, which suggests that both DIM-10 and DNA methylation promote silencing of constitutive heterochromatin.
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Affiliation(s)
- Andrew D Klocko
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Calvin A Summers
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Marissa L Glover
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Robert Parrish
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - William K Storck
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Kevin J McNaught
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Nicole D Moss
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Kirsten Gotting
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Aurelian Stewart
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Ariel M Morrison
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Laurel Payne
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Shin Hatakeyama
- Laboratory of Genetics, Faculty of Science, Shimo-ohkubo 255, Saitama University, Sakura-ward, 338-8570, JAPAN
| | - Eric U Selker
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
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Navarro-Escalante L, Zhao C, Shukle R, Stuart J. BSA-Seq Discovery and Functional Analysis of Candidate Hessian Fly ( Mayetiola destructor) Avirulence Genes. FRONTIERS IN PLANT SCIENCE 2020; 11:956. [PMID: 32670342 PMCID: PMC7330099 DOI: 10.3389/fpls.2020.00956] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 06/10/2020] [Indexed: 05/17/2023]
Abstract
The Hessian fly (HF, Mayetiola destructor) is a plant-galling parasite of wheat (Triticum spp.). Seven percent of its genome is composed of highly diversified signal-peptide-encoding genes that are transcribed in HF larval salivary glands. These observations suggest that they encode effector proteins that are injected into wheat cells to suppress basal wheat immunity and redirect wheat development towards gall formation. Genetic mapping has determined that mutations in four of these genes are associated with HF larval survival (virulence) on plants carrying four different resistance (R) genes. Here, this line of investigation was pursued further using bulked-segregant analysis combined with whole genome resequencing (BSA-seq). Virulence to wheat R genes H6, Hdic, and H5 was examined. Mutations associated with H6 virulence had been mapped previously. Therefore, we used H6 to test the capacity of BSA-seq to map virulence using a field-derived HF population. This was the first time a non-structured HF population had been used to map HF virulence. Hdic virulence had not been mapped previously. Using a structured laboratory population, BSA-seq associated Hdic virulence with mutations in two candidate effector-encoding genes. Using a laboratory population, H5 virulence was previously positioned in a region spanning the centromere of HF autosome 2. BSA-seq resolved H5 virulence to a 1.3 Mb fragment on the same chromosome but failed to identify candidate mutations. Map-based candidate effectors were then delivered to Nicotiana plant cells via the type III secretion system of Burkholderia glumae bacteria. These experiments demonstrated that the genes associated with virulence to wheat R genes H6 and H13 are capable of suppressing plant immunity. Results are consistent with the hypothesis that effector proteins underlie the ability of HFs to survive on wheat.
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Affiliation(s)
| | - Chaoyang Zhao
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA, United States
| | - Richard Shukle
- USDA-ARS and Department of Entomology, Purdue University, West Lafayette, IN, United States
| | - Jeffrey Stuart
- Department of Entomology, Purdue University, West Lafayette, IN, United States
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Jørgensen TR, Burggraaf AM, Arentshorst M, Schutze T, Lamers G, Niu J, Kwon MJ, Park J, Frisvad JC, Nielsen KF, Meyer V, van den Hondel CA, Dyer PS, Ram AF. Identification of SclB, a Zn(II)2Cys6 transcription factor involved in sclerotium formation in Aspergillus niger. Fungal Genet Biol 2020; 139:103377. [DOI: 10.1016/j.fgb.2020.103377] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Revised: 02/07/2020] [Accepted: 02/14/2020] [Indexed: 10/24/2022]
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Identification of a PRC2 Accessory Subunit Required for Subtelomeric H3K27 Methylation in Neurospora crassa. Mol Cell Biol 2020; 40:MCB.00003-20. [PMID: 32179551 DOI: 10.1128/mcb.00003-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 03/11/2020] [Indexed: 02/07/2023] Open
Abstract
Polycomb repressive complex 2 (PRC2) catalyzes methylation of histone H3 at lysine 27 (H3K27) in genomic regions of most eukaryotes and is critical for maintenance of the associated transcriptional repression. However, the mechanisms that shape the distribution of H3K27 methylation, such as recruitment of PRC2 to chromatin and/or stimulation of PRC2 activity, are unclear. Here, using a forward genetic approach in the model organism Neurospora crassa, we identified two alleles of a gene, NCU04278, encoding an unknown PRC2 accessory subunit (PAS). Loss of PAS resulted in losses of H3K27 methylation concentrated near the chromosome ends and derepression of a subset of associated subtelomeric genes. Immunoprecipitation followed by mass spectrometry confirmed reciprocal interactions between PAS and known PRC2 subunits, and sequence similarity searches demonstrated that PAS is not unique to N. crassa PAS homologs likely influence the distribution of H3K27 methylation and underlying gene repression in a variety of fungal lineages.
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Abstract
Methylation of histone H3 lysine 27 (H3K27) is widely recognized as a transcriptionally repressive chromatin modification but the mechanism of repression remains unclear. We devised and implemented a forward genetic scheme to identify factors required for H3K27 methylation-mediated silencing in the filamentous fungus Neurospora crassa and identified a bromo-adjacent homology (BAH)-plant homeodomain (PHD)-containing protein, EPR-1 (effector of polycomb repression 1; NCU07505). EPR-1 associates with H3K27-methylated chromatin, and loss of EPR-1 de-represses H3K27-methylated genes without loss of H3K27 methylation. EPR-1 is not fungal-specific; orthologs of EPR-1 are present in a diverse array of eukaryotic lineages, suggesting an ancestral EPR-1 was a component of a primitive Polycomb repression pathway.
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Gostinčar C, Turk M, Zajc J, Gunde‐Cimerman N. Fifty Aureobasidium pullulans genomes reveal a recombining polyextremotolerant generalist. Environ Microbiol 2019; 21:3638-3652. [PMID: 31112354 PMCID: PMC6852026 DOI: 10.1111/1462-2920.14693] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 04/17/2019] [Accepted: 05/20/2019] [Indexed: 01/31/2023]
Abstract
The black yeast Aureobasidium pullulans is a textbook example of a generalistic and ubiquitous fungus thriving in a wide variety of environments. To investigate whether A. pullulans is a true generalist, or alternatively, whether part of its versatility can be attributed to intraspecific specialization masked by cryptic diversification undetectable by traditional phylogenetic analyses, we sequenced and analysed the genomes of 50 strains of A. pullulans from different habitats and geographic locations. No population structure was observed in the sequenced strains. Decay of linkage disequilibrium over shorter physical distances (<100 bp) than in many sexually reproducing fungi indicates a high level of recombination in the species. A homothallic mating locus was found in all of the sequenced genomes. Aureobasidium pullulans appears to have a homogeneous population genetics structure, which is best explained by good dispersal and high levels of recombination. This means that A. pullulans is a true generalist that can inhabit different habitats without substantial specialization to any of these habitats at the genomic level. Furthermore, in the future, the high level of A. pullulans recombination can be exploited for the identification of genomic loci that are involved in the many biotechnologically useful traits of this black yeast.
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Affiliation(s)
- Cene Gostinčar
- Department of Biology, Biotechnical FacultyUniversity of Ljubljana, Jamnikarjeva 101, SI‐1000LjubljanaSlovenia
- Lars Bolund Institute of Regenerative Medicine, BGI‐QingdaoQingdao 266555China
| | - Martina Turk
- Department of Biology, Biotechnical FacultyUniversity of Ljubljana, Jamnikarjeva 101, SI‐1000LjubljanaSlovenia
| | - Janja Zajc
- Department of Biology, Biotechnical FacultyUniversity of Ljubljana, Jamnikarjeva 101, SI‐1000LjubljanaSlovenia
- National Institute of BiologyVečna pot 111, SI‐1000LjubljanaSlovenia
| | - Nina Gunde‐Cimerman
- Department of Biology, Biotechnical FacultyUniversity of Ljubljana, Jamnikarjeva 101, SI‐1000LjubljanaSlovenia
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Sun X, Gostinčar C, Fang C, Zajc J, Hou Y, Song Z, Gunde-Cimerman N. Genomic Evidence of Recombination in the Basidiomycete Wallemia mellicola. Genes (Basel) 2019; 10:genes10060427. [PMID: 31167502 PMCID: PMC6628117 DOI: 10.3390/genes10060427] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 05/28/2019] [Accepted: 05/30/2019] [Indexed: 12/16/2022] Open
Abstract
One of the most commonly encountered species in the small basidiomycetous sub-phylum Wallemiomycotina is Wallemia mellicola, a xerotolerant fungus with a widespread distribution. To investigate the population characteristics of the species, whole genomes of twenty-five strains were sequenced. Apart from identification of four strains of clonal origin, the distances between the genomes failed to reflect either the isolation habitat of the strains or their geographical origin. Strains from different parts of the world appeared to represent a relatively homogenous and widespread population. The lack of concordance between individual gene phylogenies and the decay of linkage disequilibrium indicated that W. mellicola is at least occasionally recombining. Two versions of a putative mating-type locus have been found in all sequenced genomes, each present in approximately half of the strains. W. mellicola thus appears to be capable of (sexual) recombination and shows no signs of allopatric speciation or specialization to specific habitats.
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Affiliation(s)
- Xiaohuan Sun
- China National GeneBank, BGI-Shenzhen, Jinsha Road, Shenzhen 518120, China.
