Fungal succession on the decomposition of three plant species from a Brazilian mangrove

Abstract

Leaf decomposition is the primary process in release of nutrients in the dynamic mangrove habitat, supporting the ecosystem food webs. On most environments, fungi are an essential part of this process. However, due to the peculiarities of mangrove forests, this group is currently neglected. Thus, this study tests the hypothesis that fungal communities display a specific succession pattern in different mangrove species and this due to differences in their ecological role. A molecular approach was employed to investigate the dynamics of the fungal community during the decomposition of three common plant species (Rhizophora mangle, Laguncularia racemosa, and Avicennia schaueriana) from a mangrove habitat located at the southeast of Brazil. Plant material was the primary driver of fungi communities, but time also was marginally significant for the process, and evident changes in the fungal community during the decomposition process were observed. The five most abundant classes common to all the three plant species were Saccharomycetes, Sordariomycetes, Tremellomycetes, Eurotiomycetes, and Dothideomycetes, all belonging to the Phylum Ascomycota. Microbotryomycetes class were shared only by A. schaueriana and L. racemosa, while Agaricomycetes class were shared by L. racemosa and R. mangle. The class Glomeromycetes were shared by A. schaueriana and R. mangle. The analysis of the core microbiome showed that Saccharomycetes was the most abundant class. In the variable community, Sordariomycetes was the most abundant one, mainly in the Laguncularia racemosa plant. The results presented in this work shows a specialization of the fungal community regarding plant material during litter decomposition which might be related to the different chemical composition and rate of degradation.

Figure 1

(a) Chao Index of richness. (b) Shannon and (c) Simpson alpha diversity indexes of the fungi community during the decomposition process of three plant species in Cananéia mangrove. Dots represent the average values of the sequenced replicates while error bars represent its standard deviation. Letters next to dots represent Tukey’s test results. Capital letters indicate differences between plants of the same time point while lower-case letters indicate differences between time points of the same plant. Omitted letters indicate that ANOVA test was not significant (p > 0.05).

Figure 2

The most abundant fungi families assembled in the three plant species (Avicennia schaueriana, Laguncularia racemosa and Rhizophora mangle) during the decomposition process. (a) Principal Coordinated analysis (PCoA) showing the β diversity of the six most abundant families in the three plant species in the four collection times (7, 15, 30, 60). The first axis explained 38.2% of the data while the second axis explained 23.4%. (b) Principal Coordinated analysis showing the β diversity of the six most abundant phyla in the three plant species where each dot represent an OTU colored according to the phylum level of the taxonomic classification.

Figure 3

Relative abundance of the 10 most common classes along with the two unclassified groups (U_) belonging to the phyla Ascomycota and Basidiomycota in the A. schaueriana plant along the 60 days of decomposition process.

Figure 4

Relative abundance of the OTUs classified as belonging to the core or variable communities determine by the Poisson distribution in the three studies plant species (Avicennia schaueriana, Laguncularia racemosa and Rhizophora mangle).

Figure 5

Taxonomic classification of the fungal OTUs identified as Generalists or Specialists found during the decomposition of mangrove leaves.

Figure 6

Identification of OTUs belonging to fungal guilds found during the decomposition of mangrove leaves. Identification was performed using FunGuild.