Identification and Characterization of Peptaibols as the Causing Agents of Pseudodiploöspora longispora Infecting the Edible Mushroom Morchella

Pseudodiploöspora longispora (previously known as Diploöspora longispora) is a pathogenic fungus of Morchella mushrooms. The molecular mechanism underlying the infection of P. longispora in fruiting bodies remains unknown. In this study, three known peptaibols, alamethicin F-50, polysporin B, and septocylindrin B (1-3), and a new analogue, longisporin A (4), were detected and identified in the culture of P. longispora and the fruiting bodies of M. sextelata infected by P. longispora. The primary amino sequence of longisporin A is defined as Ac-Aib¹-Pro²-Aib³-Ala⁴-Aib⁵-Aib⁶-Gln⁷-Aib⁸-Val⁹-Aib¹⁰-Glu¹¹-Leu¹²-Aib¹³-Pro¹⁴-Val¹⁵-Aib¹⁶-Aib¹⁷-Gln¹⁸-Gln¹⁹-Phaol²⁰. The peptaibols 1-4 greatly suppressed the mycelial growth of M. sextelata. In addition, treatment with alamethicin F-50 produced damage on the cell wall and membrane of M. sextelata. Compounds 1-4 also exhibited inhibitory activities against human pathogens including Aspergillus fumigatus, Candida albicans, methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus, and plant pathogen Verticillium dahlia. Herein, peptaibols are confirmed as virulence factors involved in the invasion of P. longispora on Morchella, providing insights into the interaction between pathogenic P. longispora and mushrooms.