- BGI-Shenzhen, Beishan Industrial Zone, Shenzhen 518083, China.
| | - Cene Gostinčar
- Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia.
- Lars Bolund Institute of Regenerative Medicine, BGI-Qingdao, Qingdao 266555, China.
| | - Chao Fang
- China National GeneBank, BGI-Shenzhen, Jinsha Road, Shenzhen 518120, China.
- BGI-Shenzhen, Beishan Industrial Zone, Shenzhen 518083, China.
| | - Janja Zajc
- Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia.
- Department of Biotechnology and Systems biology, National Institute of Biology, 1000 Ljubljana, Slovenia.
| | - Yong Hou
- China National GeneBank, BGI-Shenzhen, Jinsha Road, Shenzhen 518120, China.
- BGI-Shenzhen, Beishan Industrial Zone, Shenzhen 518083, China.
| | - Zewei Song
- China National GeneBank, BGI-Shenzhen, Jinsha Road, Shenzhen 518120, China.
- BGI-Shenzhen, Beishan Industrial Zone, Shenzhen 518083, China.
| | - Nina Gunde-Cimerman
- Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia.
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Wetzel LA, Levin TC, Hulett RE, Chan D, King GA, Aldayafleh R, Booth DS, Sigg MA, King N. Predicted glycosyltransferases promote development and prevent spurious cell clumping in the choanoflagellate S. rosetta. eLife 2018; 7:e41482. [PMID: 30556809 PMCID: PMC6322860 DOI: 10.7554/elife.41482] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 12/14/2018] [Indexed: 12/19/2022] Open
Abstract
In a previous study we established forward genetics in the choanoflagellate Salpingoeca rosetta and found that a C-type lectin gene is required for rosette development (Levin et al., 2014). Here we report on critical improvements to genetic screens in S. rosetta while also investigating the genetic basis for rosette defect mutants in which single cells fail to develop into orderly rosettes and instead aggregate promiscuously into amorphous clumps of cells. Two of the mutants, Jumble and Couscous, mapped to lesions in genes encoding two different predicted glycosyltransferases and displayed aberrant glycosylation patterns in the basal extracellular matrix (ECM). In animals, glycosyltransferases sculpt the polysaccharide-rich ECM, regulate integrin and cadherin activity, and, when disrupted, contribute to tumorigenesis. The finding that predicted glycosyltransferases promote proper rosette development and prevent cell aggregation in S. rosetta suggests a pre-metazoan role for glycosyltransferases in regulating development and preventing abnormal tumor-like multicellularity.
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Affiliation(s)
- Laura A Wetzel
- Department of Molecular and Cell BiologyUniversity of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
| | - Tera C Levin
- Department of Molecular and Cell BiologyUniversity of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
| | - Ryan E Hulett
- Department of Molecular and Cell BiologyUniversity of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
| | - Daniel Chan
- Department of Molecular and Cell BiologyUniversity of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
| | - Grant A King
- Department of Molecular and Cell BiologyUniversity of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
| | - Reef Aldayafleh
- Department of Molecular and Cell BiologyUniversity of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
| | - David S Booth
- Department of Molecular and Cell BiologyUniversity of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
| | - Monika Abedin Sigg
- Department of Molecular and Cell BiologyUniversity of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
| | - Nicole King
- Department of Molecular and Cell BiologyUniversity of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
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Feng L, Jia H, Qin Y, Song Y, Tao S, Liu Y. Rapid Identification of Major QTL S Associated With Near- Freezing Temperature Tolerance in Saccharomyces cerevisiae. Front Microbiol 2018; 9:2110. [PMID: 30254614 PMCID: PMC6141824 DOI: 10.3389/fmicb.2018.02110] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 08/20/2018] [Indexed: 11/16/2022] Open
Abstract
Temperatures had a strong effect on many life history traits, including growth, development and reproduction. At near-freezing temperatures (0–4°C), yeast cells could trigger series of biochemical reactions to respond and adapt to the stress, protect them against sever cold and freeze injury. Different Saccharomyces cerevisiae strains vary greatly in their ability to grow at near-freezing temperatures. However, the molecular mechanisms that allow yeast cells to sustain this response are not yet fully understood and the genetic basis of tolerance and sensitivity to near-freeze stress remains unclear. Uncovering the genetic determinants of this trait is, therefore, of is of significant interest. In order to investigate the genetic basis that underlies near-freezing temperature tolerance in S. cerevisiae, we mapped the major quantitative trait loci (QTLs) using bulk segregant analysis (BSA) in the F2 segregant population of two Chinese indigenous S. cerevisiae strains with divergent tolerance capability at 4°C. By genome-wide comparison of single-nucleotide polymorphism (SNP) profiles between two bulks of segregants with high and low tolerance to near-freezing temperature, a hot region located on chromosome IV was identified tightly associated with the near-freezing temperature tolerance. The Reciprocal hemizygosity analysis (RHA) and gene deletion was used to validate the genes involved in the trait, showed that the gene NAT1 plays a role in the near-freezing temperature tolerance. This study improved our understanding of the genetic basis of the variability of near-freezing temperature tolerance in yeasts. The superior allele identified could be used to genetically improve the near-freezing stress adaptation of industrial yeast strains.
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Affiliation(s)
- Li Feng
- College of Enology, Northwest A&F University, Yangling, China
| | - He Jia
- College of Enology, Northwest A&F University, Yangling, China
| | - Yi Qin
- College of Enology, Northwest A&F University, Yangling, China
| | - Yuyang Song
- College of Enology, Northwest A&F University, Yangling, China
| | - Shiheng Tao
- College of Life Sciences and State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, China
| | - Yanlin Liu
- College of Enology, Northwest A&F University, Yangling, China
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Abstract
The first eukaryotic genome to be sequenced was fungal, and there continue to be more sequenced genomes in the kingdom Fungi than in any other eukaryotic kingdom. Comparison of these genomes reveals many sources of genetic variation, from single nucleotide polymorphisms to horizontal gene transfer and on to changes in the arrangement and number of chromosomes, not to mention endofungal bacteria and viruses. Population genomics shows that all sources generate variation all the time and implicate natural selection as the force maintaining genome stability. Variation in wild populations is a rich resource for associating genetic variation with phenotypic variation, whether through quantitative trait locus mapping, genome-wide association studies, or reverse ecology. Subjects of studies associating genetic and phenotypic variation include model fungi, e.g., Saccharomyces and Neurospora, but pioneering studies have also been made with fungi pathogenic to plants, e.g., Pyricularia (= Magnaporthe), Zymoseptoria, and Fusarium, and to humans, e.g., Coccidioides, Cryptococcus, and Candida.
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Jamieson K, McNaught KJ, Ormsby T, Leggett NA, Honda S, Selker EU. Telomere repeats induce domains of H3K27 methylation in Neurospora. eLife 2018; 7:31216. [PMID: 29297465 PMCID: PMC5752202 DOI: 10.7554/elife.31216] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Accepted: 12/18/2017] [Indexed: 12/31/2022] Open
Abstract
Development in higher organisms requires selective gene silencing, directed in part by di-/trimethylation of lysine 27 on histone H3 (H3K27me2/3). Knowledge of the cues that control formation of such repressive Polycomb domains is extremely limited. We exploited natural and engineered chromosomal rearrangements in the fungus Neurospora crassa to elucidate the control of H3K27me2/3. Analyses of H3K27me2/3 in strains bearing chromosomal rearrangements revealed both position-dependent and position-independent facultative heterochromatin. We found that proximity to chromosome ends is necessary to maintain, and sufficient to induce, transcriptionally repressive, subtelomeric H3K27me2/3. We ascertained that such telomere-proximal facultative heterochromatin requires native telomere repeats and found that a short array of ectopic telomere repeats, (TTAGGG)17, can induce a large domain (~225 kb) of H3K27me2/3. This provides an example of a cis-acting sequence that directs H3K27 methylation. Our findings provide new insight into the relationship between genome organization and control of heterochromatin formation.
