title: Strong morphological defects in conditional Arabidopsis abp1 knock-down mutants generated in absence of functional ABP1 protein.
abstract: The Auxin Binding Protein 1 (ABP1) is one of the most studied proteins in plants. Since decades ago, it has been the prime receptor candidate for the plant hormone auxin with a plethora of described functions in auxin signaling and development. The developmental importance of ABP1 has recently been questioned by identification of Arabidopsis thaliana abp1 knock-out alleles that show no obvious phenotypes under normal growth conditions. In this study, we examined the contradiction between the normal growth and development of the abp1 knock-outs and the strong morphological defects observed in three different ethanol-inducible abp1 knock-down mutants ( abp1-AS, SS12K, SS12S). By analyzing segregating populations of abp1 knock-out vs. abp1 knock-down crosses we show that the strong morphological defects that were believed to be the result of conditional down-regulation of ABP1 can be reproduced also in the absence of the functional ABP1 protein. This data suggests that the phenotypes in  abp1 knock-down lines are due to the off-target effects and asks for further reflections on the biological function of ABP1 or alternative explanations for the missing phenotypic defects in the abp1 loss-of-function alleles.
authors.affiliation: Institute of Science and Technology Austria, Klosterneuberg, Austria.|Institute of Plant Genetics and Biotechnology, Slovak Academy of Sciences, Nitra, Slovakia.
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Michalko
authors.affiliation: Institute of Science and Technology Austria, Klosterneuberg, Austria.|Department of Experimental Plant Biology, Faculty of Sciences, Charles University, Prague, Czech Republic.
authors.forename: Matouš
authors.initials: M
authors.lastname: Glanc
authors.affiliation: Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay , Versailles, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Perrot-Rechenmann
authors.affiliation: Institute of Science and Technology Austria, Klosterneuberg, Austria.
authors.forename: Jiří
authors.initials: J
authors.lastname: Friml
keywords: AUXIN BINDING PROTEIN 1 (ABP1); Arabidopsis; auxin; knock-down mutant; off-target