Root Exudates Are a Functional Trait That Influence Root Microbiome Interactions.

Exudates are an important plant root trait that function to influence the surrounding environment including the rhizosphere and nearby soil. Root exudates have many different roles including increasing nutrient availability, providing lubrication for root growth, signaling interactions with soil microbes such as rhizobia and mycorrhizal fungi and promoting the growth of microorganisms while helping to protect against pathogens. Root exudates include low molecular weight compounds such as carbohydrates, amino acids, flavonols, organic acids and hormones that have been estimated to account for 10 to 40% of photosynthetically fixed carbon. Emerging advanced methods are now available to study the metabolites exuded from roots and the communities of soil microbes around the root. These technologies may now be used to answer important questions regarding the interactions between roots and microbial communities in soil, such as: how do plant roots recruit soil microbes to the rhizosphere and endosphere; do microbes stimulate root exudation through signaling molecules and how do plant-derived carbon exudates and signaling molecules shape rhizobiomes? The project that will be described is using the natural chemical diversity of exudates within different maize lines. The work that will be described involves screening a large number of maize lines to identify the ones that differ in root exudates. Root exudate data will be presented along with data showing how the root microbiome changes are dependent on root exudate composition. The potential functional significance of these changes in the microbiome will also be discussed.