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Affiliation(s)
- Kirsty Jamieson
- Institute of Molecular Biology, University of Oregon, Eugene, United States
| | - Kevin J McNaught
- Institute of Molecular Biology, University of Oregon, Eugene, United States
| | - Tereza Ormsby
- Institute of Molecular Biology, University of Oregon, Eugene, United States
| | - Neena A Leggett
- Institute of Molecular Biology, University of Oregon, Eugene, United States
| | - Shinji Honda
- Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Eric U Selker
- Institute of Molecular Biology, University of Oregon, Eugene, United States
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Zaccaron M, Sharma S, Bluhm BH. MoNSTR-seq, a restriction site-associated DNA sequencing technique to characterize Agrobacterium-mediated transfer-DNA insertions in Phomopsis longicolla. Lett Appl Microbiol 2018; 66:19-24. [PMID: 29108115 DOI: 10.1111/lam.12817] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 10/14/2017] [Accepted: 10/24/2017] [Indexed: 11/26/2022]
Abstract
Phomopsis longicolla (Hobbs) causes Phomopsis seed decay and stem lesions in soybean (Glycine max). In this study, a novel, high-throughput adaptation of RAD-seq termed MoNSTR-seq (Mutation analysis via Next-generation DNA Sequencing of T-DNA Regions) was developed to determine the genomic location of T-DNA insertions in P. longicolla mutants. Insertional mutants were created via Agrobacterium tumefaciens-mediated transformation, and one mutant, strain PL343, was further investigated due to impaired stem lesion formation. Mutation analysis via Next-generation DNA Sequencing of T-DNA Regions, in which DNA libraries are created with two distinct restriction enzymes and customized adapters to simultaneously enrich both T-DNA insertion borders, was developed to characterize the genomic lesion in strain PL343. MoNSTR-seq successfully identified a T-DNA insertion in the predicted promoter region of a gene encoding a cellobiose dehydrogenase (CDH1), and the position of the T-DNA insertion in strain PL343 was confirmed by Sanger sequencing. Thus, MoNSTR-seq represents an effective tool for molecular genetics in P. longicolla, and is readily adaptable for use in diverse fungal species. SIGNIFICANCE AND IMPACT OF THE STUDY This study describes MoNSTR-seq (Mutation analysis via Next-generation DNA Sequencing of T-DNA Regions), an adaptation of restriction site-associated DNA sequencing (RAD-seq) to identify the position of transfer-DNA (T-DNA) insertions in the genome of Phomopsis longicolla, an important pathogen of soybean. The technique enables high-throughput characterization of mutants generated via Agrobacterium tumefaciens-mediated transformation (ATMT), thus accelerating gene discovery via forward genetics. This technique represents a significant advancement over existing approaches to characterize T-DNA insertions in fungal genomes. With minor modifications, this technique could be easily adapted to taxonomically diverse fungal pathogens and additional mutagenesis cassettes.
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Affiliation(s)
- M Zaccaron
- Department of Plant Pathology, University of Arkansas, Fayetteville, AR, USA
| | - S Sharma
- Department of Plant Pathology, University of Arkansas, Fayetteville, AR, USA
| | - B H Bluhm
- Department of Plant Pathology, University of Arkansas, Fayetteville, AR, USA
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Arentshorst M, Ram AFJ. Parasexual Crossings for Bulk Segregant Analysis in Aspergillus niger to Facilitate Mutant Identification Via Whole Genome Sequencing. Methods Mol Biol 2018; 1775:277-287. [PMID: 29876825 DOI: 10.1007/978-1-4939-7804-5_22] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The industrially important fungus Aspergillus niger is known to reproduce only asexually. The parasexual cycle of fungi can be used for crossing two different strains to produce segregants or progeny with combined mutations even in fungi without a known sexual cycle. In A. niger, the parasexual cycle has been extensively used to establish linkage groups and to generate genetic maps. With the advent of whole genome sequencing, the parasexual cycle has received renewed attention as a method to create segregants for bulk segregant analysis. Bulk segregant analysis is a genetic technique used to link and ultimately identify the mutation associated with a particular phenotype. In this chapter we describe the procedure for setting up parasexual crossings in A. niger. The segregants obtained with this method can be used in combination with next-generation sequencing to map mutations in the organism.
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Affiliation(s)
- Mark Arentshorst
- Molecular Microbiology and Biotechnology, Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | - Arthur F J Ram
- Molecular Microbiology and Biotechnology, Institute of Biology Leiden, Leiden University, Leiden, The Netherlands.
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Plasticity of the MFS1 Promoter Leads to Multidrug Resistance in the Wheat Pathogen Zymoseptoria tritici. mSphere 2017; 2:mSphere00393-17. [PMID: 29085913 PMCID: PMC5656749 DOI: 10.1128/msphere.00393-17] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 09/21/2017] [Indexed: 11/20/2022] Open
Abstract
The ascomycete Zymoseptoria tritici is the causal agent of Septoria leaf blotch on wheat. Disease control relies mainly on resistant wheat cultivars and on fungicide applications. The fungus displays a high potential to circumvent both methods. Resistance against all unisite fungicides has been observed over decades. A different type of resistance has emerged among wild populations with multidrug-resistant (MDR) strains. Active fungicide efflux through overexpression of the major facilitator gene MFS1 explains this emerging resistance mechanism. Applying a bulk-progeny sequencing approach, we identified in this study a 519-bp long terminal repeat (LTR) insert in the MFS1 promoter, a relic of a retrotransposon cosegregating with the MDR phenotype. Through gene replacement, we show the insert as a mutation responsible for MFS1 overexpression and the MDR phenotype. Besides this type I insert, we found two different types of promoter inserts in more recent MDR strains. Type I and type II inserts harbor potential transcription factor binding sites, but not the type III insert. Interestingly, all three inserts correspond to repeated elements present at different genomic locations in either IPO323 or other Z. tritici strains. These results underline the plasticity of repeated elements leading to fungicide resistance in Z. tritici and which contribute to its adaptive potential. IMPORTANCE Disease control through fungicides remains an important means to protect crops from fungal diseases and to secure the harvest. Plant-pathogenic fungi, especially Zymoseptoria tritici, have developed resistance against most currently used active ingredients, reducing or abolishing their efficacy. While target site modification is the most common resistance mechanism against single modes of action, active efflux of multiple drugs is an emerging phenomenon in fungal populations reducing additionally fungicides' efficacy in multidrug-resistant strains. We have investigated the mutations responsible for increased drug efflux in Z. tritici field strains. Our study reveals that three different insertions of repeated elements in the same promoter lead to multidrug resistance in Z. tritici. The target gene encodes the membrane transporter MFS1 responsible for drug efflux, with the promoter inserts inducing its overexpression. These results underline the plasticity of repeated elements leading to fungicide resistance in Z. tritici.
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Abstract
The genetic material, contained on chromosomes, is often described as the "blueprint for life." During nuclear division, the chromosomes are pulled into each of the two daughter nuclei by the coordination of spindle microtubules, kinetochores, centromeres, and chromatin. These four functional units must link the chromosomes to the microtubules, signal to the cell when the attachment is made so that division can proceed, and withstand the force generated by pulling the chromosomes to either daughter cell. To perform each of these functions, kinetochores are large protein complexes, approximately 5MDa in size, and they contain at least 45 unique proteins. Many of the central components in the kinetochore are well conserved, yielding a common core of proteins forming consistent structures. However, many of the peripheral subcomplexes vary between different taxonomic groups, including changes in primary sequence and gain or loss of whole proteins. It is still unclear how significant these changes are, and answers to this question may provide insights into adaptation to specific lifestyles or progression of disease that involve chromosome instability.
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Erlendson AA, Friedman S, Freitag M. A Matter of Scale and Dimensions: Chromatin of Chromosome Landmarks in the Fungi. Microbiol Spectr 2017; 5:10.1128/microbiolspec.FUNK-0054-2017. [PMID: 28752814 PMCID: PMC5536859 DOI: 10.1128/microbiolspec.funk-0054-2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Indexed: 02/06/2023] Open
Abstract
Chromatin and chromosomes of fungi are highly diverse and dynamic, even within species. Much of what we know about histone modification enzymes, RNA interference, DNA methylation, and cell cycle control was first addressed in Saccharomyces cerevisiae, Schizosaccharomyces pombe, Aspergillus nidulans, and Neurospora crassa. Here, we examine the three landmark regions that are required for maintenance of stable chromosomes and their faithful inheritance, namely, origins of DNA replication, telomeres and centromeres. We summarize the state of recent chromatin research that explains what is required for normal function of these specialized chromosomal regions in different fungi, with an emphasis on the silencing mechanism associated with subtelomeric regions, initiated by sirtuin histone deacetylases and histone H3 lysine 27 (H3K27) methyltransferases. We explore mechanisms for the appearance of "accessory" or "conditionally dispensable" chromosomes and contrast what has been learned from studies on genome-wide chromosome conformation capture in S. cerevisiae, S. pombe, N. crassa, and Trichoderma reesei. While most of the current knowledge is based on work in a handful of genetically and biochemically tractable model organisms, we suggest where major knowledge gaps remain to be closed. Fungi will continue to serve as facile organisms to uncover the basic processes of life because they make excellent model organisms for genetics, biochemistry, cell biology, and evolutionary biology.
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Affiliation(s)
- Allyson A. Erlendson
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
| | - Steven Friedman
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
| | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
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Friedman S, Freitag M. Centrochromatin of Fungi. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2017; 56:85-109. [PMID: 28840234 DOI: 10.1007/978-3-319-58592-5_4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The centromere is an essential chromosomal locus that dictates the nucleation point for assembly of the kinetochore and subsequent attachment of spindle microtubules during chromosome segregation. Research over the last decades demonstrated that centromeres are defined by a combination of genetic and epigenetic factors. Recent work showed that centromeres are quite diverse and flexible and that many types of centromere sequences and centromeric chromatin ("centrochromatin") have evolved. The kingdom of the fungi serves as an outstanding example of centromere plasticity, including organisms with centromeres as diverse as 0.15-300 kb in length, and with different types of chromatin states for most species examined thus far. Some of the species in the less familiar taxa provide excellent opportunities to help us better understand centromere biology in all eukaryotes, which may improve treatment options against fungal infection, and biotechnologies based on fungi. This review summarizes the current knowledge of fungal centromeres and centrochromatin, including an outlook for future research.
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Affiliation(s)
- Steven Friedman
- Department of Biochemistry and Biophysics, Oregon State University, 2011 ALS Bldg, Corvallis, OR, 97331, USA
| | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, 2011 ALS Bldg, Corvallis, OR, 97331, USA.
