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The Journal of Cell Biology Dec 2018Microtubule-severing enzymes generate internal breaks in microtubules. They are conserved in eukaryotes from ciliates to mammals, and their function is important in... (Review)
Review
Microtubule-severing enzymes generate internal breaks in microtubules. They are conserved in eukaryotes from ciliates to mammals, and their function is important in diverse cellular processes ranging from cilia biogenesis to cell division, phototropism, and neurogenesis. Their mutation leads to neurodegenerative and neurodevelopmental disorders in humans. All three known microtubule-severing enzymes, katanin, spastin, and fidgetin, are members of the meiotic subfamily of AAA ATPases that also includes VPS4, which disassembles ESCRTIII polymers. Despite their conservation and importance to cell physiology, the cellular and molecular mechanisms of action of microtubule-severing enzymes are not well understood. Here we review a subset of cellular processes that require microtubule-severing enzymes as well as recent advances in understanding their structure, biophysical mechanism, and regulation.
Topics: ATPases Associated with Diverse Cellular Activities; Animals; Class III Phosphatidylinositol 3-Kinases; Humans; Katanin; Microtubule-Associated Proteins; Microtubules; Spastin
PubMed: 30373906
DOI: 10.1083/jcb.201612104 -
Plant Science : An International... Nov 2016Optimization of water foraging by plants is partially achieved by the ability of roots to direct growth towards high water potential, a phenomenon termed hydrotropism.... (Review)
Review
Optimization of water foraging by plants is partially achieved by the ability of roots to direct growth towards high water potential, a phenomenon termed hydrotropism. In contrast to gravitropism and phototropism, which require auxin redistribution, as suggested by the Cholodny-Went theory, hydrotropism is not mediated by the phytohormone auxin, which raises questions about the mechanism underlying this tropic response. Here we specify the open questions in this field of research and discuss the possible interactions of abscisic acid, calcium and reactive oxygen species as part of a dynamic system of sensing water potential in the root tip, transmission of the signal to the root elongation zone and promoting root curvature towards water. We conclude that root hydrotropism is mediated by inter-cellular signals that are not explained by the Cholodny-Went theory.
Topics: Adaptation, Physiological; Droughts; Gravitation; Plant Growth Regulators; Plant Roots; Signal Transduction; Stress, Physiological; Tropism; Water
PubMed: 27717476
DOI: 10.1016/j.plantsci.2016.09.004 -
Current Biology : CB Sep 2017Plants are sessile organisms rooted in one place. The soil resources that plants require are often distributed in a highly heterogeneous pattern. To aid foraging, plants... (Review)
Review
Plants are sessile organisms rooted in one place. The soil resources that plants require are often distributed in a highly heterogeneous pattern. To aid foraging, plants have evolved roots whose growth and development are highly responsive to soil signals. As a result, 3D root architecture is shaped by myriad environmental signals to ensure resource capture is optimised and unfavourable environments are avoided. The first signals sensed by newly germinating seeds - gravity and light - direct root growth into the soil to aid seedling establishment. Heterogeneous soil resources, such as water, nitrogen and phosphate, also act as signals that shape 3D root growth to optimise uptake. Root architecture is also modified through biotic interactions that include soil fungi and neighbouring plants. This developmental plasticity results in a 'custom-made' 3D root system that is best adapted to forage for resources in each soil environment that a plant colonises.
Topics: Gravitropism; Phototropism; Plant Roots; Seedlings; Soil
PubMed: 28898665
DOI: 10.1016/j.cub.2017.06.043 -
Journal of Experimental Botany Nov 2019In the literature, Helianthus annuus L. (sunflower) movements are generally described as heliotropic. It is generally believed that the leaves and flowers of the growing... (Review)
Review
In the literature, Helianthus annuus L. (sunflower) movements are generally described as heliotropic. It is generally believed that the leaves and flowers of the growing H. annuus plant track the sun as the sun moves across the sky from east to west. This paper, however, challenges current interpretation regarding H. annuus movements, as the literature generally excludes the rotation of the earth around its own axis, gravity, and the possible role of gravitation. The general exclusion of the earth's rotation in the literature may also have resulted in flawed research design in studies conducted on H. annuus movements, which in turn may have directed researchers towards the misinterpretation of results. This paper aims to include the possible role of the Earth's rotation, gravity, and gravitation when describing H. annuus movements and to provide possible alternative explanations for the results achieved by researchers. This paper further includes concepts and examples relevant to plant movements, such as the rhythms often associated with plant movements, the physiology of plant movements, referring to turgor pressure as the main force behind plant movements, and plant rhythmic clocks and their characteristics, in order to explain the alternative views and to relate them to H. annuus movements.
