From mycoheterotrophy to mutualism: mycorrhizal specificity and functioning in Ophioglossum vulgatum sporophytes. Issue 4 (23rd January 2015)

• Record Type: Journal Article
• Authors: Field, Katie J.; Leake, Jonathan R.; Tille, Stefanie; Allinson, Kate E.; Rimington, William R.; Bidartondo, Martin I.; Beerling, David J.; Cameron, Duncan D.
• Is Part Of: New phytologist. Volume 205:Issue 4(2015)
• Page Start: 1492
• Page End: 1502
• Publication Date: 2015-01-23
• Subjects: competition -- ferns -- mycoheterotrophy -- mycorrhiza -- Ophioglossaceae -- Ophioglossum vulgatum -- specificity -- symbiosis; Botany -- Periodicals; 580
• DOI: 10.1111/nph.13263
• Languages: English
• ISSNs: 0028-646X

Abstract

Summary: Mycorrhizal functioning in the fern Ophioglossum is complex and poorly understood. It is unknown whether mature O. vulgatum sporophytes form mutualistic associations with fungi of the Glomeromycota and with what specificity. Are green sporophytes able to 'repay' fungal carbon (C) invested in them by mycorrhizal partners during the initially heterotrophic gametophyte and early sporophyte stages of the lifecycle? We identified fungal partners of O. vulgatum sporophytes using molecular techniques and supplied them with 33 P‐orthophosphate and O. vulgatum sporophytes with 14 CO2 . We traced the movement of fungal‐acquired nutrients and plant‐fixed C between symbionts and analysed natural abundance 13 C and 15 N isotope signatures to assess nutritional interactions. We found fungal specificity of O. vulgatum sporophytes towards a mycorrhizal fungus closely related to Glomus macrocarpum . Our radioisotope tracers revealed reciprocal C‐for‐phosphorus exchange between fern sporophytes and fungal partners, despite competition from surrounding vegetation. Monocultures of O. vulgatum were enriched in 13 C and 15 N, providing inconclusive evidence of mycoheterotrophy when experiencing competition from the surrounding plant community. We show mutualistic and specific symbiosis between a eusporangiate fern and fungi of the Glomeromycota. Our findings suggest a 'take now, pay later' strategy of mycorrhizal functioning through the lifecycle O. vulgatum, from mycoheterotrophic gametophyte to mutualistic aboveground sporophyte.