Genotypic variation in above-belowground interactions: Evidence from AM fungal-plant-herbivore systems

Background/Question/Methods

Awareness of the role of above-belowground interactions in structuring communities and ecosystems is growing, however we are still far from making generalizations as great variation in above-belowground interactions has been identified in multiple systems.  In this talk I aim to address the role of genotypic variation in driving variation in above-belowground interactions, and I will focus on genotypic variation in the arbuscular mycorrhizal fungal-plant-herbivore interaction.

Results/Conclusions

Herbivore genotypic variation has rarely been included as a factor in above-belowground studies.  We conducted a study varying aphid genotype and aphid facultative endosymbiont on potato plants  associated with three different soil communities.  We found that both variation in aphid genotype and variation in aphid endosymbiont presence influenced plant allocation patterns in some, but not all, soil communities.  In particular, allocation to tubers varied due to both soil community and aphid genotype while the presence of a facultative endosymbiont reduced allocation to roots with potential consequences for AM fungi.

Plant genotypic variation, however, can also influence the outcome of above-belowground interactions.  In a study in the potato system described above, plant allocation patterns were influenced by both soil communities and aphids with potential consequences for both above- and belowground organisms.  In the AM fungi-Plantago lanceolata-Junonia coenia system, plant genotype influenced P. lanceolata allocation patterns in response to both AM fungi and J. coenia, and influenced trade-offs between plant defense, tolerance and growth.

Very few studies have addressed the roles of AM fungal genotypic diversity in above-belowground interactions.  Here I will address previous work and future avenues of research in this area.

Together this research shows that the incorporation of genotypic variation in the study of above-belowground research in part explains the vast variation in the observed effects in these interactions.