TY - JOUR AB - Maintaining fertility in a fluctuating environment is key to the reproductive success of flowering plants. Meiosis and pollen formation are particularly sensitive to changes in growing conditions, especially temperature. We have previously identified cyclin-dependent kinase G1 (CDKG1) as a master regulator of temperature-dependent meiosis and this may involve the regulation of alternative splicing (AS), including of its own transcript. CDKG1 mRNA can undergo several AS events, potentially producing two protein variants: CDKG1L and CDKG1S, differing in their N-terminal domain which may be involved in co-factor interaction. In leaves, both isoforms have distinct temperature-dependent functions on target mRNA processing, but their role in pollen development is unknown. In the present study, we characterize the role of CDKG1L and CDKG1S in maintaining Arabidopsis fertility. We show that the long (L) form is necessary and sufficient to rescue the fertility defects of the cdkg1-1 mutant, while the short (S) form is unable to rescue fertility. On the other hand, an extra copy of CDKG1L reduces fertility. In addition, mutation of the ATP binding pocket of the kinase indicates that kinase activity is necessary for the function of CDKG1. Kinase mutants of CDKG1L and CDKG1S correctly localize to the cell nucleus and nucleus and cytoplasm, respectively, but are unable to rescue either the fertility or the splicing defects of the cdkg1-1 mutant. Furthermore, we show that there is partial functional overlap between CDKG1 and its paralog CDKG2 that could in part be explained by overlapping gene expression. AU - Nibau, Candida AU - Dadarou, Despoina AU - Kargios, Nestoras AU - Mallioura, Areti AU - Fernandez-Fuentes, Narcis AU - Cavallari, Nicola AU - Doonan, John H. ID - 8924 JF - Frontiers in Plant Science TI - A functional kinase is necessary for cyclin-dependent kinase G1 (CDKG1) to maintain fertility at high ambient temperature in Arabidopsis VL - 11 ER - TY - JOUR AB - Cell production and differentiation for the acquisition of specific functions are key features of living systems. The dynamic network of cellular microtubules provides the necessary platform to accommodate processes associated with the transition of cells through the individual phases of cytogenesis. Here, we show that the plant hormone cytokinin fine‐tunes the activity of the microtubular cytoskeleton during cell differentiation and counteracts microtubular rearrangements driven by the hormone auxin. The endogenous upward gradient of cytokinin activity along the longitudinal growth axis in Arabidopsis thaliana roots correlates with robust rearrangements of the microtubule cytoskeleton in epidermal cells progressing from the proliferative to the differentiation stage. Controlled increases in cytokinin activity result in premature re‐organization of the microtubule network from transversal to an oblique disposition in cells prior to their differentiation, whereas attenuated hormone perception delays cytoskeleton conversion into a configuration typical for differentiated cells. Intriguingly, cytokinin can interfere with microtubules also in animal cells, such as leukocytes, suggesting that a cytokinin‐sensitive control pathway for the microtubular cytoskeleton may be at least partially conserved between plant and animal cells. AU - Montesinos López, Juan C AU - Abuzeineh, A AU - Kopf, Aglaja AU - Juanes Garcia, Alba AU - Ötvös, Krisztina AU - Petrášek, J AU - Sixt, Michael K AU - Benková, Eva ID - 8142 IS - 17 JF - The Embo Journal SN - 0261-4189 TI - Phytohormone cytokinin guides microtubule dynamics during cell progression from proliferative to differentiated stage VL - 39 ER - TY - JOUR AB - Protein abundance and localization at the plasma membrane (PM) shapes plant development and mediates adaptation to changing environmental conditions. It is regulated by ubiquitination, a post-translational modification crucial for the proper sorting of endocytosed PM proteins to the vacuole for subsequent degradation. To understand the significance and the variety of roles played by this reversible modification, the function of ubiquitin receptors, which translate the ubiquitin signature into a cellular response, needs to be elucidated. In this study, we show that TOL (TOM1-like) proteins function in plants as multivalent ubiquitin receptors, governing ubiquitinated cargo delivery to the vacuole via the conserved Endosomal Sorting Complex Required