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Sap

Sap is the vital fluid that circulates through vascular plants, serving as the primary medium for transporting water, nutrients, minerals, sugars, hormones, and other essential compounds between different parts of the plant.^[1] It flows through two main types of vascular tissues: the xylem, which conducts xylem sap upward from roots to leaves and stems, and the phloem, which transports phloem sap bidirectionally to distribute photosynthates and signaling molecules throughout the plant.^[2] Xylem sap is primarily composed of water (often over 95%), dissolved minerals, and low concentrations of organic compounds, driven by transpiration pull and root pressure to support photosynthesis and structural growth.^[3] In contrast, phloem sap is nutrient-dense, containing up to 30% sugars (mainly sucrose), amino acids, hormones, and metabolites, and moves via pressure-flow mechanisms from source tissues like leaves to sink tissues such as roots, fruits, and growing shoots.^[4] This dual transport system is crucial for plant nutrition, development, and response to environmental stresses, enabling the redistribution of resources and defense compounds while maintaining hydraulic balance.^[5] Sap production and flow vary by plant species, season, and environmental conditions; for instance, in deciduous trees like maples, xylem sap becomes enriched with sugars during early spring, allowing for syrup extraction.^[3] In addition to its physiological roles, sap can exude from wounds or specialized structures, sometimes forming resins or latex in certain plants, which provide protective barriers against herbivores and pathogens.^[6] Sap-feeding insects, such as aphids, exploit phloem sap as a primary food source, often excreting excess sugary waste known as honeydew.^[1] Understanding sap dynamics has practical implications in agriculture, forestry, and biotechnology, including crop yield optimization and the study of plant-pathogen interactions.^[5]

Definition and Overview

Biological Definition

Sap is defined as the aqueous fluid transported through the vascular tissues of plants, specifically the xylem and phloem, serving as the primary medium for long-distance movement of essential substances.^[7] This fluid primarily consists of water as its major constituent, along with dissolved minerals and sugars such as sucrose, which contribute to its osmotic properties and nutritional value.^[7] In vascular plants, sap enables the circulation of resources from roots to shoots and vice versa, distinguishing it from fluids in non-vascular plants that lack such specialized transport systems.^[8] Unlike cell sap, which refers to the dilute solution of water, amino acids, glucose, salts, and other solutes contained within the central vacuole of individual plant cells, vascular sap is a dynamic, circulating medium confined to the conductive elements of the phloem and xylem.^[9] Similarly, sap is distinct from plant exudates like nectar, a sugar-rich secretion produced by specialized floral nectaries to attract pollinators, rather than being part of the plant's internal transport network.^[10] These distinctions highlight sap's specialized role in systemic resource allocation, separate from localized cellular or glandular fluids. Sap plays a crucial role in nutrient transport, supporting plant growth and metabolism.^[7] The term "sap" derives from Old English sæp, meaning "juice" or "fluid," rooted in Proto-Germanic sapam and ultimately from the Proto-Indo-European sab-, denoting "juice" or "fluid."^[11] This etymology reflects its early association with plant juices, with the word entering botanical contexts in the 16th century alongside emerging descriptions of plant physiology in herbal and scientific texts.^[11]

Physiological Role

Sap plays a critical role in plant physiology by facilitating the transport of essential resources that support photosynthesis and overall metabolic processes. Xylem sap delivers water and mineral nutrients from the roots to the leaves, enabling the maintenance of cellular hydration necessary for photosynthetic reactions, while phloem sap distributes photosynthates such as sugars produced during photosynthesis from source leaves to sink tissues like roots and developing fruits.^[12] This bidirectional transport system ensures efficient resource allocation, with xylem flow driven primarily by transpiration pull and phloem movement powered by pressure gradients generated by sugar loading.^[13] Without these functions, plants would be unable to sustain energy production and growth under varying environmental conditions.^[14] Beyond nutrient delivery, sap contributes to structural integrity through its influence on turgor pressure, the hydrostatic force that presses the plasma membrane against the cell wall, providing mechanical support to non-woody tissues. The water component of xylem sap is primarily responsible for generating this pressure, which drives cell expansion during growth and maintains upright posture in herbaceous plants, preventing wilting during water stress.^[15] In response to injury, sap aids wound healing by clotting; phloem sap proteins form disulphide cross-links to create a polymer seal, reinforced by callose deposition, which rapidly blocks vascular conduits and limits fluid loss.^[16] This mechanism, triggered by calcium signaling waves propagating at approximately 1 cm/min through the vascular system, is essential for compartmentalizing damage and preserving hydraulic continuity.^[17] Sap also serves as a conduit for plant signaling, transporting hormones that coordinate developmental and stress responses. Auxins, such as indole-3-acetic acid (IAA), are mobilized via phloem for long-distance signaling from shoots to roots, regulating processes like apical dominance and lateral root formation through passive flow and specific transporters like ABCB1.^[18] Similarly, xylem facilitates the upward transport of auxins and other hormones like abscisic acid (ABA) with the transpiration stream, enabling systemic responses to environmental cues.^[19] In defense against pathogens, sap contains antimicrobial compounds, including pathogenesis-related proteins (PR1) and lipid-binding proteins, which inhibit microbial growth and modulate xylem tissue morphology to restrict vascular wilt fungi.^[20] These elements collectively enhance plant resilience by integrating transport, mechanical support, and biochemical defense into a unified physiological framework.^[21]

