A New Species of Scutellospora with a Coiled Germination Shield

Summary Although the molecular phylogeny, evolution and biodiversity of arbuscular mycorrhizal fungi (AMF) are becoming clearer, phylotaxonomically reliable sequence data are still limited. To fill this gap, a data set allowing resolution and environmental tracing across all taxonomic levels is provided. Two overlapping nuclear DNA regions, totalling c. 3 kb, were analysed: the small subunit (SSU) rRNA gene (up to 1800 bp) and a fragment spanning c. 250 bp of the SSU rDNA, the internal transcribed spacer (ITS) region (c. 475–520 bp) and c. 800 bp of the large subunit (LSU) rRNA gene. Both DNA regions together could be analysed for 35 described species, the SSU rDNA for c. 76 named and 18 as yet undefined species, and the ITS region or LSU rDNA, or a combination of both, for c. 91 named and 16 as yet undefined species. Present phylogenetic analyses, based on the three rDNA markers, provide reliable and robust resolution from phylum to species level. Altogether, 109 named species and 27 cultures representing as yet undefined species were analysed. This study provides a reference data set for molecular systematics and environmental community analyses of AMF, including analyses based on deep sequencing.

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“…Nevertheless, it has long been indicated that Scutellospora is nonmonophyletic (e.g. Kramadibrata et al. , 2000; da Silva et al.…”

Section: Discussionmentioning

confidence: 99%

Phylogenetic reference data for systematics and phylotaxonomy of arbuscular mycorrhizal fungi from phylum to species level

et al. 2011

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“…All AM fungi are members of the Glomeromycota, which is currently subdivided into four orders (153). So far, approximately 150 species of AM fungi have been described and the identification of new species is ongoing (96).…”

Section: The Am Fungimentioning

confidence: 99%

Signaling in the Arbuscular Mycorrhizal Symbiosis

Harrison

2005

Annu. Rev. Microbiol.

651

449

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Many microorganisms form symbioses with plants that range, on a continuous scale, from parasitic to mutualistic. Among these, the most widespread mutualistic symbiosis is the arbuscular mycorrhiza, formed between arbuscular mycorrhizal (AM) fungi and vascular flowering plants. These associations occur in terrestrial ecosystems throughout the world and have a global impact on plant phosphorus nutrition. The arbuscular mycorrhiza is an endosymbiosis in which the fungus inhabits the root cortical cells and obtains carbon provided by the plant while it transfers mineral nutrients from the soil to the cortical cells. Development of the symbiosis involves the differentiation of both symbionts to create novel symbiotic interfaces within the root cells. The aim of this review is to explore the current understanding of the signals and signaling pathways used by the symbionts for the development of the AM symbiosis. Although the signal molecules used for initial communication are not yet known, recent studies point to their existence. Within the plant, there is evidence of arbuscular mycorrhiza-specific signals and of systemic signaling that influences phosphate-starvation responses and root development. The landmark cloning of three plant signaling proteins required for the development of the symbiosis has provided the first insights into a signaling pathway that is used by AM fungi and by rhizobia for their symbiotic associations with legumes.

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“…Both sporiferous saccules and germination shields have been used as supplementary characters in taxonomic considerations (e.g. Walker and Sanders 1986;Spain 1992;Franke and Morton 1994;Kramadibrata et al 2000;Hafeel 2004). …”

Section: Introductionmentioning

confidence: 99%

Acaulosporoid glomeromycotan spores with a germination shield from the 400-million-year-old Rhynie chert

et al. 2008

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This work has been made available by the University of Kansas Libraries' Office of Scholarly Communication and Copyright. Please share your stories about how Open Access to this article benefits you.This is the published version of the article, made available with the permission of the publisher. The original published version can be found at the link below. Dotzler, N., Walker, C., Krings, M., Hass, H., Kerp, H., Taylor, T., Agerer, R. 2009. Acaulosporoid glomeromycotan spores with a germination shield from the 400-million-year-old Rhynie chert. Mycol Progress 8:9-18. Abstract Scutellosporites devonicus from the Early Devonian Rhynie chert is the only fossil glomeromycotan spore taxon known to produce a germination shield. This paper describes a second type of glomeromycotan spore with a germination shield from the Rhynie chert. In contrast to S. devonicus, however, these spores are acaulosporoid and develop laterally in the neck of the sporiferous saccule. Germination shield morphology varies, from plate-like with single or double lobes to tongue-shaped structures usually with infolded margins that are distally fringed or palmate. Spore walls are complex and appear to be constructed of at least three wall groups, the outermost of which includes the remains of the saccule. The complement of features displayed by the fossils suggests a relationship with the extant genera Ambispora, Otospora, Acaulospora or Archaeospora, but which of these is the closest extant relative cannot be determined. The acaulosporoid spores from the Rhynie chert document that this spore type was in existence already ∼400 mya, and thus contribute to a more complete understanding of the evolutionary history of the Glomeromycota. This discovery pushes back the evolutionary origin of all main glomeromycotan groups, revealing that they had evolved before rooted land plants had emerged.

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A New Species of Scutellospora with a Coiled Germination Shield

Cited by 25 publications

References 19 publications

Phylogenetic reference data for systematics and phylotaxonomy of arbuscular mycorrhizal fungi from phylum to species level

Phylogenetic reference data for systematics and phylotaxonomy of arbuscular mycorrhizal fungi from phylum to species level

Signaling in the Arbuscular Mycorrhizal Symbiosis

Acaulosporoid glomeromycotan spores with a germination shield from the 400-million-year-old Rhynie chert

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