Systems approaches reveal that ABCB and PIN proteins mediate co-dependent auxin efflux

Mellor, Nathan L; Voß, Ute; Ware, Alexander; Janes, George; Barrack, Duncan; Bishopp, Anthony; Bennett, Malcolm J; Geisler, Markus; Wells, Darren M; Band, Leah R

Abstract

Members of the B family of membrane-bound ATP-binding cassette (ABC) transporters represent key components of the auxin-efflux machinery in plants. Over the last two decades experimental studies have shown that modifying ABCB expression affects auxin distribution and plant phenotypes. However, precisely how ABCB proteins transport auxin in conjunction with the more widely studied family of PIN-formed (PIN) auxin efflux transporters is unclear, and studies using heterologous systems have produced conflicting results.

Here, we integrate ABCB localization data into a multicellular model of auxin transport in the Arabidopsis thaliana root tip to predict how ABCB-mediated auxin transport impacts organ-scale auxin distribution. We use our model to test five potential ABCB–PIN regulatory interactions, simulating the auxin dynamics for each interaction and quantitatively comparing the predictions with experimental images of the DII-VENUS auxin reporter in wild type and abcb single and double loss-of-function mutants. Only specific ABCB–PIN regulatory interactions result in predictions that recreate the experimentally observed DII-VENUS distributions and long-distance auxin transport. Our results suggest that ABCBs enable auxin efflux independently of PINs; however, PIN-mediated auxin efflux is predominantly through a co-dependent efflux where co-localised with ABCBs.

Citation

Mellor, N. L., Voß, U., Ware, A., Janes, G., Barrack, D., Bishopp, A., …Band, L. R. (2022). Systems approaches reveal that ABCB and PIN proteins mediate co-dependent auxin efflux. Plant Cell, 34(6), 2309–2327. https://doi.org/10.1093/plcell/koac086

• Journal Article Type: Article
• Acceptance Date: Mar 10, 2022
• Online Publication Date: Mar 18, 2022
• Publication Date: 2022-06
• Deposit Date: Mar 22, 2022
• Publicly Available Date: Mar 22, 2022
• Journal: The Plant Cell
• Print ISSN: 1040-4651
• Electronic ISSN: 1532-298X
• Publisher: American Society of Plant Biologists
• Peer Reviewed: Peer Reviewed
• Volume: 34
• Issue: 6
• Pages: 2309–2327
• DOI: https://doi.org/10.1093/plcell/koac086
• Keywords: Cell Biology; Plant Science
• Public URL: https://nottingham-repository.worktribe.com/output/7644332
• Publisher URL: https://academic.oup.com/plcell/article/34/6/2309/6550511