Daniel Croll

Publications (19) View all

• Article: Coevolution and life cycle specialization of plant cell wall degrading enzymes in a hemibiotrophic pathogen.

  Patrick C Brunner, Stefano F F Torriani, Daniel Croll, Eva H Stukenbrock, Bruce A McDonald
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  ABSTRACT: Zymoseptoria tritici is an important fungal pathogen on wheat that originated in the Fertile Crescent. Its closely related sister species Z. pseudotritici and Z. ardabiliae infect wild grasses in the same region. This recently emerged host-pathogen system provides a rare opportunity to investigate the evolutionary processes shaping the genome of an emerging pathogen. Here, we investigate genetic signatures in plant cell wall degrading enzymes (PCWDEs) that are likely affected by or driving coevolution in plant-pathogen systems. We hypothesize four main evolutionary scenarios and combine comparative genomics, transcriptomics and selection analyses to assign the majority of PCWDEs in Z. tritici to one of these scenarios. We found widespread differential transcription among different members of the same gene family, challenging the idea of functional redundancy and suggesting instead that specialized enzymatic activity occurs during different stages of the pathogen life-cycle. We also find that natural selection has significantly affected at least 19 of the 48 identified PCWDEs. The majority of genes showed signatures of purifying selection, typical for the scenario of conserved substrate optimization. However, six genes showed diversifying selection that could be attributed to either host adaptation or host evasion. This study provides a powerful framework to better understand the roles played by different members of multi-gene families and to determine which genes are the most appropriate targets for wet lab experimentation, for example to elucidate enzymatic function during relevant phases of a pathogen's life-cycle.
  Molecular Biology and Evolution 03/2013; · 5.55 Impact Factor
• Article: Breakage-fusion-bridge cycles and large insertions contribute to the rapid evolution of accessory chromosomes in a fungal pathogen

  Daniel Croll, Marcello Zala, Bruce A McDonald
  PLoS Genetics 01/2013; · 8.69 Impact Factor
• Article: Significant genetic and phenotypic changes arising from clonal growth of a single spore of an arbuscular mycorrhizal fungus over multiple generations.

  Martine O Ehinger, Daniel Croll, Alexander M Koch, Ian R Sanders
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  ABSTRACT: Arbuscular mycorrhizal fungi (AMF) are highly successful plant symbionts. They reproduce clonally producing multinucleate spores. It has been suggested that some AMF harbor genetically different nuclei. However, recent advances in sequencing the Glomus irregulare genome have indicated very low within-fungus polymorphism. We tested the null hypothesis that, with no genetic differences among nuclei, no significant genetic or phenotypic variation would occur among clonal single spore lines generated from one initial AMF spore. Furthermore, no additional variation would be expected in the following generations of single spore lines. Genetic diversity contained in one initial spore repeatedly gave rise to genetically different variants of the fungus with novel phenotypes. The genetic changes represented quantitative changes in allele frequencies, most probably as a result of changes in the frequency of genetic variation partitioned on different nuclei. The genetic and phenotypic variation is remarkable, given that it arose repeatedly from one clonal individual. Our results highlight the dynamic nature of AMF genetics. Even though within-fungus genetic variation is low, some is probably partitioned among nuclei and potentially causes changes in the phenotype. Our results are important for understanding AMF genetics, as well as for researchers and biotechnologists hoping to use AMF genetic diversity for the improvement of AMF inoculum.
  New Phytologist 08/2012; 196(3):853-61. · 6.64 Impact Factor
• Article: Population genetic structure of Mycosphaerella graminicola and Quinone Outside Inhibitor (QoI) resistance in the Czech Republic

  Jana Drabešová, Pavel Ryšánek, Patrick C Brunner, Bruce A McDonald, Daniel Croll
  European Journal of Plant Pathology 08/2012; · 1.41 Impact Factor
• Source

  Available from: Francis Michel Martin

  Article: The transcriptome of the arbuscular mycorrhizal fungus Glomus intraradices (DAOM 197198) reveals functional tradeoffs in an obligate symbiont.

  E Tisserant, A Kohler, P Dozolme-Seddas, R Balestrini, K Benabdellah, A Colard, D Croll, C Da Silva, S K Gomez, R Koul, [......], U Paszkowski, N Requena, S A Rensing, C Roux, I R Sanders, Y Shachar-Hill, G Tuskan, J P W Young, V Gianinazzi-Pearson, F Martin
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  ABSTRACT: • The arbuscular mycorrhizal symbiosis is arguably the most ecologically important eukaryotic symbiosis, yet it is poorly understood at the molecular level. To provide novel insights into the molecular basis of symbiosis-associated traits, we report the first genome-wide analysis of the transcriptome from Glomus intraradices DAOM 197198. • We generated a set of 25,906 nonredundant virtual transcripts (NRVTs) transcribed in germinated spores, extraradical mycelium and symbiotic roots using Sanger and 454 sequencing. NRVTs were used to construct an oligoarray for investigating gene expression. • We identified transcripts coding for the meiotic recombination machinery, as well as meiosis-specific proteins, suggesting that the lack of a known sexual cycle in G. intraradices is not a result of major deletions of genes essential for sexual reproduction and meiosis. Induced expression of genes encoding membrane transporters and small secreted proteins in intraradical mycelium, together with the lack of expression of hydrolytic enzymes acting on plant cell wall polysaccharides, are all features of G. intraradices that are shared with ectomycorrhizal symbionts and obligate biotrophic pathogens. • Our results illuminate the genetic basis of symbiosis-related traits of the most ancient lineage of plant biotrophs, advancing future research on these agriculturally and ecologically important symbionts.
  New Phytologist 11/2011; 193(3):755-69. · 6.64 Impact Factor