Medicago truncatula is a legume plant that forms a mutualistic relationship with rhizobia, a nitrogen-fixing bacteria. In this interaction, M. truncatula and rhizobia undergo a resource-exchange of carbon and nitrogen. However, in the presence of parasitic nematodes, the amount of benefits that the mutualistic partners receive is reduced. In this project, we investigated whether the plant and rhizobia genotype play a role in how much of an effect nematodes have on the mutualism. 

We found that plant and rhizobia fitness in the presence of nematodes differs between the rhizobia strains. Plants inoculated with R282 experienced little change in both plant and rhizobia fitness when infected with nematodes. However, plants inoculated with R154 experienced a decrease in both plant and rhizobia fitness during nematode infection. 

We also found that the plants continue to receive the same amount of benefit per nodule, even when nematodes are present. This indicates that while plant and rhizobia fitness may decrease under some rhizobia strains, the overall relationship between the two partners does not change. 

To find out more about the interaction between plants and rhizobia under nematode infection, we will conduct an elemental analysis to look at the carbon-nitrogen exchange between the partners. This analysis will allow us to see if both partners are equally benefitting from the relationship or if the benefits are skewed towards one partner.