Comparative study of microbial structure and functional profile of sunflower rhizosphere grown in two fields.

BACKGROUND: Microbial communities inhabiting the rhizosphere play pivotal roles in determining plant health and yield. Manipulation of the rhizosphere microbial community is a promising means to enhance the productivity of economically viable and important agricultural crops such as sunflower (Helianthus annuus). This study was designed to gain insights into the taxonomic and functional structures of sunflower rhizosphere and bulk soil microbiome at two different locations (Sheila and Itsoseng) in South Africa. RESULTS: Microbial DNA extracted from the sunflower rhizosphere and bulk soils was subjected to next-generation sequencing using 16S amplicon sequencing technique. Firmicutes, Actnobacteria and Proteobacteria predominated sunflower rhizosphere soils. Firmicutes, Cyanobacteria, Deinococcus-Thermus and Fibrobacteres were positively influenced by Na+ and clay content, while Actinobacteria, Thaumarchaeota, Bacteroidetes, Planctomycetes, Aquificae and Chloroflexi were positively influenced by soil resistivity (Res) and Mg2+. The community-level physiological profiling (CLPP) analysis showed that the microbial communities in SHR and ITR used the amino acids tryptophan and malic acid efficiently. The metabolisms of these carbon substrates may be due to the dominant nature of some of the organisms, such as Actinobacteria in the soils. CONCLUSION: The CLPP measurements of soil from sunflower rhizosphere were different from those of the bulk soil and the degree of the variations were based on the type of carbon substrates and the soil microbial composition. This study has shown the presence of certain taxa of rhizobacteria in sunflower rhizosphere which were positively influenced by Na+ and Mg2+, and taxa obtained from SHR and ITR were able to effectively utilized tryptophan and malic acid. Many unclassified microbial groups were also discovered and it is therefore recommended that efforts should further be made to isolate, characterize and identify these unclassified microbial species, as it might be plausible to discover new microbial candidates that can further be harnessed for biotechnological purpose.

Effects of soil properties and carbon substrates on bacterial diversity of two sunflower farms.

The sustainable production of sunflower (Helianthus annuus) is crucial and one way to accomplish this feat is to have an understanding of the beneficial bacteria of sunflower rhizosphere. Similarly, the respiratory response of these bacteria needs to be studied to understand their roles in the ecosystem. This study was therefore conceptualized to gain insights into the effects of soil properties and carbon substrate utilization on bacterial community diversity of sunflower rhizosphere grown in Ditsobottla and Kraaipan, North West Province, South Africa. Extracted DNA from sunflower rhizosphere and bulk soils was subjected to 16S amplicon sequencing. Significant differences were observed in the alpha and beta diversities of the soil bacterial communities (p < 0.05). At the order level, among all the bacterial taxa captured in the farms, Bacillales were the most dominant. The abundance of Lactobacillales, Bacillales, Rhizobiales, Enterobacteriales, Burkholderiales, Flavobacteriales, Sphingomonadales, Myxococcales, and Nitrosomonadales obtained from Ditsobottla rhizosphere soil (R1) was positively influenced by organic matter (OM), while the abundance of Planctomycetales, Cytophagales, Gemmatimonadales, Nitrospirales and Caulobacteriales from Kraaipan rhizosphere soil (R2) was positively influenced by total N and pH. Bacterial communities of all the soil samples utilized the different carbon substrates (three amino acids, six carbohydrates, and three carboxylic acids) as an energy source. Significant differences (p < 0.05) were only observed in tryptophan and methionine amended soils. Unclassified bacteria were also captured in this study, such bacteria can further be harnessed for sustainable production of sunflower and other agricultural crops.

Amplicon sequencing data profiling of bacterial community connected with the rhizospheric soil from sunflower plants.

This article presents dataset on the bacterial community structure associated with rhizospheric sunflower soils from Lichtenburg, South Africa. The Illumina Miseq sequencing of 16S rRNA gene amplicon unveiled the bacterial community diversities as well as generated metagenomic library from sunflower rhizospheric soils to understand the diversities and distribution. The metagenome contained a total of 41,471 sequences with 45,975 operational taxonomic units (OTUs). Metagenome sequence information is obtainable at NCBI under the Bioproject assigned accession number PRJNA782103. Taxonomic hits distribution from USEARCH analysis at phylum level classification of BN_E discovered predominantly Actinobacteria (33.89%), followed by Proteobacteria (35.45%), Firmicutes (6.45%), Planctomycetes (4.12%), Chloroflexi (4.28%) and Gemmatimonadetes (2.40%). Also, USEARCH assisted analysis of BN_F sample also detected the prevalence of Actinobacteria (45.92%), Proteobacteria (23.23%), Firmicutes (3.84%), Planctomycetes (6.46%), Chloroflexi (4.94%) and Gemmatimonadetes (1.99%), which take part in vital ecological functions and biogeochemical activities needed for plant growth and health.

High-Throughput Sequencing Survey of Sunflower Soil.

Plant rhizobiomes are responsible for major soil processes in the immediate plant environment, but our knowledge of the linkage between below-ground microbiota diversity and plant health is limited. We studied the bacterial and archaeal communities of sunflower rhizosphere organisms by comparing the composition of these communities to bulk soils at three farms in the North West province of South Africa. We evaluated and described a plethora of bacterial and archaeal taxa.