Guapirioid ectomycorrhiza: a novel fungus-plant subtype is described associated to Guapira opposita (Nyctaginaceae) in the Brazilian restinga

Aim of study: Despite its recognized ecosystemic importance, knowledge about mycorrhizal associations in Brazil is still dearth, and the diversity of the native mycorrhizal fungi remains unknown. In this study, we characterized morpho-anatomically and molecularly the ectomycorrhizae found associated with Guapira opposita in the restinga, vegetation established on sandy soil. Area of study: Coastal of the Atlantic Forest of southern Brazil, Florianópolis: Parque Natural Municipal das Dunas da Lagoa da Conceição, Monumento Natural Municipal da Lagoa do Peri and Parque Natural Municipal da Lagoa do Jacaré das Dunas do Santinho. Material and methods: The ectomycorrhizae found were morphotyped and described according to standard criteria. Plant and fungi were molecularly identified using sequences of the ITS region of rDNA. Main results: Ten morphotypes were identified associated with G. opposita, including the native threatened species Austroboletus festivus. Members of the clade /tomentella-thelephora were the most representative in our study, with six taxa. Based on particular characteristics, such as short, and simple or long and thin branched ectomycorrhizal systems, close connections between the layered ectomycorrhizal mantle and the cortical root cells, absence of a Hartig net and other fungal elements in the cortex, we propose the name ‘Guapirioid ectomycorrhiza’ for this new morphology. Research highlights: The results presented in this work confirm the presence of ectomycorrhizae in the restinga and suggest the existence of a diversity, above and below-ground, much greater than previously known. Furthermore, our data confirm the morphological and possibly ecological differences of tropical ectomycorrhizae from those known from temperate forests.