Soil and Rhizosphere Associated Fungi in Gray Mangroves (Avicennia marina) from the Red Sea — A Metagenomic Approach

Marta Filipa Simões,André Antunes,Cristiane A Ottoni,Mohammad Shoaib Amini,Intikhab Alam,Hanin Alzubaidy,Noor-Azlin Mokhtar,John A.C Archer,Vladimir B Bajic

doi:10.1016/j.gpb.2015.07.002

Abstract

Covering a quarter of the world’s tropical coastlines and being one of the most threatened ecosystems, mangroves are among the major sources of terrestrial organic matter to oceans and harbor a wide microbial diversity. In order to protect, restore, and better understand these ecosystems, researchers have extensively studied their microbiology, yet few surveys have focused on their fungal communities. Our lack of knowledge is even more pronounced for specific fungal populations, such as the ones associated with the rhizosphere. Likewise, the Red Sea gray mangroves (Avicennia marina) remain poorly characterized, and understanding of their fungal communities still relies on cultivation-dependent methods. In this study, we analyzed metagenomic datasets from gray mangrove rhizosphere and bulk soil samples collected in the Red Sea coast, to obtain a snapshot of their fungal communities. Our data indicated that Ascomycota was the dominant phylum (76%–85%), while Basidiomycota was less abundant (14%–24%), yet present in higher numbers than usually reported for such environments. Fungal communities were more stable within the rhizosphere than within the bulk soil, both at class and genus level. This finding is consistent with the intrinsic patchiness in soil sediments and with the selection of specific microbial communities by plant roots. Our study indicates the presence of several species on this mycobiome that were not previously reported as mangrove-associated. In particular, we detected representatives of several commercially-used fungi, e.g., producers of secreted cellulases and anaerobic producers of cellulosomes. These results represent additional insights into the fungal community of the gray mangroves of the Red Sea, and show that they are significantly richer than previously reported.

Highlights

Mangroves are endangered coastal biotopes that approximately cover a quarter of the world’s tropical coastlines [1−3]. They are associated with a wide range of ecological benefits, such as being a major source of terrestrial organic matter to oceans and are well recognized, yet poorly studied, biodiversity hotspots [2,4]
In one of the very few studies available, Abdel-Wahad et al [9] used a targeted metagenomic approach to look into fungal diversity of the soil and rhizosphere in grey mangroves from the Red Sea
In order to decrease the paucity of data on fungal communities present in rhizosphere and in the grey mangroves of the Red Sea, we analyzed samples collected from this specific environment

Summary

Introduction

Mangroves are endangered coastal biotopes that approximately cover a quarter of the world’s tropical coastlines [1−3]. In one of the very few studies available, Abdel-Wahad et al [9] used a targeted metagenomic approach to look into fungal diversity of the soil and rhizosphere in grey mangroves from the Red Sea. They recorded a total of 29 different fungal species isolated from wood pieces on the mangroves and surrounding beaches, the rhizosphere remained under-studied. In order to decrease the paucity of data on fungal communities present in rhizosphere and in the grey mangroves of the Red Sea, we analyzed samples collected from this specific environment.

Results

Conclusion