Chemical Composition

Inorganic Components

The water content of sap varies by type; xylem sap consists primarily of water (over 95% by volume), serving as the solvent for dissolved minerals absorbed by plant roots from the soil, while phloem sap has higher solute levels, with water comprising approximately 70-80%.^[22]^[4] The major inorganic ions include potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺), and nitrates (NO₃⁻), which are taken up through root systems and transported via xylem or phloem pathways.^[23] These ions originate from soil minerals and nutrient solutions, with their uptake influenced by rootstock genetics and environmental factors such as soil fertility.^[23] Trace elements, including iron (Fe), zinc (Zn), and phosphorus (P), occur in much lower concentrations within sap and play essential roles in enzymatic functions and metabolic processes.^[24] Their levels vary significantly with soil pH, as acidic conditions enhance the availability of Fe and Zn while neutral to alkaline soils favor P solubility.^[25] For instance, xylem sap from plants in fertile, nitrogen-rich soils exhibits elevated nitrate concentrations compared to those in nutrient-poor environments.^[26] The pH of sap reflects ionic balances and differs between types: xylem sap typically ranges from 5 to 7, contributing to its mildly acidic nature due to higher nitrate and cation levels, whereas phloem sap is more alkaline at 7 to 8, supporting solute stability.^[27] Organic sugars present in sap can enhance the solubility of these inorganic ions, facilitating their transport.^[28]

Organic Components

Sap's organic components are dominated by carbon-based molecules that support energy transfer, metabolic processes, and signaling within plants. Carbohydrates, particularly sugars, form the bulk of these organics, providing osmotic pressure for fluid movement and serving as primary energy reserves. Amino acids facilitate nitrogen distribution, while hormones and secondary metabolites regulate physiological responses. Proteins and enzymes, though less abundant, enable localized biochemical reactions. Sugars constitute the majority of organic solutes in sap, with sucrose being the dominant form in phloem, typically at concentrations of 10-25% by weight, which optimizes viscosity for efficient transport and minimizes microbial contamination due to its non-reducing nature.^[29] In xylem sap, glucose and fructose predominate at lower levels, often around 5-10 mM each, supporting hydration and immediate metabolic needs in growing tissues.^[30] These sugars not only fuel respiration and growth but also maintain turgor pressure essential for cell expansion. Amino acids represent a crucial organic fraction for nitrogen metabolism and transport, comprising up to several percent of sap solutes depending on plant nitrogen status. Glutamine is particularly prominent, accounting for up to 20% of nitrogen transport in phloem, as it serves as a stable, high-nitrogen carrier synthesized from ammonium assimilation in source tissues.^[31] Other amino acids, such as asparagine and glutamate, complement this by enabling remobilization of nitrogen to sinks like developing seeds or roots. Hormones and secondary metabolites add regulatory and protective dimensions to sap's organic profile. Cytokinins, transported primarily in xylem and phloem, promote cell division, bud growth, and delay leaf senescence at nanomolar concentrations.^[32] Abscisic acid, present in both sap types, coordinates stress responses, including stomatal closure during drought to conserve water.^[32] Phenolics, a diverse class of secondary metabolites, function in defense by inhibiting pathogen enzymes and deterring herbivores, with compounds like flavonoids accumulating in sap under attack.^[33] Although proteins and enzymes are rare in sap—typically less than 1% of total organics—they include functional elements like P-proteins for sieve tube sealing and metabolic facilitators. Invertases, which catalyze sucrose hydrolysis to glucose and fructose, are among these, aiding sugar unloading at sinks; their molecular weights generally range from 20 to 100 kDa, reflecting glycosylated structures adapted for vascular stability.^[34]^[35] Mineral ions from the inorganic fraction, such as potassium, enhance the solubility and stability of these organics within the aqueous sap matrix.^[5]

