Soil microbial communities from olive cultivars are shaped by seasonality and geographical scales

Soil biodiversity is essential to sustain healthy ecosystems supporting the maintenance of the environment and agricultural practices. Soils provide vital habitat for microorganisms which play determinant roles through organic matter transformation and nutrient cycling, which have a great impact in agriculture and food production and climate regulation. Understanding soil microbiome is becoming a relevant matter for supporting plant productivity and plant health. Unravelling the function and structure of microbial communities prevailing in soils is essential for a better understanding of plant development. However, the vast majority of soil microorganisms remain unknown and their variability at regional and temporal seasonal scale is still an unexplored field. In this study, soils associated to the rhizosphere of three olive varieties were sampled during autumn 2018 and spring 2019 in three olive orchards with differences in physicochemical soil characteristics and climate, located in the provinces of Jaén, Córdoba and Málaga, in Andalusia, Southern Spain. Bacterial and fungal populations were analysed using Illumina MiSeq platform to determine the structure and diversity of soil microbial communities and how those environmental factors may affect them. Sequencing data resulted in a total of 730 bacteria OTUs, distributed in 23 phyla and 312 genera while there were 553 fungal OTUs divided in 8 phyla and 280 genera. Proteobacteria was the most abundant bacterial phylum across olive orchard location (30.37%-5.52%) followed by Actinobacteria (10.72%-5.49%) and Bacteroidetes (7.73%-0.89%). There was circa 50% abundance reduction of these phyla on samples taken in autumn compared to that sampled in the spring. Unique bacterial genera differed according to field location in Jaén (72), Córdoba (45) and Málaga (48) while the shared bacteria genera among plots was 82. Fungi results showed Ascomycota (49.13%-3.13%) and Basidiomycota (25.64%-2.79%) as the two most abundant phyla in all olive orchards. A reduction on the abundance of Ascomycota was noticed on samples from autumn to spring (37.84% and 20.42%, respectively), while Basidiomycota displayed a distinct behavior (11.89% to 20.27%). Exclusive fungal genera varied from Jaén (50), Córdoba (7) and Málaga (14), whereas the core fungal genera among fields was 28. This information can contribute to generate new knowledge regarding temporal and spatial scale insights on soil microbiome associated to olive crop that may be considered to increase plant health and soil biodiversity.

Study supported by Projects 01LC1620 SOILMAN, XF-ACTORS 727987 (EU-H2020) and AGL2016-75606-R (MICINN Spain and FEDER-EU).