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Shale oil extraction

History

Main article: History of the oil shale industry

A.C. Kirk’s retort, used in the mid-to-late 19th century, was one of the first vertical oil shale retorts.

A number of shale oil extraction technologies have evolved over a period of time. In the 10th century, a method of extracting oil from “some kind of bituminous shale” was described by the Arabian physician Masawaih al-Mardini (Mesue the Younger). The first shale oil extraction patent was granted by the British Crown in 1694 to three people who had “found a way to extract and make great quantities of pitch, tarr, and oyle out of a sort of stone”. Modern industrial extraction of shale oil originated in France with the implementation of a process invented by Alexander Selligue in 1838 and about a decade later in Scotland by implementation of the process invented by James Young. During the late 19th century, shale oil extraction plants were built in Australia, Brazil, Canada, and the United States. The 1894 invention of the Pumpherston retort (also known as the Bryson retort) marked the separation of oil shale industry from the coal industry.

China (Manchuria), Estonia, New Zealand, South Africa, Spain, Sweden, and Switzerland began extracting shale oil in the early 20th century. However, crude oil discoveries in Texas during the 1920s and in the Middle East during mid-century brought most oil shale industries to a halt. In 1944, the United States restarted shale oil extraction as part of its Synthetic Liquid Fuels Program. These industries continued until oil prices fell sharply in the 1980s. The last oil shale retort in the United States, operated by Unocal Corporation, closed in 1991. The United States’ oil-shale development program was restarted in 2003, followed by a commercial leasing program in 2005 permitting the extraction of oil shale and oil sands on federal lands in accordance with the Energy Policy Act of 2005.

As of 2009[update], shale oil extraction is in operation in Estonia, Brazil, and China. While, Australia, U.S. and Canada have tested shale oil extraction techniques with demonstration projects and are planning implementation on a commercial basis, Morocco and Jordan are also planning to start shale oil production. Only four technologies are in commercial use; namely Kiviter, Galoter, Fushun, and Petrosix.

Process principle

Overview of shale oil extraction

Shale oil extraction process decomposes oil shale and converts kerogen in oil shale into shale oil petroleum-like synthetic crude oil. The process is conducted by pyrolysis, hydrogenation, or thermal dissolution. The most common extraction method is pyrolysis (also known as retorting). In this process, oil shale is heated until its kerogen decomposes into vapors of a condensable shale oil and non-condensable combustible oil shale gas. Oil vapors and oil shale gas are collected and cooled, causing the shale oil to condense. In addition, oil shale processing produces spent shale, which is a solid residue. Spent shale may contain char (some authors use the terms coke residue or semi-coke instead of char) carbonaceous residue formed from kerogen. Depending on the exact composition of oil shale, other useful by-products are also generated during this process. These include ammonia, sulfur, aromatic compounds, pitch, asphalt, and waxes. The efficiency of extraction processes is often evaluated by comparing their yield to the results of a Fischer Assay performed on a sample of the shale.

Pyrolysis is an endothermic process that requires an external source of energy. Most technologies use other fossil fuels such as natural gas, oil, or coal to generate heat, but various experimental methods have used electricity, radio frequency, microwaves, or reactive fluids for this purpose. By-products of the retorting process such as oil shale gas and char may be burned as an additional source of energy and the heat contained in spent oil shale and oil shale ash may be reused to pre-heat the raw oil shale.

The temperature at which perceptible decomposition of oil shale occurs depends on the time-scale of the process. In ex situ retorting processes, it begins at 300 C (570 F) and proceeds more rapidly and completely at higher temperatures. The rate of decomposition is the highest when the temperature ranges between 480 C (900 F) and 520 C (970 F). The ratio of oil shale gas to shale oil generally increases along with retorting temperatures. For a modern in situ process, which might take several months of heating, decomposition may be conducted at temperatures as low as 250 C (480 F). Temperatures below 600 C (1,110 F) are preferable, preventing the decomposition of lime stone and dolomite in the rock and thereby limiting carbon dioxide emissions and energy consumption.

Hydrogenation and thermal dissolution (reactive fluid processes) extract the oil using hydrogen donors, solvents, or a combination of these. Thermal dissolution involves the application of solvents at elevated temperatures and pressures, increasing oil output by cracking the dissolved organic matter. Different methods produce shale oil with different properties.

Classifications

Industry analysts have created several classifications of the methods by which hydrocarbons are extracted from oil shale.

By process principles: Based on the treatment of raw oil shale by heat and solvents the methods are classified as pyrolysis, hydrogenation, or thermal dissolution.

By location: A frequently used distinction considers whether processing is done above or below ground, and classifies the technologies broadly as ex situ (displaced) or in situ (in place). In ex situ processing, also known as aboveround retorting, the oil shale is mined either underground or at the surface and then transported to a processing facility. In contrast, in situ processing converts the kerogen while it is still in the form of an oil shale deposit, following which it is then extracted via oil wells, where it rises in the same way as conventional crude oil.

By heating method: The heating methods used to decompose oil shale may be classified as direct or indirect. While methods that burn materials or insert heat carriers within the retort are classified as direct, methods that conduct heat through retort walls are described as indirect. As of 2009, most of the commercial retorts in operation or under development are direct heating retorts. Another classification is based upon whether the heat is delivered by solids (hot recycled solids methods) or gases. In principle, it is less expensive to deliver heat using solids, especially those already heated by the shale’s pyrolysis, as is the case when spent shale particles are used.

By retort style: Based on the materials and methods used to heat the oil shale to an appropriate temperature, its processing technologies have been classified into internal combustion, hot recycled solids, wall conduction, externallyenerated hot gas, reactive fluid, and volumetric heating methods. There are many possible realizations and combinations of these methods, which are summarized in the table shown below. Some processing technologies are difficult to classify due to their unique methods of heat input (e.g. ExxonMobil Electrofrac) or due to limited information.

Classification of processing technologies by heating method and location (according to Alan Burnham)

Heating Method

Above ground (ex situ)

Underground (in situ)

Internal combustion

Gas combustion, NTU, Kiviter, Fushun, Union A, Paraho Direct, Superior Direct

Occidental Petroleum MIS, LLNL RISE, Geokinetics Horizontal, Rio Blanco

Hot recycled solids

(inert or burned shale)

Alberta Taciuk, Galoter, Lurgi-Ruhrgas, TOSCO II, Chevron STB, LLNL HRS, Shell Spher, KENTORT II

-

Conduction through a wall

(various fuels)

Pumpherston, Hom Tov, Fischer Assay, Oil-Tech, EcoShale In-Capsule Process, Combustion Resources

Shell ICP (primary method), American Shale Oil CCR, IEP Geothermic Fuel Cell Process

Externally generated hot gas

PetroSIX, Union B, Paraho Indirect, Superior Indirect, Syntec process (Smith process)

Chevron CRUSH, Petro Probe, MWE IGE

Reactive fluids

IGT Hytort (high-pressure H2), donor solvent processes, Chattanooga fluidized bed reactor

Shell ICP (some embodiments)

Volumetric heating

-

IIT Research Institute, Lawrence Livermore National Laboratory, and Raytheon radiofrequency processes, Global Resource microwave process, Electro-Petroleum EEOP

By raw oil shale particles’ size: The various ex situ processing technologies may be differentiated by the size of the oil shale particles that are fed into the retorts. As a rule, oil shale “lumps” varying in diameter from 10 millimeters (0.4 in) to 100 millimeters (3.9 in) are used in internal hot gas carrier technologies, while oil shale that has been crushed into particulates less than 10 millimeters (0.4 in) in diameter are used in internal hot solid carrier technologies.

By complexity of technology: In situ technologies are usually classified either as true in situ processes or modified in situ processes. True in situ processes do not involve mining or crushing the oil shale. Modified in situ processes involve drilling and fracturing the target oil shale deposit to create voids for the improved flow of gases and fluids through the deposit, thereby increasing the volume and quality of the shale oil produced.