Types of Sap

Xylem Sap

Xylem sap is a dilute aqueous solution composed mainly of water, with solute concentrations typically less than 1%, dominated by mineral ions such as potassium, calcium, magnesium, and nitrate, alongside trace amounts of sugars, amino acids, and organic acids.^[12]^[36] This low organic content, particularly sugars at levels far below those in other plant fluids, reflects its role in mineral nutrient uptake from soil rather than energy transport.^[30] The sap flows unidirectionally upward through the xylem vessels from roots to shoots, facilitating long-distance delivery without backflow.^[12] The primary function of xylem sap is hydraulic transport, where water movement is powered by transpiration pull generated by evaporation from leaf surfaces, creating a continuous column that draws sap from the roots.^[14] This process not only supplies water to maintain cell turgor and enable photosynthesis but also distributes essential mineral nutrients to support growth and metabolism throughout the plant.^[14] Unlike the nutrient-rich phloem sap, xylem sap prioritizes passive water ascent over active solute distribution.^[30] Xylem sap is characteristically clear and odorless, appearing as a transparent fluid when extracted. During active transpiration, it sustains negative pressures under tension, often reaching -10 atmospheres or greater in tall plants or dry conditions to counteract gravity and maintain flow.^[37] In species like sugar maple (Acer saccharum), springtime root pressure can elevate this to positive values, up to several atmospheres, driving enhanced sap exudation for seasonal recovery and growth initiation.^[38]

Phloem Sap

Phloem sap is a viscous fluid primarily composed of sugars, with sucrose serving as the dominant carbohydrate at concentrations typically ranging from 10% to 25% by weight, alongside smaller amounts of hexoses like glucose and fructose.^[5] This sugar-rich composition accounts for much of the sap's osmotic potential, while amino acids constitute about 5-15% of the total solutes, including key compounds such as glutamine, asparagine, aspartate, and glutamate that vary by plant species and environmental conditions.^[5] Additionally, phloem sap contains plant hormones like auxins, cytokinins, gibberellins, and abscisic acid, which facilitate signaling during transport.^[5] The sap flows through sieve tubes in a bidirectional manner, allowing for flexible distribution within the phloem network.^[2] The primary function of phloem sap is to enable source-to-sink transport of photosynthates, moving organic nutrients produced in photosynthetic tissues (sources, such as leaves) to non-photosynthetic sink tissues (such as roots, developing fruits, and storage organs) to support growth, metabolism, and development.^[39] This translocation ensures that energy-rich compounds like sucrose are efficiently allocated to areas of high demand, maintaining plant vigor and enabling responses to environmental cues like light and nutrient availability.^[39] For instance, in growing fruits or tubers, the influx of photosynthates via phloem sap drives expansion and accumulation of reserves.^[3] Phloem sap operates under positive turgor pressure, which can reach up to 2 MPa, generated by osmotic influx of water into sieve tubes and driving bulk flow through the system.^[3] Its sticky consistency arises from P-proteins—specialized phloem-specific proteins that form filamentous or granular structures to seal sieve plates upon injury, preventing loss of valuable nutrients while contributing to the sap's viscosity.^[40] Researchers often study phloem sap composition by observing aphids, which insert their stylets into sieve tubes to feed; the insects' honeydew exudate provides a non-invasive sample rich in unaltered sap components for analysis.^[41]

