Hydraulic signaling in plants

Hydraulic signals in plants are detected as changes in the organism's water potential that are caused by environmental stress like drought or wounding.[1] The cohesion and tension properties of water allow for these water potential changes to be transmitted throughout the plant.

Plants respond to external stimuli through thigmomorphogenesis. For example, bending a shoot can cause arrestment of growth on another area of the plant. These types of nonlocal responses can be induced by long distance signaling. Long distance communication in plants must satisfy two things: First, signaling must occur rapidly to an apical area of the plant; Second, the signal must be perceived at the apical site and be converted to a physiological or thigmorphogenetic response. One form of long distance signaling is through hydraulic pulses from the roots to the shoots of a plant.[2] Tree branches and stems contain microchannels that make up the xylem network and serve to carry water longitudinally. Stimuli like wounding can cause tension and compression of plant tissues, which pinches the cross section of the shoot. Hydraulic signaling begins with a local response like water expulsion, creating a suction in the vascular system. The compression of the cross section will then lead to a general increase of hydraulic pressure in the channels of the shoot.[2] This extensive change in hydraulic pressure will lead to activation of hydraulic sensors.

Water potential

The driving force of the movement of water is the water potential gradient. The water potential gradient is defined by comparing the potential energy of water to pure water at standard conditions. This water potential gradient must be maintained from the soil through the plant and into the air via transpiration.[1] In the xylem, water is transported throughout the plant following increasing water potential differences. These differences are determined by soil water availability and vapor pressure deficit.[3]  If this gradient is flipped the translocation of water will occur in the opposite direction. The water potential is the combination of the pressure potential, the osmotic potential and the gravitational contribution.  The translocation of water can be restricted by resistances like stomatal aperture, xylem structure related resistance to flow etc.[1]

Long-distance signaling

In order for plants to respond and adapt to external stimuli, long distance signaling is required.[4] In general terms, long distance signaling is defined as the ability to have a widespread response when just one distinct area is stimulated.[4]  In plants, water uptake must be tightly controlled, so long-distance signaling by hydraulic cues coordinate plants above and below-ground organs.[1]  The daily physiological behavior of plants is tightly controlled by hydraulic signals.[3]  Gradients of water potentials are transferred across the plant through hydraulic signals. If the hydraulic signal originated in the root, it will result in local water potential changes, and consequently turgor changes. The water potential changes can be due to dry soil,  water loss via transpiration or physically wounding the plant.  These local water potential changes are then transmitted quickly over long-distances as hydraulic signals. Hydraulic signaling is fast and effective because of the cohesion and tension properties of water.[1] Hydraulic signals can be propagated downward or upward, relaying water potential gradients throughout the entire plant.

Hydraulic signals can be sensed in a few ways all relating to how an increase in water potential affects the plants.  Because water leaves the cell, there is a reduction in the pressure potential and an increase in solute concentration.  This is one way the hydraulic signal can be sensed, through sensing the osmotic environment.  Increase in water potential also causes mechanical forces on the cell wall and plasma membrane of the cell.  This is the second way to sense hydraulic signaling, by sensing the changes in the mechanical forces on the cell wall.[1]

Experimental methods for studying hydraulic signaling

Linear beam theory

Biomimetic systems can be used to mimic the microchannels inside branches.[2] These synthetic plant systems are made from polydimethylsiloxane (PDMS) and 3D molded like branches and filled with a silicone oil (with viscosity 1 Pa*s). Channels are connected by a differential pressure sensor. The initial branch is straight and the internal water pressure is equal to the atmospheric pressure |Pref-P0=0|. Hydraulic pulses are then induced by automated linear motor deplacement, creating a bend in the synthetic branches which results in a rise in overpressure (Pref), reaching a value of |Pref-P0| or deltaP. Returning back to the initial state of the branch will bring the value of deltaP back to 0. The observation is that overpressure increases quadratically with bending strain. This response changes with variation in beam rigidity.