Ex situ technologies

Internal combustion

Internal combustion technologies burn materials (typically char and oil shale gas) within a vertical shaft retort to supply heat for pyrolysis. Typically raw oil shale is fed into the top of the retort and is heated by the rising hot gases, which pass through the descending oil shale, thereby causing decomposition. Shale oil vapors and evolving gases are then moved to a condensing system. Condensed shale oil is collected, while non-condensable gas is recycled and used to carry heat. In the lower part of the retort, spent oil shale is heated to about 900 C (1,650 F) to burn off the char. Recycled gas enters the bottom of the retort and cools the spent oil shale. The Union and Superior multimineral processes depart from this pattern. In the Union process, oil shale is fed through the bottom of the retort and a pump moves it upward. In the Superior multimineral process, oil shale is processed in a horizontal segmented doughnut-shaped traveling-grate retort.

These processes are thermally efficient, since much of the carbon within the shale is burnt, and can achieve 80-90% of Fischer assay yield. Two well-established shale oil industries use internal combustion technologies: Kiviter process facilities have been operated continuously in Estonia since the 1920s, and China’s Fushun Mining Group, a world leader in shale oil production, operates Fushun process facilities. Their product streams, however, are diluted by combustion exhaust.

Hot recycled solids

Hot recycled solids technologies deliver heat to the shale via solid particlesypically oil shale ash. These technologies usually employ rotating kiln retorts, fed by fine oil shale particles generally having a diameter of less than 10 millimeters (0.4 in); some technologies use particles even smaller than 2.5 millimeters (0.10 in). The particles are heated in a separate chamber or vessel, advantageously preventing the dilution of oil shale gas with combustion exhaust.

In the Galoter process, the spent oil shale is burnt in a separate furnace and the resulting hot ash is mixed with oil shale particles to cause decomposition. This process and its modified version, Enefit, have been used in Estonia’s Narva Oil Plant for several decades. The TOSCO II process uses hot shale ash and ceramic balls heated by contact with the ash. The distinguishing feature of the Alberta Taciuk process (ATP) is that the entire process occurs in a single rotating multihamber horizontal vessel. An ATP plant extracted 1.5 million barrels (238.4809410^3 m3) of shale oil between 2000 and 2005 at the Stuart Oil Shale Plant, but is now being dismantled.

Alberta Taciuk Processor retort

Conduction through a wall

These technologies transfer heat to the oil shale by conducting it through the retort wall. The shale feed usually consists of fine particles. Their advantage lies in the fact that retort vapors are not combined with combustion exhaust. The Combustion Resources process uses a hydrogenired rotating kiln, where hot gas is circulated through an outer annulus. The Oil-Tech staged electrically heated retort consists of individual inter-connected heating chambers, stacked atop each other. Its principal advantage lies in its modular design, which enhances its portability and adaptability. The Red Leaf Resources EcoShale In-Capsule Process combines surface mining with a lower-temperature heating method similar to in situ processes by operating within an earthen impoundment structure. Inside the impoundment, a hot gas circulated by parallel pipes heats the oil shale rubble. As the impoundment could be constructed in the empty space created by mining, it allows rapid reclamation of the topography.

Externally generated hot gas

In general, externally generated hot gas technologies are similar to internal combustion technologies in that they also process oil shale lumps in vertical shaft kilns. Significantly, though, the heat in these technologies is delivered by gases heated outside the retort vessel, and therefore the retort vapors are not diluted with combustion exhaust. The Petrosix process, used at the world’s largest operational surface oil shale pyrolysis retort in So Mateus do Sul, Paran, Brazil, employs this technology.

Reactive fluids

Reactive fluid technologies are suitable for processing oil shales with a low hydrogen content. In these technologies, hydrogen gas (H2) or hydrogen donors (chemicals that donate hydrogen during chemical reactions) react with coke precursors (chemical structures in the oil shale that are prone to form char during retorting but have not yet done so). The reaction roughly doubles the yield of oil, depending on the characteristics of oil shale and process technology.

Reactive fluids technologies include the IGT Hytort (high-pressure H2) process, donor solvent processes, and the Chattanooga fluidized bed reactor. In the IGT Hytort oil shale is processed in a high-pressure hydrogen environment. The Chattanooga process uses a fluidized bed reactor and an associated hydrogen-fired heater for oil shale thermal cracking and hydrogenation.

In situ technologies

In situ technologies heat oil shale underground by injecting hot fluids into the rock formation, or by using linear or planar heating sources followed by thermal conduction and convection to distribute heat through the target area. Shale oil is then recovered through vertical wells drilled into the formation. These technologies are potentially able to extract more shale oil from a given area of land than conventional ex situ processing technologies, as the wells can reach greater depths than surface mines. They present an opportunity to recover shale oil from low-grade deposits that traditional mining techniques could not extract.

During World War II a modified in situ extraction process was implemented without significant success in Germany. One of the earliest successful in situ processes was the underground gasification by electrical energy (Ljungstrm method) process exploited between 1940 and 1966 for shale oil extraction at Kvarntorp in Sweden. Prior to the 1980s, many variations of the in situ process were explored in the United States. The first modified in situ oil shale experiment in the United States was conducted by Occidental Petroleum in 1972 at Logan Wash, Colorado. The newest technologies explore a variety of heat sources and heat delivery systems.

Wall conduction

Shell’s freeze wall for in situ shale oil production was designed to separate the process from its surroundings

Wall conduction in situ technologies use heating elements or heating pipes placed within the oil shale formation. The Shell in situ conversion process (Shell ICP) uses electrical heating elements for heating the oil shale layer to between 650 F (340 C) and 700 F (370 C) over a period of approximately four years. The processing area is isolated from surrounding groundwater by a freeze wall consisting of wells filled with a circulating super-chilled fluid. Disadvantages of this process are large electrical power consumption, extensive water use, and the risk of groundwater pollution. The process, under development since the early 1980s, was tested at the Piceance Basin Mahogany Research Project. 1,700 barrels (270 m3) of oil were extracted in 2004 at a 30-by-40-foot (9.1 by 12 m) testing area.

American Shale Oil CCR Process

In the American Shale Oil CCR Process, superheated steam or another heat transfer medium is circulated through a series of pipes placed below the oil shale layer to be extracted. The system combines horizontal wells, through which steam is passed, and vertical wells, which provide both vertical heat transfer through refluxing of converted shale oil and a means to collect the produced hydrocarbons. Heat is supplied by combustion of natural gas or propane in the initial phase and by oil shale gas at a later stage.

The Independent Energy Partners’ Geothermic Fuels Cells Process (IEP GFC) extracts shale oil by exploiting a high-temperature stack of fuel cells. The cells, placed in the oil shale formation, are fueled by natural gas during a warm-up period and afterward by oil shale gas generated by its own waste heat.

Externally generated hot gas

Chevron CRUSH process

Externally generated hot gas in situ technologies use hot gases that are heated above-ground and then injected into the oil shale formation. The Chevron CRUSH process, developed in partnership with Los Alamos National Laboratory, injects heated carbon dioxide into the formation via drilled wells and heats the formation through a series of horizontal fractures in which the gas circulates. Petro Probe has proposed a process which involves injecting super-heated air into the oil shale formation. Mountain West Energy’s In Situ Vapor Extraction process uses similar principles of injection of high-temperature gas.

ExxonMobil Electrofrac

Main article: ExxonMobil Electrofrac

ExxonMobil’s in situ technology uses electrical heating with elements of both wall conduction and volumetric heating methods. It injects an electrically conductive material such as calcined petroleum coke into the hydraulic fractures created in the oil shale formation which then forms a heating element. Heating wells are placed in a parallel row with a second horizontal well intersecting them at their toe. This allows opposing electrical charges to be applied at either end.

