87 research outputs found
Large differences in carbohydrate degradation and transport potential among lichen fungal symbionts.
Lichen symbioses are thought to be stabilized by the transfer of fixed carbon from a photosynthesizing symbiont to a fungus. In other fungal symbioses, carbohydrate subsidies correlate with reductions in plant cell wall-degrading enzymes, but whether this is true of lichen fungal symbionts (LFSs) is unknown. Here, we predict genes encoding carbohydrate-active enzymes (CAZymes) and sugar transporters in 46 genomes from the Lecanoromycetes, the largest extant clade of LFSs. All LFSs possess a robust CAZyme arsenal including enzymes acting on cellulose and hemicellulose, confirmed by experimental assays. However, the number of genes and predicted functions of CAZymes vary widely, with some fungal symbionts possessing arsenals on par with well-known saprotrophic fungi. These results suggest that stable fungal association with a phototroph does not in itself result in fungal CAZyme loss, and lends support to long-standing hypotheses that some lichens may augment fixed CO2 with carbon from external sources
Large proportion of wood dependent lichens in boreal pine forest are confined to old hard wood
Indigenous knowledge and use of lichens by the lichenophilic communities of the Nepal Himalaya
Expanding taxon sampling disentangles evolutionary relationships and reveales a new family in Peltigerales (Lecanoromycetidae, Ascomycota).
Lichens that incorporate cyanobacterial symbionts
(cyanolichens) are an ecologically key group of species
used as biomonitors at all latitudes. Cyanolichen
evolution is however based on intense studies of few keystone
species and the bulk of species diversity, especially of
small species in cold climates, has yet to be accounted for in
phylogenetic studies. We assembled an expanded data set
including members of all nine currently accepted
Peltigeralean families as well as hitherto undersampled representatives
of small, radially symmetrical, placodioid cyanolichen
genera from the Northern and Southern
Hemispheres. Bayesian and maximum likelihood consensus
trees from our multilocus analyses (nuSSU, nuLSU and
mtSSU) recovered the genera Koerberia, Vestergrenopsis
and Steinera as a new, fully supported, family-level clade
within the Peltigerales. This clade is further supported by a
posteriori morphological analysis and we describe it here as
the new family Koerberiaceae. The recently described and
physiognomically similar genus Steineropsis, by contrast, is
recovered as sister to Protopannaria in the Pannariaceae
(Collematineae). Previous analyses have recovered strong
monophyletic groups around Pannariaceae, Lobariaceae and
Peltigeraceae.We discuss in detail the phylogenetic relationships
of all these taxa, provide a pan-Peltigeralean overview
of phenotypic characteristics and illustrate all major ascus
apical structures. Our topology provides strong backbone
support for the sister relationship of Peltigerineae to
Collematineae as well as for most currently recognized
families of the Peltigerales. The following new combinations
are made: Steinera symptychia (Tuck.) T. Sprib. &
Muggia, and Vestergrenopsis sonomensis (Tuck.) T. Sprib.
& Muggia
Grimmia brittoniae, a rare moss endemic to northwestern Montana
The rare moss Grimmia brittoniae Williams Mas recently rediscovered at its type locality and discovered at two additional locations, bringing the total number of known locations to four. This distinct moss is restricted to calcareous rock outcrops at low elevations in northwestern Montana, including areas threatened by past and present development. VA:IB
Reassessing evolutionary relationships in Siplonema (Peltigerales, Lecanoromycetes)
Spilonema was originally described to accommodate an unusual group of cyanolichens with thread-like, cushion-forming thalli, and has long been placed in Coccocarpiaceae based on ascomatal development. However, Spilonema is the only genus of Peltigerales to include species lichenized with the cyanobacterial genus Stigonema, and the evolutionary relationships of Spilonema to other genera in the family have yet to be tested using molecular data. We present evidence from combined nuclear 28S, 18S and mitochondrial 12S rDNA to confirm the placement of the core species of Spilonema (S. paradoxum and S. revertens) in Coccocarpiaceae. Our data further show that despite possessing a different genus of photobiont (Scytonema), the north Pacific endemic genus Spilonemella must be included within Spilonema, suggesting that closely related species of the genus have changed photobionts in the course of evolution. However, we recovered Spilonema dendroides, one of the only lichens known to associate with the cyanobacterial genus Hyphomorpha, as only distantly related to the Coccocarpiaceae. The evolutionary relationships of this species are as yet unclear but it may occupy a basal position in the Peltigerales. We create for this species the new genus Erinacellus T. Sprib., Muggia & T\uf8nsberg
Convergent evolution of a symbiotic duet: the case of the lichen genus POlychidium (Peltigerales, Ascomycota)
Premise of the study: Thallus architecture has long been a powerful guide for classifying lichens and has often trumped photobiont association and ascomatal type, but the reliability of these characters to predict phylogenetic affi nity has seldom been tested. The cyanolichen genus Polychidium unites species that have strikingly similar gross morphology but consort with different photobiont genera. If Polychidium were found to be monophyletic, photobiont switching among closely related species would be suggested. If, however, species were found to arise in different lineages, a convergent body plan and ascomatal type evolution would be inferred.
