Ectomycorrhizal fungal communities of Coccoloba uvifera (L.) L. mature trees and seedlings in the neotropical coastal forests of Guadeloupe (Lesser Antilles)

Abstract

We studied belowground and aboveground diversity and distribution of ectomycorrhizal (EM) fungal species colonizing Coccoloba uvifera (L.) L. (seagrape) mature trees and seedlings naturally regenerating in four littoral forests of the Guadeloupe island (Lesser Antilles). We collected 546 sporocarps, 49 sclerotia, and morphotyped 26,722 root tips from mature trees and seedlings. Seven EM fungal species only were recovered among sporocarps (Cantharellus cinnabarinus, Amanita arenicola, Russula cremeolilacina, Inocybe littoralis, Inocybe xerophytica, Melanogaster sp., and Scleroderma bermudense) and one EM fungal species from sclerotia (Cenococcum geophilum). After internal transcribed spacer (ITS) sequencing, the EM root tips fell into 15 EM fungal taxa including 14 basidiomycetes and 1 ascomycete identified. Sporocarp survey only weakly reflected belowground assessment of the EM fungal community, although 5 fruiting species were found on roots. Seagrape seedlings and mature trees had very similar communities of EM fungi, dominated by S. bermudense, R. cremeolilacina, and two Thelephoraceae: shared species represented 93 % of the taxonomic EM fungal diversity and 74 % of the sampled EM root tips. Furthermore, some significant differences were observed between the frequencies of EM fungal taxa on mature trees and seedlings. The EM fungal community composition also varied between the four investigated sites. We discuss the reasons for such a species-poor community and the possible role of common mycorrhizal networks linking seagrape seedlings and mature trees in regeneration of coastal forests.

Ectomycorrhizal fungi are shared between seedlings and adults in a monodominant Gilbertiodendron dewevrei rain forest in Cameroon

“…Similarly, a recent origin of the EM symbiosis and/or stress conditions may reduce the fungal diversity (Séne et al . ). Finally, the lack of difference in richness of EM fungal taxa between the mixed and monodominant forests may, in part, be due to the dominance of generalist EM fungi (Onguene & Kuyper , Richard et al .…”

“…): based on this index, the diversity is lower than in monodominant Oreomunnea mexicana (Fisher's alpha = 89.5) but higher than in Coccoloba uvifera forests (Fisher's alpha = 3.67 for seedlings and 3.32 for adult trees; Séne et al . ) or under Pakaraimaea dipterocarpaceae (Fisher's alpha = 19.8; Smith et al . ); yet they are in the range of mixed EM tropical forests, which is equally large (Fisher's alpha = 4–183; Corrales et al .…”

“…We performed PCR amplification and sequencing of the internal transcribed spacers and 5.8S region (ITS) of the ribosomal DNA with primers ITS1‐F and ITS4, or otherwise ITS1‐F and ITS4B as in Séne et al . (). We edited sequences using CodonCode Aligner v.4.1.1 (LI‐COR, Inc., MA).…”

Ectomycorrhizal associations in the tropics – biogeography, diversity patterns and ecosystem roles

“…Several other ECM fungal lineages also are locally important in tropical ecosystems but their diversity and dominance are variable depending on the continent, type of forest and tree hosts. Species in the /scleroderma–pisolithus lineage are prevalent in some forest types, and taxa in this group often dominate the roots of specific plant taxa, such as Gnetum and Coccoloba (Tedersoo & Põlme, ; Séne et al ., ). Members of the /clavulina lineage are common worldwide but are particularly diverse in several Neotropical forests (Morris et al ., ; Smith et al ., ; Uehling et al ., ).…”

“…All of these factors may be important in structuring their ECM fungal communities. Hosts such as Coccoloba uvifera , Pisonia grandis and Pisonia sandwicensis inhabit stressful, saline coastal habitats and they always associate with a small suite of specific ECM fungi (Chambers et al ., ; Suvi et al ., ; Hayward & Hynson, ; Séne et al ., ). In the case of Alnus , specificity is linked to the co‐migration of plants and their ECM fungi from the northern hemisphere (Kennedy et al ., ).…”