TY - JOUR AB - Flowering plants display the highest diversity among plant species and have notably shaped terrestrial landscapes. Nonetheless, the evolutionary origin of their unprecedented morphological complexity remains largely an enigma. Here, we show that the coevolution of cis-regulatory and coding regions of PIN-FORMED (PIN) auxin transporters confined their expression to certain cell types and directed their subcellular localization to particular cell sides, which together enabled dynamic auxin gradients across tissues critical to the complex architecture of flowering plants. Extensive intraspecies and interspecies genetic complementation experiments with PINs from green alga up to flowering plant lineages showed that PIN genes underwent three subsequent, critical evolutionary innovations and thus acquired a triple function to regulate the development of three essential components of the flowering plant Arabidopsis: shoot/root, inflorescence, and floral organ. Our work highlights the critical role of functional innovations within the PIN gene family as essential prerequisites for the origin of flowering plants. AU - Zhang, Yuzhou AU - Rodriguez Solovey, Lesia AU - Li, Lanxin AU - Zhang, Xixi AU - Friml, Jiří ID - 8986 IS - 50 JF - Science Advances TI - Functional innovations of PIN auxin transporters mark crucial evolutionary transitions during rise of flowering plants VL - 6 ER - TY - JOUR AB - Drought and salt stress are the main environmental cues affecting the survival, development, distribution, and yield of crops worldwide. MYB transcription factors play a crucial role in plants’ biological processes, but the function of pineapple MYB genes is still obscure. In this study, one of the pineapple MYB transcription factors, AcoMYB4, was isolated and characterized. The results showed that AcoMYB4 is localized in the cell nucleus, and its expression is induced by low temperature, drought, salt stress, and hormonal stimulation, especially by abscisic acid (ABA). Overexpression of AcoMYB4 in rice and Arabidopsis enhanced plant sensitivity to osmotic stress; it led to an increase in the number stomata on leaf surfaces and lower germination rate under salt and drought stress. Furthermore, in AcoMYB4 OE lines, the membrane oxidation index, free proline, and soluble sugar contents were decreased. In contrast, electrolyte leakage and malondialdehyde (MDA) content increased significantly due to membrane injury, indicating higher sensitivity to drought and salinity stresses. Besides the above, both the expression level and activities of several antioxidant enzymes were decreased, indicating lower antioxidant activity in AcoMYB4 transgenic plants. Moreover, under osmotic stress, overexpression of AcoMYB4 inhibited ABA biosynthesis through a decrease in the transcription of genes responsible for ABA synthesis (ABA1 and ABA2) and ABA signal transduction factor ABI5. These results suggest that AcoMYB4 negatively regulates osmotic stress by attenuating cellular ABA biosynthesis and signal transduction pathways. AU - Chen, Huihuang AU - Lai, Linyi AU - Li, Lanxin AU - Liu, Liping AU - Jakada, Bello Hassan AU - Huang, Youmei AU - He, Qing AU - Chai, Mengnan AU - Niu, Xiaoping AU - Qin, Yuan ID - 8283 IS - 16 JF - International Journal of Molecular Sciences SN - 16616596 TI - AcoMYB4, an Ananas comosus L. MYB transcription factor, functions in osmotic stress through negative regulation of ABA signaling VL - 21 ER - TY - JOUR AB - Clathrin-mediated endocytosis (CME) is a crucial cellular process implicated in many aspects of plant growth, development, intra- and inter-cellular signaling, nutrient uptake and pathogen defense. Despite these significant roles, little is known about the precise molecular details of how it functions in planta. In order to facilitate the direct quantitative study of plant CME, here we review current routinely used methods and present refined, standardized quantitative imaging protocols which allow the detailed characterization of CME at multiple scales in plant tissues. These include: (i) an efficient electron microscopy protocol for the imaging of Arabidopsis CME vesicles in situ, thus providing a method for the detailed characterization of the ultra-structure of clathrin-coated vesicles; (ii) a detailed protocol and analysis for quantitative live-cell fluorescence microscopy to precisely