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    The Société de Transport de Montréal is to buy 8 biodiesel-electric hybrid buses that will use 20% less fuel and cut 330 tons of GHG emissions per annum. Courrier Ahuntsic - April 3, 2007.

    Thailand mandates B2, a mixture of 2% biodiesel and 98% diesel. According to Energy Minister Piyasvasti Amranand, the mandate comes into effect by April next year. Bangkok Post - April 3, 2007.

    In what is described as a defeat for the Bush administration, the U.S. Supreme Court ruled [*.pdf] today that environmental officials have the power to regulate greenhouse gas emissions that spur global warming. By a 5-4 vote, the nation's highest court told the U.S. Environmental Protection Agency to reconsider its refusal to regulate carbon dioxide and other emissions from new cars and trucks that contribute to climate change. Reuters - April 2, 2007.

    Goldman Sachs estimates that, in the absence of current trade barriers, Latin America could supply all the ethanol required in the US and Europe at a cost of $45 per barrel – just over half the cost of US-made ethanol. EuroToday - April 2, 2007.

    The Kauai Island Utility Cooperative signed a long-term purchase power agreement last week with Green Energy Team, LLC. The 20-year agreement enables KIUC to purchase power from Green Energy's proposed 6.4 megawatt biomass-to-energy facility, which will use agricultural waste to generate power. Honolulu Advertiser - April 2, 2007.

    The market trend to heavier, more powerful hybrids is eroding the fuel consumption advantage of hybrid technology, according to a study done by researchers at the University of British Columbia. GreenCarCongress - March 30, 2007.

    Hungarian privately-owned bio-ethanol project firm Mabio is planning to complete an €80-85 million ethanol plant in Southeast Hungary's Csabacsud by end-2008. Onet/Interfax - March 29, 2007.

    Energy and engineering group Abengoa announces it has applied for planning permission to build a bioethanol plant in north-east England with a capacity of about 400,000 tonnes a year. Reuters - March 29, 2007.

    The second European Summer School on Renewable Motor Fuels will be held in Warsaw, Poland, from 29 to 31 August 2007. The goal of the event is to disseminate the knowledge generated within the EU-funded RENEW (Renewable Fuels for Advanced Powertrains) project and present it to the European academic audience and stakeholders. Topics on the agenda include generation of synthetic gas from biomass and gas cleaning; transport fuel synthesis from synthetic gas; biofuel use in different motors; biomass potentials, supply and logistics, and technology, cost and life-cycle assessment of BtL pathways. Cordis News - March 27, 2007.

    Green Swedes want even more renewables, according to a study from Gothenburg University. Support for hydroelectricity and biofuels has increased, whereas three-quarters of people want Sweden to concentrate more on wind and solar too. Swedes still back the nuclear phase-out plans. The country is Europe's largest ethanol user. It imports 75% of the biofuel from Brazil. Sveriges Radio International - March 27, 2007.

    Fiat will launch its Brazilian-built flex-fuel Uno in South Africa later this year. The flex-fuel Uno, which can run on gasoline, ethanol or any combination of the two fuels, was displayed at the Durban Auto Show, and is set to become popular as South Africa enters the ethanol era. Automotive World - March 27, 2007.

    Siemens Power Generation (PG) is to supply two steam turbine gensets to a biomass-fired plant in Três Lagoas, 600 kilometers northwest of São Paulo. The order, valued at €22 million, was placed by the Brazilian company Pöyry Empreendimentos, part of VCP (Votorantim Celulose e Papel), one of the biggest cellulose producers in the Americas. PRDomain - March 25, 2007.

    Asia’s demand for oil will nearly double over the next 25 years and will account for 85% of the increased demand in 2007, Organization of Petroleum Exporting Countries (Opec) officials forecast yesterday at a Bangkok-hosted energy conference. Daily Times - March 24, 2007.

    Portugal's government expects total investment in biomass energy will reach €500 million in 2012, when its target of 250MW capacity is reached. By that date, biomass will reduce 700,000 tonnes of carbon emissions. By 2010, biomass will represent 5% of the country's energy production. Forbes - March 22, 2007.

    The Scottish Executive has announced a biomass action plan for Scotland, through which dozens of green energy projects across the region are set to benefit from an additional £3 million of funding. The plan includes greater use of the forestry and agriculture sectors, together with grant support to encourage greater use of biomass products. Energy Business Review Online - March 21, 2007.

