Andy's review on inter organismic lipid transfer is out in Current Opinion in Plant Biology.

Cross-kingdom lipid transfer in arbuscular mycorrhiza symbiosis and beyond

Keymer A, Gutjahr C

Current Opinion in Plant Biology 44: 137-144.

Arbuscular mycorrhiza (AM) is a widespread symbiosis between most land plants and fungi of the Glomeromycotina, which has existed for more than 400 million years. AM fungi (AMF) improve plant nutrition with mineral nutrients and conversely, their growth and development is fueled by organic carbon supplied from their host. Recent studies demonstrated independently and with different experimental approaches that lipids are transferred from plants to fungi in addition to sugars, and that AMF are dependent on this lipid supply because they lack genes encoding fatty acid synthase I subunits. Dependence on host lipids or lipid parasitism occur in a range of interorganismic associations with participants from almost all kingdoms. Thus, these phenomena seem rather common in mutualistic and parasitic interactions.