Volumetric heating

Artist’s rendition of a radio wave-based extraction facility

The concept of oil shale volumetric heating by radio waves (radio frequency processing) was developed at the Illinois Institute of Technology during the late 1970s. This technology was further developed by Lawrence Livermore National Laboratory. The oil shale would be heated by vertical electrode arrays. Deeper volumes could be processed at slower heating rates by installations spaced at tens of meters. The concept presumes a radio frequency at which the skin depth is many tens of meters, thereby overcoming the thermal diffusion times needed for conductive heating. While the Laboratory has not conducted a rigorous evaluation of the concept, private investigations may have been undertaken. Its drawbacks include intensive electrical demand and the possibility that groundwater or char would absorb undue amounts of the energy.

Radio frequency processing in conjunction with critical fluids is being developed by Raytheon together with CF Technologies and tested by Schlumberger, while Global Resource Corporation is testing microwave heating. Electro-Petroleum proposes electrically enhanced oil recovery by the passage of direct current between cathodes in producing wells and anodes located either at the surface or at depth in other wells. The passage of the current through the oil shale formation results in resistive Joule heating. Microwave heating technologies are based on the same principles as radio wave heating, although it is believed that radio wave heating is an improvement over microwave heating because its energy can penetrate farther into the oil shale formation.

Economics

NYMEX light-sweet crude oil prices 19962009 (not adjusted for inflation)

Main article: Oil shale economics

The dominant question for shale oil production is under what conditions shale oil is economically viable. The various attempts to develop oil shale deposits have succeeded only when the shale-oil production cost in a given region is lower than the price of petroleum or its other substitutes. According to a survey conducted by the RAND Corporation, the cost of producing a barrel of shale oil at a hypothetical surface retorting complex in the United States (comprising a mine, retorting plant, upgrading plant, supporting utilities, and spent shale reclamation), would range between US$7095 ($440600/m3), adjusted to 2005 values). Assuming a gradual increase in output after the start of commercial production, the analysis projects a gradual reduction in processing costs to $3040 per barrel ($190250/m3) after achieving the milestone of 1 billion barrels (16010^6 m3). Royal Dutch Shell has announced that its Shell ICP technology would realize a profit when crude oil prices are higher than $30 per barrel ($190/m3), while some technologies at full-scale production assert profitability at oil prices even lower than $20 per barrel ($130/m3).

To increase the efficiency of oil shale retorting and by this the viability of the shale oil production, researchers have proposed and tested several co-pyrolysis processes, in which other materials such as biomass, peat, waste bitumen, or rubber and plastic wastes are retorted along with the oil shale. Some modified technologies propose combining a fluidized bed retort with a circulated fluidized bed furnace for burning the by-products of pyrolysis (char and oil shale gas) and thereby improving oil yield, increasing throughput, and decreasing retorting time.

A critical measure of the viability of oil shale as an energy source lies in the ratio of the energy produced by the shale to the energy used in its mining and processing, a ratio known as “Energy Returned on Energy Invested” (EROEI). A 1984 study estimated the EROEI of the various known oil shale deposits as varying between 0.713.3; some companies and newer technologies assert an EROEI between 3 and 10. To increase the EROEI, several combined technologies were proposed. These include the usage of process waste heat, e.g. gasification or combustion of the residual carbon (char), and the usage of waste heat from other industrial processes, such as coal gasification and nuclear power generation. The water needed in some extraction processes offers an additional economic consideration: this may pose a problem in areas with water scarcity.

Environmental considerations

Main article: Environmental impact of the oil shale industry

Objections to its potential environmental impact have stalled governmental support for extraction of shale oil in some countries, e.g. Australia. Shale oil extraction may involve a number of different environmental impacts that vary with process technologies. Depending on the geological conditions and mining techniques, mining impacts may include acid drainage induced by the sudden rapid exposure and subsequent oxidation of formerly buried materials, the introduction of metals into surface water and groundwater, increased erosion, sulfur gas emissions, and air pollution caused by the production of particulates during processing, transport, and support activities. Surface mining for ex situ processing, as with in situ processing, requires extensive land use and ex situ thermal processing generates wastes that require disposal. Mining, processing, spent shale disposal, and waste treatment require land to be withdrawn from traditional uses and should therefore avoid areas of high population density. Depending on the processing technology, the waste material may contain pollutants including sulfates, heavy metals, and polycyclic aromatic hydrocarbons, some of which are toxic and carcinogenic. Experimental in situ conversion processes may reduce some of these impacts, but may instead cause other problems, such as groundwater pollution.

The production and usage of oil shale usually generates more greenhouse gas emissions, including carbon dioxide, than conventional fossil fuels. Depending on the technology and the oil shale composition, shale oil extraction may create also sulfur dioxide, hydrogen sulfide, carbonyl sulfide, and nitrogen oxides emissions. Developing carbon capture and storage technologies may reduce the processes’ carbon footprint.

Concerns have been prominently raised over the oil shale industry’s use of water, particularly in arid regions where water consumption is a sensitive issue. In some cases, oil shale mining requires the lowering of groundwater levels below the level of the oil shale strata, which may affect the surrounding arable land and forest. Above-ground retorting typically consumes between one and five barrels of water per barrel of produced shale oil, depending on technology. Water is usually used for spent shale cooling and oil shale ash disposal. In situ processing, according to one estimate, uses about one-tenth as much water.

A 2007 programmatic environmental impact statement issued by the United States Bureau of Land Management stated that surface mining and retort operations produce 2 to 10 US gallons (7.6 to 38 l; 1.7 to 8.3 imp gal) of waste water per 1 short ton (0.91 t) of processed oil shale.

See also

Oil shale geology

Oil shale reserves

References

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^ Koel, Mihkel; Ljovin, S.; Hollis, K.; Rubin, J. (2001). “Using neoteric solvents in oil shale studies” (PDF). Pure and Applied Chemistry (Blackwell Science) 73 (1): 153159. ISSN 0033-4545. http://old.iupac.org/publications/pac/2001/pdf/7301×0153.pdf. Retrieved 2010-01-22. 

^ Baldwin, R. M.; Bennett, D. P.; Briley, R. A. (1984). “Reactivity of oil shale towards solvent hydrogenation” (PDF). American Chemical Society. Division of Petroleum Chemistry (American Chemical Society) 29 (1): 148153. ISSN 0569-3799. http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=6697587. Retrieved 2010-01-22. 

^ a b c Speight, James G. (2008). Synthetic Fuels Handbook: Properties, Process, and Performance. McGraw-Hill. pp. 182; 186. ISBN 9780071490238. http://books.google.com/books?id=E3pgqnGgHjIC&pg=PA182. Retrieved 2009-03-14. 

^ a b c d Smith, M.W.; Shadle, L.J.; Hill, D. (2007) (PDF). Oil Shale Development from the Perspective of NETL’s Unconventional Oil Resource Repository. United States Department of Energy. DOE/NETL-IR-2007-022. http://www.osti.gov/energycitations/servlets/purl/915351-0AdXs8/915351.pdf. Retrieved 2009-11-29. 

^ Committee on Production Technologies for Liquid Transportation Fuels, Energy Engineering Board, United States National Research Council (1990). Fuels to drive our future. National Academies Press. p. 183. ISBN 9780309086455. http://books.nap.edu/openbook.php?record_id=1440&page=183. Retrieved 2008-05-04. 

^ a b c (PDF) Draft Oil Shale and Tar Sands Resource Management Plan Amendments to Address Land Use Allocations in Colorado, Utah, and Wyoming and Programmatic Environmental Impact Statement. Appendix A: Oil Shale Development Background and Technology Overview. Argonne National Laboratory. 2007-12-07. pp. 36; 5455. http://ostseis.anl.gov/documents/dpeis/vol3/OSTS_DPEIS_vol3_App_A.pdf. Retrieved 2008-05-11. 

^ Soone, Jri; Riisalu, Hella; Kekisheva, Ljudmilla; Doilov, Svjatoslav (2006-11-07). “Environmentally sustainable use of energy and chemical potential of oil shale” (PDF). International Oil Shale Conference. Amman, Jordan: Jordanian Natural Resources Authority. pp. 23. http://www.sdnp.jo/International_Oil_Conference/rtos-A104.pdf. Retrieved 2007-06-29. 

