Symbiosis is commonly associated with gene loss, but ectomycorrhizal fungi appear to have expanded genomes. The genus Amanita encompasses both asymbiotic and ectomycorrhizal species, and we are currently working with the genomes of six of these species to identify the genetic hallmarks of symbiosis.
Wolfe BE, RE Tulloss, A Pringle. 2012. The irreversible loss of a decomposition pathway marks the single origin of an ectomycorrhizal symbiosis. PLoS ONE 7(7): e39597 [download]
A phylogeny of one group
of transposable elements