Nonlinear poroelastic coupling

In a nonlinear poroelastic system, elastic tubes begin straight. When bent, elastic strain increases proportionally with the distance from the initial position. This induces a bending elastic energy per unit of volume that is quadratically related to the transverse radius. The system will lower this elastic energy by squeezing its cross section. This transverse compression leads to a decrease in the channel volume creating a global increase in pressure. Therefore, the mechanism of generating hydraulic pressure is due to the coupling of bending and the transverse deformation of the elastic beam.[2]

Hydraulic signaling in natural branches

Louf et al. has conducted research on hydraulic signaling in 3 species: P. sylvestris, Quercus ilex, and P.alba. Their findings can be summarized by these points: Bending of a branch leads to an increase in xylem water pressure. The magnitude of response depends on the species of plant and the environmental conditions. Hydraulic pulses were found to be greater in trees grown outside with stiffer properties, also proving that elasticity plays a role in hydraulic pulses.[2]

Mechanism

The overall pathway of hydraulic signaling in plants is similar to that of a sensory pathway, starting with basic perception of the signal by a sensor, which then converts the hydraulic signal into a chemical signal: abscisic acid or ABA.[1] This conversion to a chemical signal leads to the control of different physiological responses in the plant since ABA is a plant hormone known to mediate many plant developmental processes including organ size, stomatal closure, and dormancy in the plants’ seeds and buds.[5]

Hydraulic signals are primarily detected as decreases in water potential,[1] usually caused by increases in solute concentration or drought. This decrease in water potential is systemic and transferred throughout the plant vascular network via the xylem. Water follows down the water potential gradient from parenchyma cells into the xylem, ultimately leading to a decrease in pressure potential and osmotic potential in the adjacent cells to the xylem.  The hydraulic sensor, which is yet to be known, resides on the inner membrane of the parenchyma cells and detects the decreases in pressure and solute potential through an unknown mechanism. After detection, the unidentified sensor initiates a signal cascade, leading to a calcium transient and subsequent reactive oxygen species (ROS) formation. These ROS are proposed to go on to target ABA biosynthesis enzymes, leading to synthesis of ABA in the parenchyma and later export to regions of the plant requiring the appropriate responses. In an example, ABA response to a hydraulic signal from the roots- a decrease in water potential- is thought to reach the guard cells to stimulate stomatal closure. Despite an unidentified hydraulic sensor(s) and the mechanism of which this sensor detects decreases in pressure and solute potential in the parenchyma, this primary site of ABA biosynthesis is thought to additionally participate as the main location of hydraulic signal perception, vital to mediation of water potential in the plant.[1]

ABA

Abscisic acid (ABA) is a phytohormone that plays a significant role in the plants’ response to drought conditions. During drought, its biosynthesis is triggered and controls many physiological responses.  ABA triggers root growth at low concentrations and closes stomata to prevent water loss from transpiration. ABA is essential for hydraulic signals because of its response to local water potential changes.  ABA is also known to increase hydraulic conductance by increasing aquaporin expression.[1]

Hydraulic sensors

Although sensor(s) for hydraulic signals are unknown and still being investigated, several sensor candidates have been suggested. One candidate for a hydraulic signal sensor has been MCA1,[6] a plasma membrane protein correlated with mechanosensing via calcium-mediated influx in Arabidopsis thaliana. Research has found that MCA1 increased cytoplasmic calcium concentrations in response to a mechanosensory input: plasma membrane distortion in Arabidopsis.

Another sensor candidate proposed are PERKs,[7] members of the proline-rich receptor kinase family in Arabidopsis as well. PERK4 specifically plays a crucial role in abscisic acid (ABA) signalling and response and has shown to be an ABA- and calcium-activated protein kinase. Both MCA1 and PERK4 appear to correlate with cytoplasmic calcium gradients and an early response to hydraulic signals since calcium is known to be involved in plants’ early responses to mechanosensation.[1]

Despite research on these sensor candidates, both ABA and calcium gradient participation in early events of hydraulic signaling have made it particularly difficult to distinguish the order of which each part plays in the hydraulic signaling pathway.[1]

MCA1

MCA1 has been identified as a candidate for a Ca2+ permeable mechanosensitive channel in Arabidopsis thaliana.[1] Overexpression of plasma membrane protein MCA1 causes an increase in calcium uptake from the roots, which then causes an increase in free calcium in the cytoplasm. MCA1 expression in yeast mutants lacking a high affinity calcium influx system will also increase calcium uptake.[8]

