Nouvelles observations sur les spores d'Epichloe typhina (Fr. ex Tul.), Clavicipitacée pathogène des graminées

Epichloe typhina is an ascomycete and phytopathogenic fungus with 3 types of spores: spermatia, ascospores and conidia. All these spores are produced by the epiphytic stage of the fungus that forms mycelial stroma choking the inflorescences of Pooideae grasses. The role of each spore in infection processes is not well known. Spore germination on artificial and natural media was studied. Spermatia germinate bipolarly and their role seems to be limited to that of male gametes. Ascospores form germ-tubes for mycelial production and also conidiophores that produce a new generation of asexual spores. Although these spores are morphologically identical to spermatia, they not only form a germ-tube but also a conidiophore producing a new generation of conidia. We describe for the first time a mycelial net formed by aggregation of ascospores, producing a huge quantity of conidia under wet conditions.