examine the temporal interplay of endocytosis components during single CME events; (iii) a semi-automated analysis to allow the quantitative characterization of global internalization of cargos in whole plant tissues; and (iv) an overview and validation of useful genetic and pharmacological tools to interrogate the molecular mechanisms and function of CME in intact plant samples. AU - Johnson, Alexander J AU - Gnyliukh, Nataliia AU - Kaufmann, Walter AU - Narasimhan, Madhumitha AU - Vert, G AU - Bednarek, SY AU - Friml, Jiří ID - 8139 IS - 15 JF - Journal of Cell Science SN - 0021-9533 TI - Experimental toolbox for quantitative evaluation of clathrin-mediated endocytosis in the plant model Arabidopsis VL - 133 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 - Background ESCRT-III is a membrane remodelling filament with the unique ability to cut membranes from the inside of the membrane neck. It is essential for the final stage of cell division, the formation of vesicles, the release of viruses, and membrane repair. Distinct from other cytoskeletal filaments, ESCRT-III filaments do not consume energy themselves, but work in conjunction with another ATP-consuming complex. Despite rapid progress in describing the cell biology of ESCRT-III, we lack an understanding of the physical mechanisms behind its force production and membrane remodelling. Results Here we present a minimal coarse-grained model that captures all the experimentally reported cases of ESCRT-III driven membrane sculpting, including the formation of downward and upward cones and tubules. This model suggests that a change in the geometry of membrane bound ESCRT-III filaments—from a flat spiral to a 3D helix—drives membrane deformation. We then show that such repetitive filament geometry transitions can induce the fission of cargo-containing vesicles. Conclusions Our model provides a general physical mechanism that explains the full range of ESCRT-III-dependent membrane remodelling and scission events observed in cells. This mechanism for filament force production is distinct from the mechanisms described for other cytoskeletal elements discovered so far. The mechanistic principles revealed here suggest new ways of manipulating ESCRT-III-driven processes in cells and could be used to guide the engineering of synthetic membrane-sculpting systems. AU - Harker-Kirschneck, Lena AU - Baum, Buzz AU - Šarić, Anđela ID - 10354 IS - 1 JF - BMC Biology KW - cell biology SN - 1741-7007 TI - Changes in ESCRT-III filament geometry drive membrane remodelling and fission in silico VL - 17 ER - TY - JOUR AB - The molecular machinery of life is largely created via self-organisation of individual molecules into functional assemblies. Minimal coarse-grained models, in which a whole macromolecule is represented by a small number of particles, can be of great value in identifying the main driving forces behind self-organisation in cell biology. Such models can incorporate data from both molecular and continuum scales, and their results can be directly compared to experiments. Here we review the state of the art of models for studying the formation and biological function of macromolecular assemblies in living organisms. We outline the key ingredients of each model and their main findings. We illustrate the contribution of this class of simulations to identifying the physical mechanisms behind life and diseases, and discuss their future developments. AU - Hafner, Anne E AU - Krausser, Johannes AU - Šarić, Anđela ID - 10355 JF - Current Opinion in Structural Biology KW - molecular biology KW - structural biology SN - 0959-440X TI - Minimal coarse-grained models for molecular self-organisation in biology VL - 58 ER - TY - JOUR AB - Twisted bilayer graphene has recently emerged as a platform for hosting correlated phenomena. For twist angles near θ ≈ 1.1°, the low-energy electronic structure of twisted bilayer graphene features isolated bands with a flat dispersion1,2. Recent experiments have observed a variety of low-temperature phases that appear to be driven by electron interactions, including insulating states, superconductivity and magnetism3,4,5,6. Here we report electrical transport measurements up to room temperature for twist angles varying between 0.75° and 2°. We find that the resistivity, ρ, scales linearly with temperature, T, over a wide range of T