Tag Archives: fusarium

Postdoc: USDA Bacterial Foodborne Pathogens and Mycology Research unit

The Bacterial Foodborne Pathogens and Mycology Research Unit at USDA-NCAUR in Peoria, Illinois, has two postdoctoral associate positions available.

  1. The successful applicant will study comparative genomics of Fusarium in order to elucidate genetic mechanisms that have given rise to the current diversity and distribution of secondary metabolite and pathogenicity-related genes in the F. fujikuroispecies complex.  For a more detailed description of the position and information on how to apply, please go to https://www.usajobs.gov/GetJob/ViewDetails/361765700or contact Robert Proctor (robert.proctor@ars.usda.gov; tel. 309-681-6380).
  2. The successful applicant will use molecular biological and microbiological techniques to identify and characterize the microbial genes that modify, detoxify, or otherwise confer resistance to mycotoxins.  For a more detailed description of the position and information on how to apply, please go to https://www.usajobs.gov/GetJob/ViewDetails/360735200 or contact Susan McCormick(Susan.McCormick@ars.usda.gov; tel. 309-681-6381).

 

 

Molecular Biologist: Fusarium USDA-ARS Peoria, IL

via Todd Ward

Research Molecular Biologist in Fusarium

The incumbent serves as a Research Molecular Biologist in the Bacterial Foodborne Pathogens and Mycology (BFP) Research Unit, National Center for Agricultural Utilization Research (NCAUR), Peoria, Illinois.  BFP scientists conduct research in genetics, microbiology, chemistry, and plant biology to produce information and technologies needed to enhance food safety and crop production in the U.S. and around the world.  The incumbent will conduct research on the molecular biology and biochemistry of production and detoxification of Fusarium mycotoxins, and elucidate the role of mycotoxins and other secondary metabolites in plant-pathogen interactions.

Duties

Specific research objectives include: 1) identification and characterization of mycotoxin detoxification genes as a mechanism to reduce/eliminate the toxins in grain-based food and feed; 2) determination of the genetic bases and ecological significance of variation in types of trichothecene mycotoxins produced byFusarium; and 3) identification and characterization of plant and fungal genes that affect biosynthesis of trichothecenes and other mycotoxins produced by Fusarium.  A combination of molecular, biological, genomic, and phenotypic data generated by the incumbent, or made available through collaborative efforts, will be used to accomplish these objectives.

Applications can be made here at the USDA site

Trichoderma reesei genome paper published

TrichodermaThe Trichoderma reesei genome paper was recently published in Nature Biotechnology from Diego Martinez at LANL with collaborators at JGI, LBNL, and others. This fungus was chosen for sequencing because it was found on canvas tents eating the cotton material suggesting it may be a good candidate for degrading cellulose plant material as part of cellulosic ethanol or other biofuels production.  The fungus also has starring roles in industrial processes like making stonewashed jeans due to its prodigious cellulase production.

The most surprising findings from the paper include the fact that there are so few members of some of the enzyme families even though this fungus is able to generate enzymes with so much cellulase activity. The authors found that there is not a significantly larger number of glucoside hydrolases which is a collection of carbohydrate degrading enzymes great for making simple sugars out of complex ones. In fact, several plant pathogens compared (Fusarium graminearum and Magnaporthe grisea) and the sake fermenting Aspergillus oryzae all have more members of this family than does.  T. reesei has almost the least (36) copies of a cellulose binding domain (CBM) of any of the filamentous ascomycete fungi.  They used the CAZyme database (carbohydrate active enzymes) database which has done a fantastic job building up profiles of different enzymes involved in carhohydrate degradation binding, and modifications.

Whether T. reesei is really the best cellulose degrading fungus is definitely an open question.  That it works well in the industrial culture that it has been utilized in is important, but there may be other species of fungi with improved cellulase activity and who may in fact have many more copies of cellulases.  So it will be good to add other fungi to the mix with quantitative information about degradation to try and glean what are the most important combination of enzymes and activities.

One technical note.  The comparison of copy number differences employed in the paper is a simple enough Chi-Squared, work that I’ve done with Matt Hahn and others include a gene family size comparison approach that also taked into account phylogenetic distances and assumes a birth-death process of gene family size change.  It would be great to apply the copy number differences through this or other approaches that just evaluate gene trees for these domains to see where the differences are significant and if they can be polarized to a particular branch of the tree.

So will this genome sequence lead to cheaper, better biofuel production? Certainly it provides an important toolkit to start systematically testing individual cellulase enzymes. It’s hard to say how fast this will make an impact, but the work of JBEI and a host of other research groups and biotech companies are going to be able to systematically test out the utility of these individual enzymes.