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22
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Reilly MC, Magnuson JK, Baker SE. Approaches to understanding protein hypersecretion in fungi. FUNGAL BIOL REV 2016. [DOI: 10.1016/j.fbr.2016.06.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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23
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Bischof RH, Ramoni J, Seiboth B. Cellulases and beyond: the first 70 years of the enzyme producer Trichoderma reesei. Microb Cell Fact 2016; 15:106. [PMID: 27287427 PMCID: PMC4902900 DOI: 10.1186/s12934-016-0507-6] [Citation(s) in RCA: 280] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 06/01/2016] [Indexed: 11/10/2022] Open
Abstract
More than 70 years ago, the filamentous ascomycete Trichoderma reesei was isolated on the Solomon Islands due to its ability to degrade and thrive on cellulose containing fabrics. This trait that relies on its secreted cellulases is nowadays exploited by several industries. Most prominently in biorefineries which use T. reesei enzymes to saccharify lignocellulose from renewable plant biomass in order to produce biobased fuels and chemicals. In this review we summarize important milestones of the development of T. reesei as the leading production host for biorefinery enzymes, and discuss emerging trends in strain engineering. Trichoderma reesei has very recently also been proposed as a consolidated bioprocessing organism capable of direct conversion of biopolymeric substrates to desired products. We therefore cover this topic by reviewing novel approaches in metabolic engineering of T. reesei.
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Affiliation(s)
- Robert H Bischof
- Austrian Centre of Industrial Biotechnology (ACIB) GmbH c/o Institute of Chemical Engineering, TU Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria
| | - Jonas Ramoni
- Molecular Biotechnology, Research Area Biochemical Technology, Institute of Chemical Engineering, TU Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria
| | - Bernhard Seiboth
- Austrian Centre of Industrial Biotechnology (ACIB) GmbH c/o Institute of Chemical Engineering, TU Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria. .,Molecular Biotechnology, Research Area Biochemical Technology, Institute of Chemical Engineering, TU Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria.
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Pulido-Tamayo S, Duitama J, Marchal K. EXPLoRA-web: linkage analysis of quantitative trait loci using bulk segregant analysis. Nucleic Acids Res 2016; 44:W142-6. [PMID: 27105844 PMCID: PMC4987886 DOI: 10.1093/nar/gkw298] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 04/11/2016] [Indexed: 11/13/2022] Open
Abstract
Identification of genomic regions associated with a phenotype of interest is a fundamental step toward solving questions in biology and improving industrial research. Bulk segregant analysis (BSA) combined with high-throughput sequencing is a technique to efficiently identify these genomic regions associated with a trait of interest. However, distinguishing true from spuriously linked genomic regions and accurately delineating the genomic positions of these truly linked regions requires the use of complex statistical models currently implemented in software tools that are generally difficult to operate for non-expert users. To facilitate the exploration and analysis of data generated by bulked segregant analysis, we present EXPLoRA-web, a web service wrapped around our previously published algorithm EXPLoRA, which exploits linkage disequilibrium to increase the power and accuracy of quantitative trait loci identification in BSA analysis. EXPLoRA-web provides a user friendly interface that enables easy data upload and parallel processing of different parameter configurations. Results are provided graphically and as BED file and/or text file and the input is expected in widely used formats, enabling straightforward BSA data analysis. The web server is available at http://bioinformatics.intec.ugent.be/explora-web/.
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Affiliation(s)
- Sergio Pulido-Tamayo
- Department of Information Technology, iGent Toren, Technologiepark 15, 9052 Gent, Belgium Department of Plant Biotechnology and Bioinformatics, UGent, Technologiepark 927, 9052 Gent, Belgium Bioinformatics Institute Ghent, Technologiepark 927, 9052 Gent, Belgium Department of Microbial and Molecular Systems, KU Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium
| | - Jorge Duitama
- Agrobiodiversity Research Area, International Center for Tropical Agriculture (CIAT), 763537 Cali, Colombia
| | - Kathleen Marchal
- Department of Information Technology, iGent Toren, Technologiepark 15, 9052 Gent, Belgium Department of Plant Biotechnology and Bioinformatics, UGent, Technologiepark 927, 9052 Gent, Belgium Bioinformatics Institute Ghent, Technologiepark 927, 9052 Gent, Belgium Department of Genetics, University of Pretoria, Hatfield Campus, Pretoria 0028, South Africa
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Sarrocco S. Dung-inhabiting fungi: a potential reservoir of novel secondary metabolites for the control of plant pathogens. PEST MANAGEMENT SCIENCE 2016; 72:643-652. [PMID: 26662623 DOI: 10.1002/ps.4206] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 11/19/2015] [Accepted: 12/01/2015] [Indexed: 06/05/2023]
Abstract
Coprophilous fungi are a large group of saprotrophic fungi mostly found in herbivore dung. The number of these fungi undergoing investigation is continually increasing, and new species and genera continue to be described. Dung-inhabiting fungi play an important ecological role in decomposing and recycling nutrients from animal dung. They produce a large array of bioactive secondary metabolites and have a potent enzymatic arsenal able to utilise even complex molecules. Bioactive secondary metabolites are actively involved in interaction with and defence against other organisms whose growth can be inhibited, resulting in an enhanced ecological fitness of producer strains. Currently, these antibiotics and bioactive secondary metabolites are of interest in medicine in particular, while very little information is available concerning their potential use in agriculture. This review introduces the ecology of dung-inhabiting fungi, with particular emphasis on the production of antibiotic compounds as a means to compete with other microorganisms. Owing to the fast pace of technological progress, new approaches to predicting the biosynthesis of bioactive metabolites are proposed. Coprophilous fungi should be considered as elite candidate organisms for the discovery of novel antifungal compounds, above all in view of their exploitation for crop protection.
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Affiliation(s)
- Sabrina Sarrocco
- Department of Agriculture, Food and Environment, University of Pisa, Pisa, Italy
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26
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Adhvaryu K, Firoozi G, Motavaze K, Lakin-Thomas P. PRD-1, a Component of the Circadian System of Neurospora crassa, Is a Member of the DEAD-box RNA Helicase Family. J Biol Rhythms 2016; 31:258-71. [PMID: 27029286 DOI: 10.1177/0748730416639717] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The circadian rhythms found in almost all organisms are driven by molecular oscillators, including transcription/translation feedback loops (TTFLs). However, TTFL-independent oscillators can drive rhythms in both eukaryotes and prokaryotes. The fungus Neurospora crassa is a model organism for studying the molecular mechanism of the circadian clock. Although a circadian TTFL involving the proteins FRQ, WC-1, and WC-2 is well-characterized in N. crassa, rhythms can still be observed in the absence of this feedback loop. These rhythms are said to be driven by 1 or more FRQ-less oscillator(s) (FLOs). The prd-1 mutation lengthens the period in frq wild type and was previously shown to severely disrupt FRQ-less rhythms in frq null mutants under several different conditions; therefore, the prd-1 gene product is a candidate for a component of a FLO. We report here that prd-1 also disrupts free-running rhythms in wc-1 null mutants, confirming its effects on FRQ-less rhythms. We have now mapped and identified the prd-1 gene as NCU07839, a DEAD-box RNA helicase dbp-2 Complementation with the wild-type gene corrects the rhythm defects of the prd-1 mutant in the complete circadian system (when the FRQ-based TTFL is intact) and also the free-running FRQ-less rhythm on low choline. A PRD-1-GFP fusion protein localizes to the nucleus. The prd-1 mutant has a single base pair change in the first base of an intron that results in abnormally spliced transcripts. FRQ-less rhythms on low choline, or entrained to heat pulses, were only marginally affected in strains carrying deletions of 2 other RNA helicases (prd-6 and msp-8). We conclude that PRD-1 is a member of an RNA helicase family that may be specifically involved in regulating rhythmicity in N. crassa in both the complete circadian system and FLO(s).
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Affiliation(s)
| | | | - Kamyar Motavaze
- Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario M5T 1R4, Canada
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27
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Pomraning KR, Kim YM, Nicora CD, Chu RK, Bredeweg EL, Purvine SO, Hu D, Metz TO, Baker SE. Multi-omics analysis reveals regulators of the response to nitrogen limitation in Yarrowia lipolytica. BMC Genomics 2016; 17:138. [PMID: 26911370 PMCID: PMC4766638 DOI: 10.1186/s12864-016-2471-2] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 02/12/2016] [Indexed: 01/03/2023] Open
Abstract
Background Yarrowia lipolytica is an oleaginous ascomycete yeast that stores lipids in response to limitation of nitrogen. While the enzymatic pathways responsible for neutral lipid accumulation in Y. lipolytica are well characterized, regulation of these pathways has received little attention. We therefore sought to characterize the response to nitrogen limitation at system-wide levels, including the proteome, phosphoproteome and metabolome, to better understand how this organism regulates and controls lipid metabolism and to identify targets that may be manipulated to improve lipid yield. Results We found that ribosome structural genes are down-regulated under nitrogen limitation, during which nitrogen containing compounds (alanine, putrescine, spermidine and urea) are depleted and sugar alcohols and TCA cycle intermediates accumulate (citrate, fumarate and malate). We identified 1219 novel phosphorylation sites in Y. lipolytica, 133 of which change in their abundance during nitrogen limitation. Regulatory proteins, including kinases and DNA binding proteins, are particularly enriched for phosphorylation. Within lipid synthesis pathways, we found that ATP-citrate lyase, acetyl-CoA carboxylase and lecithin cholesterol acyl transferase are phosphorylated during nitrogen limitation while many of the proteins involved in β-oxidation are down-regulated, suggesting that storage lipid accumulation may be regulated by phosphorylation of key enzymes. Further, we identified short DNA elements that associate specific transcription factor families with up- and down-regulated genes. Conclusions Integration of metabolome, proteome and phosphoproteome data identifies lipid accumulation in response to nitrogen limitation as a two-fold result of increased production of acetyl-CoA from excess citrate and decreased capacity for β-oxidation. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2471-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kyle R Pomraning
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA.
| | - Young-Mo Kim
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA.
| | - Carrie D Nicora
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA.
| | - Rosalie K Chu
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA.
| | - Erin L Bredeweg
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA.
| | - Samuel O Purvine
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA.
| | - Dehong Hu
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA.
| | - Thomas O Metz
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA.
| | - Scott E Baker
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA.