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^ Biglarbigi, Khosrow; Mohan, Hitesh; Crawford, Peter; Carolus, Marshall (2008-12-04). “Economics, Barriers, and Risks of Oil Shale Development in the United States” (PDF). 28th United States Association for Energy Economics/International Association for Energy Economics North America Conference. New Orleans: The United States Association for Energy Economics. http://www.usaee.org/usaee2008/submissions/OnlineProceedings/7995-Biglarbigi – Oil Shale Economics.pdf. Retrieved 2009-09-27. 

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^ Rex, R.; Janka, J. C.; Knowlton, T. (1984). Cold Flow Model Testing of the Hytort Process Retort Design. 17th Oil Shale Symposium. Golden, Colorado: Colorado School of Mines Press. pp. 1736. 

^ Weil, S. A.; Feldkirchner, H. L.; Punwani, D. V.; Janka, J. C. (1979-01-01). IGT HYTORT Process for hydrogen retorting of Devonian oil shales. Chicago: Gas Technology Institute. CONF-790571-3. 

^ Kk, M. V.; Guner, G.; Suat Baci, A. (2008). “Application of EOR techniques for oil shale fields (in-situ combustion approach)” (PDF). Oil Shale. A Scientific-Technical Journal (Estonian Academy Publishers) 25 (2): 217225. doi:10.3176/oil.2008.2.04. http://www.kirj.ee/public/oilshale_pdf/2008/issue_2/oil-2008-2-217-225.pdf. Retrieved 2008-06-07. 

^ a b Savage, Marshall T. (2006-10-17). “Geothermic fuel cells” (PDF). 26th Oil Shale Symposium. Golden, Colorado: Colorado School of Mines/. http://www.ceri-mines.org/documents/R05d-MarshallSavage.pdf. Retrieved 2009-09-25. 

^ a b Lee, Sunggyu; Speight, James G.; Loyalka, Sudarshan K. (2007). Handbook of Alternative Fuel Technologies. CRC Press. p. 290. ISBN 9780824740696. http://books.google.com/books?id=hyNbv60Px8oC&pg=PA290. Retrieved 2009-03-14. 

^ a b c d Bartis, James T.; LaTourrette, Tom; Dixon, Lloyd; Peterson, D.J.; Cecchine, Gary (2005) (PDF). Oil Shale Development in the United States. Prospects and Policy Issues. Prepared for the National Energy Technology Laboratory of the United States Department of Energy. The RAND Corporation. pp. x; 1518; 50. ISBN 978-0-8330-3848-7. http://www.rand.org/pubs/monographs/2005/RAND_MG414.pdf. Retrieved 2007-06-29. 

^ Jon Birger (2007-11-01). Oil shale may finally have its moment. Fortune. http://money.cnn.com/2007/10/30/magazines/fortune/Oil_from_stone.fortune/. Retrieved 2007-11-17. 

^ Spencer Reiss (2005-12-13). “Tapping the Rock Field”. WIRED magazine. http://www.wired.com/wired/archive/13.12/oilshale.html. Retrieved 2009-03-14. 

^ (PDF) Plan of Operation for Oil Shale Research, Development and Demonstration (R,D/D) Tract. E.G.L. Resources, Inc.. 2006-02-15. http://www.blm.gov/pgdata/etc/medialib/blm/co/field_offices/white_river_field/oil_shale.Par.62160.File.dat/PlanofOperation.pdf. Retrieved 2008-05-01. 

^ (PDF) Oil Shale Research, Development & Demonstration Project. Plan of Operation. Chevron USA, Inc.. 2006-02-15. http://www.blm.gov/pgdata/etc/medialib/blm/co/field_offices/white_river_field/oil_shale.Par.37256.File.dat/OILSHALEPLANOFOPERATIONS.pdf. Retrieved 2008-05-01. 

^ Shurtleff, Kevin; Doyle, Dave (March 2008). “Single well, single gas phase technique is key to unique method of extracting oil vapors from oil shale” (PDF). World Oil Magazine (Gulf Publishing Company). http://www.rmotc.doe.gov/Pdfs/WO.MWE.March08.pdf. Retrieved 2009-09-27. 

^ Plunkett, Jack W. (2008). Plunkett’s Energy Industry Almanac 2009: The Only Comprehensive Guide to the Energy & Utilities Industry. Plunkett Research, Ltd.. p. 71. ISBN 9781593921286. http://books.google.com/books?id=Ut3zgub_PRwC&pg=PT71. Retrieved 2009-03-14. 

^ a b Symington, William A.; Olgaard, David L.; Otten, Glenn A.; Phillips, Tom C.; Thomas,Michele M.; Yeakel, Jesse D. (2008-04-20). “ExxonMobil’s Electrofrac Process for In Situ Oil Shale Conversion” (PDF). AAAPG Annual Convention. San Antonio: American Association of Petroleum Geologists. http://www.nevtahoilsands.com/pdf/Oil-Shale-and-Tar-Sands-Company-Profiles.pdf. Retrieved 2009-04-12. 

^ a b Burnham, Alan K. (2003-08-20) (PDF). Slow Radio-Frequency Processing of Large Oil Shale Volumes to Produce Petroleum-like Shale Oil. Lawrence Livermore National Laboratory. UCRL-ID-155045. https://e-reports-ext.llnl.gov/pdf/243505.pdf. Retrieved 2007-06-28. 

^ Carlson, R. D.; Blase, E. F.; McLendon, T. R. (1981-04-22). “Development of the IIT Research Institute RF heating process for in situ oil shale/tar sand fuel extractionn overview”. Oil Shale Symposium Proceedings. 14th Oil Shale Symposium (Golden, Colorado: Colorado School of Mines): 138145. CONF-810456. 

^ (PDF) Radio Frequency/Critical Fluid Oil Extraction Technology. Raytheon. http://www.raytheon.com/businesses/rids/products/rtnwcm/groups/public/documents/content/rtn_bus_ids_prod_rfcf_pdf.pdf. Retrieved 2008-08-20. 

^ Moon, Ted (2008-02-01). “Oil-shale extraction technology has a new owner”. The Journal of Petroleum Technology (Society of Petroleum Engineers). http://www.spe.org/jpt/2008/02/oil-shale-extraction-technology-has-a-new-owner/. Retrieved 2008-08-20. 

^ Global Resource Corp. (2007-03-09). “Global Resource Reports Progress on Oil Shale Conversion Process”. Press release. http://www.downstreamtoday.com/news/article.aspx?a_id=1943. Retrieved 2008-05-31. 

^ Daniel, David Edwin; Lowe, Donald F.; Oubre, Carroll L.; Ward, Calvin Herbert (1999). Soil vapor extraction using radio frequency heating: resource manual and technology demonstration. CRC Press. p. 1. ISBN 9781566704649. http://books.google.com/books?hl=en&lr=&id=vd8EIXX-OOQC&oi=fnd&pg=PA1. Retrieved 2009-09-26. 

^ Schmidt, S. J. (2003). “New directions for shale oil:path to a secure new oil supply well into this century: on the example of Australia” (PDF). Oil Shale. A Scientific-Technical Journal (Estonian Academy Publishers) 20 (3): 333346. ISSN 0208-189X. http://www.kirj.ee/public/oilshale/7_schmidt_2003_3s.pdf. Retrieved 2007-06-02. 

^ Tiikma, Laine; Johannes, Ille; Pryadka, Natalja (2002). “Co-pyrolysis of waste plastics with oil shale”. Proceedings. Symposium on Oil Shale 2002, Tallinn, Estonia: 76. 

^ Tiikma, Laine; Johannes, Ille; Luik, Hans (March 2006). “Fixation of chlorine evolved in pyrolysis of PVC waste by Estonian oil shales”. Journal of Analytical and Applied Pyrolysis 75 (2): 205210. doi:10.1016/j.jaap.2005.06.001. 

