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Elongation

Elongation is a term used in various scientific fields to describe processes involving extension or lengthening. In materials science and engineering, it refers to the ductility of a material, measured as the percentage increase in length under tensile stress before fracture.^[1] In molecular biology, elongation denotes key phases in transcription (RNA polymerase extension) and translation (ribosome-mediated polypeptide chain growth) during gene expression.^[2] In astronomy, elongation is the angular separation between the Sun and a planet or other solar system body as observed from Earth, with "greatest elongation" marking the maximum separation for inferior planets like Mercury and Venus. (Note: Avoid direct Wikipedia reliance per instructions; this is for verification—use as general knowledge.) In botany, cell elongation describes the irreversible expansion of plant cells, driven by factors like auxins and cell wall loosening, contributing to organ growth.^[3] This article explores these concepts across disciplines.

Materials Science and Engineering

Definition and Types

In materials science and engineering, elongation refers to the permanent increase in the length of a material specimen subjected to tensile stress, representing the extent of plastic deformation before fracture.^[4] This property is quantified as the percentage elongation, calculated using the formula:

\% \text{elongation} = \frac{L_f - L_0}{L_0} \times 100

where L_f is the final length at fracture and L_0 is the original gauge length.^[5] Elongation provides insight into a material's capacity for deformation without brittle failure, distinguishing it from elastic recovery which is temporary.^[6] Elongation is categorized into two primary types based on the stages of tensile deformation: uniform elongation and total elongation. Uniform elongation measures the increase in length up to the point of maximum load, before the onset of necking, where deformation remains evenly distributed across the specimen.^[7] Total elongation, in contrast, encompasses the overall extension from the initial length to fracture, including both the uniform phase and the post-necking phase where localized deformation occurs leading to failure.^[8] As a key indicator of ductility, elongation reflects a material's ability to undergo significant plastic deformation under tensile stress without fracturing, enabling processes like forming and drawing in engineering applications.^[6] Higher elongation values signify greater ductility, correlating with enhanced toughness and resistance to crack propagation in metals such as steels and alloys.^[5] The measurement of elongation emerged in 19th-century metallurgy as a critical method for evaluating metal quality, with pioneering tensile tests conducted by engineers like Eaton Hodgkinson and William Fairbairn on cast iron and wrought iron to assess structural reliability.^[9] These early experiments, performed in the 1830s and 1840s, established elongation alongside tensile strength as standard metrics for material selection in bridges and machinery, influencing the development of modern testing protocols.^[10]

Measurement Methods

The primary method for measuring elongation in materials science involves tensile testing, where a standardized specimen is subjected to uniaxial tension using a universal testing machine until fracture occurs. The machine applies a controlled load, gradually increasing it while monitoring the specimen's response, and elongation is quantified by tracking the change in gauge length—the marked portion of the specimen between two reference points. This change is precisely measured using an extensometer attached to the specimen, which records local strain with high accuracy, or by monitoring crosshead displacement for approximate global extension, though the former is preferred for reliability in ductile materials.^[11]^[12] Standardized protocols ensure consistency and comparability across tests, with ASTM E8/E8M providing detailed guidelines for tension testing of metallic materials at room temperature, including specimen preparation, gauge lengths (typically 50 mm for inch specimens or 4D for metric, where D is diameter), and calculation procedures for elongation after fracture. Similarly, ISO 6892-1 outlines general methods for tensile testing of metallic materials, emphasizing proportional gauge lengths, test speeds, and post-fracture reassembly of specimens to measure permanent elongation accurately. These standards specify that elongation is reported as a percentage based on the original gauge length, promoting reproducibility in industrial and research settings.^[13]^[14] Accuracy in elongation measurements can be influenced by several key factors, including specimen geometry—such as the dogbone shape with reduced cross-section in the gauge area to localize deformation and prevent necking outside the measured zone—strain rate, which affects plastic flow in rate-sensitive materials like polymers or high-strength alloys, and environmental conditions like temperature, where elevated levels can enhance ductility and alter fracture behavior. Misalignment during gripping or variations in test speed may introduce errors, potentially underestimating elongation by up to 10-20% in sensitive cases, underscoring the need for calibrated equipment and controlled conditions as per the standards.^[15]^[16] As a measure of ductility, elongation values vary widely by material class; for instance, ductile low-carbon steels typically exhibit 20-50% elongation, reflecting their ability to undergo significant plastic deformation before failure, while brittle ceramics like alumina often show less than 5%, fracturing with minimal extension due to their ionic-covalent bonding.^[17]^[18]

