@article{8931,
  abstract     = {Auxin is a major plant growth regulator, but current models on auxin perception and signaling cannot explain the whole plethora of auxin effects, in particular those associated with rapid responses. A possible candidate for a component of additional auxin perception mechanisms is the AUXIN BINDING PROTEIN 1 (ABP1), whose function in planta remains unclear.
Here we combined expression analysis with gain- and loss-of-function approaches to analyze the role of ABP1 in plant development. ABP1 shows a broad expression largely overlapping with, but not regulated by, transcriptional auxin response activity. Furthermore, ABP1 activity is not essential for the transcriptional auxin signaling. Genetic in planta analysis revealed that abp1 loss-of-function mutants show largely normal development with minor defects in bolting. On the other hand, ABP1 gain-of-function alleles show a broad range of growth and developmental defects, including root and hypocotyl growth and bending, lateral root and leaf development, bolting, as well as response to heat stress. At the cellular level, ABP1 gain-of-function leads to impaired auxin effect on PIN polar distribution and affects BFA-sensitive PIN intracellular aggregation.
The gain-of-function analysis suggests a broad, but still mechanistically unclear involvement of ABP1 in plant development, possibly masked in abp1 loss-of-function mutants by a functional redundancy.},
  author       = {Gelová, Zuzana and Gallei, Michelle C and Pernisová, Markéta and Brunoud, Géraldine and Zhang, Xixi and Glanc, Matous and Li, Lanxin and Michalko, Jaroslav and Pavlovicova, Zlata and Verstraeten, Inge and Han, Huibin and Hajny, Jakub and Hauschild, Robert and Čovanová, Milada and Zwiewka, Marta and Hörmayer, Lukas and Fendrych, Matyas and Xu, Tongda and Vernoux, Teva and Friml, Jiří},
  issn         = {0168-9452},
  journal      = {Plant Science},
  keywords     = {Agronomy and Crop Science, Plant Science, Genetics, General Medicine},
  publisher    = {Elsevier},
  title        = {{Developmental roles of auxin binding protein 1 in Arabidopsis thaliana}},
  doi          = {10.1016/j.plantsci.2020.110750},
  volume       = {303},
  year         = {2021},
}

@article{1221,
  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.},
  author       = {Michalko, Jaroslav and Glanc, Matous and Perrot Rechenmann, Catherine and Friml, Jirí},
  journal      = {F1000 Research },
  publisher    = {F1000 Research},
  title        = {{Strong morphological defects in conditional Arabidopsis abp1 knock-down mutants generated in absence of functional ABP1 protein}},
  doi          = {10.12688/f1000research.7654.1},
  volume       = {5},
  year         = {2016},
}

@article{1509,
  abstract     = {The Auxin Binding Protein1 (ABP1) has been identified based on its ability to bind auxin with high affinity and studied for a long time as a prime candidate for the extracellular auxin receptor responsible for mediating in particular the fast non-transcriptional auxin responses. However, the contradiction between the embryo-lethal phenotypes of the originally described Arabidopsis T-DNA insertional knock-out alleles (abp1-1 and abp1-1s) and the wild type-like phenotypes of other recently described loss-of-function alleles (abp1-c1 and abp1-TD1) questions the biological importance of ABP1 and relevance of the previous genetic studies. Here we show that there is no hidden copy of the ABP1 gene in the Arabidopsis genome but the embryo-lethal phenotypes of abp1-1 and abp1-1s alleles are very similar to the knock-out phenotypes of the neighboring gene, BELAYA SMERT (BSM). Furthermore, the allelic complementation test between bsm and abp1 alleles shows that the embryo-lethality in the abp1-1 and abp1-1s alleles is caused by the off-target disruption of the BSM locus by the T-DNA insertions. This clarifies the controversy of different phenotypes among published abp1 knock-out alleles and asks for reflections on the developmental role of ABP1.},
  author       = {Michalko, Jaroslav and Dravecka, Marta and Bollenbach, Tobias and Friml, Jirí},
  journal      = {F1000 Research },
  publisher    = {F1000 Research},
  title        = {{Embryo-lethal phenotypes in early abp1 mutants are due to disruption of the neighboring BSM gene}},
  doi          = {10.12688/f1000research.7143.1},
  volume       = {4},
  year         = {2015},
}