New Findings on the Biology and Ecology of the Ecuadorian Amazon Fungus Polyporus leprieurii var. yasuniensis

Abstract

Polyporus leprieurii var. yasuniensis is a prolific wood-decay fungus inhabiting the forest floor of one of the most biodiverse places on earth, the Yasuní National Park in Ecuador. Basidiocarps and aerial rhizomorphs are commonly found growing on woody debris distributed along the floor of this forest ecosystem. Because of the extraordinary abundance of this fungus in the tropical rainforest, we carried out investigations to better understand the biological and ecological aspects contributing to its prolific distribution. Data on growth inhibition in paired competition studies with sixteen fungal isolates exemplifies defense mechanisms used to defend its territory, including pseudosclerotial plates and the development of a melanized rhizomorphic mat. Results of biomass loss on eleven types of tropical wood in microcosm experiments demonstrated the broad decay capacity of the fungus. In and ex situ observations provided information on how long rhizomorphs can prevail in highly competitive ecosystems as well as stressful conditions in the laboratory. Finally, high concentrations of metal ions occur on rhizomorphs as compared to colonized wood. Sequestration of metal ions from the environment by the melanized rhizomorphs may offer protection against competitors. The development of melanized rhizomorphs is key to find and colonize new substrates and resist changing environmental conditions.

Diverse Xylaria in the Ecuadorian Amazon and their mode of wood degradation

“…The melanized morphological barriers appear to function well to allow these fungi to persist in abundance in this extreme environment. We know that melanin produced by other fungi can act to bind metal ions providing a metal ion sheath that functions to provide additional protection for the fungus (McDougall and Blanchette 1996 ; Rizzo et al 1992 ; Toapanta Albán et al 2022 ). This is also likely functioning in a similar manner for Xylaria species.…”

“…At Yasuní National Park, several cosmopolitan species of fungi have been identified with most of the species being in the family Polyporaceae (Toapanta Albán, 2014 ). Other recent studies identified some unusual Basidiomycota in Yasuní National Park (Toapanta Albán et al 2021 , 2022 ). These species produce aerial melanized rhizomorphs to facilitate colonization of substrates and better survive in the very wet environment of the rainforest.…”

“…Cultures used for the decay experiments were incubated at 22 °C for 14 days. Agar microcosms were used to assess the decay potential of the Xylaria isolates following methods adapted from Toapanta et al (Toapanta Albán et al 2022 ). Wood from four species of tropical trees were selected based on their varying heartwood densities and extractives (Table 1 ).…”

Screening of Antibacterial Activity of Some Resupinate Fungi, Reveal Gloeocystidiellum lojanense sp. nov. (Russulales) against E. coli from Ecuador

“…Ecuador, considered within the megadiverse countries worldwide [ 75 , 76 , 77 ], has as consequence a great diversity of fungi [ 27 , 29 , 33 , 34 ] that require integrative taxonomic research to discover new species such as G. lojanense with bioactive potential and applications in several sectors such as human health.…”

“…in the order Polyporales, have been evaluated for antimicrobial activity [ 26 ]. However, there is still a low number of prospective mushroom studies, especially in neotropical areas such as Ecuador, where these organisms are still poorly cataloged [ 27 , 28 , 29 , 30 ], characterized morphologically and molecularly [ 31 , 32 , 33 , 34 ], or even more chemically characterized by evaluating the metabolites that they generate [ 35 ]. However, mushrooms with medicinal properties, from an ethnomycological point of view, have been reported in Ecuador [ 36 , 37 , 38 , 39 ].…”