Abstract Detail

The rise and fall of photosynthate: Evolution of plant/fungus interactions from paleobotanical and phylogenomic perspectives

Field, Katie [1], Rimington, William [2], Leake, Jonathan [3], Cameron, Duncan [3], Duckett, Jeff [4], Bidartondo, Martin I. [2], Pressel, Silvia [4].

Mutualism between ancient plant lineages (Haplomitriopsida liverworts) and Mucoromycotina fungi and its response to atmospheric CO₂.

The discovery that members of Mucoromycotina, an ancient and partially-saprotrophic fungal lineage, associate with the basal liverwort lineage Haplomitriopsida, has cast considerable doubt on the widely-held view that arbuscular mycorrhizal fungi of Glomeromycota formed the sole ancestral plant-fungus symbiosis. New evidence has shown that representatives of nearly all, extant early branching lineages of land plants actually harbor members of both fungal lineages, sometimes simultaneously. We aimed to resolve whether these dual associations with both Glomeromycota and Mucoromycotina fungi, or indeed those between liverworts and Mucoromycotina fungi alone, are mutualistic or how their functioning may have been affected by the fall in atmospheric CO₂ concentration ([CO₂]) following plant terrestrialization.
We measured carbon-for-nutrient exchanges between genera of the most basal group of extant liverworts (Haplomitrium & Treubia) hosting exclusive Mucoromycotina associations, and the early-branching liverwort genera Neohodgsonia and Allisonia which host simultaneous dual partnerships with Glomeromycota and Mucoromycotina fungi. By supplying ¹⁴CO­₂ to the plants and ³³P-orthophosphate and ¹⁵N-ammonium chloride to the fungal associates, we quantified nutrient uptake and efficiency of each symbiosis at both a replicated Paleozoic [CO₂] of 1,500 ppm and a modern-day lower [CO₂] of 440 ppm.
We compared our findings to those from identical experiments investigating liverwort-Glomeromycota relationships, showing that both plant-Mucoromycotina and dual Glomeromycota and Mucoromycotina fungal-plant symbiotic associations are mutualistic and mycorrhiza-like. Further, we demonstrate greater nutrient benefit for reduced carbon outlay in plants with Mucoromycotina and dual fungal associations compared to non-vascular plants colonized solely by Glomeromycota fungi at 440 ppm [CO₂]. Our findings suggest a more versatile and shifting evolutionary scenario in early plant-fungal symbioses than has previously been assumed and demonstrate the pressing need for further functional studies across land plant and fungal phylogenies.

Related Links:
Katie Field webpage
Katie Field twitter feed

1 - University of Leeds, School of Biology, Faculty of Biological Sciences, Miall Building, Leeds, West Yorkshire, LS2 9JT, UK
2 - Imperial College London, Life Sciences, London, SW7 2AZ, UK
3 - University of Sheffield, Animal and Plant Sciences, Alfred Denny Building , Western Bank, Sheffield, South Yorkshire, S10 2TN, UK
4 - Natural History Museum, Life Sciences, Cromwell Road, London, SW7 5BD, UK

Keywords:
none specified

Presentation Type: Symposium Presentation
Session: SY12
Location: Hall A/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 2:15 PM
Number: SY12003
Abstract ID:406
Candidate for Awards:None