Andy's bio-protocol in collaboration with Claudia Huber and Wolfgang Eisenreich is online!

Tracking Lipid Transfer by Fatty Acid Isotopolog Profiling from

Host Plants to Arbuscular Mycorrhiza Fungi

Andreas Keymer1, 2, #, Claudia Huber3, #, Wolfgang Eisenreich3, * and Caroline Gutjahr1, 2, *


1Genetics, Faculty of Biology, LMU Munich, Biocenter Martinsried, Germany; 2Plant Genetics, School of

Life Sciences Weihenstephan, Technical University Munich (TUM), Freising, Germany; 3Biochemistry,

Technical University Munich (TUM), Garching, Germany


*For correspondence: caroline.gutjahr@tum.de; wolfgang.eisenreich@mytum.de

#Contributed equally to this work


[Abstract] Lipid transfer from host plants to arbuscular mycorrhiza fungi was hypothesized for several

years because sequenced arbuscular mycorrhiza fungal genomes lack genes encoding cytosolic fatty

acid synthase (Wewer et al., 2014; Rich et al., 2017). It was finally shown by two independent

experimental approaches (Jiang et al., 2017; Keymer et al., 2017; Luginbuehl et al., 2017). One

approach used a technique called isotopolog profiling (Keymer et al., 2017). Isotopologs are molecules,

which differ only in their isotopic composition. For isotopolog profiling an organism is fed with a heavy

isotope labelled precursor metabolite. Subsequently, the labelled isotopolog composition of metabolic

products is analysed via mass spectrometry. The detected isotopolog pattern of the metabolite(s) of

interest yields information about metabolic pathways and fluxes (Ahmed et al., 2014). The following

protocol describes an experimental setup, which enables separate isotopolog profiling of fatty acids in

plant roots colonized by arbuscular mycorrhiza fungi and their associated fungal extraradical mycelium,

to elucidate fluxes between both symbiotic organisms. We predict that this strategy can also be used to

study metabolite fluxes between other organisms if the two interacting organisms can be physically