Topics: Helianthus; Movement; Phototropism; Sunlight
PubMed: 31504705
DOI: 10.1093/jxb/erz381 -
Plants (Basel, Switzerland) Jul 2020Light absorption by plants changes the composition of light inside vegetation. Blue (B) and red (R) light are used for photosynthesis whereas far-red (FR) and green... (Review)
Review
Light absorption by plants changes the composition of light inside vegetation. Blue (B) and red (R) light are used for photosynthesis whereas far-red (FR) and green light are reflected. A combination of UV-B, blue and R:FR-responsive photoreceptors collectively measures the light and temperature environment and adjusts plant development accordingly. This developmental plasticity to photoreceptor signals is largely regulated through the phytohormone auxin. The phytochrome, cryptochrome and UV Resistance Locus 8 (UVR8) photoreceptors are inactivated in shade and/or elevated temperature, which releases their repression of Phytochrome Interacting Factor (PIF) transcription factors. Active PIFs stimulate auxin synthesis and reinforce auxin signalling responses through direct interaction with Auxin Response Factors (ARFs). It was recently discovered that shade-induced hypocotyl elongation and petiole hyponasty depend on long-distance auxin transport towards target cells from the cotyledon and leaf tip, respectively. Other responses, such as phototropic bending, are regulated by auxin transport and signalling across only a few cell layers. In addition, photoreceptors can directly interact with components in the auxin signalling pathway, such as Auxin/Indole Acetic Acids (AUX/IAAs) and ARFs. Here we will discuss the complex interactions between photoreceptor and auxin signalling, addressing both mechanisms and consequences of these highly interconnected pathways.
PubMed: 32722230
DOI: 10.3390/plants9080940 -
International Journal of Molecular... Mar 2023The root is an important organ for obtaining nutrients and absorbing water and carbohydrates, and it depends on various endogenous and external environmental... (Review)
Review
The root is an important organ for obtaining nutrients and absorbing water and carbohydrates, and it depends on various endogenous and external environmental stimulations such as light, temperature, water, plant hormones, and metabolic constituents. Auxin, as an essential plant hormone, can mediate rooting under different light treatments. Therefore, this review focuses on summarizing the functions and mechanisms of light-regulated auxin signaling in root development. Some light-response components such as phytochromes (PHYs), cryptochromes (CRYs), phototropins (PHOTs), phytochrome-interacting factors (PIFs) and constitutive photo-morphorgenic 1 (COP1) regulate root development. Moreover, light mediates the primary root, lateral root, adventitious root, root hair, rhizoid, and seminal and crown root development via the auxin signaling transduction pathway. Additionally, the effect of light through the auxin signal on root negative phototropism, gravitropism, root greening and the root branching of plants is also illustrated. The review also summarizes diverse light target genes in response to auxin signaling during rooting. We conclude that the mechanism of light-mediated root development via auxin signaling is complex, and it mainly concerns in the differences in plant species, such as barley ( L.) and wheat ( L.), changes of transcript levels and endogenous IAA content. Hence, the effect of light-involved auxin signaling on root growth and development is definitely a hot issue to explore in the horticultural studies now and in the future.
Topics: Indoleacetic Acids; Signal Transduction; Plant Growth Regulators; Phytochrome; Light Signal Transduction; Plant Roots; Gene Expression Regulation, Plant; Arabidopsis Proteins
PubMed: 36982350
DOI: 10.3390/ijms24065253 -
Fungal Genetics and Biology : FG & B Sep 2017Fungi, like other organisms, actively sense the environmental light conditions in order to drive adaptive responses, including protective mechanisms against the... (Review)
Review
Fungi, like other organisms, actively sense the environmental light conditions in order to drive adaptive responses, including protective mechanisms against the light-associated stresses, and to regulate development. Ecological niches are characterized by different light regimes, for instance light is absent underground, and light spectra from the sunlight are changed underwater or under the canopy of foliage due to the absorption of distinct wavelengths by bacterial, algal and plant pigments. Considering the fact that fungi have evolved to adapt to their habitats, the complexities of their 'visual' systems may vary significantly. Fungi that are pathogenic on plants experience a special light regime because the host always seeks the optimum light conditions for photosynthesis - and the pathogen has to cope with this environment. When the pathogen lives under the canopy and is indirectly exposed to sunlight, it is confronted with an altered light spectrum enriched for green and far-red light. Botrytis cinerea, the gray mold fungus, is an aggressive plant pathogen mainly infecting the above-ground parts of the plant. As outlined in this review, the Leotiomycete maintains a highly sophisticated light signaling machinery, integrating (near)-UV, blue, green, red and far-red light signals by use of at least eleven potential photoreceptors to trigger a variety of responses, i.e. protection (pigmentation, enzymatic systems), morphogenesis (conidiation, apothecial development), entrainment of a circadian clock, and positive and negative tropism of multicellular (conidiophores, apothecia) and unicellular structures (conidial germ tubes). In that sense, 'looking through the eyes' of this plant pathogen will expand our knowledge of fungal photobiology.
