Exploring and capitalizing on genotypic variation of the oat microbiome

Background/Question/Methods

With an increasing global population and a changing global climate it is imperative that we continuously adapt and improve our agricultural methods. Oats are a hardy crop that can tolerate relatively inhospitable conditions, including both low and high temperatures, low nutrient availability, and low water availability. Despite their low value as a money crop, oats could have a high value when it comes to conferring benefits to subsequent crops through soil legacy effects (i.e. persistent changes to the microbial soil community).To investigate the effect of genotype specific soil legacy on the health of subsequently planted crops, we used a plant-soil feedback approach within a controlled greenhouse environment under high and low nutrient conditions. Soil conditioned by eight oat genotypes served as the microbial inoculum for oat and corn plants grown in autoclaved background soil within planter pots in a greenhouse. Phenotypic and rhizosphere community (bacterial and fungal) data was collected from each corn plant, and the initial soil inoculum communities were sequenced as well. We hypothesized that soil inoculum communities would cluster by oat genotype and that the inoculum cultivating genotype would describe more variation in corn biomass under low rather than high nutrient conditions.

Results/Conclusions

The fungal communities within inoculum replicates (taken from replicated oat field plots in a randomized block design) exhibited significant clustering by conditioning oat genotype when analyzed by permutational analysis of virulence (permanova; P = 0.046). Bacterial communities displayed very weak to no evidence of genotype specific clustering (P = 0.158). Contrary to our hypothesis, the soil conditioning oat genotype described more variation in oat and corn biomass in high nutrient conditions (15% and 44% respectively). Community measurements of the starting inocula (i.e. richness and diversity) did not significantly correlate with corn biomass under either treatment. Permanova showed weak evidence that the final corn root fungal community structure is correlated with the inoculum conditioning oat genotype (P = 0.109), which is noteworthy considering this correlation persisted through mediation by a corn host. Together, these results indicate that oat genotypes exhibit specific soil legacies which differentially affect the health of subsequently planted corn and oat crops. This genotypic variability in microbiome selection could inform future crop rotation programs with the goal of optimizing soil legacies for the health of subsequent crops and provide information for potential crop breeding programs focused on the selection of specific, desirable members of the microbial community.