Geosiphon-Nostoc Endosymbiosis

Classification

Higher order taxa

Domain: Bacteria, Phylum: Cyanobacteria, Class: Cyanophyceae, Order: Nostocales, Family: Nostocaceae, Genus: Nostoc

Domain: Fungi, Phylum: Mucoromycota, Class: Glomeromycetes, Order: Archaeosporales, Family: Geosiphonaceae, Genus: Geosiphon

Species

Nostoc punctiforme (ATTC: 29133) Geosiphon pyriformis (NCBI: 50956)

Description and significance

Nostoc punctiforme is a filamentous cyanobacterium that can be photoautotrophic, diazotrophic, heterotrophic, and/or symbiotic. This species of cyanobacteria has vegetative cells that can differentiate into heterocysts, spore-like akinetes, or motile filaments called hormogonia. This species is also broadly symbiotic, forming relationships with fungi, bryophytes, gymnosperms, and angiosperms. The genome contains a large number of unique genes that likely play essential roles in cell differentiation and symbiosis.- “An overview of the genome of Nostoc punctiforme, a multicellular, symbiotic cyanobacterium”

Geosiphon pyriformis is a glomeromycete fungus and obligate symbiont commonly found in soil. Glomeromycete fungi are usually arbuscular mycorrhizae that form a symbiotic relationship with vascular plants and brophytes. While most glomeromycete fungi form these arbuscular mycorrhizal (AM) relationships, Geosiphon pyriformis has not been observed in AM relationships with plants. Geosiphon pyriformis "may also be symbiotic with plants. If so an ecological network could exist among AMF, vascular plants, brophytes, and cyanobacteria, with extensive sharing and exchange among the symbiotic partners." (Schubler 2012)