Topics: Botrytis; Circadian Clocks; Cryptochromes; Light; Photoreceptors, Microbial; Phototropism; Plant Components, Aerial; Signal Transduction; Virulence
PubMed: 28648816
DOI: 10.1016/j.fgb.2017.06.002 -
Journal of Experimental Botany Jan 2018Auxin has emerged as a key player in the adjustment of plant morphology to the challenge imposed by variable environmental conditions. Shade-avoidance responses,... (Review)
Review
Auxin has emerged as a key player in the adjustment of plant morphology to the challenge imposed by variable environmental conditions. Shade-avoidance responses, including the promotion of stem and petiole growth, leaf hyponasty, and the inhibition of branching, involve an intimate connection between light and auxin signalling. Low activity of photo-sensory receptors caused by the presence of neighbouring vegetation enhances the activity of PHYTOCHROME INTERACTING FACTORs (PIFs), which directly promote the expression of genes involved in auxin biosynthesis, conjugation, transport, perception, and signalling. In seedlings, neighbour signals increase auxin levels in the foliage, which then moves to the stem, where it reaches epidermal tissues to promote growth. However, this model only partially accounts for shade-avoidance responses (which may also occur in the absence of increased auxin levels), and understanding the whole picture will require further insight into the functional significance of the multiple links between shade and auxin networks.
Topics: Indoleacetic Acids; Light; Phototropism; Plant Development; Plant Growth Regulators; Signal Transduction
PubMed: 29036463
DOI: 10.1093/jxb/erx295 -
Ying Yong Sheng Tai Xue Bao = the... Mar 2024Insect visual electrophysiological techniques are important to study the electrical characteristics of photoreceptor cells and visual neurons in insects, including... (Review)
Review
Insect visual electrophysiological techniques are important to study the electrical characteristics of photoreceptor cells and visual neurons in insects, including electroretinography (ERG) and microelectrode intracellular recording (MIR). ERG records the changes of voltage or electric current in the retina of insects in response to different light stimuli, which occurs outside the cell. MIR records the changes in individual photoreceptor cells or visual neurons of an insect exposed to different lights, which occurs inside the cell. Insect visual electrophysiological techniques can explore the mechanism of electrophysiological response of insects' vision to light and reveal their sensitive light spectra and photoreceptor types. This review introduced the basic structure and the principle of ERG and MIR, and summarized their applications in insect researches in the past 20 years, which would provide references for elucidating the mechanism of light perception in insects and the use of insect phototropism to control pests.
Topics: Animals; Insecta; Electroretinography; Photoreceptor Cells, Invertebrate; Vision, Ocular; Microelectrodes; Electrophysiological Phenomena; Electrophysiology
PubMed: 38646774
DOI: 10.13287/j.1001-9332.202403.032 -
The New Phytologist Aug 2023Plants perceive the direction of gravity during skotomorphogenic growth, and of gravity and light during photomorphogenic growth. Gravity perception occurs through the...
Plants perceive the direction of gravity during skotomorphogenic growth, and of gravity and light during photomorphogenic growth. Gravity perception occurs through the sedimentation of starch granules in shoot endodermal and root columella cells. In this study, we demonstrate that the Arabidopsis thaliana GATA factors GNC (GATA, NITRATE-INDUCIBLE, CARBON METABOLISM-INVOLVED) and GNL/CGA1 (GNC-LIKE/CYTOKININ-RESPONSIVE GATA1) repress starch granule growth and amyloplast differentiation in endodermal cells. In our comprehensive study, we analysed gravitropic responses in the shoot, root and hypocotyl. We performed an RNA-seq analysis, used advanced microscopy techniques to examine starch granule size, number and morphology and quantified transitory starch degradation patterns. Using transmission electron microscopy, we examined amyloplast development. Our results indicate that the altered gravitropic responses in hypocotyls, shoots and roots of gnc gnl mutants and GNL overexpressors are due to the differential accumulation of starch granules observed in the GATA genotypes. At the whole-plant level, GNC and GNL play a more complex role in starch synthesis, degradation and starch granule initiation. Our findings suggest that the light-regulated GNC and GNL help balance phototropic and gravitropic growth responses after the transition from skotomorphogenesis to photomorphogenesis by repressing the growth of starch granules.
Topics: Arabidopsis; GATA Transcription Factors; Arabidopsis Proteins; Cytokinins; Starch; Gravitropism; Mutation; Plant Roots; Transcription Factors
PubMed: 37219878
DOI: 10.1111/nph.18992