Jianfeng Wang, Jie Jin and Yurong Bi
Plant roots are colonized by an immense number of microbes, including epiphytic and endophytic microbes, which can promote plant growth and alter host root development. Previous studies showed that auxin plays key roles in regulating many different aspects of plant growth and development. However, the precise role of auxin signaling and polar auxin transport in modulating root development during plant-beneficial microbe interactions is unknown. The present short communication summarizes the scattered evidence in support of known host root alterations by beneficial microbes, implying the key role of auxin signaling and polar auxin transport in modulating beneficial effects of microbes in plants.