The effect of type and combination of fertilizers on eukaryotic microbiome of date palm rhizosphere

The date palm ( Phoenix dactylifera ) is an important cultivated crop in arid areas. Here, we studied the effect of plant genotype and type of fertilizers on the eukaryotic community structures of the date palm rhizosphere. Samples were collected from one wild population, five cultivars from two farms, and a factorial fertilizer experiment (organic, chemical, and biofertilizer) in Qatar. The eukaryotic communities were sequenced using a next-generation sequencing method. A total of 2422 Operational Taxonomic Units (OTUs) were identified as belonging to 15 phyla, Chlorophyta , Streptophyta , Imbricatea , Chytridiomycota , Ascomycota , Olpidiomycota , being dominant. The wild-type date palms showed a low number of OTUs compared to cultivated date palms, potentially due to the strong influence of soil salinity and low moisture level. However, the wild-type date palm hosted the highest number of unique OTUs. PCA revealed that the eukaryotic microbiome of the wild date palms was separated from the cultivated date palms and that the eukaryotic microbial diversity varied between date palm cultivars in similar environments. Using the highest amounts of biofertilizer and chemical fertilizer decreased the species diversity within the samples. However, a high concentration of biofertilizer combined with a low concentration of chemical fertilizers enhanced the eukaryotic diversity within the samples. We conclude that cultivar type (biotic factor), type of fertilizer, and dosage (abiotic factor) play significant roles in determining the microbiome diversity of the rhizosphere. The wild date palm population could potentially host salt and drought-tolerating eukaryotes that should be further investigated for future development of biofertilizers suitable for drylands.