Production and Flow

Biosynthesis Processes

Xylem sap is formed primarily in the roots through the uptake of water and dissolved minerals from the soil. Water enters root cells via osmosis, driven by a lower water potential in the root symplast compared to the soil solution, which is established by the active transport of mineral ions into the root endodermis and stele.^[42] These ions, including potassium, calcium, and nitrate, are loaded into xylem vessels by specialized transporters in the pericycle and xylem parenchyma cells, creating an osmotic gradient that facilitates water influx and generates root pressure under certain conditions.^[43] This process ensures the dilute, ion-rich composition of xylem sap, essential for long-distance transport. Mycorrhizal associations, particularly arbuscular mycorrhizal fungi, enhance this formation by extending the root system's absorptive surface and improving hydraulic conductivity, thereby increasing water and nutrient uptake into the xylem, especially under nutrient-limited soils.^[44] Phloem sap loading occurs mainly in the leaves, where photosynthates from mesophyll cells are actively concentrated into sieve elements. In many plants, sucrose synthesized in the mesophyll cytosol is exported to the apoplast and then actively imported into the phloem companion cells via sucrose-proton symporters, powered by the proton motive force across the plasma membrane; this apoplastic pathway predominates in herbaceous species and allows for high sucrose concentrations (up to 500-700 mM) in the phloem.^[45] Alternatively, in symplastic loaders like some trees and Cucurbitaceae, sucrose moves passively through plasmodesmata from mesophyll cells to the phloem, often coupled with polymer trapping where sucrose is converted to larger oligosaccharides (e.g., raffinose) to prevent back-diffusion.^[45] The conversion of starch to sucrose in mesophyll cells, particularly during the night when starch reserves in chloroplasts are mobilized, involves key enzymes such as sucrose-phosphate synthase (SPS), which catalyzes the formation of sucrose-6-phosphate from UDP-glucose and fructose-6-phosphate in the cytosol, followed by dephosphorylation to sucrose; this pathway ensures a steady supply of osmotically active solutes for loading.^[46] The biosynthesis of both xylem and phloem sap is tightly regulated by environmental factors and internal signals to match plant demands. Light intensity positively regulates phloem loading by boosting photosynthetic carbon fixation and sucrose synthesis in mesophyll cells, leading to increased export rates during daylight hours; for instance, high light enhances structural adaptations in companion cells of apoplastic loaders, such as membrane invaginations that support greater transporter activity.^[47] In contrast, drought stress reduces xylem sap production by limiting root water uptake through lowered soil moisture availability and stomatal closure, which decreases transpiration-driven gradients and ion accumulation in roots.^[48] Phloem loading under drought may initially increase sucrose concentrations in leaves due to inhibited sink growth, but severe water deficits ultimately impair loading by reducing photoassimilate production.^[47] Diurnal cycles further modulate production, with peak phloem loading and sucrose export occurring during the day via photosynthesis and a nighttime contribution from starch breakdown, while xylem sap ion loading follows similar patterns tied to root metabolic activity.^[49]

Transport Mechanisms

Sap transport in plants occurs through two primary vascular tissues: xylem and phloem, each employing distinct mechanisms to facilitate the movement of water, minerals, and nutrients. In xylem, the cohesion-tension theory explains the ascent of sap, primarily driven by transpiration from leaves, which creates negative pressure or tension in the xylem vessels. This tension pulls a continuous column of water upward from the roots, relying on the cohesive forces between water molecules and adhesive forces to the vessel walls, allowing transport even in tall trees against gravity.^[14] A secondary mechanism in xylem transport is root pressure, generated by active ion uptake in root cells that lowers solute potential, drawing water osmotically into the xylem and creating positive pressure to push sap upward. This process is most evident at night or in conditions of low transpiration, leading to guttation, where excess water is exuded as droplets from leaf hydathodes. However, root pressure typically contributes minimally to overall transport in mature plants, supporting only short-distance movement of a few meters.^[14]^[50] In phloem, the mass flow hypothesis, also known as the pressure flow model, describes the bulk movement of nutrient-rich sap from source regions (e.g., photosynthesizing leaves) to sink regions (e.g., growing tissues or storage organs). Osmotic loading of sugars at the source lowers solute potential, causing water to enter from the xylem and build turgor pressure; this creates a hydrostatic pressure gradient (ΔP related to the reflection coefficient σ and solute potential difference Δψ_s) that propels sap through sieve tubes toward areas of lower pressure at sinks, where unloading reduces turgor.^[2]^[51] Several environmental and structural factors influence sap flow rates in both xylem and phloem. Temperature affects viscosity of the sap, with higher temperatures reducing viscosity and thereby enhancing flow, as observed in increased sap velocities in warmed tree canopies. Vessel diameter plays a critical role, as flow resistance decreases dramatically with larger diameters according to principles akin to Poiseuille's law, where hydraulic conductivity scales with the fourth power of the radius, favoring efficient transport in wider conduits. Additionally, blockages such as air embolisms in xylem, formed under drought-induced tension, disrupt continuity of the water column and reduce overall hydraulic conductivity, potentially leading to widespread transport failure if unrepaired.^[52]^[53]

