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Updated: Aug 12, 2025

Shootward Movement of CFDA Tracer Loaded in the Bottom Sink Tissues of Arabidopsis
Published on: May 11, 2019
ABCB-mediated shootward auxin transport feeds into the root clock
Jian Chen1,2, Yangjie Hu3, Pengchao Hao4
1Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.
Abstract:
Although strongly influenced by environmental conditions, lateral root (LR) positioning along the primary root appears to follow obediently an internal spacing mechanism dictated by auxin oscillations that prepattern the primary root, referred to as the root clock. Surprisingly, none of the hitherto characterized PIN- and ABCB-type auxin transporters seem to be involved in this LR prepatterning mechanism. Here, we characterize ABCB15, 16, 17, 18, and 22 (ABCB15-22) as novel auxin-transporting ABCBs. Knock-down and genome editing of this genetically linked group of ABCBs caused strongly reduced LR densities. These phenotypes were correlated with reduced amplitude, but not reduced frequency of the root clock oscillation. High-resolution auxin transport assays and tissue-specific silencing revealed contributions of ABCB15-22 to shootward auxin transport in the lateral root cap (LRC) and epidermis, thereby explaining the reduced auxin oscillation. Jointly, these data support a model in which LRC-derived auxin contributes to the root clock amplitude.
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