RT Journal Article SR Electronic T1 ABCB-mediated auxin transport in outer root tissues regulates lateral root spacing in Arabidopsis JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.07.22.206300 DO 10.1101/2020.07.22.206300 A1 Jian Chen A1 Yangjie Hu A1 Pengchao Hao A1 Yuqin Zhang A1 Ohad Roth A1 Maria F. Njo A1 Lieven Sterck A1 Yun Hu A1 Yunde Zhao A1 Markus Geisler A1 Eilon Shani A1 Tom Beeckman A1 Steffen Vanneste YR 2020 UL http://biorxiv.org/content/early/2020/07/22/2020.07.22.206300.abstract AB Root branching is an important strategy to explore efficiently large volumes of soil. To economize this process, lateral roots (LR) are formed along the growing root at discrete positions that are instructed by oscillating auxin signals derived from the lateral root cap (LRC). This assumes that auxin moves from the LRC across multiple layers to accumulate in the pericycle. Here, we identified, using gene silencing and CRISPR based approaches, a group of five genetically linked, closely related ABCBs that control LR spacing by modulating the amplitude of the auxin oscillation. The transporters localize to the plasma membrane and reveal significant auxin export activity. These ABCBs are mainly expressed in the LRC and epidermis where they contribute to auxin transport towards the root oscillation zone. Our findings highlight the importance of auxin transport in the outer tissues of the root meristem to regulate LR spacing.Competing Interest StatementThe authors have declared no competing interest.