    The U.S. Dep't of Agriculture's Forest Service has selected 26 small businesses and community groups to receive US$6.2 million in grants from for the development of innovative uses for woody biomass. American Agriculturalist - March 21, 2007.

    Three universities, a government laboratory, and several companies are joining forces in Colorado to create what organizers hope will be a major player in the emerging field of converting biomass into fuels and other products. The Colorado Center for Biorefining & Biofuels, or C2B2, combines the biofuels and biorefining expertise of the University of Colorado, Colorado State University, the Colorado School of Mines, and the Colorado-based National Renewable Energy Laboratory (NREL). Founding corporate members include Dow Chemical, Chevron, ConocoPhillips, and Shell. C&EN - March 20, 2007.

    The city of Rome has announced plans to run its public bus fleet on a fuel mix of 20 per cent biodiesel. The city council has signed an accord that would see its 2800 buses switch to the blended fuel in order to cut greenhouse gas emissions and local air pollution. A trial of 200 buses, if successful, would see the entire fleet running on the biofuel mix by the end of 2008. Estimates put the annual emission savings at 40,000 tonnes of carbon dioxide. CarbonPositive - March 19, 2007.

    CODON (Dutch Biotech Study Association) organises a symposium on the 'Biobased Economy' in Wageningen, Netherlands, home of one of Europe's largest agricultural universities. In a biobased economy, chemistry companies and other non-food enterprises primarily use renewable materials and biomass as their resources, instead of petroleum. The Netherlands has the ambition to have 30% of all used materials biobased, by 2030. FoodHolland - March 19, 2007.

    Energy giants BP and China National Petroleum Corp, the PRC's biggest oil producer, are among the companies that are in talks with Guangxi Xintiande Energy Co about buying a stake in the southern China ethanol producer to expand output. Xintiande Energy currently produces ethanol from cassava. ChinaDaily - March 16, 2007.

    Researchers at eTEC Business Development Ltd., a biofuels research company based in Vienna, Austria, have devised mobile facilities that successfully convert the biodiesel by-product glycerin into electricity. The facilities, according to researchers, will provide substantial economic growth for biodiesel plants while turning glycerin into productive renewable energy. Biodiesel Magazine - March 16, 2007.

    Ethanol Africa, which plans to build eight biofuel plants in the maize belt, has secured funding of €83/US$110 million (825 million Rand) for the first facility in Bothaville, its principal shareholder announced. Business Report - March 16, 2007.

    A joint venture between Energias de Portugal SGPS and Altri SGPS will be awarded licences to build five 100 MW biomass power stations in Portugal's eastern Castelo Branco region. EDP's EDP Bioelectrica unit and Altri's Celulose de Caima plan to fuel the power stations with forestry waste material. Total investment on the programme is projected at €250/US$333 million with 800 jobs being created. Forbes - March 16, 2007.

    Indian bioprocess engineering firm Praj wins €11/US$14.5 million contract for the construction of the wheat and beet based bio-ethanol plant for Biowanze SA in Belgium, a subsidiary of CropEnergies AG (a Sudzucker Group Company). The plant has an ethanol production capacity of 300,000 tons per year. IndiaPRWire - March 15, 2007.

    Shimadzu Scientific Instruments announced the availability of its new white paper, “Overview of Biofuels and the Analytical Processes Used in their Manufacture.” The paper is available for free download at the company’s website. The paper offers an overview of the rapidly expanding global biofuel market with specific focus on ethanol and biodiesel used in auto transportation. It provides context for these products within the fuel market and explains raw materials and manufacturing. Most important, the paper describes the analytical processes and equipment used for QA testing of raw materials, in-process materials, and end products. BusinessWire - March 15, 2007.

    Côte d'Ivoire's agriculture minister Amadou Gon has visited the biofuels section of the Salon de l'Agriculture in Paris, one of the largest fairs of its kind. According to his communication office, the minister is looking into drafting a plan for the introduction of biofuels in the West African country. AllAfrica [*French] - March 13, 2007.