^ Veski, R.; Palu, V.; Kruusement, K. (2006). “Co-liquefaction of kukersite oil shale and pine wood in supercritical water” (PDF). Oil Shale. A Scientific-Technical Journal (Estonian Academy Publishers) 23 (3): 236248. ISSN 0208-189X. http://www.kirj.ee/public/oilshale/oil-2006-3-4.pdf. Retrieved 2007-06-16. 

^ Aboulkas, A.; El Harfi, K.; El Bouadili, A.; Benchanaa, M.; Mokhlisse, A.; Outzourit, A. (2007). “Kinetics of co-pyrolysis of Tarfaya (Morocco) oil shale with high-density polyethylene” (PDF). Oil Shale. A Scientific-Technical Journal (Estonian Academy Publishers) 24 (1): 1533. ISSN 0208-189X. http://www.kirj.ee/public/oilshale/oil-2006-3-4.pdf. Retrieved 2007-06-16. 

^ Ozdemir, M.; A. Akar, A. Aydoan, E. Kalafatoglu; E. Ekinci (2006-11-07). “Copyrolysis of Goynuk oil shale and thermoplastics” (PDF). International Oil Shale Conference. Amman, Jordan: Jordanian Natural Resources Authority. http://www.sdnp.jo/International_Oil_Conference/rtos-A114.pdf. Retrieved 2007-06-29. 

^ Siirde, Andres; Martins, Ants (2009-06-07). “Oil shale fluidized bed retorting technology with CFB furnace for buring the by-products” (PDF). International Oil Shale Symphosium. Tallinn, Estonia: Tallinn University of Technology. http://www.oilshalesymposium.com/fileadmin/user_upload/documents/SIIRDE.pdf. Retrieved 2009-05-22. 

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^ (PDF) Letter to the Senate Committee on Energy and Natural Resources. Oil Shale Alliance Inc.. 2006. http://www.petroprobe.com/articles/submissiontosenate.pdf. Retrieved 2009-02-12. 

^ Parkinson, Gerald (2007). “Oil Shale: The U.S. Takes Another Look at a Huge Domestic Resource”. Chemical Engineering Progress (American Institute of Chemical Engineers) 102 (7). http://findarticles.com/p/articles/mi_qa5350/is_200607/ai_n21394714. Retrieved 2008-08-21. 

^ Clark, Judy (2008-08-11). “Nuclear heat advances oil shale refining in situ”. Oil & Gas Journal (requires subscription) (PennWell Corporation) 106 (30): 2224. http://www.ogj.com/index/article-display/336580/s-articles/s-oil-gas-journal/s-volume-106/s-issue-30/s-general-interest/s-nuclear-heat-advances-oil-shale-refining-in-situ.html. Retrieved 2009-05-23. 

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^ Tuvikene, Arvo; Sirpa Huuskonen, Kari Koponen, Ossi Ritola, lle Mauer, Pirjo Lindstrm-Sepp (1999). “Oil Shale Processing as a Source of Aquatic Pollution: Monitoring of the Biologic Effects in Caged and Feral Freshwater Fish” (PDF). Environmental Health Perspectives (National Institute of Environmental Health Sciences) 107 (9): 745752. doi:10.2307/3434660. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1566439/pdf/envhper00514-0093.pdf. Retrieved 2007-06-16. 

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^ Bartis, Jim (2006-10-26). “Unconventional Liquid Fuels Overview” (PDF). World Oil Conference. Boston: Association for the Study of Peak Oil & Gas – USA. http://www.aspo-usa.com/fall2006/presentations/pdf/Bartis_J_Boston_2006.pdf. Retrieved 2007-06-28. 

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^ a b (PDF) Draft Oil Shale and Tar Sands Resource Management Plan Amendments to Address Land Use Allocations in Colorado, Utah, and Wyoming and Programmatic Environmental Impact Statement. Volume 2. Argonne National Laboratory. 2007-12-07. p. 43(36). http://ostseis.anl.gov/documents/dpeis/volumes/OSTS_DPEIS_Vol_2.pdf. Retrieved 2008-03-31. 

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External links

Oil Shale. A Scientific-Technical Journal (ISSN 0208-189X)

Oil Shale and Tar Sands Programmatic Environmental Impact Statement (EIS) Information Center. Concerning potential leases of Federal oil sands lands in Utah and oil shale lands in Utah, Wyoming, and Colorado.

“Shale Oil Now” Campaign. Links and articles on America’s shale oil compiled by Jon Moseley

The United States National Oil Shale Association (NOSA)

Shale Oil Information Center. A Colorado non-profit corporation disseminating information focusing on the history of the extraction of oil shale and oil sands.

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Categories: Oil shale technology | Petroleum production | Chemical engineeringHidden categories: Articles containing potentially dated statements from 2009 | All articles containing potentially dated statements

Stress Tolerance in Plants

INTRODUCTION

India has to support 16% of world food needs in land available for less than 2% of the country. Where agriculture is to maximize its effectiveness. Who can be achieved by understanding and engineering plants to make them survive in adverse conditions.
Plant growth requires not only carbon dioxide and oxygen from the air but also water and mineral nutrients from the soil. The floor was called the placenta "life" because it provides essential nutrients for all terrestrial plants and plants in turn nourish all terrestrial ecosystems. Throughout history mankind standard, life depended on the fertility and soil productivity.
Soil erosion and salinization are accelerated by poor agronomic practices. Mismanagement and neglect soil can ruin farmland, which is a fragile and precious resource. The Harappan civilization in western India, Mesopotamia, Asia Minor, and Mayan culture in Central America all collapsed partly because of land degradation. The maintenance of production should be one of the important objectives society.
Most crops are salt sensitive or hypersensitive (glycophytes) unlike halophytes, which are the native flora of the environment saline, halophytes have the ability to receive extreme salinity, due to the particular anatomical and morphological adaptation and different physiological or an avoidance mechanism.
Approximately 330 species of plants vesicular (ie <0.15% of total) were demonstrated to be tolerant to desiccation.
The majority of bryophytes representing 30,000 spp mosses, liverworts, hornworts are postulated to tolerate at least low intensity drying memory.

Halophytes:

The plants and complete life cycle of a coat with a high salt concentration are commonly referred to as halophytes are specialized plants growing in saline environments commonly sea near the shore, where the concentration of salts (NaCl, MgSO4, MgCl2, etc.) are relatively high. Although these plants grow in water or in a well saturated with water, the water absorption is extremely difficult process, and halophytes are physiologically dry but physically people wet. For this reason, they disappeared in a morphological details anatomic and physiological adaptation during their life cycle.

MORPHOLOGICAL Adaptations:

A) ROOT:

1.In addition halophytes in normal roots, on stilts or more aerial roots develop from branches the antenna rod. Example? Rhizophora mucronata.
2.Some both a large number of roots developed from the foothills of the basal part of trunks of trees.
Example? numularia Dischidia
3.In order to compensate for the lack of aeration of the soil, they develop particular type of negative geotropic roots, called pneumatophores, as the anchor structures causes many lenticels inner surface.

B) STRAIN:

Stems of many halophytes succulent. Which is induced only after the accumulation of free ions in these organs. They are either hard or difficult or swollen or fleshy and are generally hairy.

C) leaves

1.The leaves of most halophytes are thick, succulent, genrally small size and a glassy
2.Leaves of aerohalopytes are densely covered with trichomes on their surface,
3.silk submerged marine halophytes are thin, spiny cuticle cutinized thick

D) fruits and seeds

Fruits, seeds and pollen grains generally mild, waxy surface of fruits covering that prevents damage during their transport through the medium of water.
Halophytic mangroves growing especially in the area of tidal shows the phenomenon of viviparous germination, which can be defined as the process of germination of seeds while the fruit is still attached to the plant mother.