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Hu MJ, Zhang HP, Liu K, Cao JJ, Wang SX, Jiang H, Wu ZY, Lu J, Zhu XF, Xia XC, Sun GL, Ma CX, Chang C. Cloning and Characterization of TaTGW-7A Gene Associated with Grain Weight in Wheat via SLAF-seq-BSA. FRONTIERS IN PLANT SCIENCE 2016; 7:1902. [PMID: 28066462 PMCID: PMC5167734 DOI: 10.3389/fpls.2016.01902] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 12/01/2016] [Indexed: 05/18/2023]
Abstract
Thousand-grain weight (TGW) of wheat (Triticum aestivum L.) contributes significantly to grain yield. In the present study, a candidate gene associated with TGW was identified through specific-locus amplified fragment sequencing (SLAF-seq) of DNA bulks of recombinant inbred lines (RIL) derived from the cross between Jing 411 and Hongmangchun 21. The gene was located on chromosome 7A, designated as TaTGW-7A with a complete genome sequence and an open reading frame (ORF). A single nucleotide polymorphism (SNP) was present in the first exon between two alleles at TaTGW-7A locus, resulting in a Val to Ala substitution, corresponding to a change from higher to lower TGW. Cleaved amplified polymorphic sequence (CAPS) (TGW7A) and InDel (TG9) markers were developed to discriminate the two alleles TaTGW-7Aa and TaTGW-7Ab for higher and lower TGW, respectively. A major QTL co-segregating with TaTGW-7A explained 21.7-27.1% of phenotypic variance for TGW in the RIL population across five environments. The association of TaTGW-7A with TGW was further validated in a natural population and Chinese mini-core collections. Quantitative real-time PCR revealed higher transcript levels of TaTGW-7Aa than those of TaTGW-7Ab during grain development. High frequencies of the superior allele TaTGW-7Aa for higher TGW in Chinese mini-core collections (65.0%) and 501 wheat varieties (86.0%) indicated a strong and positive selection of this allele in wheat breeding. The molecular markers TGW7A and TG9 can be used for improvement of TGW in breeding programs.
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Affiliation(s)
- Ming-Jian Hu
- College of Agronomy, Anhui Agricultural University – Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, The Ministry of AgricultureHefei, China
| | - Hai-Ping Zhang
- College of Agronomy, Anhui Agricultural University – Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, The Ministry of AgricultureHefei, China
| | - Kai Liu
- College of Agronomy, Anhui Agricultural University – Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, The Ministry of AgricultureHefei, China
| | - Jia-Jia Cao
- College of Agronomy, Anhui Agricultural University – Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, The Ministry of AgricultureHefei, China
| | - Sheng-Xing Wang
- College of Agronomy, Anhui Agricultural University – Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, The Ministry of AgricultureHefei, China
| | - Hao Jiang
- College of Agronomy, Anhui Agricultural University – Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, The Ministry of AgricultureHefei, China
| | - Zeng-Yun Wu
- College of Agronomy, Anhui Agricultural University – Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, The Ministry of AgricultureHefei, China
| | - Jie Lu
- College of Agronomy, Anhui Agricultural University – Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, The Ministry of AgricultureHefei, China
| | - Xiao F. Zhu
- College of Agronomy, Anhui Agricultural University – Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, The Ministry of AgricultureHefei, China
| | - Xian-Chun Xia
- College of Agronomy, Anhui Agricultural University – Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, The Ministry of AgricultureHefei, China
- National Wheat Improvement Center/The National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural SciencesBeijing, China
| | - Gen-Lou Sun
- College of Agronomy, Anhui Agricultural University – Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, The Ministry of AgricultureHefei, China
- Department of Biology, Saint Mary’s University, HalifaxNS, Canada
| | - Chuan-Xi Ma
- College of Agronomy, Anhui Agricultural University – Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, The Ministry of AgricultureHefei, China
| | - Cheng Chang
- College of Agronomy, Anhui Agricultural University – Key Laboratory of Wheat Biology and Genetic Improvement on Southern Yellow & Huai River Valley, The Ministry of AgricultureHefei, China
- *Correspondence: Cheng Chang,
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Identification of a Classical Mutant in the Industrial Host Aspergillus niger by Systems Genetics: LaeA Is Required for Citric Acid Production and Regulates the Formation of Some Secondary Metabolites. G3-GENES GENOMES GENETICS 2015; 6:193-204. [PMID: 26566947 PMCID: PMC4704718 DOI: 10.1534/g3.115.024067] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The asexual filamentous fungus Aspergillus niger is an important industrial cell factory for citric acid production. In this study, we genetically characterized a UV-generated A. niger mutant that was originally isolated as a nonacidifying mutant, which is a desirable trait for industrial enzyme production. Physiological analysis showed that this mutant did not secrete large amounts of citric acid and oxalic acid, thus explaining the nonacidifying phenotype. As traditional complementation approaches to characterize the mutant genotype were unsuccessful, we used bulk segregant analysis in combination with high-throughput genome sequencing to identify the mutation responsible for the nonacidifying phenotype. Since A. niger has no sexual cycle, parasexual genetics was used to generate haploid segregants derived from diploids by loss of whole chromosomes. We found that the nonacidifying phenotype was caused by a point mutation in the laeA gene. LaeA encodes a putative methyltransferase-domain protein, which we show here to be required for citric acid production in an A. niger lab strain (N402) and in other citric acid production strains. The unexpected link between LaeA and citric acid production could provide new insights into the transcriptional control mechanisms related to citric acid production in A. niger. Interestingly, the secondary metabolite profile of a ΔlaeA strain differed from the wild-type strain, showing both decreased and increased metabolite levels, indicating that LaeA is also involved in regulating the production of secondary metabolites. Finally, we show that our systems genetics approach is a powerful tool to identify trait mutations.
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Genome-wide redistribution of H3K27me3 is linked to genotoxic stress and defective growth. Proc Natl Acad Sci U S A 2015; 112:E6339-48. [PMID: 26578794 DOI: 10.1073/pnas.1511377112] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
H3K9 methylation directs heterochromatin formation by recruiting multiple heterochromatin protein 1 (HP1)-containing complexes that deacetylate histones and methylate cytosine bases in DNA. In Neurospora crassa, a single H3K9 methyltransferase complex, called the DIM-5,-7,-9, CUL4, DDB1 Complex (DCDC), is required for normal growth and development. DCDC-deficient mutants are hypersensitive to the genotoxic agent methyl methanesulfonate (MMS), but the molecular basis of genotoxic stress is unclear. We found that both the MMS sensitivity and growth phenotypes of DCDC-deficient strains are suppressed by mutation of embryonic ectoderm development or Su-(var)3-9; E(z); Trithorax (set)-7, encoding components of the H3K27 methyltransferase Polycomb repressive complex-2 (PRC2). Trimethylated histone H3K27 (H3K27me3) undergoes genome-wide redistribution to constitutive heterochromatin in DCDC- or HP1-deficient mutants, and introduction of an H3K27 missense mutation is sufficient to rescue phenotypes of DCDC-deficient strains. Accumulation of H3K27me3 in heterochromatin does not compensate for silencing; rather, strains deficient for both DCDC and PRC2 exhibit synthetic sensitivity to the topoisomerase I inhibitor Camptothecin and accumulate γH2A at heterochromatin. Together, these data suggest that PRC2 modulates the response to genotoxic stress.
