Overexpression of the Auxin Binding PROTEIN1 Modulates PIN-Dependent Auxin Transport in Tobacco Cells

Abstract

BackgroundAuxin binding protein 1 (ABP1) is a putative auxin receptor and its function is indispensable for plant growth and development. ABP1 has been shown to be involved in auxin-dependent regulation of cell division and expansion, in plasma-membrane-related processes such as changes in transmembrane potential, and in the regulation of clathrin-dependent endocytosis. However, the ABP1-regulated downstream pathway remains elusive.Methodology/Principal FindingsUsing auxin transport assays and quantitative analysis of cellular morphology we show that ABP1 regulates auxin efflux from tobacco BY-2 cells. The overexpression of ABP1can counterbalance increased auxin efflux and auxin starvation phenotypes caused by the overexpression of PIN auxin efflux carrier. Relevant mechanism involves the ABP1-controlled vesicle trafficking processes, including positive regulation of endocytosis of PIN auxin efflux carriers, as indicated by fluorescence recovery after photobleaching (FRAP) and pharmacological manipulations.Conclusions/SignificanceThe findings indicate the involvement of ABP1 in control of rate of auxin transport across plasma membrane emphasizing the role of ABP1 in regulation of PIN activity at the plasma membrane, and highlighting the relevance of ABP1 for the formation of developmentally important, PIN-dependent auxin gradients.

Complementation of the embryo-lethal T-DNA insertion mutant of AUXIN-BINDING-PROTEIN 1 (ABP1) with abp1 point mutated versions reveals crosstalk of ABP1 and phytochromes

“…9 ). Short-term effects of NPA inhibition showed down-regulation of PIN protein activity, which consequently would lead to an increased auxin concentration in the cytosol ( Covanová et al , 2013 ) with the logical consequence of re-quantifying TIR1/AFB-dependent transcriptional abundance of auxin marker genes ( Scherer et al , 2012 ).…”

Decrease of Auxin Binding Protein 1 Gene Expression Alters Shoot Development in Ramie

“…Membrane vesicles carrying PIN proteins undergo dynamic recycling to and from the PM and auxin regulates its own transport by inhibiting the endocytic step of this recycling [34][35][36]. It is believed that ABP1 mediates the effect of auxin on endocytosis and that ABP1 can control the clathrin-mediated internalization of PIN proteins, which regulate the amount and dynamics of PIN auxin efflux carriers at the PM [37][38][39][40][41]. It is likely that ABP1 has an influence on cell expansion and division through being involved in the regulation of polar auxin transport, which affects leaf growth and vascular patterning in ramie.…”

PIN‐driven polar auxin transport in plant developmental plasticity: a key target for environmental and endogenous signals

“…This was shown to be mediated by the apoplastic ABP1: ABP1 normally stimulates endocytosis, and binding of auxin inhibits this activity. In this way, ABP1 provides a positive feedback loop by which exported auxin induces local stabilization of PINs at the PM, thereby enhancing auxin efflux at that same position (Robert et al ., ; Čovanová et al ., ).…”

“…This was shown to be mediated by the apoplastic ABP1: ABP1 normally stimulates endocytosis, and binding of auxin inhibits this activity. In this way, ABP1 provides a positive feedback loop by which exported auxin induces local stabilization of PINs at the PM, thereby enhancing auxin efflux at that same position (Robert et al, 2010;Covanov a et al, 2013). PIN endocytosis, transcytosis, and recycling require the actin cytoskeleton and the action of specific ADP-ribosylation factor-(ARF)-type GTPases and the corresponding ARF-GTP exchange factors (ARF-GEFs).…”