3. Dr. Omri Finkel

How plants evolved to shape their microbiota is a long-standing question in ecology and evolution. The microbiome forms a crucial part of how plants adapt to changing environments and that this microbiota optimization should be manifested in a strong genomic and phenotypic signature of adaptation. To study plant adaptation to cooperation with their microbiota, we must develop methods to carefully manipulate the soil microbiota which serves as the primary source of microbes for the plant. To understand how interactions within the microbiome affect plant health, we have been designing and constructing plant-microbe microcosms encompassing synthetic communities composed of hundreds of microbial isolates. By editing these communities, we are able to identify keystone elements in the community with strong effects on plant health. One such example is the genus Variovorax, which we showed is necessary and sufficient to maintain root growth. Using Arabidopsis, and then Sorghum as model plants, we show that the presence of Variovorax is crucial for plant growth, particularly under drought.