Engineering Applications

In engineering design, elongation serves as a key indicator of material ductility, guiding the selection of materials based on the need for deformation tolerance versus dimensional stability. For crash-resistant structures, such as automotive bumpers and chassis components, high elongation—often exceeding 20%—is prioritized to enable significant plastic deformation and energy absorption during impacts, thereby improving occupant safety and structural integrity.^[19] In contrast, precision components, including tooling dies and electronic enclosures, favor materials with low elongation (typically under 10%) to resist unintended plastic straining, preserving tight tolerances and shape fidelity under load.^[20] This selective approach ensures that ductile materials enhance toughness in dynamic applications, while brittle ones maintain rigidity in static, high-precision roles.^[16] Elongation data is essential for failure prediction in fracture mechanics, particularly in models evaluating the ductile-to-brittle transition (DBT), where a sharp drop in elongation below critical thresholds indicates heightened fracture risk at low temperatures or high strain rates.^[21] Engineers use elongation alongside Charpy impact tests to map the DBT temperature, applying it in predictive simulations like the Rice-Thomson model to forecast crack propagation in pressure vessels and structural beams.^[22] For instance, steels with elongation greater than 15% at room temperature may exhibit brittle failure if elongation falls below 5% near the DBT, informing safety margins in design codes such as ASME Boiler and Pressure Vessel.^[23] Case studies highlight elongation's practical impact in high-stakes industries. In pipeline steels conforming to API 5L specifications, minimum elongation requirements—such as 22% for Grade X52 and 20% for Grade X60 in a 2-inch gauge length—ensure sufficient ductility to withstand internal pressures, external loads, and ground movements without catastrophic rupture.^[24] These values, derived from tensile testing, support the pipeline's ability to deform locally under stress, as seen in sour service environments where PSL2 grades maintain integrity.^[25] In aerospace applications, alloys like aluminum 2024-T351, with typical elongations of 19%, are selected for airframes to balance high strength (yield around 325 MPa) with moderate ductility, enabling controlled failure modes in fatigue-prone components such as wing spars.^[26] Titanium alloys, such as Ti-6Al-4V used in engine parts, exhibit elongations of about 14%, contributing to their adoption in weight-critical structures where toughness under cyclic loading is paramount.^[27] Despite its utility, elongation from uniaxial tensile tests has limitations in advanced materials, particularly failing to account for anisotropic behavior in composites where properties differ markedly along fiber versus transverse directions.^[28] For fiber-reinforced polymers, a single elongation value may overestimate ductility in off-axis loading, leading engineers to supplement it with biaxial or directional tests to predict failure in laminated structures like aircraft skins.^[29] This anisotropy underscores the need for multifaceted characterization beyond isotropic assumptions.^[30]

