65Hyphae might have also facilitated the transition of fungi to terrestrial life 23 and confer immense 66 medical relevance to pathogenic fungi 24 . Hyphae of extant fungi rarely stick to each other in 67 vegetative mycelia and adhesion becomes key only in fruiting bodies 25-27 -which, in terms of 68 complexity level, resemble complex multicellular metazoans and plants 7,28 -or in the attachment 69 to host surfaces 29 . Thus, whereas in most multicellular lineages adhesion, cell-cell cooperation, 70communication and differentiation represent the main hurdles to the emergence of multicellular 71 precursors 3,6,30-32 , fungi might have had different obstacles to overcome. 72 73While the origins of hyphae are poorly known, information on the molecular and cellular 74 basis of hyphal morphogenesis is abundant (for recent reviews see refs [33][34][35][36][37][38] ), permitting 75 evolutionary genomic analyses of the origins of hyphae. Hyphal morphogenesis builds on cell 76 polarization networks 39 , the exo-and endocytotic machinery 40 , long range vesicle transport as 77 well as fungal-specific traits such as cell wall synthesis and assembly 41 , and the selection of 78 branching points and sites of septation 42 , among others. A key structure of hyphal growth is the 79Spitzenkörper 43 , which acts as a distribution center for vesicles transporting cell wall materials 80and various factors to the hyphal tip. The cytoplasmic microtubule network provides the 81 connection between vesicle cargo through the ER and Golgi and the Spitzenkörper, from where 82