for Transport (ESCRT) pathway. TOL2 and TOL6 interact with components of the ESCRT machinery and bind to K63-linked ubiquitin via two tandemly arranged conserved ubiquitin-binding domains. Mutation of these domains results not only in a loss of ubiquitin binding but also altered localization, abolishing TOL6 ubiquitin receptor activity. Function and localization of TOL6 is itself regulated by ubiquitination, whereby TOL6 ubiquitination potentially modulates degradation of PM-localized cargoes, assisting in the fine-tuning of the delicate interplay between protein recycling and downregulation. Taken together, our findings demonstrate the function and regulation of a ubiquitin receptor that mediates vacuolar degradation of PM proteins in higher plants. AU - Moulinier-Anzola, Jeanette AU - Schwihla, Maximilian AU - De-Araújo, Lucinda AU - Artner, Christina AU - Jörg, Lisa AU - Konstantinova, Nataliia AU - Luschnig, Christian AU - Korbei, Barbara ID - 15037 IS - 5 JF - Molecular Plant KW - Plant Science KW - Molecular Biology SN - 1674-2052 TI - TOLs function as ubiquitin receptors in the early steps of the ESCRT pathway in higher plants VL - 13 ER - TY - JOUR AB - Wound healing in plant tissues, consisting of rigid cell wall-encapsulated cells, represents a considerable challenge and occurs through largely unknown mechanisms distinct from those in animals. Owing to their inability to migrate, plant cells rely on targeted cell division and expansion to regenerate wounds. Strict coordination of these wound-induced responses is essential to ensure efficient, spatially restricted wound healing. Single-cell tracking by live imaging allowed us to gain mechanistic insight into the wound perception and coordination of wound responses after laser-based wounding in Arabidopsis root. We revealed a crucial contribution of the collapse of damaged cells in wound perception and detected an auxin increase specific to cells immediately adjacent to the wound. This localized auxin increase balances wound-induced cell expansion and restorative division rates in a dose-dependent manner, leading to tumorous overproliferation when the canonical TIR1 auxin signaling is disrupted. Auxin and wound-induced turgor pressure changes together also spatially define the activation of key components of regeneration, such as the transcription regulator ERF115. Our observations suggest that the wound signaling involves the sensing of collapse of damaged cells and a local auxin signaling activation to coordinate the downstream transcriptional responses in the immediate wound vicinity. AU - Hörmayer, Lukas AU - Montesinos López, Juan C AU - Marhavá, Petra AU - Benková, Eva AU - Yoshida, Saiko AU - Friml, Jiří ID - 8002 IS - 26 JF - Proceedings of the National Academy of Sciences SN - 0027-8424 TI - Wounding-induced changes in cellular pressure and localized auxin signalling spatially coordinate restorative divisions in roots VL - 117 ER - TY - JOUR AB - Plants, like other multicellular organisms, survive through a delicate balance between growth and defense against pathogens. Salicylic acid (SA) is a major defense signal in plants, and the perception mechanism as well as downstream signaling activating the immune response are known. Here, we identify a parallel SA signaling that mediates growth attenuation. SA directly binds to A subunits of protein phosphatase 2A (PP2A), inhibiting activity of this complex. Among PP2A targets, the PIN2 auxin transporter is hyperphosphorylated in response to SA, leading to changed activity of this important growth regulator. Accordingly, auxin transport and auxin-mediated root development, including growth, gravitropic response, and lateral root organogenesis, are inhibited. This study reveals how SA, besides activating immunity, concomitantly attenuates growth through crosstalk with the auxin distribution network. Further analysis of this dual role of SA and characterization of additional SA-regulated PP2A targets will provide further insights into mechanisms maintaining a balance between growth and defense. AU - Tan, Shutang AU - Abas, Melinda F AU - Verstraeten, Inge AU - Glanc, Matous AU - Molnar, Gergely AU - Hajny, Jakub AU - Lasák, Pavel AU - Petřík, Ivan AU - Russinova, Eugenia AU - Petrášek, Jan AU - Novák, Ondřej AU - Pospíšil, Jiří AU - Friml, Jiří ID - 7427 IS - 3 JF - Current Biology SN - 09609822 TI - Salicylic acid targets protein phosphatase 2A to attenuate growth in plants VL - 30 ER - TY - JOUR AB - Auxin is a key hormonal regulator, that governs plant growth and development in concert with other hormonal pathways. The unique feature of auxin is its polar, cell-to-cell transport that leads to the formation of local auxin maxima and gradients, which coordinate initiation and patterning of plant organs. The molecular machinery mediating polar auxin transport is one of the important points of interaction with other hormones. Multiple hormonal pathways converge at the regulation of auxin transport and form a regulatory network that integrates various developmental and environmental inputs to steer plant development. In this review, we discuss recent advances in understanding the mechanisms that underlie regulation of polar auxin transport by multiple hormonal pathways. Specifically, we focus on the post-translational mechanisms that contribute to fine-tuning of the abundance and polarity of auxin transporters at the plasma membrane and thereby enable rapid modification of the auxin flow to coordinate plant growth and development. AU - Semeradova, Hana AU - Montesinos López, Juan C AU - Benková, Eva ID - 9160 IS - 3 JF - Plant Communications SN - 2590-3462 TI - All roads lead to auxin: Post-translational regulation of auxin transport by multiple hormonal pathways VL - 1 ER - TY - JOUR AB - Multicellular development requires coordinated cell polarization relative to body axes, and translation to oriented cell division 1–3 . In plants, it is unknown how cell polarities are connected to organismal axes and translated to division. Here, we identify Arabidopsis SOSEKI proteins that integrate apical–basal and radial organismal axes to localize to polar cell edges. Localization does not depend on tissue context, requires cell wall integrity and is defined by a transferrable, protein-specific motif. A Domain of Unknown Function in SOSEKI proteins resembles the DIX oligomerization domain in the animal Dishevelled polarity regulator. The DIX-like domain self-interacts and is required for edge localization and for influencing division orientation, together with a second domain that defines the polar membrane domain. Our work shows that SOSEKI proteins locally interpret global polarity cues and can influence cell division orientation. Furthermore, this work reveals that, despite fundamental differences, cell polarity mechanisms in plants and animals converge on a similar protein domain. AU - Yoshida, Saiko AU - Van Der Schuren, Alja AU - Van Dop, Maritza AU - Van Galen, Luc AU - Saiga, Shunsuke AU - Adibi, Milad AU - Möller, Barbara AU - Ten Hove, Colette A. AU - Marhavy, Peter AU - Smith, Richard AU - Friml, Jiří AU - Weijers, Dolf ID - 6023 IS - 2 JF - Nature Plants TI - A SOSEKI-based coordinate system interprets global polarity cues in arabidopsis VL - 5 ER - TY - JOUR AB - The apical hook is a transiently formed structure that plays a protective role when the germinating seedling penetrates through the soil towards the surface. Crucial for proper bending is the local auxin maxima, which defines the concave (inner) side of the hook curvature. As no sign of asymmetric auxin distribution has been reported in embryonic hypocotyls prior to hook formation, the question of how auxin asymmetry is established in the early phases of seedling germination remains largely unanswered. Here, we analyzed the auxin distribution and expression of PIN auxin efflux carriers from early phases of germination, and show that bending of the root in response to gravity is the crucial initial cue that governs the hypocotyl bending required for apical hook formation. Importantly, polar auxin transport machinery is established gradually after germination starts as a result of tight root-hypocotyl interaction and a proper balance between abscisic acid and gibberellins. AU - Zhu, Qiang AU - Gallemi, Marçal AU - Pospíšil, Jiří AU - Žádníková, Petra AU - Strnad, Miroslav AU - Benková, Eva ID - 6897 IS - 17 JF - Development TI - Root gravity response module guides differential growth determining both root bending and apical hook formation in Arabidopsis VL - 146 ER - TY - JOUR AU - Artner, Christina AU - Benková, Eva ID - 6920 IS - 10 JF - Molecular Plant SN - 1674-2052 TI - Ethylene and cytokinin - partners in root growth regulation VL - 12 ER - TY - JOUR AU - Benková, Eva AU - Dagdas, Yasin ID - 7394 IS - 12 JF - Current Opinion in Plant Biology SN - 1369-5266 TI - Editorial overview: Cell biology in the era of omics? VL - 52 ER -