Regulation of organ straightening and plant posture by an actin–myosin XI cytoskeleton

  title={Regulation of organ straightening and plant posture by an actin–myosin XI cytoskeleton},
  author={Keishi Okamoto and Haruko Ueda and Tomoo Shimada and Kentaro Tamura and Takehide Kato and Masao Tasaka and Miyo Terao Morita and Ikuko Hara-Nishimura},
  journal={Nature Plants},
Plants are able to bend nearly every organ in response to environmental stimuli such as gravity and light1,2. After this first phase, the responses to stimuli are restrained by an independent mechanism, or even reversed, so that the organ will stop bending and attain its desired posture. This phenomenon of organ straightening has been called autotropism3 and autostraightening4 and modelled as proprioception5. However, the machinery that drives organ straightening and where it occurs are mostly… 
How to Investigate the Role of the Actin-Myosin Cytoskeleton in Organ Straightening.
A method for assessing the straightening ability of organs by clinostat analysis using Arabidopsis thaliana inflorescence stems of actin and myosin xi mutants as examples is described.
Functions of plant-specific myosin XI: from intracellular motility to plant postures.
Arabidopsis Myosins XI1, XI2, and XIK Are Crucial for Gravity-Induced Bending of Inflorescence Stems
It is shown that class XI but not class VIII myosins are required for stem gravitropism of Arabidopsis, indicating a role of class XI myosin in this process.
Diversity of Plant Actin–Myosin Systems
The diversity entwined with plant evolution is discussed and a new model for intracellular transport regulated by multiple actin–myosin isoforms is proposed.
Myosin-driven transport network in plants is functionally robust and distinctive
The Kurth et al. paper shows that the green branch of the tree of life has evolved a very dense and largely unique endomembrane transport network empowered by myosins XI, which is well recognized that long-range cargo transport is actin-centric in fungal and plant cells but mostly relies on microtubule-based motors in vertebrates.
Gravitropic Movement in Wheat Coleoptile is Regulated by Ultradian Growth Oscillations
In perturbed (tilted) coleoptiles, a non-trivial coupling between the oscillatory dynamics of curvature and elongation is discovered, which appears to be critical to the postural control of the organ, and indicates the presence of a mechanism that is capable of affecting the relationship between elongation rate, differential growth, and curvature.
Actin-myosin XI: an intracellular control network in plants.
Plant Actin Cytoskeleton: New Functions from Old Scaffold
This chapter highlights some of the recent advances toward understanding how the actin cytoskeleton modulates plant growth, form, and adaptation to the environment and discusses some recently discovered plant proteins that function in actin-mediated biological processes that are unique to plants.
Nutations in Plant Shoots: Endogenous and Exogenous Factors in the Presence of Mechanical Deformations
It is shown that, in the absence of endogenous cues, pendular and circular oscillations arise as a critical length is attained, thus suggesting the occurrence of a Hopf bifurcation reminiscent of flutter instabilities exhibited by structural systems under nonconservative loads.


Regulation of plant gravity sensing and signaling by the actin cytoskeleton.
Modifications in the trafficking of auxin efflux transporters are considered as possible mechanisms for the enhanced gravity responses observed in plant organs when the actin cytoskeleton is disrupted by chemical inhibitors.
Plant-Specific Myosin XI, a Molecular Perspective
The molecular properties of tobacco 175-kDa myosin XI and Arabidopsis thaliana are summarized and a detailed comparison of the functional domains of these myosins with the functional domain of myOSin V is compared to look for possible diversification in enzymatic and mechanical properties among myosIn XI members concomitant with their regulation.
Unifying model of shoot gravitropism reveals proprioception as a central feature of posture control in plants
It is shown that gravitropic straightening shares common traits across species, organs, and orders of magnitude, and the minimal dynamic model accounting for these traits is not the widely cited gravisensing law but one that also takes into account the sensing of local curvature, what is described here as a graviproprioceptive law.
Disruption of the F-actin cytoskeleton limits statolith movement in Arabidopsis hypocotyls.
A model for gravitropism in stem-like organs is proposed in which F-actin modulates the gravity response by actively participating in statolith repositioning within the endodermal statocytes.
Myosin XI Is Essential for Tip Growth in Physcomitrella patens[W]
It is demonstrated that the two myosin XI genes present in the moss Physcomitrella patens are functionally redundant, localize to the apical region of actively growing protonemal cells, and play a key role in tip growth.
Myosin-dependent endoplasmic reticulum motility and F-actin organization in plant cells
A model whereby dynamic three-way interactions between ER, F-actin, and myosins determine the architecture and movement patterns of the ER strands, and cause cytosol hauling traditionally defined as cytoplasmic streaming is suggested.
Enhanced Gravitropism of Roots with a Disrupted Cap Actin Cytoskeleton1
It is demonstrated that disrupting the actin cytoskeleton in the cap leads to the persistence of a signal established by a previous gravistimulus, which means actin could function in root gravitropism by providing a mechanism to regulate the proliferation of a Gravitropic signal originating from the cap to allow the root to attain its correct orientation or set point angle.
Arabidopsis Myosin XI: A Motor Rules the Tracks1[C][W][OPEN]
A myosin triple knockout mutant has altered cytoskeletal organization and single filament turnover. Plant cell expansion relies on intracellular trafficking of vesicles and macromolecules, which
Class XI Myosins Are Required for Development, Cell Expansion, and F-Actin Organization in Arabidopsis[W][OA]
It is shown that myosin-dependent transport is critical for the growth of plant cells and entire plants as well as for proper organization of the cell interior, establishing critical roles of myOSin-driven transport and F-actin organization during polarized and diffuse cell growth and indicating that myOSins are key factors in plant growth and development.
Disruption of the Actin Cytoskeleton Results in the Promotion of Gravitropism in Inflorescence Stems and Hypocotyls of Arabidopsis1
The results suggest that actin MFs are not a necessary component of gravitropism in inflorescence stems and hypocotyls, and this is the first study to demonstrate a prominent actinMF network in endodermal cells in the putative gravity-perceiving cells in stems.