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Genome sequencing of the Trichoderma reesei QM9136 mutant identifies a truncation of the transcriptional regulator XYR1 as the cause for its cellulase-negative phenotype. BMC Genomics 2015; 16:326. [PMID: 25909478 PMCID: PMC4409711 DOI: 10.1186/s12864-015-1526-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 04/13/2015] [Indexed: 02/08/2023] Open
Abstract
Background Trichoderma reesei is the main industrial source of cellulases and hemicellulases required for the hydrolysis of biomass to simple sugars, which can then be used in the production of biofuels and biorefineries. The highly productive strains in use today were generated by classical mutagenesis. As byproducts of this procedure, mutants were generated that turned out to be unable to produce cellulases. In order to identify the mutations responsible for this inability, we sequenced the genome of one of these strains, QM9136, and compared it to that of its progenitor T. reesei QM6a. Results In QM9136, we detected a surprisingly low number of mutagenic events in the promoter and coding regions of genes, i.e. only eight indels and six single nucleotide variants. One of these indels led to a frame-shift in the Zn2Cys6 transcription factor XYR1, the general regulator of cellulase and xylanase expression, and resulted in its C-terminal truncation by 140 amino acids. Retransformation of strain QM9136 with the wild-type xyr1 allele fully recovered the ability to produce cellulases, and is thus the reason for the cellulase-negative phenotype. Introduction of an engineered xyr1 allele containing the truncating point mutation into the moderate producer T. reesei QM9414 rendered this strain also cellulase-negative. The correspondingly truncated XYR1 protein was still able to enter the nucleus, but failed to be expressed over the basal constitutive level. Conclusion The missing 140 C-terminal amino acids of XYR1 are therefore responsible for its previously observed auto-regulation which is essential for cellulases to be expressed. Our data present a working example of the use of genome sequencing leading to a functional explanation of the QM9136 cellulase-negative phenotype. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1526-0) contains supplementary material, which is available to authorized users.
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Urban M, King R, Hassani-Pak K, Hammond-Kosack KE. Whole-genome analysis of Fusarium graminearum insertional mutants identifies virulence associated genes and unmasks untagged chromosomal deletions. BMC Genomics 2015; 16:261. [PMID: 25881124 PMCID: PMC4404607 DOI: 10.1186/s12864-015-1412-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 02/27/2015] [Indexed: 12/24/2022] Open
Abstract
Background Identifying pathogen virulence genes required to cause disease is crucial to understand the mechanisms underlying the pathogenic process. Plasmid insertion mutagenesis of fungal protoplasts is frequently used for this purpose in filamentous ascomycetes. Post transformation, the mutant population is screened for loss of virulence to a specific plant or animal host. Identifying the insertion event has previously met with varying degrees of success, from a cleanly disrupted gene with minimal deletion of nucleotides at the insertion point to multiple-copy insertion events and large deletions of chromosomal regions. Currently, extensive mutant collections exist in laboratories globally where it was hitherto impossible to identify all the affected genes. Results We used a whole-genome sequencing (WGS) approach using Illumina HiSeq 2000 technology to investigate DNA tag insertion points and chromosomal deletion events in mutagenised, reduced virulence F. graminearum isolates identified in disease tests on wheat (Triticum aestivum). We developed the FindInsertSeq workflow to localise the DNA tag insertions to the nucleotide level. The workflow was tested using four mutants showing evidence of single and multi-copy insertions in DNA blot analysis. FindInsertSeq was able to identify both single and multi-copy concatenation insertion sites. By comparing sequencing coverage, unexpected molecular recombination events such as large tagged and untagged chromosomal deletions, and DNA amplification were observed in three of the analysed mutants. A random data sampling approach revealed the minimum genome coverage required to survey the F. graminearum genome for alterations. Conclusions This study demonstrates that whole-genome re-sequencing to 22x fold genome coverage is an efficient tool to characterise single and multi-copy insertion mutants in the filamentous ascomycete Fusarium graminearum. In some cases insertion events are accompanied with large untagged chromosomal deletions while in other cases a straight-forward insertion event could be confirmed. The FindInsertSeq analysis workflow presented in this study enables researchers to efficiently characterise insertion and deletion mutants. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1412-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Martin Urban
- Department of Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK.
| | - Robert King
- Department of Computational and Systems Biology, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK.
| | - Keywan Hassani-Pak
- Department of Computational and Systems Biology, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK.
| | - Kim E Hammond-Kosack
- Department of Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK.
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Abstract
We report the elucidation of the complete genome of the Neurospora crassa (Shear and Dodge) strain FGSC 73, a mat-a, trp-3 mutant strain. The genome sequence around the idiotypic mating type locus represents the only publicly available sequence for a mat-a strain. 40.42 Megabases are assembled into 358 scaffolds carrying 11,978 gene models.
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Chen W, Yao J, Chu L, Yuan Z, Li Y, Zhang Y. Genetic mapping of the nulliplex-branch gene (gb_nb1) in cotton using next-generation sequencing. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2015; 128:539-47. [PMID: 25575840 DOI: 10.1007/s00122-014-2452-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 12/24/2014] [Indexed: 05/21/2023]
Abstract
Using bulked segregant analysis based on next-generation sequencing, the recessive nulliplex-branch gene was mapped between two SNP markers ~600 kb apart. In a "nulliplex-branch" cotton mutant, most of the flowers arise directly from leaf axils on the main shoot, which usually does not have a fruiting branch. A nulliplex-branch is a useful trait by which to study cotton architecture; however, the genetic basis of this mutant has remained elusive. In this study, bulked segregant analysis combined with next-generation sequencing technology was used to finely map the underlying genes that result in a nulliplex-branch plant. The nulliplex-branch Pima cotton variety, Xinhai-18, was crossed with the normal branch upland cotton line, TM-1, resulting in an F2 population. The nulliplex-branch trait was found to be controlled by the recessive gene gb_nb1. Allelic single-nucleotide polymorphisms (SNPs) were discovered by reduced-representation sequencing between the parents, and their profiles were also characterized in the nulliplex-branch and normal branch bulks constructed using the F2 plants. A candidate ~9.0 Mb-long region comprising 42 SNP markers was found to be associated with gb_nb1, which helped localize it at the ~600-kb interval on Chr 16 by segregation analysis in the F2 population. The closely linked markers with gb_nb1 developed in this study will facilitate the marker-assisted selection of the nulliplex-branch trait, and the fine map constructed will accelerate map-based cloning of gb_nb1.
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Affiliation(s)
- Wei Chen
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, The Chinese Academy of Agricultural Sciences, Anyang, 455004, China
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Schierenbeck L, Ries D, Rogge K, Grewe S, Weisshaar B, Kruse O. Fast forward genetics to identify mutations causing a high light tolerant phenotype in Chlamydomonas reinhardtii by whole-genome-sequencing. BMC Genomics 2015; 16:57. [PMID: 25730202 PMCID: PMC4336690 DOI: 10.1186/s12864-015-1232-y] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 01/12/2015] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND High light tolerance of microalgae is a desired phenotype for efficient cultivation in large scale production systems under fluctuating outdoor conditions. Outdoor cultivation requires the use of either wild-type or non-GMO derived mutant strains due to safety concerns. The identification and molecular characterization of such mutants derived from untagged forward genetics approaches was limited previously by the tedious and time-consuming methods involving techniques such as classical meiotic mapping. The combination of mapping with next generation sequencing technologies offers alternative strategies to identify genes involved in high light adaptation in untagged mutants. RESULTS We used the model alga Chlamydomonas reinhardtii in a non-GMO mutation strategy without any preceding crossing step or pooled progeny to identify genes involved in the regulatory processes of high light adaptation. To generate high light tolerant mutants, wildtype cells were mutagenized only to a low extent, followed by a stringent selection. We performed whole-genome sequencing of two independent mutants hit1 and hit2 and the parental wildtype. The availability of a reference genome sequence and the removal of shared bakground variants between the wildtype strain and each mutant, enabled us to identify two single nucleotide polymorphisms within the same gene Cre02.g085050, hereafter called LRS1 (putative Light Response Signaling protein 1). These two independent single amino acid exchanges are both located in the putative WD40 propeller domain of the corresponding protein LRS1. Both mutants exhibited an increased rate of non-photochemical-quenching (NPQ) and an improved resistance against chemically induced reactive oxygen species. In silico analyses revealed homology of LRS1 to the photoregulatory protein COP1 in plants. CONCLUSIONS In this work we identified the nuclear encoded gene LRS1 as an essential factor for high light adaptation in C. reinhardtii. The causative random mutation within this gene was identified by a rapid and efficient method, avoiding any preceding crossing step, meiotic mapping, or pooled progeny. Our results open up new insights into mechanisms of high light adaptation in microalgae and at the same time provide a simplified strategy for non-GMO forward genetics, a crucial precondition that could result in the identification of key factors for economically relevant biological processes within algae.
