Category Archives: genome

An Inky-cap mushroom genome

Francis Martin has written up a delightful summary pointing to our publication of the genome of Coprinopsis cinereus which appears in the early edition of PNAS and will grace the cover at the end of the month.  I encourage you to take a look at Francis’s post and the paper, available as Open Access from PNAS.  I’ll do my best to post a summary of the paper when I get a free moment.

For now I’ll leave you with a picture of this cute little mushroom fruting in the lab and a link to many more at Flickr.

Mature Coprinus cinereus (Coprinopsis cinerea)

Methylation to the max!

A new paper from the Zilberman lab at UC Berkeley shows the application of high throughput sequencing to the study of DNA methylation in eukaryotes.  They generate an huge data set of whole genome methylation patterns in several plants, animals, and five fungi including early diverging Zygomycete.

The work was performed using Bisulfite sequencing (Illumina) to capture methylated DNA, RNA-Seq of mRNA. The also performed some ChIP-Seq of H2A.Z on pufferfish to look at the nucleosome positioning in that species. For aligning the reads, they used BowTie to align the bisulfite sequences (though I’d be curious how a new aligner, BRAT, designed for Bisulfite seq reads would perform) to the genome.  They also sequenced mRNA via RNA-Seq to assay gene expression for some of the species.

They find several interesting patterns in animal and fungal genomes.  I’ll highlight one in the fungi. They find an unexpected pattern in U. reesii of reduced CGs in repeats, which shows signatures of a RIP-like process, are also methylated.  This finding is also consistent with observations in Coccidioides (Sharpton et al, Genome Res 2009) that showed depleted CGs pairs in repeats.  Since the phenomenon is also found in Coccidioides genomes this methylation of some repeats is likely not unique to U. reesii but may be important in recent evolution of the Onygenales fungi or the larger Eurotiales fungi.  There are several other interesting findings with the first such study that shows methylation data for Zygomycete fungi and a basidiomycete close to my heart, Coprinopsis.  It will be interesting is to dig deeper into this data and see how the patterns of methylation compare to other genomic features and the mechanisms regulating methylation process.

Zemach, A., McDaniel, I., Silva, P., & Zilberman, D. (2010). Genome-Wide Evolutionary Analysis of Eukaryotic DNA Methylation Science DOI: 10.1126/science.1186366

I’ll have the truffles and huitlacoche

Black TruffleA couple of papers should have captured your attention lately in the realm of fungal genomics.

One is the publication of the genome of the black truffle Tuber melanosporum. This appears as an advanced publication at Nature (OA by virtue of Nature’s agreement on genome papers) along with a NYT writeup and is a tasty exploration of the genome of an ascomycete ectomycorrhizal (ECM) fungus. There are several gems in there including the differences in transposable element content, content of gene families related to carbohydrate metabolism. This genome helps open the doorway for exploring the several independent origins of ECM in both ascomycete and basidiomycete fungi.

I’ll also point out there is some work on the analysis of mating type locus found in this genome has applied aspects suggesting that inoculation of roots with both mating types may increase truffle yields in truffle farms. Evidence for sexual reproduction is also discovered from this genome analysis based on the sexual cycle genes present and the structure of the MAT locus.  Much like what was revealed in the genome analysis of the previously ‘asexual’ species Aspergillus fumigatus (and later reconstitution of a sexual cycle), the Tuber genome has the potential for mating and is a heterothallic (outcrossing) fungus based on its mating type locus -just like many other filamentous Ascomycete species.

A second paper I encourage you take a look at (those with a Science subscription) is from Virginia Walbot’s lab on the formation of tumors by U. maydis in Maize. These tumors end up destroying the corn but can produce a delicious (to some) dish that is huitlacooche. The idea that the fungus is co-opting the host system by secreting proteins that acted in the same way as native proteins and that it has a tissue or organ specific repertoire was one that her lab has been pursuing. U. maydis can grow inside corn without detection and  the formation of tumors seems to be a manipulation of the plant as much as it is the pathogen directly taking resources from the plant.  It reminds me a bit of the production of secondary metabolites that can control plant growth like gibberellins produced by fungi.  This kind of manipulation and also ability to evade detection suggests a pretty specific set of controls that prevent the fungus from doing the wrong thing at the wrong time (to avoid detection). So they set out to see if there are a set of organ specific genes that the fungus uses during infection that would suggest a very host-specific strategy by this corn smut.