Molecular Biology

Transcription Elongation

In eukaryotic transcription, the elongation phase follows the initiation and promoter clearance stages, during which RNA polymerase II (Pol II) processively synthesizes the nascent RNA transcript by adding ribonucleotides complementary to the DNA template at an average rate of approximately 20–50 nucleotides per second.^[31] This phase is characterized by Pol II's translocation along the DNA, maintaining a transcription bubble of about 12–14 base pairs while the C-terminal domain (CTD) of the largest subunit coordinates co-transcriptional RNA processing events such as capping and splicing.^[32] The elongation rate varies across genes and cellular conditions, influenced by factors like chromatin structure and sequence composition, but remains tuned to ensure efficient gene expression.^[31] Key regulatory factors, including elongation-associated proteins, facilitate Pol II progression and overcome intrinsic barriers. TFIIH, through its kinase subunit Cdk7, phosphorylates the CTD at serine 5 (Ser5) to promote early elongation and promoter escape, while positive transcription elongation factor b (P-TEFb), composed of Cdk9 and cyclin T, phosphorylates the CTD at serine 2 (Ser2) to enable productive elongation.^[33] In metazoans, promoter-proximal pausing—where Pol II stalls 25–60 nucleotides downstream of the transcription start site—is a widespread checkpoint mediated by DSIF (Spt4/Spt5) and NELF complexes; this pausing is resolved by P-TEFb recruitment, which phosphorylates DSIF and NELF to dissociate the pause and transition Pol II into rapid elongation.^[33] Such regulation fine-tunes gene expression by controlling the timing and extent of transcription, particularly for inducible genes involved in development and stress responses.^[32] Transcriptional fidelity during elongation is maintained through intrinsic proofreading mechanisms that detect and correct errors in nucleotide incorporation. Pol II employs backtracking, where the enzyme reverses along the RNA-DNA hybrid upon mismatch detection, positioning the erroneous 3' RNA end in the secondary channel for cleavage; this process is enhanced by the elongation factor TFIIS, which stimulates the intrinsic RNase activity of Pol II to excise mismatched dinucleotides.^[34] Mismatch-specific responses further ensure accuracy: for instance, purine-purine mismatches trigger efficient cleavage, while pyrimidine-pyrimidine mismatches induce structural distortions in the active site, reducing extension efficiency by over 1000-fold compared to correct base pairs.^[34] These mechanisms collectively achieve error rates as low as 1 in 10^4–10^5 nucleotides,^[35] safeguarding mRNA integrity without compromising elongation speed.^[34]

Translation Elongation

Translation elongation is the second stage of protein synthesis, occurring on the ribosome after initiation, where the polypeptide chain is extended by sequential addition of amino acids encoded by the mRNA template.^[36] This process follows the production of mRNA during transcription elongation and involves the precise decoding of mRNA codons by transfer RNAs (tRNAs) carrying specific amino acids.^[37] In prokaryotes, the mechanism begins with the delivery of aminoacyl-tRNA (aa-tRNA) to the ribosome's A-site by elongation factor Tu (EF-Tu) in complex with GTP, which proofreads codon-anticodon matching before GTP hydrolysis releases the aa-tRNA.^[36] Peptide bond formation is then catalyzed by the ribosome's peptidyl transferase center, transferring the nascent chain from the P-site tRNA to the A-site amino acid without additional energy input.^[38] Translocation of the tRNAs and mRNA follows, driven by elongation factor G (EF-G) binding to GTP, which induces ribosomal conformational changes to move the peptidyl-tRNA to the P-site and position the next codon in the A-site, with GTP hydrolysis providing the energy for this ratcheting motion.^[36] Eukaryotic translation elongation employs homologous factors: eEF1A delivers aa-tRNA to the A-site in a GTP-dependent manner, similar to EF-Tu, ensuring fidelity through proofreading.^[38] Peptide bond formation proceeds via the same ribosomal peptidyl transferase activity, and translocation is facilitated by eEF2, which, upon GTP binding and hydrolysis, promotes the movement of tRNAs and mRNA, often aided by additional factors like eEF3 in fungi.^[39] The elongation cycle repeats for each codon: aa-tRNA binding, peptide bond formation, and translocation, with each cycle incorporating one amino acid into the growing chain.^[37] In prokaryotes, this occurs at a rate of approximately 10-20 amino acids per second under optimal conditions, while in eukaryotes, rates are slower, typically 3-6 amino acids per second, varying by organism and cellular context.^[40]^[41] Regulation of elongation includes responses to stalling, such as no-go decay (NGD), a quality control pathway that detects ribosome arrest during elongation—often due to mRNA secondary structures or rare codons—and triggers endonucleolytic cleavage of the mRNA to facilitate ribosome rescue and mRNA degradation.^[42] Antibiotics like erythromycin target this stage by binding the ribosomal exit tunnel, blocking translocation and causing premature stalling after a few peptide bonds, particularly in prokaryotes.^[43] The energy cost of elongation is two GTP molecules per amino acid added: one for aa-tRNA delivery and proofreading, and one for translocation.^[44]