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Tuesday, April 03, 2007

German dairy products group to make bioethanol from whey

A major advantage of biofuels is that they can be made from a wide variety of biomass feedstocks, including agro-industrial waste-streams. German dairy products group Theo Müller now adds a feedstock by announcing [*German] that it will start to produce bioethanol from whey (lactoserum), a byproduct from cheese production. The group with its seat in Leppersdorf near Dresden, will start the construction of a dedicated ethanol plant this month.

The company is investing €20/US$27 million in the complex, which will be the first to make biofuel from whey. Stefan Müller, CEO of the group, says that by the end of 2007 production will come online and when maximum capacity is reached, the plant will make 10 million liters (2.64 million gallons) of ethanol per year.

Whey or milk plasma is the acidic liquid remaining after milk has been curdled and strained; it is a by-product of the manufacture of cheese or casein. Typically every 100 kg of milk will give about 10-20 kg of cheese depending on the variety, and about 80-90 kg of liquid whey. Its disposal is a major problem for the dairy industry, partly due to its composition. It has a low solids content and a very unfavorable lactose : protein ratio which makes it difficult to utilize as-is. The biological oxygen demand (BOD) is 32,000 to 60,000 ppm, which creates a very severe disposal problem.

Despite continuing efforts to find uses for the whey, either as-is or in dry form, or its major components (high quality protein and lactose), it is estimated that as much as 40-50% of the whey produced is disposed off as sewage, with the rest being used primarily for animal feed or human food. World production is estimated at 80 to 130 million tons per year:
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Given this waste problem, scientists been looking into ways to utilise the resource, and since the 1980s they have been hinting at the fact that there is an opportunity to use whey as an ethanol feedstock. Global interest in the biofuel and high oil prices now make commercial production viable.

Whey ethanol production is similar to that relying on starchy feedstocks. The lactose present in whey is yeast fermented and the resultant ethanol is distilled off and then purified to one of eight grades depending on its intended end use.

For the German dairy products group, whey is a biofuel feedstock that comes at a very low cost because it produces a vast quantity of it that poses a waste problem. "For this reason, we are very competitive and independent of the price developments on the biofuels market", says Müller.

There is a small body of research on the production of ethanol from whey.

More information:

Scott L. Terrell, Alain Bernard, and Richard B. Bailey, "Ethanol from Whey: Continuous Fermentation with a Catabolite Repression-Resistant Saccharomyces cerevisiae Mutant", Appl Environ Microbiol. 1984 September; 48(3): 577–580.

Ron Hamilton (AnchorProducts, Tirau): The Manufacture of Ethanol from Whey [*.pdf] - s.d. New Zealand Institute of Chemistry.

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Researchers analyse greenhouse gas balance of different biofuels produced in the U.S.

Researchers from Colorado State University and the U.S. Department of Agriculture, Agricultural Research Service have conducted the first of its kind, complete analysis of greenhouse gas emissions from different forms of biofuel production found in the U.S. The results revealed that a variety of bioenergy crops used for biofuels have the potential to reduce the amount of greenhouse gas emissions per unit of energy generated as compared to greenhouse gases emitted from fossil fuels. The researchers published their results in the April 2007 issue of Ecological Applications.

William Parton, researcher from Colorado State's Natural Resource Ecology Laboratory, or NREL, says "We have performed a unique analysis of the net biofuel greenhouse emissions from major biofuel cropping systems by combining ecosystem computer model data with estimates of the amount fossil fuels used to grow and produce crops for biofuels."