Human Uses

Culinary Applications

Sap from various tree species has been utilized in culinary traditions worldwide, primarily for its natural sweetness derived from sucrose and other sugars. In North America, maple sap is harvested and processed into a staple sweetener. The province of Quebec in Canada produces approximately 70% of the world's maple syrup supply, with over 13,000 producers tapping sugar maple trees seasonally.^[54]^[55] Maple sap collection occurs during late winter and early spring, when freezing nights and thawing days create pressure that drives the sap upward in the trees. Producers drill small taps into the trunks to collect the clear, watery liquid, which contains about 2% sugar. To produce maple syrup, the sap is boiled to evaporate water, typically requiring a 40:1 ratio of sap to finished syrup, resulting in a thick, amber liquid used in pancakes, desserts, and beverages.^[56]^[57] In Asia and Africa, palm sap, often called toddy, serves as a versatile ingredient in food and drink production. Extracted from species like the palmyra or date palm by tapping the inflorescences, the sap has a sucrose content of 10-15%, making it suitable for both fresh consumption and processing. When allowed to ferment naturally, it becomes palm wine, a mildly alcoholic beverage enjoyed in social settings across regions like India, Indonesia, and West Africa. Alternatively, the sap is boiled down to create jaggery, a solid sugar block used in sweets, curries, and confections.^[58]^[59] Other saps contribute to regional cuisines with lighter, nutrient-enhanced profiles. In Northern Europe, birch sap is tapped in spring and consumed fresh as a low-sugar drink, containing about 1.1% sugars alongside vitamins such as C and B-group nutrients, often flavored or carbonated for modern beverages. In Mexico, agave sap from the maguey plant is fermented into pulque, a viscous, milky drink central to central Mexican culinary culture, produced by harvesting the sap from mature plants and allowing wild yeast fermentation over 24-48 hours.^[60]^[61]

Medicinal and Industrial Uses

Sap from various plants has been utilized in traditional medicine for its therapeutic properties, particularly in wound healing and as a laxative. The latex sap of Aloe vera, which contains aloin—an anthraquinone compound—has been employed as a potent stimulant laxative due to its ability to promote bowel movements by irritating the intestinal lining. ^[62] Additionally, the gel derived from Aloe vera leaves, often associated with the plant's sap components, accelerates wound healing by enhancing collagen synthesis, reducing inflammation, and promoting tissue regeneration in topical applications. ^[63] Latex sap from the rubber tree (Hevea brasiliensis), composed primarily of cis-1,4-polyisoprene dispersed in a colloidal suspension with approximately 60-70% water content, exhibits anti-inflammatory effects in biomedical contexts. ^[64] The serum fraction of this latex demonstrates anti-inflammatory, antimicrobial, and angiogenic properties, supporting its use in wound dressings and tissue regeneration. ^[65] Historically, sap from the date palm (Phoenix dactylifera) played a role in ancient Egyptian embalming rituals, where fermented palm sap—known as palm wine—was used as an antibacterial rinse to cleanse the body and prevent decomposition during mummification. ^[66] In industrial applications, gum arabic, derived from the exudate sap of Acacia species such as Acacia senegal, serves as a versatile emulsifier and stabilizer in the food and pharmaceutical industries, preventing ingredient separation in products like beverages and tablets. ^[67] ^[68] Similarly, pine sap resin, rich in terpenes, has been processed for adhesives and varnishes; since the 19th century, distillation of pine resin has yielded turpentine oil and rosin, key components in these materials for their binding and protective qualities. ^[69] ^[70] Modern biotechnology research involves the extraction of phloem proteins from plant sap. ^[71]

Ecological Significance

Interactions with Fauna

Sap serves as a critical resource for various herbivores, particularly phloem-feeding insects such as aphids and scale insects, which pierce plant vascular tissues to access the nutrient-rich, sugar-laden phloem sap. These hemipterans extract sugars and amino acids directly from the phloem, often excreting excess fluids as honeydew, a sugary byproduct that attracts ants in a classic example of mutualism. Ants, in return, protect the aphids and scale insects from predators and parasites, enhancing their survival while gaining a carbohydrate source from the honeydew.^[72]^[73] In pollination and seed dispersal, nectar—derived from phloem sap through enzymatic modification in floral nectaries—acts as a reward to lure pollinators such as bees, butterflies, and birds. This modified sap, rich in sucrose and other sugars, encourages these animals to visit flowers, facilitating pollen transfer and reproductive success in angiosperms. Additionally, sap leaking from plant wounds attracts birds like sapsuckers and insects such as beetles, which feed on the exudate; this interaction can aid wound healing by removing potential pathogens and insects drawn to the site.^[10]^[74]^[75]^[76]^[77] Sap also functions as a defense mechanism against herbivores, with certain plants producing toxic variants to deter feeding. For instance, milkweed species (Asclepias spp.) exude latex sap containing cardenolides, cardiac glycosides that disrupt ion transport in herbivores' cells, causing toxicity and often death upon ingestion. This chemical defense has driven an evolutionary arms race, where specialist insects like monarch butterflies (Danaus plexippus) have developed resistance through mutations in target proteins, such as Na+/K+-ATPase, allowing them to sequester cardenolides for their own protection against predators while generalist herbivores remain vulnerable.^[78]^[79]^[80]

