Roots of crop plants associated with taxonomically diverse microbiota. Understanding the functions of root microbiota and systematically obtaining the cultured root microbes are crucial steps for harnessing crop microbiome in sustainable agriculture. Recently, we identified root bacterial microbiota members significantly associated with crop growth by performing large scale associations of root microbiota, growth traits and genotypic variations of field-grown crops. Using individual bacteria and synthetic community approaches, we validated the functions of root microbiota members in controlled conditions. In addition, genomes of root-derived bacterial culture collections showed the metabolic and functional capacity of root microbiota. These data and resources allow us to reveal the functions and co-adaptation of root microbiota and field-grown crops.