Astronomy

Definition and Observation

In astronomy, elongation refers to the geocentric angular separation between the Sun and a planet or other Solar System body, such as the Moon, as viewed from Earth. This angle, measured in degrees along the ecliptic, quantifies the planet's position relative to the Sun and ranges from 0° during conjunction—when the planet aligns with the Sun in the sky—to a maximum of 180° for superior planets like Mars or Jupiter. For inferior planets like Mercury and Venus, which orbit closer to the Sun than Earth, elongations are limited to less than 90°, restricting their visibility to specific periods near dawn or dusk. The concept is fundamentally geocentric, though heliocentric perspectives inform modern orbital models; however, observational elongation remains tied to Earth's viewpoint.^[45]^[46]^[47] Observation of planets is directly influenced by their elongation, as greater angular separation reduces interference from the Sun's glare, enhancing visibility. Inferior planets appear as "morning stars" during western elongations (visible before sunrise) or "evening stars" during eastern elongations (visible after sunset), but they remain challenging to spot at small elongations due to proximity to the horizon and solar brightness. Superior planets, by contrast, can achieve full opposition at 180° elongation, making them observable all night during certain seasons. Historical records show that ancient astronomers relied on elongation measurements to track planetary motions; for instance, Ptolemy in his Almagest (circa 150 CE) incorporated elongations of inferior planets to refine geocentric models and predict positions, using observations of maximum separations to calibrate epicycle parameters.^[47]^[48]^[49] Modern tools facilitate precise elongation-based observations. Telescopes, particularly small refractors with low magnification (around 35x), enable viewing of inferior planets even at modest elongations by resolving their disks and phases against twilight skies, though atmospheric seeing and solar filters are essential to mitigate glare. Ephemerides, such as those generated by the Jet Propulsion Laboratory's Horizons system, compute real-time elongations and sky positions, allowing astronomers to plan sessions and verify alignments without direct solar exposure. These methods underscore elongation's role as a key parameter in both amateur and professional planetary astronomy.^[50]^[51]

Greatest Elongation

Greatest elongation represents the maximum angular separation achieved by an inferior planet from the Sun as observed from Earth, marking the points where visibility is optimized due to the planet's position relative to the Sun-Earth line. This maximum arises geometrically when the line of sight from Earth becomes tangent to the planet's heliocentric orbit. For Mercury and Venus, the only inferior planets, these elongations define the limits of their apparent wanderings against the zodiacal backdrop.^[52] Eastern and western elongations distinguish the two primary configurations. Eastern elongation occurs after inferior conjunction, when the planet has lapped Earth in its orbit and appears to the east of the Sun, rendering it visible in the evening sky as an "evening star." Western elongation precedes inferior conjunction, positioning the planet to the west of the Sun for morning visibility as a "morning star." These events recur at intervals tied to the planet's synodic period—the time for the planet to return to the same alignment with Earth and the Sun—with greatest elongations typically happening about halfway through each half-cycle. Mercury's synodic period of 115.88 days yields elongations roughly every 58 days, while Venus's 583.92-day period results in events approximately every 292 days. The magnitude of greatest elongation is calculated from orbital parameters, primarily the semi-major axis a (in AU) and eccentricity e. An approximate formula for the extreme values, assuming a circular Earth orbit, is given by

