FUNGI DIVERSITY IN THE RHIZOSPHERE OFAspilia prulisetaSchweif. ext Schweif IN THE SEMI-ARID EASTERN KENYA

Abstract

Semi-arid eastern Kenya is a fragile ecosystem with continuous cultivation of dryland pulses and grains. Farmers use artificial fertilizers most of which are deleterious to the environment. Previous studies have shown that soil microbes in the rhizosphere could be used to sustainably enhance levels of soil mineral nutrients and soil health. However, few studies have examined fungal diversity in the rhizosphere of wild and native Aspilia pruliseta shrub. In this study, amplicons of Internal Transcribed Spacer (ITS) region on Total Community DNA using Illumina sequencing were used to explore the fungal community composition within the rhizosphere. Operational taxonomic units (OTUs) were analyzed using QIIME 1.8.0, taxonomy assigned via BLASTn against SILVA 119 database. Hierarchical clustering was done using R programming software. 72,093, 50,539 and 43,506 sequence reads were obtained from samples MC1 a , MC2 a and MC3 a respectively representing rhizosphere depth 0-20 cm, 21-40 cm and 41-60 cm. A total of 373 OTUs were realized at 3% genetic distance. Taxonomic analysis revealed that the genera Glomus was most prevalent in all soil depths with 85.60 % of the OTUs in depth 0-20 cm, 69.04 % in depth 21-40 cm and 48.45 % in depth 41-60 cm. The results revealed high levels of obligate arbuscular mycorrhiza fungi that if commercially cultured could enhance phosphates uptake in crops.

Trends in Microbial Community Composition and Function by Soil Depth

“…As for rhizosphere fungal communities, there have also been reports of significant variations by depth [ 87 , 152 ], associated with changes in rhizosphere chemistry. For example, rhizosphere pH will foster different levels of bacteria and fungi across depths, as fungi are normally more favored in zones of the rhizosphere with higher acidity [ 87 , 153 ]. Similar to bacteria, fungal communities in the rhizosphere do not necessarily decrease in diversity with root depth; there are many fungal taxa elevated or exclusively found around roots in deeper horizons [ 152 , 154 ].…”