Translocation and utilization of fungal storage lipid in the arbuscular mycorrhizal symbiosis

Berta Bago, Warren Zipfel, Rebecca M. Williams, Jeongwon Jun, Raoul Arreola, Peter Lammers, Philip E. Pfeffer, Yair Shachar-Hill

Research output: Contribution to journalArticle

Abstract

The arbuscular mycorrhizal (AM) symbiosis is responsible for huge fluxes of photosynthetically fixed carbon from plants to the soil. Carbon is transferred from the plant to the fungus as hexose, but the main form of carbon stored by the mycobiont at all stages of its life cycle is triacylglycerol. Previous isotopic labeling experiments showed that the fungus exports this storage lipid from the intraradical mycelium (IRM) to the extraradical mycelium (ERM). Here, in vivo multiphoton microscopy was used to observe the movement of lipid bodies through the fungal colony and to determine their sizes, distribution, and velocities. The distribution of lipid bodies along fungal hyphae suggests that they are progressively consumed as they move toward growing tips. We report the isolation and measurements of expression of an AM fungal expressed sequence tag that encodes a putative acyl-coenzyme A dehydrogenase; its deduced amino acid sequence suggests that it may function in the anabolic flux of carbon from lipid to carbohydrate. Time-lapse image sequences show lipid bodies moving in both directions along hyphae and nuclear magnetic resonance analysis of labeling patterns after supplying 13C-labeled glycerol to either extraradical hyphae or colonized roots shows that there is indeed significant bidirectional translocation between IRM and ERM. We conclude that large amounts of lipid are translocated within the AM fungal colony and that, whereas net movement is from the IRM to the ERM, there is also substantial recirculation throughout the fungus.

Original languageEnglish (US)
Pages (from-to)108-124
Number of pages17
JournalPlant Physiology
Volume128
Issue number1
DOIs
StatePublished - 2002
Externally publishedYes

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ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science

Cite this

Bago, B., Zipfel, W., Williams, R. M., Jun, J., Arreola, R., Lammers, P., Pfeffer, P. E., & Shachar-Hill, Y. (2002). Translocation and utilization of fungal storage lipid in the arbuscular mycorrhizal symbiosis. Plant Physiology, 128(1), 108-124. https://doi.org/10.1104/pp.128.1.108