Natural genetic variation and negative density effects in plant-nematode interactions.

Arabidopsis thaliana is a suitable host for phytoparasitic nematodes of the genus Meloidogyne. Successful nematode infection leads to the formation of root galls. We tested for natural genetic variation and inoculation density effects on nematode reproductive success in the interaction between A. thaliana and Meloidogyne javanica. We inoculated different Arabidopsis genotypes with two sources of nematodes at two different doses, using a mild protocol for inoculum preparation. We counted root galls and egg masses 2 months after inoculation. We obtained a high number of successful nematode infections. Infection success differed among Arabidopsis genotypes in interaction with the nematode source. Overall, infection success and reproductive success of nematodes were lower at a higher inoculum dose of nematodes. Our results indicate that natural genetic variation in both host plants and nematodes, as well as short- and long-term negative density effects, shape nematode reproductive success.