before falling again owing to interband activation. The T-linear response is much larger than observed in monolayer graphene for all measured devices, and in particular increases by more than three orders of magnitude in the range where the flat band exists. Our results point to the dominant role of electron–phonon scattering in twisted bilayer graphene, with possible implications for the origin of the observed superconductivity. AU - Polshyn, Hryhoriy AU - Yankowitz, Matthew AU - Chen, Shaowen AU - Zhang, Yuxuan AU - Watanabe, K. AU - Taniguchi, T. AU - Dean, Cory R. AU - Young, Andrea F. ID - 10621 IS - 10 JF - Nature Physics KW - general physics and astronomy SN - 1745-2473 TI - Large linear-in-temperature resistivity in twisted bilayer graphene VL - 15 ER - TY - JOUR AB - We demonstrate a method for manipulating small ensembles of vortices in multiply connected superconducting structures. A micron-size magnetic particle attached to the tip of a silicon cantilever is used to locally apply magnetic flux through the superconducting structure. By scanning the tip over the surface of the device and by utilizing the dynamical coupling between the vortices and the cantilever, a high-resolution spatial map of the different vortex configurations is obtained. Moving the tip to a particular location in the map stabilizes a distinct multivortex configuration. Thus, the scanning of the tip over a particular trajectory in space permits nontrivial operations to be performed, such as braiding of individual vortices within a larger vortex ensemble—a key capability required by many proposals for topological quantum computing. AU - Polshyn, Hryhoriy AU - Naibert, Tyler AU - Budakian, Raffi ID - 10622 IS - 8 JF - Nano Letters KW - mechanical engineering KW - condensed matter physics KW - general materials science KW - general chemistry KW - bioengineering SN - 1530-6984 TI - Manipulating multivortex states in superconducting structures VL - 19 ER - TY - JOUR AB - The discovery of superconductivity and exotic insulating phases in twisted bilayer graphene has established this material as a model system of strongly correlated electrons. To achieve superconductivity, the two layers of graphene need to be at a very precise angle with respect to each other. Yankowitz et al. now show that another experimental knob, hydrostatic pressure, can be used to tune the phase diagram of twisted bilayer graphene (see the Perspective by Feldman). Applying pressure increased the coupling between the layers, which shifted the superconducting transition to higher angles and somewhat higher temperatures. AU - Yankowitz, Matthew AU - Chen, Shaowen AU - Polshyn, Hryhoriy AU - Zhang, Yuxuan AU - Watanabe, K. AU - Taniguchi, T. AU - Graf, David AU - Young, Andrea F. AU - Dean, Cory R. ID - 10625 IS - 6431 JF - Science KW - multidisciplinary SN - 0036-8075 TI - Tuning superconductivity in twisted bilayer graphene VL - 363 ER - TY - JOUR AB - Since the discovery of correlated insulators and superconductivity in magic-angle twisted bilayer graphene (tBLG) ([1, 2], JCCM April 2018), theorists have been excitedly pursuing the alluring mix of band topology, symmetry breaking, Mott insulators and superconductivity at play, as well as the potential relation (if any) to high-Tc physics. Now a new stream of experimental work is arriving which further enriches the story. To briefly recap Episodes 1 and 2 (JCCM April and November 2018), when two graphene layers are stacked with a small rotational mismatch θ, the resulting long-wavelength moire pattern leads to a superlattice potential which reconstructs the low energy band structure. When θ approaches the “magic-angle” θM ∼ 1 ◦, the band structure features eight nearly-flat bands which fill when the electron number per moire unit cell, n/n0, lies between −4 < n/n0 < 4. The bands can be counted as 8 = 2 × 2 × 2: for each spin (2×) and valley (2×) characteristic of monolayergraphene, tBLG has has 2× flat bands which cross at mini-Dirac points. AU - Yankowitz, Mathew AU - Chen, Shaowen AU - Polshyn, Hryhoriy AU - Watanabe, K. AU - Taniguchi, T. AU - Graf, David AU - Young, Andrea F. AU - Dean, Cory R. AU - Sharpe, Aaron L. AU - Fox, E.J. AU - Barnard, A.W. AU - Finney, Joe ID - 10664 JF - Journal Club for Condensed Matter Physics TI - New correlated phenomena in magic-angle twisted bilayer graphene/s VL - 03 ER -