MCA2

MCA2 is a paralog of MCA1 that was identified in Arabidopsis thaliana. Protein sequencing technology reveals that the two genes are 72.7% identical and 89.4% similar in amino acid sequence, making MCA2 a reasonable gene to use in studies to determine the function of MCA1 in calcium uptake. Reverse transcription PCR analysis indicates that MCA2 is expressed in the plasma membrane in leaves, flowers, roots, and stems. Knockout of the MCA2 gene causes a decrease in calcium uptake in the roots, relative to the wildtype, suggesting that the MCA2 gene is involved in calcium uptake.[8]

Using GUS staining, researchers were able to find expressions of MCA1 and MCA2 in the pericycle and endodermis of the root in Arabidopsis. No expression was identified in the cortex or epidermis. Rise in cytosolic calcium levels in the pericycle and endodermis under drought conditions suggest that these cells play a role in calcium signaling. The spatial expression of MCA1 and MCA2 and the changes in calcium concentration in the pericycle and endodermis suggests that both MCA1 and MCA2 play a role in symplastic calcium transport and signaling.[8]

PERK4

Proline-rich extensin-like receptor kinases 4 (PERK4) is a gene expressed in the roots and flowers in Arabidopsis thaliana that localizes in the plasma membrane and plays a role in ABA signaling.[1] Using protein motif analysis, a membrane localization signal, a transmembrane domain, and an intracellular kinase domain were identified in PERK4. To study the role of PERK4 and ABA, mutants were made by inserting T-DNA. PERK4 mutants showed a decrease in ABA sensitivity which affects seedling germination and root tip growth. Mutating PERK4 causes cytosolic free calcium levels to decrease in roots relevant to the wild type. The function of PERK4 has been proposed in early stage ABA signalling to inhibit root elongation by disturbing cytoplasmic calcium gradients.[7]

Ongoing research

Arabidopsis thaliana has been a primary model system in the search for the hydraulic sensor however, has not yet produced a certain answer.[1] Screens for plant mutants affected in hydraulic signaling have been necessary yet, none have been reported so far.[9] Some plant mutants have been distinguished by using the Arabidopsis line pAtH-B6::LUC [10] with lesions upstream of ABA action.[1] Recent years prior to 2013 have shown more hydraulic sensor candidates such as osmosensors and turgor sensors[1] however, research is ongoing as to the specific roles they may play in hydraulic signaling in plants.

