Assessing the impact of successive soil cultivation on Meloidogyne enterolobii infection and soil bacterial assemblages

Soil cultivation may change the soil microbiome and alter interactions between plants and parasites. This work aimed to evaluate temporal changes in plant health, soil microbiome abundance and incidence of the emergent plant-parasitic nematode, Meloidogyne enterolobii, in two soil fields with different agricultural uses. Soil samples were collected from a commercial tomato production field (agricultural soil) and a single-cultivation strawberry field (native soil) for two successive years. Tomato plants cv. Early Girl were grown in a greenhouse, and three groups of inoculums were used: Fusarium only, M. enterolobii only and Fusarium + M. enterolobii. After 45 days, plants were evaluated for growth parameters and nematode reproduction and soil bacterial assemblages were assessed using cultivation-independent sequencing methods (V3/V4 region of the 16S rRNA). Among both soil types, the average root fresh weight increased (56%), along with shoot fresh weight (82%) and fruit fresh weight (76%) in the second year. Moreover, there was an 80.5% decrease in eggs present per root system from the first year to the second. The relative abundance of bacterial assemblages from Year 1 to Year 2 changed for most of the top phyla (e.g., Actinobacteria, Bacteroidetes and Chloroflexi) and genera (e.g., Bacillus, Streptomyces and Flavisolibacter). This study suggests that soil management and year-to-year variation can lead to a shift in overall bacterial assemblages, better crop yield and an overall decrease in nematode reproduction.