Study results revealed that when compared with the life cycle of gasoline and diesel, biofuels reduce the amount of greenhouse gases that enter the atmosphere:
  • grain based, 'first generation' ethanol and biodiesel from corn and soybean rotations reduced greenhouse gas emissions by nearly 40 percent
  • cellulosic ethanol from reed canarygrass reduced greenhouse gas emissions by 85 percent
  • cellulosic ethanol from switchgrass and hybrid poplar reduced greenhouse gas emissions by about 115 percent
The numbers for corn based ethanol contradict earlier research, which shows marginal GHG emissions reductions for the fuel (earlier post). In any case, hybrid poplar and switchgrass were found to offset the largest amounts of fossil fuels and therefore reduced emissions the most out of the studied crops. Parton, along with Stephen Del Grosso, USDA scientist and NREL researcher, and Paul Adler from the USDA used the DAYCENT biogeochemistry model [*.pdf, see image, click to enlarge], developed by Parton and Del Grosso, to assess soil greenhouse gas fluxes and biomass yields for corn, soybean, alfalfa, hybrid poplar, reed canarygrass and switchgrass.
"Although fossil fuel inputs are required to produce and process biofuels, hybrid poplar and switchgrass converted to ethanol compensate for these emissions and actually remove greenhouse gasses from the atmosphere when the benefits of co-products are included. Greenhouse gas savings from biomass gasification for electricity generation are even greater. This research provides the basis for evaluating net biofuel greenhouse gas emissions and highlights the need to improve the technologies used for large scale conversion of biomass to energy and to more fully exploit agricultural co-products." -- Stephen Del Grosso, USDA scientist and NREL researcher.
Ethanol and biodiesel from corn and soybean are currently the main biofuel crops in the United States, but the perennial crops alfalfa, hybrid poplar, reed canarygrass and switchgrass have been proposed as future dedicated energy crops:
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Bioenergy crops are able to offset carbon dioxide emissions by converting atmospheric carbon dioxide into organic carbon in biomass and soil, but the production of biofuels requires fossil fuels and impacts greenhouse gas fluxes. The primary sources of greenhouse gas emissions associated with crop production are soil nitrous oxide emissions and the CO2 emissions from farm machinery, farm inputs and agricultural processes. Colorado State and USDA scientists quantified all of these factors to determine the net effect of several bioenergy crops on greenhouse gas emissions.

Researchers found that, once the DAYCENT results were combined with estimates of the amounts of fossil fuels used to provide farm inputs and operate agricultural machinery and the amount of fossil fuel offsets from biomass yields, they were able to calculate the net greenhouse gas fluxes for each cropping system.

"We used extensive observed greenhouse gas flux and crop yield data to verify DAYCENT model predictions of crop yields and net greenhouse gas fluxes from all of the biofuel crop rotations. DAYCENT model results were combined with life cycle analyses of crop production, conversion to biofuel, and fossil fuel displaced to estimate net greenhouse gas emissions," said Parton.

This study was a unique and complete analysis of bioenergy cropping for several reasons. Different crops vary with respect to length of plant life cycle, yields, biomass conversion efficiencies, required nutrients, net soil carbon balance, nitrogen losses and other characteristics which in turn impact management operations. Additionally, crops have different requirements for farm machinery inputs from planting, growing, soil tillage, applying fertilizer and pesticide and finally harvesting. The researchers were able to use life cycle analyses and the DAYCENT model to account for all of these factors as well as integrate climate, soil properties and land use to accurately evaluate the impact of bioenergy cropping systems on crop production, soil organic carbon and greenhouse gas fluxes.

Image: the carbon cycle, of which bioenergy cropping systems are a part.

More information:
The article in Ecological Applications is not yet online, but an abstract can be found here:

Adler, P.R., Del Grosso, S.J., Parton, W.J. 2007. "Cellulosic and Grain Bioenergy Crops Reduce Net Greenhouse Gas Emissions Associated with Transportation Fuels" [*abstract]. USDA Symposium on Greenhouse Gases & Carbon Sequestration in Agriculture and Forestry. p.32

On the DAYCENT model, see: D.S. Ojima , S.J. Del Grosso, W.J. Parton, A.R. Mosier and C. Keough, Model Overview, Testing and Application to Agroecosystems [*.pdf], Global Carbon Project.

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Algae biofuel company's claims questioned

At the Biopact, we are critical of biofuel companies who claim they can produce huge amounts of liquid fuels from algae. Often, these claims are mere marketing stunts and not based on any credible science (earlier post). If algae-to-biofuels ventures work out, then the better for all of us. But if they prove to be more difficult to pull off, the hype should end and some modesty would be welcome.

Now South Africa's most important investigative programme 'Carte Blanche' put the matter to the test by investigating the claims made by the much-feted algae biofuels startup De Beers Fuel (previous post). The researchers confirmed our doubts: the company massively exaggerates its ability to produce biodiesel from algae and has been spreading seriously incorrect information.

De Beers Fuel of Mookgopong, in Limpopo – which has no connection to diamond mining giant De Beers – has been claiming production of 6000 litres of algae-based biodiesel an hour. De Beers Fuel founder Frik de Beer is on record saying that “our current production on the pilot plant is 144 000 litres in 24 hours – we’re running the plant 25 days a month, it is all consumed locally, and we have 50-million litres of diesel on our order book per month”.

