Rhizosphere microbial community of maize and summer annuals

Rhizosphere microbial communities are critically important for plant productivity. There is evidence that plant species and genotypes select distinct rhizosphere communities, however, knowledge of the drivers and extent of this variation remains limited. We grew 11 annual species and 11 maize (Zea mays) inbred lines in replicated monocultures to assess the influence of host phylogeny, growth and nitrogen economy on rhizosphere communities. Growth characteristics, bacterial community composition and potential activity of extracellular enzymes were assayed at anthesis. Microbial community composition and activity shifted markedly between bulk and rhizosphere soil and this effect was modulated by plant species and genotype. Across species rhizosphere beta-diversity was positively correlated with host phylogenetic distance and variation in plant growth characteristics. In particular, longer lifespan, high nitrogen use efficiency and larger seed size were associated with an increase in abundance of Actinobacteria and increased enzyme activity in the rhizosphere. These results indicate that plant evolutionary history and life history strategy influence rhizosphere community composition and activity. These findings can inform efforts to manage rhizosphere communities in agricultural systems via integration of plant phylogenetic and functional diversity.