References

  1. ^ a b c d e f g h i j k l m n o p q Christmann A, Grill E, Huang J (June 2013). "Hydraulic signals in long-distance signaling". Current Opinion in Plant Biology. 16 (3): 293–300. doi:10.1016/j.pbi.2013.02.011. PMID 23545219.
  2. ^ a b c d e Louf JF, Guéna G, Badel E, Forterre Y (October 2017). "Universal poroelastic mechanism for hydraulic signals in biomimetic and natural branches". Proceedings of the National Academy of Sciences of the United States of America. 114 (42): 11034–11039. Bibcode:2017PNAS..11411034L. doi:10.1073/pnas.1707675114. PMC 5651757. PMID 28973910.
  3. ^ a b Huber AE, Bauerle TL (March 2016). "Long-distance plant signaling pathways in response to multiple stressors: the gap in knowledge". Journal of Experimental Botany. 67 (7): 2063–79. doi:10.1093/jxb/erw099. PMID 26944636.
  4. ^ a b Jia W, Zhang J (October 2008). "Stomatal movements and long-distance signaling in plants". Plant Signaling & Behavior. 3 (10): 772–7. doi:10.4161/psb.3.10.6294. PMC 2634372. PMID 19513229.
  5. ^ Seo M, Koshiba T (January 2002). "Complex regulation of ABA biosynthesis in plants". Trends in Plant Science. 7 (1): 41–8. doi:10.1016/S1360-1385(01)02187-2. PMID 11804826.
  6. ^ Nakagawa Y, Katagiri T, Shinozaki K, Qi Z, Tatsumi H, Furuichi T, et al. (February 2007). "Arabidopsis plasma membrane protein crucial for Ca2+ influx and touch sensing in roots". Proceedings of the National Academy of Sciences of the United States of America. 104 (9): 3639–44. Bibcode:2007PNAS..104.3639N. doi:10.1073/pnas.0607703104. PMC 1802001. PMID 17360695.
  7. ^ a b Bai L, Zhang G, Zhou Y, Zhang Z, Wang W, Du Y, et al. (October 2009). "Plasma membrane-associated proline-rich extensin-like receptor kinase 4, a novel regulator of Ca signalling, is required for abscisic acid responses in Arabidopsis thaliana". The Plant Journal. 60 (2): 314–27. doi:10.1111/j.1365-313X.2009.03956.x. PMID 19566594.
  8. ^ a b c Yamanaka T, Nakagawa Y, Mori K, Nakano M, Imamura T, Kataoka H, et al. (March 2010). "MCA1 and MCA2 that mediate Ca2+ uptake have distinct and overlapping roles in Arabidopsis". Plant Physiology. 152 (3): 1284–96. doi:10.1104/pp.109.147371. PMC 2832256. PMID 20097794.
  9. ^ Wang ZY, Xiong L, Li W, Zhu JK, Zhu J (May 2011). "The plant cuticle is required for osmotic stress regulation of abscisic acid biosynthesis and osmotic stress tolerance in Arabidopsis". The Plant Cell. 23 (5): 1971–84. doi:10.1105/tpc.110.081943. PMC 3123942. PMID 21610183.
  10. ^ Christmann A, Hoffmann T, Teplova I, Grill E, Müller A (January 2005). "Generation of active pools of abscisic acid revealed by in vivo imaging of water-stressed Arabidopsis". Plant Physiology. 137 (1): 209–19. doi:10.1104/pp.104.053082. PMC 548852. PMID 15618419.

Read other articles:

German uni Mainz University of Applied SciencesHochschule MainzTypePublicEstablishedFounded in 1996.[1] Emerging from the Electoral Academy of Painting and Sculpture (Kurfürstliche Maler- und Bildhauerakademie), founded in Mainz in 1757, as well as from the Grand Ducal State Construction School (Großherzoglichen Landesbaugewerkschule) founded in Darmstadt in 1876.ChancellorDr. Valérie SchüllerPresidentProf. Dr. Susanne WeissmanAdministrative staff410[2]Students5,538 (WiSe ...

 

Der Titel dieses Artikels ist mehrdeutig. Weitere Bedeutungen sind unter Siedenburg (Begriffsklärung) aufgeführt. Wappen Deutschlandkarte 52.78.933055555555639Koordinaten: 52° 42′ N, 8° 56′ O Basisdaten Bundesland: Niedersachsen Landkreis: Diepholz Samtgemeinde: Siedenburg Höhe: 39 m ü. NHN Fläche: 14,23 km2 Einwohner: 1287 (31. Dez. 2022)[1] Bevölkerungsdichte: 90 Einwohner je km2 Postleitzahl: 27254 Vorwahl: 04272 Kfz...

 

This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages) The neutrality of this article is disputed. Relevant discussion may be found on the talk page. Please do not remove this message until conditions to do so are met. (February 2013) (Learn how and when to remove this template message) This article needs to be updated. Please help update this article to reflect recent events or newly available ...

Detail uit het Tapijt van Bayeux waarop Rogier van Beaumont mogelijk te zien is aan de tafel (tweede van links). Rogier van Beaumont (? - 1094) was een Normandisch edelman en heer van Beaumont, Vieilles, Pont-Audemer en Beaumontel. Hij werd geboren voor 1035 als zoon van Humphrey de Vieilles en Aubrée de la Haie en had minstens twee broers, Robert en Willem.[1] Hij huwde tussen 1045 en 1046 met Adela van Meulan waarmee hij minstens drie zonen en één dochter kreeg.[2] Hij wo...

