Panaeolus papilionaceus (Bull.) Quél. [=P. campanulatus (L.) Quél.] [=P. sphinctrinus (Fr.) Quél.] is one of the most representative coprophilous species of the order Agaricales. It is frequently found fruiting on dung of cows and horses, manure meadows and sometimes also on nitrogen-rich grassy places. This fungus usually fruits in spring, summer and fall and is widely distributed in the Northern hemisphere. P. papilionaceus is characterized by the whitish to brownish obtusely conical to bell-shaped cap with tiny white partial veil fragments hanging from the edge of the cap, gills black with whitish edges and black spore print. Molecular analyses included P. papilionaceus in the consortium of dark-spores agarics that corresponds largely with the Kühner (1980) concept of the Strophariaceae family (Gulden et al, 2005). It is also included in the tribe Panaeoleae, together with other lineages of dark-spored agarics, within the Agaricoid clade (Matheny et al., 2006).
Within the framework of the CSP15-1609 project, a total of sixteen saprobic Agaricales, that cover a number of the most important families and tribes involved in lignocellulose degradation, were proposed to be sequenced for the first time. The genome sequence of P. papilionaceus will allow comparison of its lignocellulolytic enzymes with those of the other coprophilous (or manure meadows) decayers, such as Coprinopsis cinerea (Psathyrellaceae), Agaricus bisporus (Agaricaceae) or Bolbitius vitellinus (Bolbitiaceae). P. papilionaceus (including the synonym P. sphinctrinus) was described to produce laccases and manganese peroxidases when grown on a nitrogen rich medium, in concordance with nitrogen-rich dung, the natural substrate of this fungus (Heinzkill et al., 1998). Fungal laccases are involved in the transformation of a variety of phenolic compounds including humic substances and lignin-derived aromatics, and laccase activity has been found in forest litters and soils (Baldrian, 2006).
The genome sequence of P. papilionaceus will improve our knowledge of the role of laccases and peroxidases in the decomposition of humic substances in soils. Furthermore, it will provide a better understanding the interspecific interactions between coprophilous fungi and the role of their lignocellulolytic enzymes in carbon cycling.
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