Restinga ectomycorrhizae: a work in progress

Abstract

Background: The Brazilian Atlantic Forest is one of the most biodiverse terrestrial ecoregions of the world. Among its constituents, restinga vegetation makes a particular case, acting as a buffer zone between the oceans and the forest. Covering some 80% of Brazilian coastline (over 7,300 km in length), restinga is a harsh environment where plants and fungi interact in complex ways that just now are beginning to be unveiled. Ectomycorrhizal symbiosis, in particular, plays a so far ungauged and likely underestimated role. We recently described the morpho-anatomical and molecular features of the ectomycorrhizae formed by several basidiomycetous mycobionts on the host plant Guapira opposita, but the mycorrhizal biology of restinga is still largely unexplored. Here, we report new data on the ectomycorrhizal fungal symbionts of G. opposita, based on the collection of sporomata and ectomycorrhizal root tips in restinga stands occurring in southern Brazil. Methods: To obtain a broader view of restinga mycorrhizal and ecological potential, we compiled a comprehensive and up-to-date checklist of fungal species reported or supposed to establish ectomycorrhizae on restinga-inhabiting host plants, mainly on the basis of field observations. Results: Our list comprises some 726 records, 74 of which correspond to putative ectomycorrhizal taxa specifically associated with restinga. These include several members of Boletaceae, Amanita, Tomentella/ Thelephora, Russula/ Lactifluus, and Clavulina, as well as hypogeous fungi, like the recently described Longistriata flava. Conclusions: Our survey reveals a significant diversity of the restinga ectomycorrhizal mycobiota, indicating the importance of this symbiosis for the ecological functioning of a unique yet poorly known and threatened ecosystem.

Keywords: Atlantic Forest; Brazilian fungi; Neotropics; diversity; ectomycorrhiza; fungal conservation; mycorrhizal symbiosis.

Figure 1.. Map of restinga extension (in black) along the Brazilian Atlantic coast.

Figure 2.. Ectomycorrhizal morphotypes associated with Guapira opposita roots in the restinga from South Brazil.

(a) Amanita viscidolutea; (b) Austroboletus festivus; (c) Inocybe sp.; (d) Thelephora sp1.; (e) Tomentella sp1. and Tomentella sp2.; (f) Tomentella sp3.; (g) Tomentella sp4.; (h) Tomentella sp5.; (i) Tomentella sp6.

Figure 3.. Basidiomata of selected species discussed in the text.

(a) Boletellus nordestinus; (b) Amanita crebresulcata; (c) Amanita coacta; (d) Amanita viscidolutea; (e) Cantharellus guyanensis; (f) Clavulina junduensis; (g) Clavulina incrustata; (h) Brasilioporus olivaceoflavidus; (i) Brasilioporus simoniarum; (j) Nevesoporus nigrostipitatus. Photo credits (a) Eduardo Fazolino; (h; j) Altielys C. Magnago; (i) Juli Simon.