 

هذه المقالة يتيمة إذ تصل إليها مقالات أخرى قليلة جدًا. فضلًا، ساعد بإضافة وصلة إليها في مقالات متعلقة بها. (يناير 2017) يفتقر محتوى هذه المقالة إلى الاستشهاد بمصادر. فضلاً، ساهم في تطوير هذه المقالة من خلال إضافة مصادر موثوق بها. أي معلومات غير موثقة يمكن التشكيك بها وإزالتها. ...

 

Deden JuharaAsisten Operasi KapolriMasa jabatan8 Maret 2018 – 22 Januari 2019PendahuluMochamad IriawanPenggantiRudy SufahriadiKepala Kepolisian Daerah MalukuMasa jabatan18 April 2017 – 8 Maret 2018PendahuluIlham SalahudinPenggantiAndap Budhi Revianto Informasi pribadiLahir14 Januari 1961 (umur 62)Bandung, Jawa BaratAlma materAkademi Kepolisian (1985)Karier militerPihak IndonesiaDinas/cabang Kepolisian Negara Republik IndonesiaMasa dinas1985—2019Pangkat I...

الأسطورة السوداءمعلومات عامةوصفها المصدر اللاتينيات في الولايات المتحدة: موسوعة تاريخية التأثيراتفرع من الأسطورة السوداء تعديل - تعديل مصدري - تعديل ويكي بيانات نقش قام به ثيودور دي براي عام 1598 لرجل إسباني يطعم كلابه أطفالاً و نساءً مذبوحين . تعد أعمال دي براي من الدعاية ا...

 

Cet article concerne les crimes de guerre russes. Pour les crimes de guerre de l'invasion russe de l'Ukraine, voir Crimes de guerre lors de l'invasion russe de l'Ukraine en 2022. Pour les crimes de guerre russes commis avant 1991, voir Crimes de guerre soviétiques. Un soldat russe se tient sur une fosse commune après la bataille de Komsomolskoïe pendant la seconde guerre de Tchétchénie, en 2000. Depuis 1991, les crimes de guerre russes, en violation du droit pénal international, rep...

 

Aymeric Laporte Informasi pribadiNama lengkap Aymeric Jean LouisGérard Alphonse Laporte[1]Tanggal lahir 27 Mei 1994 (umur 29)[2]Tempat lahir Agen, PrancisTinggi 189 cm (6 ft 2 in)[3]Posisi bermain Bek tengahInformasi klubKlub saat ini Al-NassrNomor 14Karier junior2000–2009 SU Agen2009–2010 Bayonne2010–2011 Athletic BilbaoKarier senior*Tahun Tim Tampil (Gol)2011–2012 Basconia 33 (2)2012 Athletic Bilbao B 8 (1)2012–2018 Athletic Bilbao 222 ...

American baseball umpire (born 1974) Not to be confused with Chris Guccione (tennis). Baseball player Chris GuccioneGuccione in 2012Born: (1974-06-24) June 24, 1974 (age 49)Salida, Colorado, U.S.MLB debutApril 25, 2000 Crew InformationUmpiring crew4Crew membersLarry Vanover (crew chief)Chris GuccioneDavid RackleyEdwin Moscoso Career highlights and awardsSpecial Assignments All-Star Games (2011, 2021) Wild Card Games/Series (2012, 2017, 2018, 2019, 2020, 2022) Division Series (2010, 2011,...

 

Bronislovas PaukštysBorn(1897-02-15)15 February 1897Kurynė [lt], Suwałki Governorate, Congress PolandDied17 December 1966(1966-12-17) (aged 69)Kaunas, Lithuanian SSRNationalityLithuanianOccupationCatholic priestKnown forRescue of Jews during World War IIAwardsRighteous Among the Nations (1977) Life Saving Cross [lt] (1999) Bronislovas Bronius Paukštys (1897–1966) was a Lithuanian Roman Catholic priest who rescued around 120 Jewish children and 25 Jewi...

