Morpho-anatomical and molecular characterization of a native mycorrhizal <i>Amanita</i> species associated with <i>Guapira opposita </i>(<i>Nyctaginaceae</i>) in the brazilian Atlantic Forest

Abstract

In this work, we characterize naturally occurring mycorrhizae formed by Amanita viscidolutea on Guapira opposita in the Atlantic Forest in Brazil. We sequenced the rDNA ITS region from the mycorrhizae and basidiomata to identify both symbionts. Amanita viscidolutea mycorrhizae were up to 43 mm long, mostly simple, and unbranched to irregularly pinnate. The fungal mantle surface was velvety to slightly cottony and white to yellowish with silver patches. Hyphal strands were infrequently present. Although the fungal mantle consisted of clampless hyphae, emanating hyphae and hyphal strands had sparsely distributed clamp connections. A unique character of the mycorrhizae was the absence of a Hartig net.

Restinga ectomycorrhizae: a work in progress

“…Out of a total of 29 morphotypes collected from soil samples, 10 were found associated with G. opposita roots, all corresponding to Basidiomycota taxa, based on molecular barcoding. 50 The best represented clade was/tomentella-thelephora, with Tomentella bursting six species ( Table 1 ); of note, two macrofungi native species from the restinga of the Atlantic Forest, namely Amanita viscidolutea and Austroboletus festivus , besides occurring as basidiomata were also found associated to G. opposita roots in our survey ( Table 1 ). 50 The most striking characteristics of Guapira ECMs, however, remain with their morpho-anatomical features, that make them rather unique.…”

“… 50 The best represented clade was/tomentella-thelephora, with Tomentella bursting six species ( Table 1 ); of note, two macrofungi native species from the restinga of the Atlantic Forest, namely Amanita viscidolutea and Austroboletus festivus , besides occurring as basidiomata were also found associated to G. opposita roots in our survey ( Table 1 ). 50 The most striking characteristics of Guapira ECMs, however, remain with their morpho-anatomical features, that make them rather unique. The short, simple or long, thin branched ectomycorrhizal systems, close connections between the layered mantle and the cortical cells, absence of a Hartig net or other fungal elements in the cortex are diagnostic characteristics that make the Guapira ECMs we observed rather unique, to the point that we proposed the term ‘Guapirioid’ to distinguish them from the other known ectomycorrhizal types ( Figure 2 ).…”

“…33,50 Our study on the ectomycorrhiza of A. viscidolutea on G. opposita has been the first detailed morpho-anatomical and molecular characterization of a naturally occurring mycorrhiza associated with a native plant host in restinga forest in South America. 33 Besides G. opposita, we can also find members of the following potential ectomycorrhizal families growing in restinga: Fabaceae, Moraceae, Myrtaceae, Nyctaginaceae, Polygonaceae, and Salicaceae. 51 As mentioned above, representatives of/tomentella-thelephora clade were the most frequently encountered taxa in our restinga surveys, a finding in line with studies based on root and soil analysis that revealed that the/tomentella-thelephora clade is diverse and dominant in neotropical habitats, 52,53 although they are generally undersampled due to their inconspicuous basidiomata, which makes it difficult to identify the sampled taxon.…”

“…25 Using transmission electron microscopy, we recently described the morpho-anatomical characteristics of the ectomycorrhiza formed between A. viscidolutea and Guapira opposita roots; both partners were identified from the ectomycorrhizal root tips through molecular analyzes. 33 Cantharellus guyanensis (MycoBank MB240517) (Figure 3e) is a widespread species that was discovered in lowland forest in French Guiana. 89 Surprisingly, the species has gone nearly a century without being recorded since Montagne proposed it.…”

“…To date, only two works have been published that link both fungus and plant partners in the restinga and present a detailed morphological and molecular characterization of the ECM ( Hysterangium atlanticum + Coccoloba spp. 32 and Amanita viscidolutea + Guapira opposita 33 ). Researches that have been developed in Brazil corroborate the urgent need to better understand the belowground diversity in the Atlantic Forest, especially considering that the restinga potentially harbors a unique community of mycorrhizal taxa.…”