Environmental Adaptations

Plants respond to drought stress by initiating stomatal closure, which reduces transpiration and thereby limits xylem sap flow to prevent excessive tension that could lead to cavitation and embolism in the xylem conduits.^[81] This closure is often the initial physiological response across various species, triggered by chemical signals such as increased sulfate or pH in the xylem sap, helping maintain hydraulic integrity under water scarcity.^[82] In parallel, phloem sap undergoes osmotic adjustment, with elevated sugar concentrations that enhance turgor pressure and sustain transport despite reduced water availability, as observed in drought-stressed trees where phloem sugar levels rise to counteract viscosity increases and support sieve element functionality.^[83]^[48] Seasonal adaptations in sap production and flow vary markedly between temperate and tropical environments. In temperate trees like maples, a spring surge in sap flow occurs primarily due to alternating freeze-thaw cycles, which generate positive pressures in the stems as ice forms in branches at night and thaws during the day, driving sap exudate; this supports early-season hydration and nutrient mobilization before full leaf expansion and the shift to transpiration-driven transport. Minor root pressure may contribute as soil temperatures rise post-winter but is not the primary driver.^[84] This pressure-driven flow, typically peaking under alternating freeze-thaw cycles, supports rapid cambial activity and nutrient mobilization but diminishes with leaf-out and the onset of transpiration-dominated transport. In contrast, tropical plants exhibit more constant phloem flow year-round, enabled by stable warm temperatures and consistent photosynthesis that maintain steady photoassimilate loading without the dormancy-induced pauses seen in temperate species.^[85] Climate change exacerbates environmental stresses on sap dynamics, particularly through warmer temperatures that heighten xylem embolism risk by increasing evaporative demand and soil dryness, leading to greater tension in the water columns. Studies in arid regions indicate that such conditions can reduce xylem sap flow by 20-30%, as seen in semi-arid plantations where drought simulations caused up to 28% declines in stand transpiration due to hydraulic limitations.^[86] Over evolutionary timescales, plants have shown shifts toward optimized sap viscosity, with adaptations in carbohydrate composition that minimize flow resistance under drought, enhancing resilience by balancing turgor maintenance and reduced embolism vulnerability in warming climates.^[48]^[87]