 

41st Governor of Kansas (1987-1991) This article is about the politician. For the composer, see Michael Haydn. For the Director of the CIA, see Michael Hayden (general). For other people, see Michael Hayden. Mike Hayden41st Governor of KansasIn officeJanuary 12, 1987 – January 14, 1991LieutenantJack D. WalkerPreceded byJohn W. CarlinSucceeded byJoan FinneySpeaker of the Kansas House of RepresentativesIn officeJanuary 10, 1983 – January 12, 1987Preceded byWendell LadySucc...

metrolijn Linea verde Statistieken Geopend 4 oktober 1969 Lengte 40,4 km Aantal stations 35 bovengronds: 18 ondergronds: 17 Eindpunten Assago Milanofiori Forum / AbbiategrassoCologno Nord / Gessate Spoorwijdte 1435 mm Stroomsysteem 1500V = (bovenleiding) Overige lijnen      Portaal    Openbaar vervoer Lijn 2 is een metrolijn in de Italiaanse stad Milaan die in 1969 werd geopend. De lijn verbindt de dorpen in het Addadal, ten noordoosten van Milaan, met ...

 

The topic of this article may not meet Wikipedia's notability guideline for music. Please help to demonstrate the notability of the topic by citing reliable secondary sources that are independent of the topic and provide significant coverage of it beyond a mere trivial mention. If notability cannot be shown, the article is likely to be merged, redirected, or deleted.Find sources: Viva Vigilante – news · newspapers · books · scholar · JSTOR (May 2016) (...

 

US Marine Corps general Gary L. ThomasGeneral Gary L. ThomasNickname(s)LurchBorn1962 (age 60–61)Austin, TexasAllegianceUnited StatesService/branchUnited States Marine CorpsYears of service1984–2021RankGeneralCommands heldAssistant Commandant of the Marine Corps2nd Marine Aircraft WingMarine Aviation Weapons and Tactics Squadron OneVMFA-323Battles/warsGulf WarWar in AfghanistanAwardsDefense Superior Service Medal (2)Legion of MeritBronze Star Medal Gary Lee Thomas[1] ...

Alaniya National ParkIUCN category II (national park)Alaniya National ParkLocationNorth Ossetia-AlaniaNearest cityVladikavkazCoordinates42°54′N 43°44′E / 42.900°N 43.733°E / 42.900; 43.733Area54,926 hectares (135,725 acres; 549 km2; 212 sq mi)EstablishedJune 2, 1998 (1998-18-02)Governing bodyFGBU AlaniaWebsitehttp://npalania.ru/ Alaniya National Park (Russian: Национальный парк «Ала́ния»), is a he...

 

Type of dragon described in various mythologies This article is about sea serpents in mythology. For actual marine snakes, see Sea snake. For other uses, see Sea serpent (disambiguation). This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages) This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may ...

 

Wappen von Windhoek Details Eingeführt unbekannt Wappenschild Aloe littoralis Wahlspruch (Devise) Suum Cuique(Jedem das Seine) Das Wappen von Windhoek ist das offizielle Stadtwappen der namibischen Hauptstadt Windhoek. Wappen der Stadtverwaltung Windhoek Beschreibung Der Entwurf für das Wappen soll von Helmut Lewin stammen, wobei das Wappen der Form des Familienwappens der Gründerfamilie der Stadt Windhoek, Familie von François, entspricht. Im grauen Wappenschild befindet sich eine Aloe l...

هذه المقالة يتيمة إذ تصل إليها مقالات أخرى قليلة جدًا. فضلًا، ساعد بإضافة وصلة إليها في مقالات متعلقة بها. (يوليو 2020) جمانة النونو معلومات شخصية اسم الولادة جمانة النونو الجنسية  لبنان الحياة العملية المهنة ممثلة، ممثلة صوت المواقع السينما.كوم صفحتها على موقع السينما تع...

 

A. A. Suhardi Raden Agustinus Suhardi (1899–1988) was a professor at Gadjah Mada University and fifth Agrarian Minister of Indonesia. Biography Suhardi was born in Klaten, Central Java in 1899.[1] He first studied at a school for native Indonesians, before moving to nearby Yogyakarta to study at a Meer uitgebreid lager onderwijs (middle school) there.[1] For high school, he moved to Batavia (modern day Jakarta) and attended Canisius College.[1] He then attended legal...

 

Strategi Solo vs Squad di Free Fire: Cara Menang Mudah!