The Auxin By Microrna160 Regulation In Response To Molecular Arf10 And 16 Control Plants Root System

The key theme of pattern formation is the precise coordination of cell division and differentiation. Plant root cap mediates the direction of root tip growth and protects internal cells. The root cap cells are continuously produced from distal stem cells, and the phytohormone auxin provides position information for root distal organization. Here we identify the Arabidopsis auxin response factors ARF10 and 16, targeted by microRNA160 (miR160), as the controller of root cap cell formation. The 35S::MIR160 plants, in which ARF10 and 16 genes are repressed, and the arf10-2arf16-2 double mutants display the same root tip defect with uncontrolled cell division and blocked cell differentiation in the root distal region, resulting in a tumor-like root apex and the loss of gravity-sensing. ARF10 and 16 play a role in restricting stem cell niche and promoting columella cell differentiation; although functionally redundant, the two ARFs are indispensable for root cap development and the auxin signal cannot bypass them to initiate columella cell production. In root auxin and miR160 regulate the expression of ARF10 and 16 genes independently, generating a pattern consistent with root cap development. We further demonstrate that miR160-uncoupled production of ARF16 exerts pleiotropic effects on plant phenotypes, and miR160 plays an essential role in regulating Arabidopsis development and growth.