Mediator subunit 16 positively modulates rice root development by associating with auxin response factor 10

The root system is important for plant growth and yield. The Mediator (MED) complex plays a key role in the recruitment and assembly of the transcription machinery for the control of gene expression. However, little information is currently available regarding Mediator-regulated root development in rice. Here, we identified a Mediator subunit OsMED16, the loss of function mutation in which resulted in weakened root system, with less crown roots and lighter root weigh. The yield per plant of osmed16 also significantly decreased compared with the wild type. Additionally, OsMED16 alters the transcription of genes related to the auxin response pathway, and physically associates with auxin response factor OsARF10. Moreover, OsARF10 binds directly to promoter of crown root initiation-related gene OsCrl5. Interestingly, OsMED16 is required for the recruitment of RNAPII to OsCrl5. Our finding provides a new insight into the molecular action of mediator subunit in root development.