Category Archives: basidiomycota

Underwater mushrooms?

ResearchBlogging.org The cover of the Jan/Feb Mycologia has a picture of a pretty weird place to find a mushroom growing – a new species of mushroom that was found fruiting underwater in the Rogue river in Oregon.  This was reported about two years ago for a discovery that was made in 2005, but this is a formal publication on the finding and species description of Psathyrella aquatica. It is quite cool to see discovery of a new habitat for mushrooms, but I expect some more work will be required to fully understand the mechanics and development dealing with the challenges of underwater growth.  I think it would be interesting to see what kind of dispersal mechanisms there are since the spores are probably forced to float downstream, if there is an animal or wind dispersal mechanism at some later stage too or whether one finds mycelium growing in the soil near and around the rivers.

The important part of identifying the species and sequencing identifying molecular marker like ITS is that when later metagenomics studies of soil are performed, the anonymous sequenced clones can be matched up to know species, and we can identify where else this fungus is found.

Frank, J., Coffan, R., & Southworth, D. (2009). Aquatic gilled mushrooms: Psathyrella fruiting in the Rogue River in southern Oregon Mycologia, 102 (1), 93-107 DOI: 10.3852/07-190

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

Jelly fungus Tremella genome available at JGI

Tremella mesenterica (from K. Findley)
Tremella mesenterica (from K. Findley)

The Tremella mesenterica genome portal is now live at the JGI. The genome is ~28Mb and the JGI annotation group predicted 8,313 genes, a significantly larger number of peptides predicted for C. neoformans (~7000; 18Mb genome) which may represent new and interesting genes or aspects of gene loss in the Cryptococcus yeast lineage.

Tremella is a Basidiomycete jelly fungus and an interesting study system from the perspective of discovery of novel lignin degrading enzymes.  It also occupies an interesting phylogenetic position being an outgroup to the human pathogenic yeast Cryptococcus neoformans and C. gattii. Comparative genomics on this system may also provide insight into the interesting evolution of the large mating-type locus that was formed through various rearrangements resulting in conversion from a tetrapolar to biopolar mating system.

Tremella may also be an important source of understanding wood degradation and how it differs in jelly fungi from the more distantly related Agaricomycotina (mushroom forming). The fungus is reasonably easy to grow in the laboratory and also to collect from nature. It can handle some desiccation to survive during a dry period only to swell up after  moisture is available.  It is also called Witch’s butter and Tom Volk has a summary of its features on his FOTM page.  It can often be confused with a phylogenetically distinct jelly fungus named Dacyromyces, usually the differences can be best be determined microscopically.  See what kinds of Tremella people have been finding at the Mushroom Observer.

See also

    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).

    On the content of (petri plate) Media

    ResearchBlogging.orgAn avid reader pointed out that I was not entirely thorough in describing that we don’t enough about the V8 agar media that is used to induce mating in Cryptococcus. In fact a great deal of work on mating in this fungus had focused on identifying what pathways are induced by V8 agar that induce mating.  It was shown that inositol stimulates mating through use of defined media containing inositol (Xue et al, 2007).  This paper interestingly explores plant-fungal interactions and Cryptococcus suggesting that mating may occur preferentially on plants in cases where inositol is abundant.

    It is also worth noting that V8 media contains a high level of copper ions and it was also pointed out to me that Jef Edman’s lab showed that melanin mutants have mating defects, and both phenotypes are suppressed by copper. And more recently (Lin et al, PLOS Genetics 2006) found that alleles of the Mac1 copper regulated transcription factor are a QTL influencing hyphal growth and melanin production, and showed that copper can enhance hyphal growth.

    So the role of copper and interplay with V8 agar media and how this induces mating is actually quite known.

    C XUE, Y TADA, X DONG, J HEITMAN (2007). The Human Fungal Pathogen Cryptococcus Can Complete Its Sexual Cycle during a Pathogenic Association with Plants Cell Host & Microbe, 1 (4), 263-273 DOI: 10.1016/j.chom.2007.05.005

    Brown rotting fungal genome published

    ResearchBlogging.orgPostia placenta genome is now published in early edition of PNAS.   Brown rotting fungi are import part of the cellulose degrading ecology of the forest as well (hopefully) providing some enzymes that will help in the ligin to biofuels process. Brown rotters break down cellulose but cannot break down lignin or lignocellulose while white rotters (like the previously sequenced Phanerochaete chrysosporium) are able to break down the lignin.  This fungus was chosen for sequencing as it is another potentially helpful fungus in the war on sugars (turning them into fuels) including recently published Trichoderma reesei and 1st basidiomycete genome Phanerochaete (all incidentally with the Diego Martinez as first author – go Diego!). It is also helpful to contrast the white and brown rotters to understand how their enzyme capabilities have changed and how these different lifestyles evolved.  There had been some issues with the initial assembly of this genome which is basically twice as big as one would expect because the dikaryon genome was sequenced – this is where two nuclei with different genomes are present as the result of fusion between two parents of opposite mating types.  When genome sequenced is performed it is hard to assemble these into a single assembly since there are really two haplotypes present.  So these haplotypes have to be sorted out to obtain the gene ‘count’ for the organism for those who like simple numbers. This is a similar situation to the Candida albicans genome, although those haplotypes are much more similar.  The main problem is that one has to generate twice as much sequence to get the same coverage of each haplotype without playing some tricks to collapse them into a consensus and them afterwards separate the haplotypes back out.  At any rate, this sequenced provided a good summary of the gene content and thus metabolic and enzymatic capabilities to match up functional data collected from LC/MS and transcriptional profiling. 