In this paper the authors evaluate the role of fungal genes specifically expressed in infection of different organs and also the role of secreted proteins in colonization of the organs.  In what is impressive and elegant work, the authors show through the use of microarrays and genetics that there is plant tissue specific gene expression of U. maydis – so infections in leaves express a different set of genes than those in seedlings.  Genetic and phenotypic evaluation of fungal strains with knockouts of sets of the predicted secreted proteins was able to confirm a role for specific secreted proteins that previously may have not had any discernible phenotype. They infect strains with knockouts of sets of genes that encode secreted proteins and compare the virulence when these strains infect individual organs of the maize host.  They showed there is significantly different virulence in the various tissues for a some of the mutants suggesting an organ-specific role for virulence of secreted proteins. They also go on to show that some of this organ specific infection requires organ-specific gene expression by evaluating maize mutants and the ability of the fungus to infect different organs.

Future work will hopefully followup to see what these secreted proteins are manipulating in the host and how they either enable virulence by protecting the pathogen, avoiding detection by turning of host responses, or co-opting host gene networks in some other way.

Martin F, Kohler A, Murat C, Balestrini R, Coutinho PM, Jaillon O, Montanini B, Morin E, Noel B, Percudani R, Porcel B, Rubini A, Amicucci A, Amselem J, Anthouard V, Arcioni S, Artiguenave F, Aury JM, Ballario P, Bolchi A, Brenna A, Brun A, Buée M, Cantarel B, Chevalier G, Couloux A, Da Silva C, Denoeud F, Duplessis S, Ghignone S, Hilselberger B, Iotti M, Marçais B, Mello A, Miranda M, Pacioni G, Quesneville H, Riccioni C, Ruotolo R, Splivallo R, Stocchi V, Tisserant E, Viscomi AR, Zambonelli A, Zampieri E, Henrissat B, Lebrun MH, Paolocci F, Bonfante P, Ottonello S, & Wincker P (2010). Périgord black truffle genome uncovers evolutionary origins and mechanisms of symbiosis. Nature PMID: 20348908

Skibbe DS, Doehlemann G, Fernandes J, & Walbot V (2010). Maize tumors caused by Ustilago maydis require organ-specific genes in host and pathogen. Science (New York, N.Y.), 328 (5974), 89-92 PMID: 20360107

a mushroom and a microsporidia walk into a bar

These papers got lost in my drafts of things to write about.  Grants and overdue manuscripts are keeping me away from the blog.

  • Published work from Gary Foster’s lab in Applied Env Micro show progress on genetic engineering tools to express introduced genes in the basidiomycete mushroom system Clitopilus passeckerianus. C. passeckarianus produces an antibiotic, pleuromutilin, an important antibiotic. Cover photo [Press] They also showed the  5′ intron is important for efficient expression, something that has been shown several times in fungi and provides more evidence for the role of introns in promoting or regulating an aspect of gene expression or translation. Perhaps by splicing-dependent export.
  • Corradi et al – the genome of the microsporidia parasite of Daphnia (water flea). It’s as big as a fungal genome at 24Mb (S.cerevisiae is about 12Mb, Neurospora crassa about 40Mb) but only has about 2,100 genes (S.cerevisiae has ~6,000, N.crassa ~ 10,000). DOI: 10.1186/gb-2009-10-10-r106

Early branching genomes available

Genome sequencing is underway on several early branches in the Opisthokont and some related linages as part of the “Origins of Multicellularity” project at the Broad Institute (BI) include some recently made available assemblies for:

  • Allomyces macrogynus (Blastocladiomycota “Chytrid”)
  • Capsaspora owczarzaki (Ichthyosporea)

Already available data from

Still in progress (BI)

Still in progress (Other centers)

Schizophyllum genome portal live at JGI

In preparation for Asilomar, JGI is releasing lots of the genome sequencing project portals. The Schizophyllum commune Genome Portal is now publicly available. Go get your white-rot gene investigation on! (Though please respect the community rules for 1st rights to publication of the genome-wide analyses).