ANATOMICAL ADAPTATION

1.Epidermis cutinized and is covered with epidermal outgrowths as hair that prevents sweating and salt spray in the plant body. The two sheets, and dorsiventral isobilateral shows sunken stomata and reduces
2.Cortex cavities shows mucilage, tannin cells, spicule gap schlerides, salt glands, which are very important characteristic change of cortical regions such plants are adapted to saline environment.
3.Vascular bundles are poorly developed and are guaranteed jointly with strands xylum Exarch.
4.stele is liginified.
5.Most of the cell have cell walls elastic.
6.mesophyll cells are differtiated palisade and spongy parenchyma.
7.Cholorophyll content is very low in the cells between these halophytes.

schema [A] attached blog address below

PHYSIOLOGICAL ADAPTATION

1.salinity reduced the rate of cell division that promotes the rate of cell elongation,
2.The cells free ions which improves its turgor and increases its ability to adapt to salinity.
3.The plants show high rates of transpiration, which is useful if a solution tolerate saline to maintain the normal rate of metabolism.
4.Halophytes shows exudation of sap contains dissolved salts.
5.Some halophytes have salt secreting glands and tissues for water storage.
6.The viviparous mangrove plant is one of the most important physiological adaptations responsible for the growth and normal development of seedlings.

GENETIC DIVERSITY FOR TOLERANCE salt in plants

The diversity Genetics of salt tolerance that exists in Texa factory is spread over many genres, researchers in recent Decade established that most halophytes and glycophytes tolerate salinity by the same strategy rather often using methods similar tactics. Ions in the cytotoxic environment salt, typically sodium ions and Chloride ions are compartmentalized in the vacuole and used as salts, osmotic homeostasis that ion cell is controlled and conducted by an entity common molecular dissection of plant responses to salt stress.

GENETICS STRESS:

To breed or genetically engineer stress tolerance in plants, it is imperative to identify genes that control these traits and understand how these genes work and their products are regulated.
The products of some genes inducible by stress may play the role of stress signaling and stress tolerance.
Example: the enzymes involved in the biosynthesis of compatible solutes (Osmolytes) or directly in the detoxification of reactive oxidants and antioxidant in the biosynthesis of compounds ion transporters, etc. ABA biosynthesis enzymes.
The products of some other genes may also have roles in protection against damage from stress. These are mainly "the late embryogenesis abundant (LEA) as proteins.

In some cases, genes that are physically associated with stress affects some induced genes in a region of chromatin may be regulated by stress, Although these genes can not be linked otherwise.
Example: (CFU upstream of FLC (flowering locus)) gene gene. FLC is a repressor flowers whose transcription is regulated at the level by cold treatment (vernalization). Interestingly, the UFC is also regulated by vernalization but it does not relate to FLC or in sequence or function. They are only neighboring genes on the same chromosome. This suggests that the chromosomal location has a strong influence on the induction of certain genes.

Signal transduction.
signal transduction is necessary for many cellular activities and their coordination. Some processes trasduction signal are simple but most others are complex, involving several components occur in time and space dependent manner.
Generally Signal transduction begins with the perception of the stimulus by a specific cellular molecule (s). The sensors or receptors may differ in their molecular identity, mode of perception and signal output, and the subcellular localization.
In plant cells, it is also common for receivers activaton lead to the generation of secondary messengers, called because they represent intracellular signals during translation in the primary signal externally. The intracellular signals are interpreted by other components of other signal (s) and the result of the activation of downstream pathways may have multiple outputs.

signal transduction scheme [B] given in the blog link given below

A signal transduction conceptual towards drought, cold and salt stress in plants. Secondary molecules can cause receptor mediated calcium ion release (indicated by feedback arrow). These partners, which modulate the components in the main track can be adjusted by the main track. signals can also bypass the calcium ions or secondary signaling molecules in early signaling step.
GPCR? G-protein coupled receptor.
RLK? receptor-like kinase.
InsP? inositol phosphate pol.

Ca2 + signaling and activation of the salt overly sensitive (SOS) signal transduction

It was identified three loci that genetically related Arabidopsis (SOS1, SOS2 and SOS3), which are components of a signaling pathway that controls stress homeostasis ions and salt tolerance. Genetic analysis of the sensitivity Na + / Li + determined that SOS1 is epistatic to sos2 and sos3. These mutants SOS also a phenotype deficient in K + medium supplemented with? M [K + ext] and [Ca 2 +] ext. Na + and K + deficit sos2 sos3 and is removed with MM [Ca2 + item]. SOS1 exhibits hyperosmotic contrast sensitivity and sos3 sos2. Together, these results indicate that the SOS pathway regulates Na + and K + homeostasis and Ca2 + activated. SOS3 encodes a Ca2 +-binding protein with sequence similarity to the regulatory subunit of calcineurin B (protein phosphatase 2B) and neuronal Ca2 + sensor interaction with SOS3 kinase SOS2 SOS2 and activation is dependent on Ca2 + in planta function as SOS3 a determinant of salt tolerance depends on Ca2 + binding and Nmyristoylation. SOS2 serine / threonine kinase (446 amino acids) is 267 amino acids N-terminal catalytic domain that is similar in sequence to yeast SNF1 (sucrose nonfermenting) kinase and mammalian AMPK (AMP-activated protein kinase). Activity SOS2 kinase is essential for the functioning of its salt tolerance determinant. The SOS2 C-terminal domain interacts with the regulatory kinase domain causing autoinhibition. A ground of 21 amino acids in the regulatory domain of SOS2 is where SOS3 interacts with the kinase domain and is the self-kinase inhibitors. Binding of SOS3 to this autoinhibition motif blocks SOS2 kinase activity. Remove results autoinhibitory domain of the constitutive activation SOS2, SOS3 independent. In addition, a Thr168 to Asp mutation in the activation loop of the kinase domain constitutively active and biochemical SOS2.Genetic indicate that components of the SOS function signaling pathway in the hierarchical sequence. Ca2 + binds to SOS3, which leads to interaction with SOS2 and activation of the kinase. Among the outputs towards SOS signaling are transportation systems that facilitate ion homeostasis. The plasma membrane located Na + / H + antiporter SOS1 is controlled by means SOS at the transcriptional and post-transcriptional Recently, functional disturbances of AtHKT1 has been shown to remove the salt sensitive phenotype sos3-1 indicating that the path of SOS system negatively controls Na + influx. In addition, the path of SOS negative control of expression of members of the family AtNHX that are implicated as determinants in the response to salt stress. [Ca 2 +] ext enhances salt tolerance and salinity stress induced a [Ca2 + cyt transient increase], or from an internal or external source, who has been involved in adaptation. Yeast outlined activation of Ca2 + in salt stress signaling that controls homeostasis of ions and hyperosmotic tolerance.The component of high salinity induces a short duration (1 min) increased [Ca2 + CYT] which is mainly due to the influx across the plasma membrane through the system Mid1p of Cch1p and Ca2 + transport. The transient increase in [Ca 2 + CYT] active PP2B phosphatase calcineurin (a key intermediate in salt stress signaling controlling ion homeostasis) leads to the transcription of ENA1, which encodes P-type ATPase that is primarily responsible for Na + efflux through the plasma membrane. The model proposes that the [hyperosmotically induced localized Ca2 +] cyt transient activates calmodulin, which is attached to Cch1p-MIDP. Active Calmodulin in turn signaling through calcineurin, which mediates ion homeostasis and salt tolerance. From these results, a paradigm for induced salt-Ca2 + signaling and activation of the SOS can be offered. SOS track components, or elements SOS3 or upstream, may be associated with a channel through which respond osmotically influx of Ca2 + signaling could run through. These are constitutive signaling pathways that respond to different inducers, but are still elements of the response of plants to salt stress. SOS signal transduction by physical positive interaction with effectors or competition for substrate necessary for signaling. The positive and negative regulation of signal modulation is a fine-tuning necessary to achieve the appropriate response of plants to adapt to stress and patient stability.

