Synthetic community (SynCom) approaches can provide functional and mechanistic insights into how plants regulate their microbiomes, and how the microbiome in turn influences plant growth and health. Microbial cultivation and reconstruction play pivotal roles in this process, which enables researchers to reproducibly investigate the interactions between plants and a major proportion of plant-associated microbes in controlled laboratory conditions. Here, we summarize the emergence, current achievements, and future opportunities for using SynCom experiments in plant microbiome research, with a focus on plant root-associated bacteria.