Based on these and other claims, the company has sold a number of biodiesel franchises to South African investors. Many of the franchises were sold under the Infiniti Biodiesel brand name.

The company’s website – which could still be accessed this morning, but has since been removed from the Internet – claimed that “92 plants involving 18 franchises” had been sold. The company’s website also claimed that five production plants were under construction.

However, when questioned by Carte Blanche, De Beer said that the company had only ever sold 41 000 litres of biodiesel and had 39 000 litres in its tanks, ready to be sold:
:: :: :: :: :: :: :: ::

De Beers Fuel was a platinum sponsor of the second African biofuels conference, which was held in Midrand last week. The company had a stand at the conference, at which it continuously showed a promotional video in which De Beer and others expanded on the firm’s production abilities.

What set apart the company from other biofuels producers in South Africa was the fact that it had entered into a partnership with GreenFuel Technologies Corporation of the US to locally promote GreenFuels’ proprietary algae technology. GreenFuels’ technology involves the production of vegetable oil from algae as a feedstock for biofuels.

The successful extraction of biofuels from algae supposedly offered a solution to the envisaged shortage of traditional biofuels feedstocks in South Africa, such as sunflower and soy oil. Investors in De Beers and Infiniti Biodiesel were given the impression that algae was an almost immediate solution to the anticipated shortage of vegetable oil for biofuels production.

However, when approached by Cart Blanche, GreenFuels CEO Paul Rodzianko said that “on an accelerated schedule, from today on, the earliest that a commercial scale facility would be available will probably be the end of next year, to the beginning of 2009.”

When approached for comment by Engineering News earlier today, a spokesperson for De Beers Fuel said that the company was preparing a formal response to the Carte Blanche programme broadcast on Sunday night in which it would comment on the contents of the programme.

This story is certainly to be continued.

More information:
A full transcript of the programme can be found here.
EngineeringNews: Investigative Carte Blanche casts doubt on De Beers Fuel - April 3, 2007.

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Conference explores the global biofuels supply chain

Quicknote bioenergy events
The Singapore based Centre for Management Technology (CMT) is organising a two-day conference on issues relating to the global supply chain of biofuels. The event will take place between June 7 and 8.

A world market for trade in bioenergy products is emerging rapidly, with both liquid and solid fuels being imported and exported, shipped across oceans, stored at ports and distributed to end markets. This new market brings challenges and opportunities to traders, shippers, brokers, logistics firms, ports and harbors.

For this reason, the conference looks at different aspects of biofuels and their supply chain:
  • what do the feedstock and trade flows look like?
  • which specifications and classifications apply to the new fuels?
  • what is the impact of regulation and feedstock availability on domestic production in US and EU and on global biofuels trade?
  • which challenges are ahead for port and terminal management? (Several European ports, like especially in Belgium and the Netherlands, are turning themselves into dedicated 'bioports')
  • what is the storage capacity (potential and current status)?
  • which Marpol regulations apply to which type of biofuels and vessels?
  • how can quality assurance be strentghened when storing and handling biofuels shipped in bulk and by ISO tank containers, road, rail and drummed stock?
  • when, where and how must biofuels be tested and what benchmark and methodologies should be applied?
  • how do oil prices/trends impact the global biofuels market?
  • given China's continuous strong growth and rising energy demand, what will be its role in the biofuels future?
Port authorities and management, shipping companies, risk managers, supply chain analysts, as well as traders and government representatives from Asia, Europe, Brazil and the US are invited as speakers to shed a light on this wide range of issues [entry ends here].
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Giant reversible swelling of nanoporous materials disovered - possible applications for storage of carbon dioxide and gaseous (bio)fuels

Scientists all over the world are participating in the quest for new materials with properties suitable for the environmentally friendly and economically feasible separation, recovery, and reuse of gaseous fuels, such as biogas and (bio-)hydrogen, and greenhouse gases like carbon dioxide, for which sequestration options are being researched. We follow developments surrounding carbon capture and storage (CCS), because they can be applied to biofuels and result in radically carbon-negative energy systems (here and here).

