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Atkin, OK; Sherlock, D; Fitter, AH; Jarvis, S; Hughes, JK; Campbell, C; Hurry, V; Hodge, A. 2009. Temperature dependence of respiration in roots colonized by arbuscular mycorrhizal fungi. New Phytologist. 182(1):188-199. The arbuscular mycorrhizal (AM) symbiosis is ubiquitous, and the fungus represents a major pathway for carbon movement in the soil-plant system. Here, we investigated the impacts of AM colonization of Plantago lanceolata and temperature on the regulation of root respiration (R). Warm-grown AM plants exhibited higher rates of R than did nonAM plants, irrespective of root mass. AM plants exhibited higher maximal rates of R (R max-R measured in the presence of an uncoupler and exogenous substrate) and greater proportional use of R max as a result of increased energy demand and/or substrate supply. The higher R values exhibited by AM plants were not associated with higher maximal rates of cytochrome c oxidase (COX) or protein abundance of either the COX or the alternative oxidase. Arbuscular mycorrhizal colonization had no effect on the short-term temperature dependence (Q10) of R. Cold-acclimated nonAM plants exhibited higher rates of R than their warm-grown nonAM counterparts. By contrast, chilling had a negligible effect on R of AM-plants. Thus, AM plants exhibited less cold acclimation than their nonAM counterparts. Overall, these results highlight the way in which AM colonization alters the underlying components of respiratory metabolism and the response of root R to sustained changes in growth temperature.
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