Pedological factors as drivers of archaeal and fungal communities in maize rhizosphere: a shotgun metagenomic sequencing approach

Abstract

South Africa is a semi-arid country in need of soil conservation methods for sustainable agroecosystem practices. Over time, researchers have worked extensively on the plant growth beneficial effects of fungi. However, archaeal groups in the soil and rhizosphere of different plants are under-studied. The impact of soil edaphic factors on the community structure of archaeal and fungal groups in the maize rhizosphere is the focus of this research. This will confirm the hypothesis that environmental factors have a significant impact on the plant–soil rhizobiome. To achieve this objective, a shotgun metagenomics approach was used to analyze maize rhizosphere and bulk soils collected from North West and Gauteng provinces of South Africa. Our findings revealed that both the maize rhizosphere and bulk soils have several archaeal and fungal phyla in common. Besides, Ascomycota (30‒51%), Thaumarchaeota (14‒26%), Euryarchaeota (19‒29%), and Crenarchaeota (8‒12%) have significantly dominated the maize rhizosphere and surrounding bulk soils. In comparison, genera such as Nitrosopumilus (Ls-18.32%, Lc-16.25%; Rs-15.45%, Rc-11.47%), Candidatus Nitrososphaera (Ls-15.29%, Lc-13.37%; Rs-10.53%, Rc-8.29%), Cenarchaeum (Ls-8.84%, Lc-8.16%; Rs-7.63%, Rc-5.38%), Chaetomium (Ls-25.15%, Lc-23.05%; Rs-14.83%, Rc-6.29%), and Neurospora (Ls-2.09%, Lc-1.95%; Rs-1.05%, Rc-0.99%) were significantly higher in maize rhizosphere soils compared to bulk soils (p < 0.05). Diversity indices showed that the archaeal and fungal composition were significantly different across samples with the presence of unclassified groups that could indicate the possibility of novel organisms in the sampling areas. The forward selection of soil edaphic factors predicted N–NH4, pH, and organic matter as the major contributing factors to the variation in the fungal and archaeal communities. To fully exploit the advantages possessed by these species, it is necessary to better understand the main environmental factors driving microbial assemblages of the soil microbiome. In addition, mapping out a culture-based method to unveil the unclassified groups could assist in the discovery of biotechnologically important archaeal and fungal groups for sustainable plant growth.