(a) Rarefaction curves of detected bacterial species of the root microbiota reach the saturation stage with increasing numbers of samples, indicating that the root microbiota in our population capture most root bacteria members from each rice subspecies. Indica and japonica varieties in two locations are shown separately. (b) Rarefaction curves of detected bacterial OTUs of the root microbiota from indica and japonica varieties reach saturation stage with increasing sequencing depth. Each vertical bar represents standard error. The numbers of replicated samples in this figure are as follows: in field I, indica (n = 201), japonica (n = 80), soil (n = 12); in field II, indica (n = 201), japonica (n = 81), soil (n = 12).