Fungos micorrízicos arbusculares em serapilheira de Mata Atlântica: colonização, riqueza e fatores que afetam sua dinâmica

Abstract

Arbuscular Mycorrhizal Fungi (AMF) form symbiotic associations with most terrestrial plant roots, mainly promoting plant growth. However, studies have also shown the presence of these fungi in leaf litter. Due to being a relatively underexplored topic, limited information is available, such as which AMF species colonize leaf litter, which biotic and/or abiotic factors influence this colonization, and whether it is a global or restricted phenomenon. In order to answer these questions, this study aimed to document the occurrence and identify the AMF species colonizing leaf litter, as well as to investigate whether factors such as litter quality, decomposition stage and soil properties influence colonization of these fungi in this context across three areas of the Atlantic Forest (RPPN Mata Estrela, Flona de Nísia Floresta and Fazenda Sapé), Rio Grande do Norte. To achieve this, litter bags were used to collect leaf litter from the plant species Hymenaea courbaril, Mimosa caesalpiniifolia, Paubrasilia echinata, and Ziziphus joazeiro. In the laboratory, the samples underwent the moist chamber technique, clarification, and DNA extraction. The first chapter revealed that only 39 studies document AMF in leaf litter, comprising 60 species distributed across 5 orders, 7 families, and 14 genera, with only 34 species identified from studies that specifically collected leaf litter for analysis. The second chapter presented an unusual approach to recover AMF from leaf litter, while the third chapter indicated that Z. joazeiro and P. echinata exhibited the highest percentages of AMF colonization, whereas H. courbaril from RPPN Mata Estrela and Flona NF, as well as M. caesalpiniifolia, present the lowest percentages. Environmental DNA sequences obtained from leaf litter corresponded to four species: Diversispora varaderana, Funneliformis caledonium, F. geosporum, and Rhizoglomus irregulare, while Glomus spinuliferum was identified through microscopic observation. Funneliformis geosporum and R. irregulare were found in more than one plant species. Diversispora varaderana and F. caledonium occurred only in M. caesalpiniifolia and H. courbaril, respectively. Furthermore, litter quality, decomposition stage and soil properties influence litter colonization by AMF. The data reveal that litter has been a rich substrate for studying AMF, but neglected in inventory sampling. AMF, along with leaf litter, still have an underexplored potential for restoration of degraded areas. Furthermore, these AMF species are, for the first time, recorded colonizing litter. The results obtained in this study are important because they highlight a little explored condition for the group, and may be a source for new descriptions and records of poorly documented species in Brazilian soils.