CHARACTERIZING MICROBIAL COMMUNITIES ASSOCIATED WITH THE NORTHERN ROOT-KNOT NEMATODE (MELOIDOGYNE HAPLA) OCCURRENCE AND SOIL HEALTH

The northern root-knot nematode Meloidogyne hapla causes extensive damage to agricultural crops globally. In addition to that, M. hapla populations with no detectable genetic or morphological differences exhibit parasitic variability (PV) or reproductive potential. However, why M. hapla populations from mineral soils with degraded soil conditions have a higher PV than populations from muck soil is unknown. To improve understanding of soil biophysicochemical conditions of the environment where M. hapla populations exhibited PV, this study characterized the soil microbial community structure associated with M. hapla occurrence and soil health conditions in 15 Michigan mineral and muck vegetable production fields, and identified core microbiome and indicator species related to PV. Soils were collected, their nematode communities were characterized and assessed for PV, and high throughput sequencing of 16S and Internal Transcribed Spacer (ITS) rDNA was used to characterize bacterial and fungal communities in soil samples. Results showed that, M. hapla-infested, as well as disturbed and degraded muck fields, had lower bacterial diversity (observed richness and Shannon) than corresponding mineral soil fields or non-infested mineral fields. Bacterial and fungal community abundance varied by soil group, soil health conditions and/or M. hapla occurrence. A core of 39 bacteria and 44 fungi OTUs occurred either across all fields or varying by soil group, soil health conditions and/or M. hapla occurrence. An indicator of 25 bacteria OTUs were associated with M. hapla presence or absence. Collectively, the results provide a foundation for in-depth understanding of the environment where M. hapla exists and conditions associated with PV.