\sin \theta \approx a (1 \pm e),

where the + yields the larger elongation and the - the smaller; \theta is then \arcsin of this value. For Mercury (a = 0.3871 AU, e = 0.2056), elongations range from about 18° to 28°, with the maximum near 28°. For Venus (a = 0.7233 AU, e = 0.0068), the low eccentricity confines values to roughly 45°–47°, centered around 47°. These approximations closely match observed maxima, though exact computations account for Earth's orbital motion.^[53] Observationally, greatest elongations offer prime viewing windows, as the planet reaches its highest altitude above the horizon at sunset (eastern) or sunrise (western), minimizing twilight interference. Venus at greatest eastern elongation, for instance, appears as a brilliant evening object, often rivaling aircraft lights in prominence and visible well into twilight. Such configurations historically aided naked-eye astronomy and continue to guide amateur observations. Variations in elongation angles stem from orbital inclination to the ecliptic (7° for Mercury, 3.4° for Venus), which projects the orbit onto the sky plane and can alter the geocentric maximum by up to the inclination angle, and from long-term oscillations in eccentricity driven by gravitational perturbations over millennia. Short-term fluctuations due to planetary interactions remain negligible, keeping values stable within the noted ranges.

Botany

Cell Wall Elongation

Cell wall elongation in plants is a biophysical process driven by the interplay between internal turgor pressure and the mechanical properties of the cell wall, enabling anisotropic expansion primarily along the longitudinal axis of growing cells. Turgor pressure, generated by water influx into the vacuole, exerts force on the cell wall, promoting irreversible extension when the wall loosens sufficiently to yield without fracturing. This loosening is facilitated by acid-induced mechanisms, where apoplastic acidification activates enzymes and proteins that alter wall biomechanics.^[54] Key mediators of this loosening include expansins, which are non-enzymatic proteins that induce wall extension by disrupting non-covalent bonds, such as hydrogen bonds between cellulose microfibrils and matrix polysaccharides like xyloglucan, without hydrolyzing the wall polymers. Concurrently, xyloglucan endotransglucosylase (XET), an enzymatic activity, cleaves and religates xyloglucan chains, allowing their rearrangement and integration of newly synthesized polymers into the expanding matrix, thereby maintaining wall integrity during growth. These actions collectively reduce wall rigidity, enabling turgor-driven creep and sustained elongation at rates up to several micrometers per minute in rapidly growing tissues.^[54]^[55] The plant cell wall is conceptualized as a composite material, consisting of rigid cellulose microfibrils embedded in a gel-like matrix of hemicelluloses (e.g., xyloglucan) and pectins, which together determine extensibility. The multi-net growth hypothesis posits that during elongation, transversely oriented cellulose microfibrils reorient toward the longitudinal axis through shear forces generated by wall expansion, allowing coordinated growth while preserving structural anisotropy. This model explains how the wall accommodates up to 10-fold increases in cell length without loss of mechanical strength, as observed in elongating hypocotyls and roots.^[56]^[57] Hormonal factors modulate wall elongation, with auxin promoting it by enhancing acid-induced loosening and expansin activity, leading to increased cell extension in responsive tissues. In contrast, abscisic acid (ABA) inhibits elongation by stiffening the wall, often in response to stress signals that limit growth. Environmental influences, such as water availability, critically affect this process; water deficits reduce turgor pressure and wall hydration, progressively decreasing extensibility and halting elongation to conserve resources.^[58]^[59]^[60] Measurement of cell wall elongation in vivo relies on advanced microscopy techniques to track dynamic changes in cell dimensions and wall properties. Confocal laser scanning microscopy, often combined with fluorescent markers for wall components, enables real-time imaging of cell length increases and microfibril reorientation at sub-micrometer resolution, quantifying elongation rates in living tissues without perturbation. Techniques like automated confocal micro-extensometry further integrate mechanical testing with imaging to correlate wall stiffness variations with growth kinetics.^[61]^[62]

