Within the framework of the CSP 'Metatranscriptomics of Forest
Soil Ecosystems' project, we are aiming to explore the interaction
of forest trees with communities of soil fungi, including
ectomycorrhizal symbionts that dramatically affect
bioenergy-relevant plant growth, and saprotrophic soil fungi
impacting carbon sequestration in forests. We are sequencing the
metatranscriptome of soil fungi (i.e., wood decayers, litter and
humus saprotrophs, and ectomycorrhizal symbionts) in woody debris,
litter/humus, rhizosphere and ectomycorrhizal roots of ecosystems
representative of major Earth ecosystems, the boreal, temperate and
mediterranean forests. We are also sequencing the genome of the
most abundant fungal species harvested on studied sites to serve as
the foundation for a reference database for metagenomics of fungi
and for a comprehensive survey of the potential soil fungal
metabolome.
The Atractiellales are a newly discovered and poorly
studied group of filamentous fungi belonging to a phylogenetically
distinct clade within the rust lineage (Pucciniomycotina).
They are characterized by several ultrastructural features,
including symplechosomes and a simple septal pore structure
surrounded by structures known as atractosomes [1]. Some species
make tiny fruiting bodies while others appear to be asexual. Some
species of Atractiellales are associated with beetles and
their galleries. Others are associated with living plants and
decaying plant debris. The isolate whose genome was sequenced
here was isolated from healthy roots of Populus deltoides.
Its mycelium is dikaryotic without clamp connections; no fruiting
has been observed despite multiple attempts to stimulate
fructification. Culture-independent sequencing studies
confirm that this species is often abundant in the root endosphere
of Populus deltoides [2] in natural ecosystems. Our
isolate (PMI 95) can grow intracellularly as a root endophyte on a
wide diversity of plants including trees (e.g. Populus,
Pinus, Quercus) and grasses (Zea mays).
This isolate was recently renamed as Atraciella rhizophila
(Bonito et al., 2017)
References
Oberwinkler, F. et al. Two new pycnidial members of the
Atractiellales: Basidiopycnis hyalina and Proceropycnis pinicola.
Mycologia 98, 637-649, doi:Doi 10.3852/Mycologia.98.4.637
(2006).
Gottel, N. R. et al. Distinct Microbial Communities within the Endosphere and Rhizosphere of Populus deltoides Roots across Contrasting Soil Types. Applied and Environmental Microbiology 77, 5934-5944 (2011).
Bonito, G. et al. Atractiella rhizophila, sp. nov., an endorrhizal fungus isolated from the Populus root microbiome. Mycologia 109:1, 18-26, doi:10.1080/00275514.2016.1271689 (2017)