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Below is a merged summary of the biological definition of sap in plants, consolidating all information from the provided segments into a single, comprehensive response. To maximize detail and clarity, I will use a table in CSV format to organize the key aspects (definition, primary components, and distinctions) across the segments, followed by a narrative summary that integrates additional details and useful URLs. This approach ensures all information is retained while maintaining readability and density.
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Sap originates from Old English sæp, Proto-Germanic *sapam, meaning plant juice or fluid; also a verb meaning to drain sap, and a simpleton derived from ...
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Turgor pressure plays a significant role in the promotion of plant growth ... As mentioned above, turgor pressure is the mechanical driver for plant cell growth.
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Oct 6, 2020 · Biotic stress (magenta arrows; right half): AED15 and PR1 act directly as anti-herbivory or antimicrobial agents in phloem sap. Several proteins ...
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Source-to-sink transport of sugar and regulation by environmental ...
Transport of photo-assimilates depends on source supply and sink demand. The role of the phloem sap sugar content in the coupling between sink demand and source ...
[38]
The Origin and Composition of Cucurbit “Phloem” Exudate - PMC
The function of P-proteins may be to prevent water loss from the xylem as well as nutrient loss from the phloem. The phloem is an extension of the symplast ...
[39]
The nutritional quality of phloem sap utilized by natural aphid ...
The amino acid content of phloem exudates from leaves and of aphid honeydew were adopted as indices of the nutritional quality of phloem sap for aphids.
[40]
Root pressure and beyond: energetically uphill water transport into ...
Dec 5, 2013 · Water is transported radially into xylem vessels, under some conditions even when the xylem sap is more dilute than the ambient medium (soil solution).
[41]
Studies of Root Function in Zea mays: III. Xylem Sap Composition at ...
Xylem Sap Composition at Maximum Root Pressure Provides Evidence of Active Transport into the Xylem and a Measurement of the Reflection Coefficient of the Root.Missing: uptake mycorrhizal associations
[42]
LbKAT3 may assist in mycorrhizal potassium uptake, and ... - NIH
Jun 20, 2023 · Compared with non-mycorrhizal plants, mycorrhizal plants absorb water and nutritional elements not only directly through roots, but also through ...
[43]
A comprehensive picture of phloem loading strategies - PMC - NIH
Thus, there are 3 recognized strategies of sucrose loading: Apoplastic and symplastic with or without polymer trapping.Missing: starch phosphate enzyme
[44]
Sucrose phosphate synthase (SPS), sucrose synthase (SUS ... - NIH
Jul 16, 2020 · This work presents new findings supporting diversified cold-response, not only between two C 4 plant species but also within one species of maize.
[45]
Source-to-sink transport of sugar and regulation by environmental ...
As a consequence of plant growth reduction or inhibition by mineral deficiency, sugar concentrations increase in plants and in phloem sap (Peuke, 2010). The ...
[46]
Drought impacts on tree phloem: from cell-level responses to ...
Feb 6, 2019 · Drought is expected to impact phloem function by decreasing the amount of available water and new photoassimilates.
[47]
Diurnal dynamics of phloem loading: theoretical consequences for ...
Phloem loading is variable and subject to a diurnal cycle. It is dominated by photosynthesis during the day and by degradation of leaf starch to sugars at night ...
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4.5.1.4: Water Absorption - Biology LibreTexts
Jul 28, 2025 · Root pressure pushes water out of the stem, moving the mercury up the tube. Although root pressure plays a small role in the transport of water ...<|separator|>
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Testing Münch Hypothesis: Long Distance Phloem Transport
The pressure flow hypothesis introduced by Ernst Münch in 1930 describes a mechanism of osmotically generated pressure differentials that are supposed to drive ...
[50]
Hydraulic Efficiency and Safety of Xylem Sap Flow in Relation to ...
As the Hagen-Poiseuille law tells, the hydraulic conductivity increases with the fourth power of conduit radius or diameter and thus wide vessels contribute ...
[51]
Sap flow through partially embolized xylem vessel networks
Jun 3, 2024 · As vessels become embolized, sap movement becomes increasingly affected by factors operating at scales beyond individual conduits, creating resistances.
[52]
Maple Syrup Production Facts and Figures
The Canadian province of Quebec produces 90% of Canada's maple syrup and 70% of the entire world's production of maple syrup. Canada exported about $360 million ...
[53]
Economic - PPAQ - Producteurs et productrices acéricoles du Québec
Québec produces an average 72% of the entire world's maple syrup. Québec accounts for an average 90% of Canadian production. Québec's maple industry contributes ...Maple Syrup -- The Numbers... · Maple Production In Québec... · Total Maple Syrup Inventory
[54]
[PDF] How to Tap and Make Maple Syrup - files
found in the sap of the sugar maple. Generally the ratio of sap to syrup for the sugar maple is 40 to 1 (40 gallons of sap yields one gallon of syrup).
[55]
How to Make Maple Syrup - State of Michigan
Sugar maples have the highest sugar content of all maples, with an approximate 40:1 water-to-sugar ratio, and are used in commercial production. Black, red and ...<|separator|>
[56]
(PDF) Palm Sap—Quality Profiles, Fermentation Chemistry, and ...
It is harvested twice daily from the tree for a period of 3 to 6 months, yielding products such as jaggery, treacle, toddy, and vinegar. ... ... To combat ...
[57]
Palmyrah palm and its products (Neera, Jaggery and Candy)
Palm sap left in the sun takes roughly two hours to turn into palm wine. Toddy has an alcohol content of about 5 %. Toddy is the term used to describe the ...
[58]
What Is Birch Water? Benefits and Downsides - Healthline
Oct 11, 2019 · These benefits may be partly due to birch water's vitamin C content ... Birch water is lower in caloriesTrusted Source and sugar than similar ...