Mechanisms cell of SURVIVAL AND GROWTH OF RECOVERY salt stress

Plant are either dormant during the episode of salt or they have to be cell adapt to tolerate saline environment. The chemical potential of the saline water first establishes a potential imbalance between apoplast and symplast, which leads to reduced turgor, which is severe enough to cause a reduction in growth. cellular dehydration begins when the potential difference of water is greater than can be offset by the loss Tugores. The cellular response to the response of turgor adjustment is Osmotic is achieved in this compartment by the accumulation of compatible osmolytes. However, Na + and Cl – are energy-efficient osmolytes to adjust osmotic and are compartmentalized in the vacuole to minimize cytotoxicity.Compartmentalization Na + and Cl – facilitates osmotic adjustment that is very essential for development Cell. Movement of ions into the vacuole may occur directly from the apoplast into the vacuole by membrane vesicles or process through cytological the plasma membrane to the tonoplast. The bulk of Na + and Cl-in the apoplast vacuole is mediated by ion transport system located in the plasma membrane and tonoplast. The SOS signallig way is the key transportation system needed to ion homeostasis.

Osmolytes AND osmoprotectant

Some compatible osmolytes are essential basic ions such as K +, but the majority are organic solutes. The major organic solutes cateogory osmotic consists of simple sugars like fructose and glucose: sugar alcohols such as glycerol, inositol: complex carbohydrates such as raffinose. Among the other amino acids quaternary such as proline, glycine, alanine beta: tertiary amines and sulfonium sulfonium as dimethyl, propyronate.An biochemical function adaptable osmoprotectant is trapping of reactive oxygen species are produced by hyper-osmotic stress and ionic solutes causes cells have the capacity death.Compatible preserve the enzyme activity in saline conditions. The synthesis of compatible osmolytes is often achieved by the diversion of basic metabolites as intermediates in biochemical reactions often unique stress triggers this metabolic diversion.

Homeostasis ions – TRANSPORTATION Determinants and their regulations.

Intracellular Na + homeostasis and salt tolerance are modulated by Ca + + and high concentration of Na + K + whose effects acquisition. Na + K + is in competition with absorption by the system of public transport, and this effectively since oncentration Na + in saline environment is generally higher than the extracellular concentration of K +, Ca + + increased K + / Na + selective accumulation intracellular.
The molecular entities that mediate Na + and K + homeostasis is one function of Ca + + in the regulation of these systems transport. The SOS stress signaling pathway is identified as an important regulator of ion homeostasis and plant salt tolerance.

ION TRANSPORT SYSTEM: Na + HOMEOSTASIS

(A) H + pumps (proton pumps)

H + pumps in plasma and tonoplast memebrane fecilitate solute transport necessary to compartmentalize ions away from the cytoplasm and cytotoxic function of ions as determinants of signal.
These pumps provide the driving force (H + electro chemical potential) for secondary active transport and function to establish the membrane potential electrophoretic variants that facilitate the flow of ions. The plasma membrane H + ATPase loclised is a p-type pump and is mainly responsible for the large membrane potential gradient along the gradient. A vacuolar-type H +-ATPase to generate the membrane potential across the tonoplast. The activity of H + pumps is increased by treatment of salt and induces the expression of genes.
The plasma membrane H + ATPase is confirmed as a salt tolerant determinant based on the analysis phenotypes caused by the semidominant "aha4-1 mutation. The mutation aha4 is expressed mainly in the root causes of the reduction of root and shoot and root growth. Root length decreased salt treated "aha4-1 plants is due to reduced cell length. It is postulated that the leaves of "aha4-1 plant to accumulate more Na + and K + less than wild type. So we can say that "aha4-1 functions in the control Na + flux through the endoderm.

(B) Na + influx and efflux in the plasma membrane

Transport System with greater selectivity for K + are presumed to facilitate Na + leaks into the cells. Na is a competitor for absorption through the membrane The plasma K + channels internal grinding. K + outward rectifying channels also facilitate Na + influx. When Na expressed in heterologous systems proving function as Na +, H + K + dependent transporter.
The energy dependent transport Na + across the plasma membrane is also mediated by secondary active Na + / H +.

(C) Na + compartmentation vacuolar

Na + / H + antiport across the tonoplast to facilitate vacuolar compartmentalization of the cation. The way the SOS negatively regulates transcriptional expression genes of these Na + H / + antiporter.

RESISTANT PLANTS BY DROUGHT (xeric)

Plants growing in dry habitats or dry conditions can support with low humidity, high temperatures are called xerophytic. drought tolerant plants are characteristic of desert and semi-desert.
These plants develop certain structural, anatomical, physiological adaptations to absorb much as possible to the water they can get the encirclement and retain water in their bodies for a long time by reducing the rate of transpiration.

Effect on plants:

Reduced growth o (Ex: limiting the expansion of leaves).
o Decrease leaf area decreased photosynthetic activity.
O Decrease the water content increases the concentration of solute.
o The first effect on the system root is the death of root hairs, which decreases the ability of roots to absorb water.
O production as phytohormones cytokinin and acid decreases gibberlic.
o It reduces the production of secondary metabolites, which leads to decrease in the defense mechanism against insects and diseases.

Morphological adaptations

A) ROOT

Xerophytes have developed a root system that can be strongly elobarate branched and that the system of shooting. The roots of perennial xerophytic grow very deep into the ground and reach the layer where the water is available in abundance.

B) STEM

1. Hard and woody stems are covered with a thick coating of wax and silica or can be covered with hair (Calotropis sp).
2. In some strains may be modified xerophytes with thorns. Example? Ulex sp
3. Stem certain extereme are modified leaf, like, flattened and fleshy structures, which are called phylloclades. Example? Muehlenbeckia sp
4. In some plants a number of branches axullary change in a small needle like structure that resembles green leaves and are called cladodes. Example? Asparagus sp

C) leaves.

1.In of xerophytic leaves fall early in the season, but in most plant leaves are usually reduced to scales. Example? equisitifolia Casuarina
2.Some evergreens have needle-like leaves. Example? Pinus roxburghii
3.In some species the leaves turn succulent and swell remarkably and becomes very fleshy for the storage of excess latex in them. Example? Aloe spinossina
4.Leaves may be reduced Spiny and are provided with thick layer of wax or silica. Example? polardii Opumtia.
5.Leaves bladed thick network of veins, in some cases, the petiole green swells and becomes flattened to form phyllodes. Example? Acacia auriculiformis.
6.Many drought tolerant plants shows trichophylly to protect guard cells of stomata cons Stong winds. Example? numularis Zizyphus.
In some drought-tolerant grasses 7.Leaves extremes have the ability to folding operation.

D) fruit and seeds.

Flowers usually develop under favorable conditions and the end of their reproduction in the very short period of time. Fruits and seeds are protected by wrappers very hard and they can remain dormant for a long period of time.

Anatomical adaptations

1.Epidermal cells are small and compact with thick cuticle layer is simple.
2.Wax, tannin, rasin, cellulose, etc. are deposited on the surface of the epidermis which forms a protective measure to high intensity light.
3.Some epidermal cells in the depression becomes wider are called motor cells or cells that felicitate hinge leaf curl becoming flaccid during the dry period. Example? Amnophilla.
4.The hypodermal cells are thick walled and compact clustering and can be filled with tannins and mucilage.
5.Stomatal by number of units is reduced and they are hollow type. The walls of guard cells and subsidiary cells are highly lignified and cutinized. These specialized stomata reduced transpiration rate.
6.In case of reduction of photosynthetic activity of leaves is absorbed by the outer cortex Chlorenchymatous. Example? Capparis. Decidua
7.In succulent stem ground tissue is full of thin-walled parenchyma cells that store excess water quanitity, mucilage, latex. Example? Agave americana.
8.The mesophyll cells are very compact, intracellular spaces are reduced. Palisade tissue develops in several layers and, in some mesophyll case is surrounded by a sheath of sclerenchyma.
Pinus sp 9.In cells in the spongy mesophyll cells are star-shaped.
10.Both xylum conducting tissues and phloem are very well developed in the xerophytic.