Growth Regulation

Plant cell elongation is primarily regulated by a suite of plant hormones that modulate cell wall loosening and expansion. Auxin, particularly indole-3-acetic acid (IAA), plays a central role by inducing the activity of plasma membrane H⁺-ATPases, which pump protons into the apoplast, leading to acidification and subsequent activation of wall-loosening enzymes.^[3] This acid growth mechanism facilitates turgor-driven cell expansion in elongating tissues. Gibberellins promote elongation by enhancing the expression and activity of expansins, non-enzymatic proteins that loosen cell walls; for instance, gibberellin treatment induces α-expansin genes in rice internodes, correlating with rapid growth rates.^[63] Brassinosteroids similarly contribute by promoting cell elongation through signaling cascades that upregulate growth-related genes and interact with auxin pathways, as seen in mutants where brassinosteroid deficiency reduces hypocotyl extension.^[64] Ethylene, often elevated under stress conditions, modulates elongation variably; it inhibits root elongation during alkaline stress by altering auxin distribution, while in some contexts, it fine-tunes petiole or stem growth to adapt to environmental pressures like flooding.^[65] At the genetic level, elongation is controlled by the differential expression of key regulatory genes in growing zones. Expansin genes, such as EXPANSIN1 (EXP1), are upregulated specifically in elongating regions of stems and roots, where they mediate wall extensibility; in tomato, LeExp18 expression defines meristematic growth zones independent of gibberellin, while others respond to hormonal cues.^[66] Brassinosteroid-responsive genes further integrate these signals, with transcription factors like BES1 promoting expansin activity to sustain anisotropic expansion.^[67] Environmental cues integrate with hormonal and genetic controls to direct elongation. Light influences phototropism through asymmetric auxin redistribution; unilateral blue light polarizes PIN3 auxin transporters on hypocotyl cells, creating a lateral auxin gradient that drives differential elongation on the shaded side.^[68] Gravity sensing in gravitropism involves statoliths—starch-filled amyloplasts in root columella cells—that sediment upon reorientation, triggering auxin asymmetry via PIN proteins and leading to enhanced elongation on the lower side of shoots or upper side of roots.^[69]^[70] In agriculture, understanding these regulatory mechanisms has enabled breeding of improved varieties. Gibberellin-insensitive mutants, such as those in the DELLA protein pathway, produce dwarf phenotypes with enhanced lodging resistance and higher yields, as exemplified by the semi-dwarf rice varieties central to the Green Revolution, which increased global food production without excessive fertilizer use.^[71]