[59]
Sustainable Production of Pulque and Maguey in Mexico - Frontiers
Pulque is a traditional Mexican fermented, non-distilled alcoholic beverage produced by fermenting the fresh sap (aguamiel) extracted from several Agave (maguey) ...
[60]
Aloe - University of Rochester Medical Center
Aloe vera has long been used in folk medicine. It's known mostly for being able to aid in the healing process of cuts and burns.Missing: sap | Show results with:sap
[61]
ALOE VERA: A SHORT REVIEW - PMC
Aloe gel not only increased collagen content of the wound but also changed collagen composition (more type III) and increased the degree of collagen cross ...
[62]
Natural Latex - an overview | ScienceDirect Topics
The raw state of NRL consists of polymer content (cis-1,4-Polyisoprene) and water. The solid polymer content consists of approximately 94% rubber hydrocarbon ...
[63]
Biomedical applications of natural rubber latex from the rubber tree ...
NRL can also be used as an occlusive membrane for GBR applications. •. NRL serum has angiogenic, anti-inflammatory, antimicrobial and osteogenic properties.
[64]
Himatanthus sucuuba - Useful Tropical Plants
The latex has shown significant anti-inflammatory and pain relieving actions. The latex can exert anti-inflammatory effects even in the acute phase of the ...
[65]
Mummification: The Ancient Egyptian Art of Embalming the Dead
Nov 23, 2023 · The cavities were cleaned and packed with palm wine and spices, and the body was then placed in natron (a naturally occurring salt) for the ...
[66]
Re‐evaluation of acacia gum (E 414) as a food additive - PMC
The Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion re‐evaluating the safety of acacia gum (E 414) as a food ...Missing: sap | Show results with:sap
[67]
Gum Arabic - an overview | ScienceDirect Topics
Gum Arabic is one of the oldest and a well-known natural gum produced from exudates of Acacia trees. Apart from the other gums, it has low viscosity and high ...
[68]
History of Turpentine
In the 18th and 19th centuries, this area became a major hub for harvesting pine resin, which was distilled into turpentine and rosin for use in naval stores, ...
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Tapping the Pine Tree... Plant Resins and their Uses
Aug 4, 2014 · Humans have gathered and used resins from plants for thousands of years. Resins have been used for waterproofing, varnishes, adhesives, art, ...
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Protein Extraction from Xylem and Phloem Sap | Request PDF
Aug 10, 2025 · The phloem sap proteomes published so far have been obtained by collecting exuded sap from direct incisions in B. napus [24,34,35], Cucurbita ...
[71]
Ecological consequences of interactions between ants and ... - NIH
The mutualistic interactions between ants and honeydew-producing hemipterans may dramatically increase the effects of ants as predators, however, because the ...
[72]
Phloem-sap feeding by animals: problems and solutions
In ecological terms, tending ants are herbivores, gaining access to phloem sap through mutualism with hemipterans. Mean δ15N values () of ant species in a ...
[73]
Sweet solutions: nectar chemistry and quality - Journals
May 2, 2022 · Nectar, the main floral reward for pollinators, varies greatly in composition and concentration. The assumption that nectar quality is equivalent to its sugar ...
[74]
Intraspecific Variability of Floral Nectar Volume and Composition in ...
Nectar components are believed to derive from phloem sap that is enzymatically processed and transformed within nectaries. An increasing body of evidence ...
[75]
Sapsucker feeding habits benefit overall forest ecology
Aug 3, 2012 · Sapsucker injuries to trees are used to the benefit migratory birds and several other wildlife species with little negative effect on tree health.
[76]
Woodpecker and Sapsucker Damage on Trees
Dec 13, 2023 · On forest trees, the wounds of attacked trees may attract insects as well as porcupines or tree squirrels. These feeding wounds may also ...
[77]
Tissue-specific plant toxins and adaptation in a specialist root ...
May 22, 2023 · ... plant defense: Evolution of cardenolides, their toxicity and induction following herbivory. ... insects against the toxic effects of cardenolides.
[78]
Insect adaptations toward plant toxins in milkweed–herbivores ...
Mar 6, 2018 · ... toxic plant compounds – the insect's ... plant defense: evolution of cardenolides, their toxicity and induction following herbivory.
[79]
Cardenolides, toxicity, and the costs of sequestration in the ... - PNAS
Apr 13, 2021 · We show that tropical milkweed produces a burdensome cardenolide toxin, and monarchs convert it to less toxic compounds, the latter sequestered for their own ...
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https://www.pnas.org/doi/10.1073/pnas.2024463118
[81]
Drought-Enhanced Xylem Sap Sulfate Closes Stomata by Affecting ...
In conclusion, xylem-derived sulfate seems to be a chemical signal of drought that induces stomatal closure via QUAC1/ALMT12 and/or guard cell ABA synthesis.
[82]
Effects of potassium and sodium supply on drought‐adaptive ...
Apr 14, 2014 · Additionally, droughted trees showed higher phloem sap sugar concentrations. K and Na supply increased maximum stomatal conductance, and the ...Tree Water Status And Leaf... · Results · Stomatal And Osmotic...
[83]
[PDF] Root Pressure in Trees: A Spring Phenomenon - Maple Research
Root pressure is a phenomenon where sap bleeds from tree wounds, not a 'pump' in the roots, and occurs under limited circumstances at certain times of the year.
[84]
Seasonal changes in temperate woody plant phloem anatomy and ...
The phloem is particularly important during these periods of seasonal change because it transports carbon, nutrients and signalling molecules such as hormones, ...
[85]
Sap flow of black locust in response to short-term drought in ... - Nature
Apr 18, 2018 · In this study, we measured the sap flow of black locust (Robinia pseudoacacia Linn.) under ambient and drought (induced by throughfall exclusion) conditions in ...Results · Leaf Area Index And Stem... · Sap Flux Density And Stand...<|separator|>
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Evolutionary relationships between drought-related traits ... - PNAS
Mar 1, 2021 · Evolutionary relationships between drought tolerance traits combined with plant–climate interactions yield positive hydraulic safety margins ...