There is also evolutionary work by other groups on the evolution of these Hypocreales fungi trying to better define when biotrophic and heterotrophic transitions occurred to sample fungi with different lifestyles that might have different cellulase enyzmes that may not have been observed. Defining the relationships of these fungi and when and how many times transitions to lifestyles occurred to choose the most diverse fungi may be an important part of discovering novel enzymes.

Also see

Martinez, D., Berka, R.M., Henrissat, B., Saloheimo, M., Arvas, M., Baker, S.E., Chapman, J., Chertkov, O., Coutinho, P.M., Cullen, D., Danchin, E.G., Grigoriev, I.V., Harris, P., Jackson, M., Kubicek, C.P., Han, C.S., Ho, I., Larrondo, L.F., de Leon, A.L., Magnuson, J.K., Merino, S., Misra, M., Nelson, B., Putnam, N., Robbertse, B., Salamov, A.A., Schmoll, M., Terry, A., Thayer, N., Westerholm-Parvinen, A., Schoch, C.L., Yao, J., Barbote, R., Nelson, M.A., Detter, C., Bruce, D., Kuske, C.R., Xie, G., Richardson, P., Rokhsar, D.S., Lucas, S.M., Rubin, E.M., Dunn-Coleman, N., Ward, M., Brettin, T.S. (2008). Genome sequencing and analysis of the biomass-degrading fungus Trichoderma reesei (syn. Hypocrea jecorina). Nature Biotechnology DOI: 10.1038/nbt1403

Fusarium graminearum genome published

The genome of the wheat and cereal pathogen Fusarium graminearum was published in Science this week in an article entitled “The Fusarium graminearum Genome Reveals a Link Between Localized Polymorphism and Pathogen Specializationtion”. The project was a collaboration of many different Fusarium research groups. The genome sequencing was spearheaded by the Broad Institute at Harvard and MIT and is part of a larger project to sequence several different species of Fusarium. The group sequenced a second strain in order to identify polymorphisms.

Some of the key findings

  • The presence of Repeat Induced point-mutation (RIP) has likely limited the amount of repetitive and duplicated sequences in the genome
  • Most of the genes unique to F. graminearum (and thus not present in 4 other Fusarium spp genomes) are found in the telomeres
  • Between the sequenced strains SNP density ranged from 0 to 17.5 polymorphisms per kb.
  • Some of the genes expressed uniquely during plant infection (408 total) include known virulence factors and many plant cell-wall degrading enzymes.
  • The genes showing some of the highest SNP diversity tended to be unique to Fusarium and often unique to F. graminearum

Clusters of genomes

As announced at the Fungal Genetics meeting, the FGI at the Broad Institute is focusing on clusters of genomes rather than single ones. Some of genome projects are already grouped.

  • Coccidioides has 3 strains already plus the outgroup Uncinocarpus and conceivable one could include Histoplasma in there. This resources will grow to 14 strains (which comprise two species) of Coccidioides contributed by FGI and one from TIGR.
  • Aspergillus currently has 8 species sequenced with several in pipeline at Broad and TIGR.
  • Fusarium group has 3 species including recently released F. oxysporium.
  • The Candida clade also have several different already sequenced genomes and of course there is the already well studied (and well utilized genome resources I’ll add) for the Saccharomyces clade.
  • There are 4 genomes (well 5 but JEC21 and B-3501 are nearly identical) of Cryptococcus.

All in all a very exciting time for comparative genomics and I’m particularly intrigued to see how people will begin to use the resources.

This work to consolidate the clusters of genomes will, I hope, be very powerful. However, I still feel we are not doing a good job translating and centralizing information from different related species into a more centralized resource. Lots of money is spent on sequencing but I don’t know that we have realized the dream of having the comparative techniques illuminate the new genomes to the point that we are learning huge new things.

It seems to me, initially there is the lure of gathering low-hanging fruit from a genome analysis (which drives the first genome(s) paper), but not always the financial support of the longer term needs of the community to feed the experimental and functional work back into the genome annotation and interpretation.  The cycle works really well for Saccharomyces cerevisiae because the curators who work with the community to insure information is deposited and that literature is gleaned to link genomic and functional information. But this is expensive in terms of funding many curators for many different projects.

It seems as we add more genomes there isn’t a very centralized effort for this type of curatorial information and so we lack the gems of high-quality annotation that is only seen in a few “model” systems.  At some point a better meta-database that builds bridges between resource and literature rich “model system” communities may help, but maybe something new will have to be created? I like thinking about this as a user-driven content via a wiki which also dynamic (and versioned!) content from automated intelligent systems to map the straight-forward things.  Tools like SCI-PHY already exist that can do this and generate robust orthology groups (or Books as the PhyloFact database organizes them) for futher analysis. The SGD wiki for yeast is a start at this, but is mostly an import of SGD data into a mediawiki framework – I wonder how this can be built upon in a more explictly comparative environment.