Studying the brown desert truffles of Israel

The Israeli Negev is the habitat of at least two brown desert truffles, the most abundant of which is the complex known as Terfezia boudieri. Using molecular phylogenetic approaches, we were able to demonstrate the existence within this complex of three cryptic species exhibiting physiological, but not morphological, discriminating characters. A culture harboring two distinct internal transcribed spacer (ITS) types led us to the discovery of long-term heterokaryons in the glebal outgrowth of these truffles (Ascomycetes). Desert truffles form endomycorrhizas or Terfezia-type ectomycorrhizas. By following the formation of mycorrhizas in a laboratory system, we were able to unravel some of the underlying conditions responsible for the establishment of each type of association. Using a similar system, we also isolated genes involved in determining mycorrhizal type. Some of these genes were further analyzed, leading to identification of a peptide of unknown function that is involved in the determination process.