Functionally different PIN proteins control auxin flux during bulbil development in Agave tequilana (original) (raw)
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Role of PIN-mediated auxin efflux in apical hook development of Arabidopsis thaliana
Development, 2010
The apical hook of dark-grown Arabidopsis seedlings is a simple structure that develops soon after germination to protect the meristem tissues during emergence through the soil and that opens upon exposure to light. Differential growth at the apical hook proceeds in three sequential steps that are regulated by multiple hormones, principally auxin and ethylene. We show that the progress of the apical hook through these developmental phases depends on the dynamic, asymmetric distribution of auxin, which is regulated by auxin efflux carriers of the PIN family. Several PIN proteins exhibited specific, partially overlapping spatial and temporal expression patterns, and their subcellular localization suggested auxin fluxes during hook development. Genetic manipulation of individual PIN activities interfered with different stages of hook development, implying that specific combinations of PIN genes are required for progress of the apical hook through the developmental phases. Furthermore, ...
bioRxiv (Cold Spring Harbor Laboratory), 2022
The plant hormone auxin and its directional transport across tissues mediate much of the remarkably adaptive and plastic development of higher plants. Positive feedback between auxin signalling and transport is a key prerequisite for self-organizing development including flexible vascular tissue formation and directional growth responses, such as gravitropism. Here we identified a mechanistic link between cell surface ABP1-based auxin perception, the associated TMK1 kinase and PIN auxin transporters. abp1 and tmk1 mutants are defective in auxin-triggered phosphorylation of PIN proteins and in PIN-mediated directional auxin transport. Auxin, via ABP1, induces activation and stabilization of TMK1, thus promoting direct interaction with and phosphorylation of PIN2. Following gravistimulation, the auxin-activated TMK1 acts along the lower root side to reinforce asymmetry in PIN2-mediated auxin fluxes for gravitropic root bending. This ABP1-TMK1-dependent positive feedback on PIN-mediated directional auxin transport is fundamental for robust root gravitropism and presumably also for other self-organizing developmental processes.
Plant embryogenesis requires AUX/LAX-mediated auxin influx
Development (Cambridge, England), 2015
The plant hormone auxin and its directional transport are known to play a crucial role in defining the embryonic axis and subsequent development of the body plan. Although the role of PIN auxin efflux transporters has been clearly assigned during embryonic shoot and root specification, the role of the auxin influx carriers AUX1 and LIKE-AUX1 (LAX) proteins is not well established. Here, we used chemical and genetic tools on Brassica napus microspore-derived embryos and Arabidopsis thaliana zygotic embryos, and demonstrate that AUX1, LAX1 and LAX2 are required for both shoot and root pole formation, in concert with PIN efflux carriers. Furthermore, we uncovered a positive-feedback loop between MONOPTEROS (ARF5)-dependent auxin signalling and auxin transport. This MONOPTEROS-dependent transcriptional regulation of auxin influx (AUX1, LAX1 and LAX2) and auxin efflux (PIN1 and PIN4) carriers by MONOPTEROS helps to maintain proper auxin transport to the root tip. These results indicate t...
Development, 2010
Dark-grown dicotyledonous seedlings form a hook-like structure at the top of the hypocotyl, which is controlled by the hormones auxin and ethylene. Hook formation is dependent on an auxin signal gradient, whereas hook exaggeration is part of the triple response provoked by ethylene in dark-grown Arabidopsis seedlings. Several other hormones and light are also known to be involved in hook development, but the molecular mechanisms that lead to the initial installation of an auxin gradient are still poorly understood. In this study, we aimed to unravel the cross-talk between auxin and ethylene in the apical hook. Auxin measurements, the expression pattern of the auxin reporter DR5::GUS and the localization of auxin biosynthesis enzymes and influx carriers collectively indicate the necessity for auxin biosynthesis and efficient auxin translocation from the cotyledons and meristem into the hypocotyl in order to support proper hook development. Auxin accumulation in the meristem and cotyl...
Signal Integration, Auxin Homeostasis, and Plant Development
Signaling and Communication in Plants, 2013
Auxin has been the most widely studied plant hormone in relation to plant development. The pattern of auxin distribution in plants plays a key role in organogenesis and tropic responses. Since auxin is synthesized by actively dividing cells, it is transported from the site of synthesis to the site of action to create auxin maxima. There has been a lot of effort in the past to dissect out the complex mechanism of auxin biosynthesis, signaling, and transport and to understand its role in controlling plant growth and development. Recently, there have been lots of reports of interaction between auxin and various hormones to regulate plant growth and development. This chapter summarizes the signaling integration cross talks and their role in affecting auxin homeostasis and plant growth and development.
MAB4-induced auxin sink generates local auxin gradients in Arabidopsis organ formation
Proceedings of the National Academy of Sciences, 2014
Significance The dynamic auxin transport driven by the auxin efflux carrier PIN-FORMED1 (PIN1) is the key element in organ formation at the shoot apical meristem. Auxin transport during organ formation consists of two distinct types: the convergence of auxin flow at the organ initiation site and the following auxin sink. Our results show that NONPHOTOTROPIC HYPOCOTYL 3-like proteins establish auxin sink, but not auxin convergence, through the control of PIN1 localization. Our study uncovers the molecular mechanism involved in auxin sink and to show its importance in organ development. Besides, we propose a model for polar auxin transport during organ formation, which has the potential to describe on a molecular level the auxin canalization hypothesis.
PLoS ONE, 2013
Background: Auxin 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 Findings: Using 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/Significance: The 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.
Developmental Roles of AUX1/LAX Auxin Influx Carriers in Plants
Frontiers in Plant Science, 2019
Plant hormone auxin regulates several aspects of plant growth and development. Auxin is predominantly synthesized in the shoot apex and developing leaf primordia and from there it is transported to the target tissues e.g. roots. Auxin transport is polar in nature and is carrier-mediated. AUXIN1/LIKE-AUX1 (AUX1/LAX) family members are the major auxin influx carriers whereas PIN-FORMED (PIN) family and some members of the P-GLYCOPROTEIN/ ATP-BINDING CASSETTE B4 (PGP/ABCB) family are major auxin efflux carriers. AUX1/ LAX auxin influx carriers are multi-membrane spanning transmembrane proteins sharing similarity to amino acid permeases. Mutations in AUX1/LAX genes result in auxin related developmental defects and have been implicated in regulating key plant processes including root and lateral root development, root gravitropism, root hair development, vascular patterning, seed germination, apical hook formation, leaf morphogenesis, phyllotactic patterning, female gametophyte development and embryo development. Recently AUX1 has also been implicated in regulating plant responses to abiotic stresses. This review summarizes our current understanding of the developmental roles of AUX1/ LAX gene family and will also briefly discuss the modelling approaches that are providing new insight into the role of auxin transport in plant development.