The rhizosphere is an important zone of interaction between the roots and soil environment that is densely populated by microbial life. The success of a soil-borne pathogen depends on its ability to survive and compete in the rhizosphere. As such, understanding the factors influencing rhizosphere community composition is important to promoting healthy crop plants, such as Potato (Solanum tuberosum). Potato is a vegetatively propagated crop and seed tubers are often planted with tare soil, or soil that adheres to the seed tuber surface, from their field of origin. Tare soil harbors both pathogenic and beneficial microbes, but how tare soil influences the rhizosphere microbiome is not known. Our hypothesis is that the potato rhizosphere is influenced by the microbiome of tare soil. To determine the relative importance of tare soil versus bulk soil on the rhizosphere microbiome, we characterized the bacterial and fungal rhizosphere communities of plants from a greenhouse experiment in which seed potatoes of differing cultivars and sources were planted in two soil types, a non-agricultural soil and potato agricultural soil. The cultivar and seed source factors were crossed with a surface sterilization treatment to test for the effect of tare soil on rhizosphere microbiome establishment.
Results/Conclusions
Our preliminary analysis suggests that the greatest proportion of variance among rhizosphere microbial communities can be attributed to the bulk soil, or the soil in which the seed tuber was planted. Given that the soil types were comprised of 90% potting soil and 10% soil inoculum, we can attribute this difference to the soil microbial community rather than soil edaphic factors. The presence of tare soil on the seed tuber did explain variability in microbial composition of the rhizosphere for fungi but not bacteria. Our ongoing analyses will examine how variation among the seed potatoes, including seed potato source and cultivar, contribute to differences among the rhizosphere microbiome and will explore how disease may vary among the seed potato groups.