Fungal community structure variability between the root rhizosphere and endosphere in a granite catena system in Kruger National Park, South Africa

Abstract

Fungi colonise various substrates such as organic matter (dead or alive) from plants or animals. These fungi can be specialists (i.e. belonging to a substrate) or generalists (i.e. surviving on different types of organisms). Fungi fulfil various functions in specialised niches, for example, acting as plant pathogens, helping in plant growth from the root systems or decomposing organic matter and fertilising soil. Species are specialised to occur in only one niche, or others can utilise or occur in various niches. For example, certain species occur only within certain plant tissues (endophytes), on the exterior surface of the plants growing above the ground (epiphytes) or below the ground in the sphere surrounding the roots (rhizosphere). Different soil types or conditions can favour certain species. This study used environmental sequencing to characterise the fungal communities associated with the root exterior and interior of Sida cordifolia, a plant growing across the varying soil conditions of the catena system. Fungal rhizosphere communities between three commonly occurring plant species – S. cordifolia, Melhania acuminata (both Malvaceae) and Kyphocarpa angustifolia (Amaranthaceae) – in one of the soil types were also studied to compare and contrast the fungal rhizosphere communities of these herbs. Molecular Operational Taxonomic Units co-occurred between niches, soil conditions and the rhizospheres of three plants at the same location, whilst others were restricted to only one niche or plant species. Results showed that soil conditions in a catena can influence the associations of fungal species between different catena zones, on the outside and inside of the roots, and that these communities also differ between plant species.

Conservation implications: This study showed that complex and sensitive fungal communities are associated with plant roots in different zones of the catena. This is most likely also true between different habitats and soil types on a larger scale. This study emphasises the need to also manage a catena system on the micro-ecological scale whilst framing conservation and management plans of the Kruger National Park.