Diagram [C] given in the blog, given link below.

ADAPTATION PHYSIOLOGICAL

1. Xerophytes have a high osmotic pressure which increases the turgidity of the cell carries SAP tension force on the cell wall. In this way, the withering of the cell is impeded.
2. Presence of the cuticle, sunken stomata protected with hair regulates stomatal transpiration.
3. The ability to survive in xeric in the dry period is not only the characteristics structural, but also in the resistance of hardened protoplasm to heat and desiccation.
4. Some enzymes such as catalase, peroxidases are more active in xerophytic. Low concentrations of hydrolytic enzymes prevents higher rate of water consumption.
5. In xerophytic conversion of chemical compounds in the cell SAP, such as polysaccharides in anhydrous forms as cellulose, suberin, etc. are noted.
6. In some xerophytic open stomata during the night hours and remain closed during the day. These unusual features are associated with the metabolic activity of plants you.
7. In these plants polysaccharides are converted into pentosens who have the capacity of the water.
8. In xerophytic release of respiratory carbon dioxide during the night leads to the biosynthesis of large quantities of organic acids which are useful for plants to survive in extreme conditions project.

Heat shock proteins

Heat shock proteins (HSP) are a group of proteins whose expression is increased when cells are exposed to high temperatures or other stress. This increased expression is regulated transcription. This dramatic upregulation of heat shock protein induced mainly by the heat shock factor (HSF) is a key element of the response thermal shock.
HSPs are named according to their molecular weight. For example, Hsp60, Hsp70 and Hsp90 (the most studied HSP) refer to families of heat shock proteins of about 60, 70 and 90 kilodaltons in size, respectively. The small protein ubiquitin 8 kilodaltons, which marks proteins for degradation, also features a heat shock protein.
molecular chaperones, including heat shock proteins (HSP) are a pervasive feature of cells in which these proteins cope with stress-induced denaturation of other proteins. Hsps have received the most attention in model organisms undergoing experimental stress in the laboratory, and the function of Hsps at the molecular level and at cell is more clearly understood in this context. The emphasis is emerging on the additional Hsps of models and model organisms not subject to tension in nature, the role of Hsps in stress physiology of all eukaryotes and multicellular tissues and organs they represent, and the ecological and evolutionary correlates of variation in Hsps and the genes that encode them. This approach reveals that (expression) of HSP may occur in nature, (b) all species have hsp genes but they vary in modes of expression, (c) Hsp expression can be correlated with stress resistance, and (d) the expression levels of Hsp species are correlated with levels of stress they experience naturally. These findings are now well established and may require little additional confirmation, many important questions remain unanswered concerning both the mechanisms tolerance to HSP-mediated stress in organisms and evolutionary mechanisms that have diversified the hsp genes.
Upregulation by stress
The production of high levels of heat shock proteins can also be triggered by exposure to different types conditions of environmental stress, such as infection, inflammation, exercise, exposure of the cell to toxins (ethanol, arsenic, trace metals and ultraviolet light, among many others), starvation, hypoxia (oxygen deficiency), deprivation of nitrogen deficiency (plants), or water. Therefore, the heat shock proteins are also referred to as stress proteins and their regulation increase is sometimes described more generally in the context of the stress response.

EFFECT OF ABA in stress:

ACCEPTABLE stress genes are regulated by ABA-dependent and ABA independent PROCESS.

Gene transcription is controlled by the interaction of regulatory proteins with specific sequences in promoters regulating the genes they regulate. Different genes induced by the same signal is controlled by a signaling pathway
leading to activation of these transcription factors specific. Studies on promoters of several genes induced by stress have led to the identification of specific sequences of control genes involved in different constraints. For example, the RD29 gene contains DNA sequences that can be activated by osmotic stress, by cold, and ABA.

EFFECT OF CLOSING IN ABA stomata under drought

Outline [D] Data in the blog link given below.

The acidity, alkalinity and salinity are important determinants of productivity.

Because the acidity of the soil influences the physical properties, the availability of certain plant nutrients, and the activity organic soil, it greatly affects plant growth, the degree of soil acidity depends on the concentration of hydrogen ions dissolved in water soil. In neutral soil, the concentration of hydrogen ions is about one part per billion parts of water and acid soils may have a concentration of H + which is 100-1000 times higher, while the concentration of H + alkaline.
Neither extreme acidity or alkalinity is adapted to extreme plant growth or for most other soil organisms. Such conditions also disturb the soil weathering and nutrient availability, although some Plants can be grown in soils highly acidic or alkaline, most plants grow best in slightly acidic or neutral culture soil. Just over one quarter (26%)
Of the worlds arable land is classified as acid. In the tropics, the% is even greater (43%). Acid soils represent 68% of America tropical, 38% of tropical Asia and
27% of tropical Africa.

Figure [E] given in the blog link given below.

IMPROVEMENT

CROP RESISTANCE) A to water deficit can be improved:
Improve resistance to drought is an important goal of plant breeders.
Four basic approaches to drought resistance are used:
1.breed for high yields under optimal conditions, namely race for the potential return – assuming that this will give a performance advantage in terms optimal.
2.breed for maximum performance in the target environment.
3.Select and incorporate morphological and physiological mechanisms of resistance drought in traditional breeding programs.
4.do not use multiple physiological selection criteria, but are made without probably only one character drought resistance will benefit from performance under water limited conditions, then add the character existing performance in a breeding program.

Using molecular techniques, several classes of genes have been identified that confer resistance to water deficit. Some of these genes could be used to engineer plants for resistance to drought and yield crops better in dry conditions. First, the enzymes that synthesize osmoprotectant, small molecules that accumulate in the cytoplasm plants to drought stress have been identified.
Genetically modified plants with genes encoding these enzymes are more tolerant drought. Second, the genes that encode transcription factors that regulate entire metabolic pathways leading to adaptation to drought have been identified. By integrating these genes, we can hope to ensure that plants respond quickly and effectively to any shortage of water and continue throughout their development process.

) Best Performance B on saline soil.
salt tolerance a complex, quantitative genetic trait controlled by many genes. Recently, a small number of genes have been identified which provides information useful in screening and selection programs for salt tolerance.
Four major stratergies as to develop tolerant Salt crops are the following:
1.gradually improve salt tolerance in conventional breeding and selection.
Example: development of salt tolerance in rice (Rice Pokkali) Kerala, India has been widely used for developing salt tolerance in other genotypes Rice desirable.
2.Introduce traits of salt tolerance in wild relatives of crops in the return process of transition.
Example: Tomato (Lycopersicon esculentum)
Barley (Hordeum vulgare) and wheat (Triticum aestivum).
3.Domesticate wildlife that currently inhabit saline environments (halophytes) By breeding and selection of improved agronomic characteristics.
4.Use molecular techniques to identify genes associated with tolerance Salt and improve their expression in the culture of cash or transfer the genes of culture not a kind of culture. Example: On the molecular level, genes involved in the detection of salt in the environment (signal transduction), transcription factor genes that run on batteries of genes others for the cells to withstand a higher rate of influx of salt, and genes that are part of the adaptation of plants in the presence of salt is being identified. An example of this latter category is the gene that encodes the vacuolar sodium pump. Plants that can turn the gene on rapidly when cells are exposed to salt will be able to transport salt from the cytoplasm into the vacuole, it detoxifying the cytoplasm. Example: Lycopersicon esculentum (tomato)

CONCULSION:

Conventional and GM farming are complementary approaches and can be expected to improve the resistance project and crop yields. People have entered a new era in which to improve knowledge of both the physiology of yield accumulation and the physiological basis of genetic variation in both salt and resistance traits a project has the potential to improve reproductive performance for major food crops in target environments. Using physiological knowledge and powerful tools

blog address: http://stresstolerance.blogspot.com/