\u2022 Methods: We tested the monophyly of Polychidium with a multilocus phylogeny based on nuclear and mitochondrial sequence data from all known Peltigeralean families and reconstructed ancestral states for specifi c thallus architecture and ascomatal ontogeny types relative to Polychidium and other clades.
\u2022 Key results: We found that Polychidium consists of two species groups that arose independently in different suborders within the Peltigerales, associated with Nostoc and Scytonema photobionts, respectively. We infer from ancestral character state reconstruction that dendroid thallus architecture evolved independently in these two lineages.
\u2022 Conclusions: The independent development of similar dendroid thallus architecture in different fungal suborders with different photobionts represents a clear and previously overlooked example of convergent evolution in lichens. Our results also suggest a pattern of character state conservation, loss, and reversion in ascomatal ontogeny types, hitherto considered conserved traits useful for higher level ascomycete systematics
Molecular support for the recognition of the Mycoblastus fucatus group as the new genus Violella (Tephromelataceae, Lecanorales)
The crustose lichen genus Mycoblastus in the Northern Hemisphere includes eight recognized species sharing large, simple ascospores produced 1\u20132 per ascus in strongly pigmented biatorine apothecia. The monophyly of Mycoblastus and the relationship of its various species to Tephromelataceae have never been studied in detail. Data from ITS rDNA and the genes coding for translation elongation factor 1- and DNA replication licensing factormini-chromosome maintenance complex 7 support the distinctness of Mycoblastus s. str. from the core of the Tephromelataceae, but recover M. fucatus and an undescribed Asian species as strongly supported within the latter group. We propose accommodating these two species in a new genus, Violella, which is characterized by its brownish inner ascospore walls, Fucatus-violet hymenial pigment granules and secondary chemistry, and discuss the position of Violella relative to Calvitimela and Tephromela. We describe the new species Violella wangii T. Sprib. & Goffinet to accommodate a new species with roccellic acid from Bhutan, China, India and the Russian Far East. We also exclude Mycoblastus indicus Awasthi & Agarwal from the genus Mycoblastus and propose for it the new combination Malmidea indica (Awasthi & Agarwal) Hafellner & T. Sprib
Electrode Design for Wire Interconnected Back Contact Solar Cells
Back contact back junction (BC-BJ) solar cells are a well-studied cell concept for high efficiency silicon solar cells. Wire interconnection is a known approach for the interconnection of solar cells with electrodes on front and rear side but has only recently been investigated in combination with back contact concepts [1]. Here, an optimal electrode design has quite different requirements. This study determines the smallest possible electrode geometry for linear electrodes on BC-BJ solar cells by conducting peel tests on geometry variations. Moreover, it is shown that the reliability of the wire interconnection is improved by implementing an optimized H-shaped pad geometry. Consequently, the H-shape is applied on BC-BJ half-cells and evaluated based on peel force measurements, as well as electroluminescence images of wire interconnected half-cells. A significant increase of peel force from below 0.1 N for linear pads to above 0.3 N for H-shaped pads, as well as a significant decrease of failure rate from 12.5 % for linear pads down to 4.5 % are demonstrated
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