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Abstract Detail



Sequence-based Identification of Fungi

Opik, Maarja [1].

MaarjAM Database: Sequence-based identification of arbuscular mycorrhizal fungi.

Arbuscular mycorrhizal fungi (AMF, Phylum Glomeromycota) are soil and root-dwelling, obligate plant root symbiotic organisms present in most terrestrial environments. Their occurrence and diversity have important roles in plant nutrition, abiotic and biotic stress (incl. pathogen) resistance and soil quality, and in diversity and functioning of host plant communities and nutrient cycling of ecosystems. Therefore, understanding the taxonomic and functional diversity of AMF is the topic of increasing importance. Diversity of AMF is nowadays commonly measured using DNA sequences of nuclear ribosomal operon markers; the most frequently used one being the SSU rRNA gene. Total AMF molecular operational taxonomic unit (MOTU) richness of SSU rRNA gene sequences suggests at least twice as high number of species present as is currently known on the basis of morphotaxonomy. These MOTUs have been organised into a common system of “virtual taxa” (VT) in a public database MaarjAM (http://maarjam.botany.ut.ee). VT are delimited as phylogenetically related clades of sequences of SSU rRNA gene; they are aimed to correspond to species level taxa. The MaarjAM database collects and systematizes sequences and meta-data from published ecological and taxonomic works. VT system allows synonymisation of original MOTU designations by providing a stable name. The stability of VT nomenclature is created via type sequences. VT nomenclature, much alike binomial taxonomic nomenclature, allows comparability among data and consistent communication among scientists. The MaarjAM database contains sequences of multiple markers, such as fungal barcoding marker ITS, LSU rRNA gene and others. Application of the VT nomenclature has allowed description of AMF diversity patterns from global to local scales. There is evidence at the global (biogeographic) scale that AMF communities differ among biomes and climatic zones. At the local scale, host ecological group related, as well as seasonal temporal patterns are apparent in root-colonising AMF community composition. Comparison of root- and soil-dwelling AMF has provided intriguing results: there can be more AMF VT colonising root than soil environment of a locality. The current challenges in DNA sequence-based identification of AMF include limited knowledge about intra- vs interspecific variation of the marker gene sequences, and related to this, need for more solid theoretical basis for sequence-based AMF species delimitation. AMF have shown exceptional intragenomic and –specific genetic variation, but such information is available about a limited number of species and isolates. I will conclude by discussing the opportunities to gain progress in these critical issues.


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MaarjAM Database


1 - University of Tartu, Department of Botany, 40 Lai Str., Tartu, 51005, Estonia

Keywords:
mycorrhizal fungi.

Presentation Type: Symposium or Colloquium Presentation
Session: SY8
Location: Room 103 AB/Kellogg Hotel and Conference Center
Date: Wednesday, June 11th, 2014
Time: 3:30 PM
Number: SY8006
Abstract ID:222
Candidate for Awards:None


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