A novel plant–fungus symbiosis benefits the host without forming mycorrhizal structures. Issue 4 (27th November 2013)

• Record Type: Journal Article
• Authors: Kariman, Khalil; Barker, Susan J.; Jost, Ricarda; Finnegan, Patrick M.; Tibbett, Mark
• Is Part Of: New phytologist. Volume 201:Issue 4(2014)
• Page Start: 1413
• Page End: 1422
• Publication Date: 2013-11-27
• Subjects: Botany -- Periodicals; 580
• DOI: 10.1111/nph.12600
• Languages: English
• ISSNs: 0028-646X

Abstract

<abstract abstract-type="main" id="nph12600-abs-0001"> <title>Summary</title> <p> <list id="nph12600-list-0001" list-type="bullet"> <list-item> <p>Most terrestrial plants form mutually beneficial symbioses with specific soil‐borne fungi known as mycorrhiza. In a typical mycorrhizal association, fungal hyphae colonize plant roots, explore the soil beyond the rhizosphere and provide host plants with nutrients that might be chemically or physically inaccessible to root systems.</p> </list-item> <list-item> <p>Here, we combined nutritional, radioisotopic (<sup>33</sup>P) and genetic approaches to describe a plant growth promoting symbiosis between the basidiomycete fungus <italic>Austroboletus occidentalis</italic> and jarrah (<italic>Eucalyptus marginata</italic>), which has quite different characteristics.</p> </list-item> <list-item> <p>We show that the fungal partner does not colonize plant roots; hyphae are localized to the rhizosphere soil and vicinity and consequently do not transfer nutrients located beyond the rhizosphere. Transcript profiling of two high‐affinity phosphate (Pi) transporter genes (<italic>EmPHT1;1</italic> and <italic>EmPHT1;2</italic>) and hyphal‐mediated <sup>33</sup>Pi uptake suggest that the Pi uptake shifts from an epidermal to a hyphal pathway in ectomycorrhizal plants (<italic>Scleroderma</italic> sp.), similar to arbuscular mycorrhizal symbioses, whereas <italic>A. occidentalis</italic> benefits its host indirectly. The enhanced rhizosphere carboxylates are linked to growth and nutritional benefits in the novel symbiosis.</p> </list-item> <list-item> <p>This work is a starting point for detailed mechanistic studies on other basidiomycete–woody plant relationships, where a continuum between heterotrophic rhizosphere fungi and plant beneficial symbioses is likely to exist.</p> </list-item> </list> </p> </abstract>