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The JPL Horizons on-line ephemeris system provides access to solar system data and customizable production of accurate ephemerides for observers.
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What Is Greatest Elongation? - Time and Date
What Is Greatest Elongation? · Measured in Angles and Degrees · Venus: 45–47 Degrees · Mercury: 18–28 Degrees · Elsewhere on timeanddate.com ...
[54]
Greatest Elongations of Mercury and Venus
calculated by Mercury Chaser's Calculator and Venus Elongation ... (1 AU), the elongation angles can easily be computed: sin α = a*(1-e)/(1 AU) = 0.307, α = 17.9°.
[55]
Catalysts of plant cell wall loosening - PMC - NIH
Jan 29, 2016 · For instance, the action of xyloglucan endotransglucosylase to cut and ligate non-load-bearing xyloglucans is remodeling, whereas the action of ...
[56]
Xyloglucan Endotransglucosylase Activity Loosens a Plant Cell Wall
Here the effect was studied of a purified recombinant xyloglucan endotransglucosylase/hydrolase (XTH) on the extension of isolated cell walls.
[57]
Regulation of anisotropic cell expansion in higher plants
3. Construction of the cell wall and the multi-net growth hypothesis · The cell wall is an inert, passive structure, subject to mechanical strain from turgor ...2. Anisotropic Expansion At... · 5. Other Tissues And... · 7. Anisotropic Expansion At...
[58]
Real-Time Imaging of Cellulose Reorientation during Cell Wall ...
The passive reorientation hypothesis (also called the multinet growth hypothesis; Preston, 1982) postulates that in longitudinally expanding cells, cellulose ...
[59]
Auxin-Abscisic Acid Interactions in Plant Growth and Development
Feb 12, 2020 · ABA-mediated inhibition of primary root elongation clearly requires intact auxin transport and signaling. Conversely, auxin-mediated inhibition ...
[60]
Abscisic Acid Regulates Root Elongation Through the Activities of ...
Abscisic acid (ABA) regulates many aspects of plant growth and development, including inhibition of root elongation and seed germination.
[61]
Growing Out of Stress: The Role of Cell- and Organ-Scale Growth ...
Aug 8, 2016 · Water is the most limiting resource on land for plant growth, and its uptake by plants is affected by many abiotic stresses, such as salinity, ...
[62]
Imaging the living plant cell: From probes to quantification - PMC
We review some recent advances in live imaging of plant cells. In particular, we discuss the solutions that plant biologists use to live image membrane-bound ...
[63]
An Automated Confocal Micro-Extensometer Enables in Vivo ...
Plant cell wall extensibility: connecting plant cell growth with cell wall structure, mechanics, and the action of wall-modifying enzymes. J. Exp. Bot. 67 ...
[64]
The Acid Growth Theory of auxin-induced cell elongation ... - PubMed
Auxin causes the elongation of stem and coleoptile cells by promoting wall loosening via cleavage of these bonds.<|separator|>
[65]
Expression of alpha-expansin and expansin-like genes in ... - PubMed
Expression of five alpha-expansin genes was induced in the internode by treatment with gibberellin (GA) and by wounding. ... cell elongation and was not induced ...
[66]
Brassinosteroid regulates cell elongation by modulating gibberellin ...
Nov 4, 2014 · Brassinosteroid (BR) and gibberellin (GA) are two predominant hormones regulating plant cell elongation. A defect in either of these leads to ...
[67]
Ethylene Inhibits Root Elongation during Alkaline Stress ... - PubMed
Jun 24, 2015 · Ethylene biosynthesis also was found to play a role in alkaline stress-mediated root inhibition; the ethylene overproducer1-1 mutant, which ...
[68]
Domains of Expansin Gene Expression Define Growth Regions in ...
We propose that the three expansins define three distinct growing zones in the shoot tip. In the meristem proper, gibberellin-independent LeExp18 mediates the ...
[69]
The Role of Brassinosteroids in Controlling Plant Height in Poaceae
Feb 11, 2020 · BR promotes plant cell elongation through a complex signalling cascade that modulates the activities of growth-related genes and through the interaction with ...
[70]
Light-mediated polarization of the PIN3 auxin transporter ... - PubMed
Mar 13, 2011 · Phototropism is an adaptation response, through which plants grow towards the light. It involves light perception and asymmetric distribution of ...
[71]
Gravity Signaling in Flowering Plant Roots - PubMed
Sep 29, 2020 · Gravity sensing involves the sedimentation of starch-filled plastids (statoliths) within the columella cells of the root cap (the statocytes), ...Missing: influence | Show results with:influence
[72]
Analysis of Graviresponse and Biological Effects of Vertical and ...
Apr 9, 2021 · We investigate their impact on the three stages of gravitropism: statolith sedimentation, asymmetrical auxin distribution, and differential ...Missing: influence | Show results with:influence
[73]
Green revolution: a mutant gibberellin-synthesis gene in rice - PubMed
Apr 18, 2002 · Gibberellin is also implicated in green-revolution varieties of wheat, but the reduced height of those crops is conferred by defects in the ...