Review: Microbiota-root-shoot-environment axis and stress tolerance in plants ($) (COPB)

Roots and shoots exist in different environments and have different functions, but each depends on the actions of the other. In recent years, many factors have been identified that move from root to shoot or vice versa to integrate their actions; these include hormones, small RNAs, peptides, and transcription factors. This fascinating review article takes things one step further, by considering how the microbes that interact with the root communicate and integrate with the shoot, and vice versa. As an example, when leaves are attacked by pathogens or insect herbivores, the composition of root exudates changes, leading to a change in root microbiota which can enhance nutrient uptake or defense. Conversely, experimental alterations of the root microbiome has been demonstrated to enhance above-ground stress responses. The authors propose that there is a circuit through which shoot-stress perception sculpts the root microbiome, bolstering above-ground stress responses. The authors compare these findings to the contributions of animal gut microbiota to host immunity and even brain activity. (Summary by Mary Williams @PlantTeaching) Curr. Opin. Plant Biol. 10.1016/j.pbi.2021.102028