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Affiliation(s)
- Lisa Schierenbeck
- />Department of Biology/Center for Biotechnology, Algae Biotechnology and Bioenergy, Bielefeld University, Universitätsstrasse 27, 33615 Bielefeld, Germany
| | - David Ries
- />Department of Biology/Center for Biotechnology, Genome Research, Bielefeld University, Universitätsstrasse 27, 33615 Bielefeld, Germany
| | - Kristin Rogge
- />Department of Biology/Center for Biotechnology, Algae Biotechnology and Bioenergy, Bielefeld University, Universitätsstrasse 27, 33615 Bielefeld, Germany
| | - Sabrina Grewe
- />Department of Biology/Center for Biotechnology, Algae Biotechnology and Bioenergy, Bielefeld University, Universitätsstrasse 27, 33615 Bielefeld, Germany
| | - Bernd Weisshaar
- />Department of Biology/Center for Biotechnology, Genome Research, Bielefeld University, Universitätsstrasse 27, 33615 Bielefeld, Germany
| | - Olaf Kruse
- />Department of Biology/Center for Biotechnology, Algae Biotechnology and Bioenergy, Bielefeld University, Universitätsstrasse 27, 33615 Bielefeld, Germany
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Characterization of the mutagenic spectrum of 4-nitroquinoline 1-oxide (4-NQO) in Aspergillus nidulans by whole genome sequencing. G3-GENES GENOMES GENETICS 2014; 4:2483-92. [PMID: 25352541 PMCID: PMC4267943 DOI: 10.1534/g3.114.014712] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
4-Nitroquinoline 1-oxide (4-NQO) is a highly carcinogenic chemical that induces mutations in bacteria, fungi, and animals through the formation of bulky purine adducts. 4-NQO has been used as a mutagen for genetic screens and in both the study of DNA damage and DNA repair. In the model eukaryote Aspergillus nidulans, 4-NQO-based genetic screens have been used to study diverse processes, including gene regulation, mitosis, metabolism, organelle transport, and septation. Early work during the 1970s using bacterial and yeast mutation tester strains concluded that 4-NQO was a guanine-specific mutagen. However, these strains were limited in their ability to determine full mutagenic potential, as they could not identify mutations at multiple sites, unlinked suppressor mutations, or G:C to C:G transversions. We have now used a whole genome resequencing approach with mutant strains generated from two independent genetic screens to determine the full mutagenic spectrum of 4-NQO in A. nidulans. Analysis of 3994 mutations from 38 mutant strains reveals that 4-NQO induces substitutions in both guanine and adenine residues, although with a 19-fold preference for guanine. We found no association between mutation load and mutagen dose and observed no sequence bias in the residues flanking the mutated purine base. The mutations were distributed randomly throughout most of the genome. Our data provide new evidence that 4-NQO can potentially target all base pairs. Furthermore, we predict that current practices for 4-NQO-induced mutagenesis are sufficient to reach gene saturation for genetic screens with feasible identification of causative mutations via whole genome resequencing.
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He Y, Yam C, Pomraning K, Chin JSR, Yew JY, Freitag M, Oliferenko S. Increase in cellular triacylglycerol content and emergence of large ER-associated lipid droplets in the absence of CDP-DG synthase function. Mol Biol Cell 2014; 25:4083-95. [PMID: 25318672 PMCID: PMC4263451 DOI: 10.1091/mbc.e14-03-0832] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cds1 is an evolutionarily conserved CDP-DG synthase. Fission yeast are used to demonstrate that cells deficient in its function exhibit markedly increased triacylglycerol content and assemble unusual ER-associated lipid droplets that recruit the triacylglycerol synthesis machinery and grow by expansion. Excess fatty acids and sterols are stored as triacylglycerols and sterol esters in specialized cellular organelles, called lipid droplets. Understanding what determines the cellular amount of neutral lipids and their packaging into lipid droplets is of fundamental and applied interest. Using two species of fission yeast, we show that cycling cells deficient in the function of the ER-resident CDP-DG synthase Cds1 exhibit markedly increased triacylglycerol content and assemble large lipid droplets closely associated with the ER membranes. We demonstrate that these unusual structures recruit the triacylglycerol synthesis machinery and grow by expansion rather than by fusion. Our results suggest that interfering with the CDP-DG route of phosphatidic acid utilization rewires cellular metabolism to adopt a triacylglycerol-rich lifestyle reliant on the Kennedy pathway.
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Affiliation(s)
- Yue He
- Temasek Life Sciences Laboratory, 117604 Singapore Department of Biological Sciences, National University of Singapore, 117543 Singapore
| | - Candice Yam
- Temasek Life Sciences Laboratory, 117604 Singapore Department of Biological Sciences, National University of Singapore, 117543 Singapore
| | - Kyle Pomraning
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
| | - Jacqueline S R Chin
- Temasek Life Sciences Laboratory, 117604 Singapore Department of Biological Sciences, National University of Singapore, 117543 Singapore
| | - Joanne Y Yew
- Temasek Life Sciences Laboratory, 117604 Singapore Department of Biological Sciences, National University of Singapore, 117543 Singapore
| | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
| | - Snezhana Oliferenko
- Department of Biological Sciences, National University of Singapore, 117543 Singapore Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, United Kingdom
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Schneeberger K. Using next-generation sequencing to isolate mutant genes from forward genetic screens. Nat Rev Genet 2014; 15:662-76. [PMID: 25139187 DOI: 10.1038/nrg3745] [Citation(s) in RCA: 138] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The long-lasting success of forward genetic screens relies on the simple molecular basis of the characterized phenotypes, which are typically caused by mutations in single genes. Mapping the location of causal mutations using genetic crosses has traditionally been a complex, multistep procedure, but next-generation sequencing now allows the rapid identification of causal mutations at single-nucleotide resolution even in complex genetic backgrounds. Recent advances of this mapping-by-sequencing approach include methods that are independent of reference genome sequences, genetic crosses and any kind of linkage information, which make forward genetics amenable for species that have not been considered for forward genetic screens so far.
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Affiliation(s)
- Korbinian Schneeberger
- Genome Plasticity and Computational Genetics, Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
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Mapping small effect mutations in Saccharomyces cerevisiae: impacts of experimental design and mutational properties. G3-GENES GENOMES GENETICS 2014; 4:1205-16. [PMID: 24789747 PMCID: PMC4455770 DOI: 10.1534/g3.114.011783] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Genetic variants identified by mapping are biased toward large phenotypic effects because of methodologic challenges for detecting genetic variants with small phenotypic effects. Recently, bulk segregant analysis combined with next-generation sequencing (BSA-seq) was shown to be a powerful and cost-effective way to map small effect variants in natural populations. Here, we examine the power of BSA-seq for efficiently mapping small effect mutations isolated from a mutagenesis screen. Specifically, we determined the impact of segregant population size, intensity of phenotypic selection to collect segregants, number of mitotic generations between meiosis and sequencing, and average sequencing depth on power for mapping mutations with a range of effects on the phenotypic mean and standard deviation as well as relative fitness. We then used BSA-seq to map the mutations responsible for three ethyl methanesulfonate−induced mutant phenotypes in Saccharomyces cerevisiae. These mutants display small quantitative variation in the mean expression of a fluorescent reporter gene (−3%, +7%, and +10%). Using a genetic background with increased meiosis rate, a reliable mating type marker, and fluorescence-activated cell sorting to efficiently score large segregating populations and isolate cells with extreme phenotypes, we successfully mapped and functionally confirmed a single point mutation responsible for the mutant phenotype in all three cases. Our simulations and experimental data show that the effects of a causative site not only on the mean phenotype, but also on its standard deviation and relative fitness should be considered when mapping genetic variants in microorganisms such as yeast that require population growth steps for BSA-seq.
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Teichert I, Nowrousian M, Pöggeler S, Kück U. The filamentous fungus Sordaria macrospora as a genetic model to study fruiting body development. ADVANCES IN GENETICS 2014; 87:199-244. [PMID: 25311923 DOI: 10.1016/b978-0-12-800149-3.00004-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Filamentous fungi are excellent experimental systems due to their short life cycles as well as easy and safe manipulation in the laboratory. They form three-dimensional structures with numerous different cell types and have a long tradition as genetic model organisms used to unravel basic mechanisms underlying eukaryotic cell differentiation. The filamentous ascomycete Sordaria macrospora is a model system for sexual fruiting body (perithecia) formation. S. macrospora is homothallic, i.e., self-fertile, easily genetically tractable, and well suited for large-scale genomics, transcriptomics, and proteomics studies. Specific features of its life cycle and the availability of a developmental mutant library make it an excellent system for studying cellular differentiation at the molecular level. In this review, we focus on recent developments in identifying gene and protein regulatory networks governing perithecia formation. A number of tools have been developed to genetically analyze developmental mutants and dissect transcriptional profiles at different developmental stages. Protein interaction studies allowed us to identify a highly conserved eukaryotic multisubunit protein complex, the striatin-interacting phosphatase and kinase complex and its role in sexual development. We have further identified a number of proteins involved in chromatin remodeling and transcriptional regulation of fruiting body development. Furthermore, we review the involvement of metabolic processes from both primary and secondary metabolism, and the role of nutrient recycling by autophagy in perithecia formation. Our research has uncovered numerous players regulating multicellular development in S. macrospora. Future research will focus on mechanistically understanding how these players are orchestrated in this fungal model system.
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Affiliation(s)
- Ines Teichert
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, Bochum, Germany
| | - Minou Nowrousian
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, Bochum, Germany
| | - Stefanie Pöggeler
- Abteilung Genetik eukaryotischer Mikroorganismen, Institut für Mikrobiologie und Genetik, Georg-August Universität Göttingen, Göttingen, Germany
| | - Ulrich Kück
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, Bochum, Germany
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Chaudhary S, Polaino S, Shakya VPS, Idnurm A. A new genetic linkage map of the zygomycete fungus Phycomyces blakesleeanus. PLoS One 2013; 8:e58931. [PMID: 23516579 PMCID: PMC3597544 DOI: 10.1371/journal.pone.0058931] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 02/08/2013] [Indexed: 12/15/2022] Open
Abstract
Phycomyces blakesleeanus is a member of the subphylum Mucoromycotina. A genetic map was constructed from 121 progeny of a cross between two wild type isolates of P. blakesleeanus with 134 markers. The markers were mostly PCR-RFLPs. Markers were located on 46 scaffolds of the genome sequence, covering more than 97% of the genome. Analysis of the alleles in the progeny revealed nine or 12 linkage groups, depending on the log of the odds (LOD) score, across 1583.4 cM at LOD 5. The linkage groups were overlaid on previous mapping data from crosses between mutants, aided by new identification of the mutations in primary metabolism mutant strains. The molecular marker map, the phenotype map and the genome sequence are overall congruent, with some exceptions. The new genetic map provides a genome-wide estimate for recombination, with the average of 33.2 kb per cM. This frequency is one piece of evidence for meiosis during zygospore development in Mucoromycotina species. At the same time as meiosis, transmission of non-recombinant chromosomes is also evident in the mating process in Phycomyces. The new map provides scaffold ordering for the genome sequence and a platform upon which to identify the genes in mutants that are affected in traits of interest, such as carotene biosynthesis, phototropism or gravitropism, using positional cloning.
