Phylogeny and ecology of meristematic ascomycetes

Melanized meristematic fungi were studied by SSU and ITS rDNA sequencing, r estriction length polymorphisms (RFLP) and nutritional physiology. Most of these fungi originated from environments with conditions of stress in tempe rature, water availability, oxygenic action, UV irradiation, electrolyte co ntent and / or scarcity of nutrients. Phylogenetically they were quite dive rse as they were found to belong to or have close affinities to at least th ree different orders of the fungal Kingdom: Chaetothyriales, Dothideales an d Pleosporales. Morphologically they were similar, which has sometimes led to the classification of unrelated fungi in a single anamorph genus. In add ition, strains may produce morphologically distinct synanamorphs. One such morphology, the muriform cell, i.e. the meristematic tissue form in agents of human chromoblastomycosis, is stimulated by factors other than acidity a lone. It is concluded that stress tolerance through vitality factors is a c apacity acquired rather often in the course of evolution, whereas pathogeni city on mammals using virulence factors is very rare.