COMMUNITY VARIATION IN MELOIDOGYNE INCOGNITA GROUP SPECIES ASSOCIATED BACTERIA

Tropical nematode species of the Meloidogyne incognita group (MIG) of root knot nematodes (RKN) are some of the most devastating crop pathogens with an estimated yearly $100 billion damage worldwide. Although our results show a small genetic diversity between and within MIG species at the genome level, there is known intraspecific and interspecific variability in their host range and infestation intensity. We set out to explore the importance of variations in MIG associated microbial communities for explaining variations in MIG polyphagy and pathogenicity, as bacteria are considered to contribute secreted effectors that might assist MIGs in their life cycle or inhibit it. We gathered bacterial metagenomics datasets for 20 RKN isolates representing M. incognita, M. javanica, M. arenaria, M. floridensis, and two closely related outgroup species, in order to characterize their microbial communities. For M. incognita we had eight isolates representing North America, Africa and South East Asia. We have found distinct bacterial community structures for each of the MIG species, but with very little variation within each of the MIG species. This included unique bacterial OTUs that were recovered from all or some of the samples within a MIG species, but were excluded from other MIG species. Our results serve as evidence for MIG species specific symbionts, that are either vertically inherited or amplified from the environment by the nematode. We will discuss possible biochemical pathways in which bacteria may assist or inhibit MIG infestation and will address the relationship between MIG infestation success and the variation in MIG associated bacterial communities, based on samples taken from eggplant plants experimental setup.