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Affiliation(s)
- Suman Chaudhary
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, United States of America
| | - Silvia Polaino
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, United States of America
| | - Viplendra P. S. Shakya
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, United States of America
| | - Alexander Idnurm
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, United States of America
- * E-mail:
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Smith KM, Galazka JM, Phatale PA, Connolly LR, Freitag M. Centromeres of filamentous fungi. Chromosome Res 2012; 20:635-56. [PMID: 22752455 DOI: 10.1007/s10577-012-9290-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
How centromeres are assembled and maintained remains one of the fundamental questions in cell biology. Over the past 20 years, the idea of centromeres as precise genetic loci has been replaced by the realization that it is predominantly the protein complement that defines centromere localization and function. Thus, placement and maintenance of centromeres are excellent examples of epigenetic phenomena in the strict sense. In contrast, the highly derived "point centromeres" of the budding yeast Saccharomyces cerevisiae and its close relatives are counter-examples for this general principle of centromere maintenance. While we have learned much in the past decade, it remains unclear if mechanisms for epigenetic centromere placement and maintenance are shared among various groups of organisms. For that reason, it seems prudent to examine species from many different phylogenetic groups with the aim to extract comparative information that will yield a more complete picture of cell division in all eukaryotes. This review addresses what has been learned by studying the centromeres of filamentous fungi, a large, heterogeneous group of organisms that includes important plant, animal and human pathogens, saprobes, and symbionts that fulfill essential roles in the biosphere, as well as a growing number of taxa that have become indispensable for industrial use.
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Affiliation(s)
- Kristina M Smith
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331-7305, USA
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Puckett SE, Reese KA, Mitev GM, Mullen V, Johnson RC, Pomraning KR, Mellbye BL, Tilley LD, Iversen PL, Freitag M, Geller BL. Bacterial resistance to antisense peptide phosphorodiamidate morpholino oligomers. Antimicrob Agents Chemother 2012; 56:6147-53. [PMID: 22985881 PMCID: PMC3497173 DOI: 10.1128/aac.00850-12] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 06/25/2012] [Indexed: 12/16/2022] Open
Abstract
Peptide phosphorodiamidate morpholino oligomers (PPMOs) are synthetic DNA mimics that bind cRNA and inhibit bacterial gene expression. The PPMO (RFF)(3)RXB-AcpP (where R is arginine, F, phenylalanine, X is 6-aminohexanoic acid, B is β-alanine, and AcpP is acyl carrier protein) is complementary to 11 bases of the essential gene acpP (which encodes acyl carrier protein). The MIC of (RFF)(3)RXB-AcpP was 2.5 μM (14 μg/ml) in Escherichia coli W3110. The rate of spontaneous resistance of E. coli to (RFF)(3)RXB-AcpP was 4 × 10(-7) mutations/cell division. A spontaneous (RFF)(3)RXB-AcpP-resistant mutant (PR200.1) was isolated. The MIC of (RFF)(3)RXB-AcpP was 40 μM (224 μg/ml) for PR200.1. The MICs of standard antibiotics for PR200.1 and W3110 were identical. The sequence of acpP was identical in PR200.1 and W3110. PR200.1 was also resistant to other PPMOs conjugated to (RFF)(3)RXB or peptides with a similar composition or pattern of cationic and nonpolar residues. Genomic sequencing of PR200.1 identified a mutation in sbmA, which encodes an active transport protein. In separate experiments, a (RFF)(3)RXB-AcpP-resistant isolate (RR3) was selected from a transposome library, and the insertion was mapped to sbmA. Genetic complementation of PR200.1 or RR3 with sbmA restored susceptibility to (RFF)(3)RXB-AcpP. Deletion of sbmA caused resistance to (RFF)(3)RXB-AcpP. We conclude that resistance to (RFF)(3)RXB-AcpP was linked to the peptide and not the phosphorodiamidate morpholino oligomer, dependent on the composition or repeating pattern of amino acids, and caused by mutations in sbmA. The data further suggest that (RFF)(3)R-XB PPMOs may be transported across the plasma membrane by SbmA.
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Affiliation(s)
| | | | | | | | | | - Kyle R. Pomraning
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA
| | | | | | | | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA
| | - Bruce L. Geller
- Department of Microbiology
- AVI BioPharma, Inc., Corvallis, Oregon, USA
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Whole-Genome Sequencing of Sordaria macrospora Mutants Identifies Developmental Genes. G3-GENES GENOMES GENETICS 2012; 2:261-70. [PMID: 22384404 PMCID: PMC3284333 DOI: 10.1534/g3.111.001479] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 12/04/2011] [Indexed: 01/22/2023]
Abstract
The study of mutants to elucidate gene functions has a long and successful history; however, to discover causative mutations in mutants that were generated by random mutagenesis often takes years of laboratory work and requires previously generated genetic and/or physical markers, or resources like DNA libraries for complementation. Here, we present an alternative method to identify defective genes in developmental mutants of the filamentous fungus Sordaria macrospora through Illumina/Solexa whole-genome sequencing. We sequenced pooled DNA from progeny of crosses of three mutants and the wild type and were able to pinpoint the causative mutations in the mutant strains through bioinformatics analysis. One mutant is a spore color mutant, and the mutated gene encodes a melanin biosynthesis enzyme. The causative mutation is a G to A change in the first base of an intron, leading to a splice defect. The second mutant carries an allelic mutation in the pro41 gene encoding a protein essential for sexual development. In the mutant, we detected a complex pattern of deletion/rearrangements at the pro41 locus. In the third mutant, a point mutation in the stop codon of a transcription factor-encoding gene leads to the production of immature fruiting bodies. For all mutants, transformation with a wild type-copy of the affected gene restored the wild-type phenotype. Our data demonstrate that whole-genome sequencing of mutant strains is a rapid method to identify developmental genes in an organism that can be genetically crossed and where a reference genome sequence is available, even without prior mapping information.
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Pomraning KR, Smith KM, Bredeweg EL, Connolly LR, Phatale PA, Freitag M. Library preparation and data analysis packages for rapid genome sequencing. Methods Mol Biol 2012; 944:1-22. [PMID: 23065605 DOI: 10.1007/978-1-62703-122-6_1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
High-throughput sequencing (HTS) has quickly become a valuable tool for comparative genetics and genomics and is now regularly carried out in laboratories that are not connected to large sequencing centers. Here we describe an updated version of our protocol for constructing single- and paired-end Illumina sequencing libraries, beginning with purified genomic DNA. The present protocol can also be used for "multiplexing," i.e. the analysis of several samples in a single flowcell lane by generating "barcoded" or "indexed" Illumina sequencing libraries in a way that is independent from Illumina-supported methods. To analyze sequencing results, we suggest several independent approaches but end users should be aware that this is a quickly evolving field and that currently many alignment (or "mapping") and counting algorithms are being developed and tested.
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Affiliation(s)
- Kyle R Pomraning
- Department of Biochemistry and Biophysics, Center for Genome Research and Biocomputing (CGRB), Oregon State University, Corvallis, OR, USA
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Rediscovery by Whole Genome Sequencing: Classical Mutations and Genome Polymorphisms in Neurospora crassa. G3-GENES GENOMES GENETICS 2011; 1:303-16. [PMID: 22384341 PMCID: PMC3276140 DOI: 10.1534/g3.111.000307] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 08/03/2011] [Indexed: 12/15/2022]
Abstract
Classical forward genetics has been foundational to modern biology, and has been the paradigm for characterizing the role of genes in shaping phenotypes for decades. In recent years, reverse genetics has been used to identify the functions of genes, via the intentional introduction of variation and subsequent evaluation in physiological, molecular, and even population contexts. These approaches are complementary and whole genome analysis serves as a bridge between the two. We report in this article the whole genome sequencing of eighteen classical mutant strains of Neurospora crassa and the putative identification of the mutations associated with corresponding mutant phenotypes. Although some strains carry multiple unique nonsynonymous, nonsense, or frameshift mutations, the combined power of limiting the scope of the search based on genetic markers and of using a comparative analysis among the eighteen genomes provides strong support for the association between mutation and phenotype. For ten of the mutants, the mutant phenotype is recapitulated in classical or gene deletion mutants in Neurospora or other filamentous fungi. From thirteen to 137 nonsense mutations are present in each strain and indel sizes are shown to be highly skewed in gene coding sequence. Significant additional genetic variation was found in the eighteen mutant strains, and this variability defines multiple alleles of many genes. These alleles may be useful in further genetic and molecular analysis of known and yet-to-be-discovered functions and they invite new interpretations of molecular and genetic interactions in classical mutant strains.
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