Abstract Detail

Symbioses: Plant, Animal, and Microbe Interactions

Field, Katie J. [1], Cameron, Duncan D [1], Leake, Jonathan, R. [1], Tille, Stefanie [1], Bidartondo, Martin I. [2], Beerling, David, J. [1].

The functional and evolutionary significance of mycorrhiza in ‘lower’ land plants.

The arbuscular mycorrhizal (AM) association is the most widespread plant-fungal symbiosis on Earth, coevolving with terrestrial plants over 400 million years ago. Today, the vast majority of land plants have this mutually beneficial symbiotic relationship with a fungal partner in which the plant normally receives soil nutrients in exchange for photosynthates. However, this view is based almost exclusively on investigations of the AM associations of higher plants whereas virtually nothing is known about their functionality in the ‘lower’, more evolutionarily ancient land plant clades (liverworts, clubmosses and ferns). There is good evidence that AM is an evolutionary ancient partnership that commenced with the earliest land plants, but the absence of information on the functioning of the symbiosis in lower plants is a major gap in our understanding of its significance in driving plant colonisation of land and the costs and benefits of plant-fungal co-evolution in lower plants is unknown.
We used ¹⁴CO₂ supplied to the plant and ³³P supplied to the fungal partners to quantify and characterize the carbon-for-mineral nutrient exchanges in AM associations in the liverwort - Pressia quadrata, a representative of the most basal clade of modern plants, and Osmunda regalis, a ‘lower’ tracheophyte fern. They were compared to a modern ‘higher’ plant, Plantago lanceolata, using the same techniques. This provides the first comparative analysis of AM functioning in higher and lower plant groups. The symbiosis is shown to provide mutualistic benefits in the lower plants, and the carbon-cost to nutrient gain benefit across plants at different stages of evolutionary advancement provides the first experimental support for the longstanding assumption that mycorrhizas co-evolved with lower-land plants to the mutual benefit of the plant and fungal partners. These findings strengthen the evidence that AM have played a crucial role in the development of the terrestrial biosphere from over 400 million years ago to the present day.

Broader Impacts:

1 - University of Sheffield, Department of Animal and Plant Sciences, Western Bank, Sheffield, S10 2TN, UK
2 - Imperial College London & Royal Botanic Gardens, Kew, TW9 3DS, England

Keywords:
arbuscular mycorrhiza
Osmunda regalis
Preissia quadrata
Plantago lanceolata
nutrient-exchange
lower land plants.

Presentation Type: Oral Paper:Papers for Topics
Session: 42
Location: 552A/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 1:45 PM
Number: 42002
Abstract ID:337