Premium
Giving and receiving: measuring the carbon cost of mycorrhizas in the green orchid, Goodyera repens
Author(s) -
Cameron Duncan D.,
Johnson Irene,
Read David J.,
Leake Jonathan R.
Publication year - 2008
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2008.02533.x
Subject(s) - repens , botany , carbon fibers , mycorrhizal fungi , biology , horticulture , mathematics , algorithm , composite number , inoculation
Summary• Direct measurement of the carbon (C) ‘cost’ of mycorrhizas is problematic. Although estimates have been made for arbuscular and ectomycorrhizal symbioses, these are based on incomplete budgets or indirect measurements. Furthermore, the conventional model of unidirectional plant‐to‐fungus C flux is too simplistic. Net fungus‐to‐plant C transfer supports seedling establishment in c . 10% of plant species, including most orchids, and bidirectional C flows occur in ectomycorrhiza utilizing soil amino acids. • Here, the C cost of mycorrhizas to the green orchid Goodyera repens was determined by measurement of simultaneous bidirectional fluxes of 14 C labelled sources using a monoxenic system with the fungus Ceratobasidium cornigerum . • Transfer of C from fungus to plant (‘up‐flow’) occurs in the photosynthesizing orchid G. repens (max. 0.06 µg) whereas over five times more current assimilate (min. 0.355 µg) is simultaneously allocated in the reverse direction to the mycorrhizal fungus (‘down‐flow’) after 8 d. Carbon is transferred rapidly, being detected in plant–fungal respiration within 31 h of labelling. • This study provides the most complete C budget for an orchid–mycorrhizal symbiosis, and clearly shows net plant‐to‐fungus C flux. The rapidity of bidirectional C flux is indicative of dynamic transfer at an interfacial apoplast as opposed to reliance on digestion of fungal pelotons.