Updated Cryptococcus serotype A annotation

SEM of clamp cell, yeast cells and sexual spore chains. Courtesy R. Velagapudi & J. Heitman

A new and improved annotation of Cryptococcus neoformans var grubii strain H99 (serotype A) has been made available in GenBank and the Broad Institute website. This update is collaboration between several groups providing data and analyses and the genome annotation team at the Broad Institute.

Some changes noted by the Broad Institute include:

“This release of gene predictions for the serotype A isolate Cryptococcus neoformans var. grubii H99 is based on a new genomic assembly provided by Dr. Fred Dietrich at the Duke Center for Genome Technology. The new assembly consists of 14 nuclear chromosomes and a single 21 KB mitochondrial chromosome, and has resulted in a reduction of the estimated genome size from 19.5 to 18.9 Mb. Improvements in the assembly and in our annotation process have resulted in a set of 6,967 predicted protein products, 335 fewer than the previous release.”

Genome survey sequencing of Witches’ Broom

Genome survey sequencing (1.9X coverage) was generated for Moniliophthora perniciosa, the cause of witches’ broom disease on cacao plants. The sequence for this basidiomycete plant pathogen was published in BMC Genomics this week. The authors report a higher number of ROS metabolism and P450 genes. Evaluating whether these copy number differences are significantly different from other basidiomycete fungi and are lineage specific expansions will help determine if these families played a role in the adaptation of this plant pathogen.

This work provides an important stepping stone in understanding and eventually controlling this pathogen which is devastating cacao plantations. An associated review describes what we have and can learn about Witches’ broom disease.

See related:

Jorge MC Mondego, Marcelo F Carazzolle, Gustavo GL Costa, Eduardo F Formighieri, Lucas P Parizzi, Johana Rincones, Carolina Cotomacci, Dirce M Carraro, Anderson F Cunha, Helaine Carrer, Ramon O Vidal, Raissa C Estrela, Odalys Garcia, Daniela PT Thomazella, Bruno V de Oliveira, Acassia BL Pires, Maria Carolina S Rio, Marcos Renato R Araujo, Marcos H de Moraes, Luis AB Castro, Karina P Gramacho, Marilda S Goncalves, Jose P Moura Neto, Aristoteles Goes Neto, Luciana V Barbosa, Mark J Guiltinan, Bryan A Bailey, Lyndel W Meinhardt, Julio CM Cascardo, Goncalo AG Pereira (2008). A genome survey of Moniliophthora perniciosa gives new insights into Witches’ Broom Disease of cacao BMC Genomics, 9 (1) DOI: 10.1186/1471-2164-9-548

P. chrysogenum genome

BBC news and GTO report the sequence of P. chrysogenum, will be published in October in Nat Biotechnology in a project based at the biotech company DSM. P. chrysogenum being the mold that fortuitously contaminated Dr Fleming’s bacterial plates.

The 13,500 reported genes in the press release is quite bit larger than relatives in the Aspergillus clade (~10,000 genes) so it will be intriguing to see what’s going on here and if there will be interesting examples of horizontal transfer like what has been investigated in Aspergillus oryzae. I am unclear as to whether the selected strain is a wild isolate or represents an industrial strain, but look forward to reading the full account of the genome.

Factoid – Most of the industrial fungal genome papers have seen publication in Nature Biotechnology (Aspergillus niger, Trichodermera reesei, and Phanerochaete chrysosporium).

Edit: 1-Oct-2008, Jonathan Badger, an author on the paper, blogs about the paper and links to the pre-print available on NBT site.