    There are several other rotting fungi that are nearly done at JGI (but the task of writing and coordinating the analyses for the papers are ongoing!) include Schizophyllum commune and Pleurotus ostreatus. There are also several more mycorrhizal and plant pathogenic basidiomycete fungi as well as some classic model systems that have finished genomes and are in the process of finalizing papers.  It is an exciting time that is just beginning as these genome and transcriptional data are integrated and compared for their different ecological, morphological, and metabolic capabilities.

    The article is unfortunately not Open Access so I haven’t even read it from home yet, but pass along this news to you, dear reader. Will get a chance to read through more than the abstract to see what glistening gems have been extracted from this genomic endeavor.
    D. Martinez, J. Challacombe, I. Morgenstern, D. Hibbett, M. Schmoll, C. P. Kubicek, P. Ferreira, F. J. Ruiz-Duenas, A. T. Martinez, P. Kersten, K. E. Hammel, A. V. Wymelenberg, J. Gaskell, E. Lindquist, G. Sabat, S. S. BonDurant, L. F. Larrondo, P. Canessa, R. Vicuna, J. Yadav, H. Doddapaneni, V. Subramanian, A. G. Pisabarro, J. L. Lavin, J. A. Oguiza, E. Master, B. Henrissat, P. M. Coutinho, P. Harris, J. K. Magnuson, S. E. Baker, K. Bruno, W. Kenealy, P. J. Hoegger, U. Kues, P. Ramaiya, S. Lucas, A. Salamov, H. Shapiro, H. Tu, C. L. Chee, M. Misra, G. Xie, S. Teter, D. Yaver, T. James, M. Mokrejs, M. Pospisek, I. V. Grigoriev, T. Brettin, D. Rokhsar, R. Berka, D. Cullen (2009). Genome, transcriptome, and secretome analysis of wood decay fungus Postia placenta supports unique mechanisms of lignocellulose conversion Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0809575106

    Coprinopsis cinereus genome annotation updated

    Coprinus cinereus genome projectThe Broad Institute in collaboration with many of the Coprinopsis cinereus (Coprinus cinerea) community of researchers have updated the genome annotation for C. cinereus with additional gene calls based on ESTs and improved gene callers. The annotation was made on the 13 chromosome assembly produced by work by SEMO fungal biology group and collaborators across the globe including a BAC map from H. Muraguchi.  Thanks to Jonathan Goldberg and colleagues at the Broad Institute for getting this updated annotation out the door.

     

    This updated annotation is able to join and split several sets of genes and the gene count sits at just under 14k genes in this 36Mb genome. There are a couple of hiccups in the GTF and Genome contig/supercontig file naming that I am told will be fixed by early next week.  Additional work to annotate the “Kinome” by the Broad team provides some promising new insight to this genome annotation as well.

    We’re using this updated genome assembly address questions about evolution of genome structure by studying syntenic conservation and aspects of crossing over points during meiosis.  The C. cinereus system has long been used as model for fungal development and morphogensis of mushrooms as it is straightforward to induce mushroom fruiting in the laboratory.  It also a model for studying meiosis due to the synchronized meiosis occurring in the cells in the cap of the mushroom.

    Happy genome shrooming.

    New species of Cryptococcus found in seawater

    A paper in IJSEM describes a new species in the Cryptococcus basidiomycete yeast lineage. The name is proposed as Cryptococcus keelungensis sp. nov. for a strain isolated from the sea surface microlayer. Its identity as a Cryptococcus sp was determined by sequencing of 26S rDNA D1/D2 and ITS loci and molecular phylogenetics. This is quite diverged from the human pathogen Cryptococcus neoformans and C. gattii as the new species falls in the order Filobasidiales while C. neoformans is classified in the order Tremellales. Interestingly, based on the phylogeny in the paper it seems to be relatively close to newly discovered Cryptococcus himalayensis.

    See also:

    C.-F. Chang, C.-F. Lee, S.-M. Liu (2008). Cryptococcus keelungensis sp. nov., an anamorphic basidiomycetous yeast isolated from the sea-surface microlayer of the north-east coast of Taiwan INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 58 (12), 2973-2976 DOI: 10.1099/ijs.0.65773-0

    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.”

    Odds and ends

    Boletus