Bacterial community shifts associated with high abundance of Rhizobium spp. in potato roots under macronutrient-deficient conditions

We evaluated the impacts of a macronutrient deficiency on the community structure of root-associated bacteria in potato (Solanum tuberosum) cultivation. Potato plants were cultivated in a long-term experimental field under a nitrogen, phosphorus, or potassium deficiency, and roots were sampled at the early flowering stage. Amplicon libraries of 16S rRNA gene were constructed for root-associated bacteria, and bacterial diversity was analyzed by means of pyrosequencing. Statistical analyses showed significantly lower species evenness in the nutrient-deficient plots compared with the value in a plot with standard fertilization. Phylogenetic analyses revealed that the abundance of Rhizobium spp. increased dramatically in all plots under a macronutrient deficiency.