Abstract
Plant development and physiology are widely determined by the polar transport of the signaling molecule auxin. This process is controlled on the cellular efflux level catalyzed by members of the PIN (pin-formed) and ABCB (ATP-binding cassette protein subfamily B)/P-glycoprotein family that can function independently and coordinately. In this study, we have identified by means of chemical genomics a novel auxin transport inhibitor (ATI), BUM (2-[4-(diethylamino)-2-hydroxybenzoyl]benzoic acid), that efficiently blocks auxin-regulated plant physiology and development. In many respects, BUM resembles the functionality of the diagnostic ATI, 1-N-naphtylphtalamic acid (NPA), but it has an IC(50) value that is roughly a factor 30 lower. Physiological analysis and binding assays identified ABCBs, primarily ABCB1, as key targets of BUM and NPA, whereas PIN proteins are apparently not directly affected. BUM is complementary to NPA by having distinct ABCB target spectra and impacts on basipetal polar auxin transport in the shoot and root. In comparison with the recently identified ATI, gravacin, it lacks interference with ABCB membrane trafficking. Individual modes or targets of action compared with NPA are reflected by apically shifted root influx maxima that might be the result of altered BUM binding preferences or affinities to the ABCB nucleotide binding folds. This qualifies BUM as a valuable tool for auxin research, allowing differentiation between ABCB- and PIN-mediated efflux systems. Besides its obvious application as a powerful weed herbicide, BUM is a bona fide human ABCB inhibitor with the potential to restrict multidrug resistance during chemotherapy.
Highlights
In plants, the auxin indolyl-3-acetic acid (IAA)4 serves as a hormone-like signaling molecule that is a key factor in plant
The investigation of polar auxin transport (PAT) streams was facilitated by using synthetic compounds that act as auxin transport inhibitors (ATIs), with the non-competitive IAA efflux inhibitor 1-Nnaphtylphtalamic acid (NPA) being the most prominent
We have identified by means of chemical genomics a novel ATI that efficiently blocks auxin-related plant physiology and development
Summary
The auxin indolyl-3-acetic acid (IAA) serves as a hormone-like signaling molecule that is a key factor in plant. Most PIN efflux carriers show predominantly polar locations in PAT tissues and developmental, organogenetic loss-of-function phenotypes and are thought to be the determinants of a “reflux loop” in the root apex [3, 8]. ABCB isoforms have been identified as primary active (ATP-dependent) auxin pumps showing auxin-related, developmental (but not organogenetic) loss-of-function phenotypes [5, 9, 10]. Despite their mostly apolar locations, they have been demonstrated to contribute to PAT and long range auxin transport [5, 11, 12]. ABCB- and PIN-mediated auxin efflux can function independently and play identical cellular but separate developmental roles [10]. The identity, number, and affinity of putative NPA-bindtransport inhibitor; NPA, 1-N-naphtylphtalamic acid; NBP, NPA-binding protein; gravacin, 3-(5-[3,4-dichlorophenyl]-2-furyl)acrylic acid; GFP, green fluorescent protein; BA, benzoic acid; BRET, bioluminescence resonance energy transfer
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
