Auxin perception and downstream events

Abstract

Auxin responses have been arbitrarily divided into two categories: genomic and non-genomic effects. Genomic effects are largely mediated by SCFTIR1/AFB-Aux/IAA auxin receptor complexes whereas it has been postulated that AUXIN BINDING PROTEIN 1 (ABP1) controls the non-genomic effects. However, the roles of ABP1 in auxin signaling and plant development were recently called into question. In this paper, we present recent progress in understanding the SCFTIR1/AFB-Aux/IAA pathway. In more detail, we discuss the current understanding of ABP1 research and provide an updated view of ABP1-related genetic materials. Further, we propose a model in which auxin efflux carriers may play a role in auxin perception and we briefly describe recent insight on processes downstream of auxin perception.

Comparative Transcriptional Analysis of Loquat Fruit Identifies Major Signal Networks Involved in Fruit Development and Ripening Process

“…EjAux-IAA and EjARF genes showed dramatic alterations in their expression levels during fruit development (Figure 6). Aux/IAA had been shown as transcriptional repressors through interactions with ARF proteins that directly bind to auxin-responsive elements in the promoters of auxin responsive genes [35]. The reduction of IAA9 transcription levels in tomato resulted in fruit development prior to pollination and fertilization by the formation of ARF-Aux/IAA heterodimers [36].…”

“…Additionally, the members of the PIN family were also identified during loquat fruit development. Although the roles of PINs have been extensively studied in vegetative development, their functions are less clear in non-climacteric fruit development [35]. qRT-PCR results indicated that high expression levels of EjPIN3 were detected at the initial stage of fruit development.…”

Effects of Auxins on PIN-FORMED2 (PIN2) Dynamics Are Not Mediated by Inhibiting PIN2 Endocytosis

“…In addition, it has been demonstrated that phenotypes observed in the Arabidopsis abp1-1 and abp1-5 alleles might not be caused by the disruption of ABP1 Enders et al, 2015). These findings call into question the results of previous publications describing a prominent role of ABP1 in embryogenesis, growth, cell division, cell expansion, and auxin signaling [see Liu (2015) and Strader and Zhao (2016) for a commentary]. It is also surprising that the inhibition effect of 1-NAA on endocytosis was observed only after a short (5 min to 60 min) but not after a long (2 h) pretreatment (Robert et al, 2010).…”

“…Several putative auxin transporters were detected and characterized. Among those the members of the PIN-FORMED protein family (PIN proteins) are regarded as important carriers acting in the efflux of auxin from cells (for reviews, see Za zímalová et al, 2010;Grunewald and Friml, 2010;Geisler et al, 2014;Pan et al, 2015;Bennett, 2015;Strader and Zhao, 2016). Some PIN family members, such as PIN1, 2, 3, 4, and 7, are localized in the plasma membrane (PM) and determine developmental processes by regulating the distribution of auxin and its local accumulation in the plant body (K re cek et al, 2009;Vanneste and Friml, 2009;Grunewald and Friml, 2010).…”

Auxin Induces Widespread Proteome Remodeling in Arabidopsis Seedlings

“…In land plants, the response to auxin is controlled by co‐receptors comprised of TIR1/AUXIN F‐BOX (TIR1/AFB) and Aux/IAA transcriptional regulators. In Arabidopsis , there are six TIR1/AFB proteins and 29 Aux/IAA proteins . The Aux/IAA proteins actively repress transcription by interacting with transcription factors called AUXIN RESPONSE FACTORS (ARFs) and recruiting a co‐repressor protein, TOPLESS (TPL).…”