In this context, a team of scientists from France, the UK and the European Synchronotron Research Facility (ESRF) have recently discovered an unprecedented giant and reversible swelling of nanoporous materials with exceptional properties: huge flexibility and profound selectivity. They published their results [*abstract] in Science this week.

Porous hybrid solids are the new materials that could make the world more environmentally friendly (earlier post). The team from Institut Lavoisier at University of Versailles have developed metal-organic three-dimensional structures with cages and channels (known as MIL, for Material Institut Lavoisier). These compounds contain metal ions (in this case chromium and iron), with organic linkers and are very flexible, and hence, can change shape very easily. They can open up or close down in response to external factors such as pressure, temperature, light or influence of gases and solvents.

Crystals behaving like lungs
The French researchers, in collaboration with the staff of the Swiss-Norwegian experimental station (called beamline) at the ESRF, have tracked, for the first time, a reversible giant increase in volume of these solids (image, click to enlarge). It ranges from 85% of their size to up the unprecedented 230%. Such a large expansion in crystalline materials has not been observed before. This reversible “breathing” action is similar to the lungs’ function in humans: they grow in size when inhaling and go back to their original size when exhaling. The lungs expand, however, by only around 40%:
:: :: :: :: :: :: :: :: :: :: ::

The huge swelling effect has been achieved in a simple way: MIL materials were immersed into solvents, and their cavities were filled and thus opened by entering solvent molecules. This made the structures grow, without breaking bonds and retaining the crystallinity of the materials. This process was monitored at the ESRF, using high-quality synchrotron radiation and the experimental results were combined with computer chemistry simulations.

The swelling process can reversed by heating the solvated form and the dry form is then recovered. In this form, the material exhibited closed pores with almost no accessible porosity. Surprisingly, the same team published a paper last autumn where they showed that some gas molecules can close, but not open, the pores upon absorption. Moreover, the closed hydrated form demonstrates a remarkable selectivity in absorption of polar and nonpolar gases.

The next step for the team is to investigate how hydrogen or green-house gases can be stored in these kinds of materials. This may open a door to ecological applications such as (bio-)hydrogen and (bio-)methane-fuelled cars or the capture of carbon dioxide in the near future.

Structures (along the c axis) of the MIL-88A, B, C, D series in their dry forms (top) and open forms (bottom). Credit: ESRF.

More information:

Serre, C. Mellot-Draznieks, S. Surblé, N. Audebrand, Y. Filinchuk, G. Férey , "Role of Solvent-Host Interactions That Lead to Very Large Swelling of Hybrid Frameworks" [*abstract], Science, 30 March 2007: Vol. 315. no. 5820, pp. 1828 - 1831, DOI: 10.1126/science.1137975.

P. L. Llewellyn, S. Bourrelly,C. Serre, Y. Filinchuk, and G. Férey, "Hydrogen Storage in the Giant-Pore Metal-Organic Frameworks MIL-100 and MIL-101" [*abstract], Angewandte Chemie International Edition, Volume 45, Issue 48, Date: December 11, 2006, Pages: 8227-8231

Philip L. Llewellyn, Sandrine Bourrelly, Christian Serre, Yaroslav Filinchuk, Gérard Férey, "How Hydration Drastically Improves Adsorption Selectivity for CO2 over CH4 in the Flexible Chromium Terephthalate MIL-53" [*abstract], Angewandte Chemie, Volume 118, Issue 46, Date: November 27, 2006, Pages: 7915-7918

On new, high-capacity and biobased methane storage tanks relying on nanoporous materials, see Biopact: The bioeconomy at work: methane storage tanks for cars made from corn cobs - February 18, 2007

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Scientists discover 'master switch' in plant communication about environmental stress

Climate change is set to have an impact on plant biodiversity (see earlier) and on the productivity of agriculture across the planet. For this reason, scientists are trying to understand how plants communicate about environmental stresses, such as a lack of water, increased salinity or nutrient deficiencies. Insights into these processes eventually allow plant biologists to breed new generations of crops that can cope with rapidly changing environments (earlier post).

Scientists have puzzled for years in understanding how plants pass signals of stress from chloroplast to nuclei (image 1, click to enlarge). They know that chloroplasts - the cellular organelles that give plants their green color - have at least three different signals that can indicate a plant is under stress.

But now a team of scientists, including Shai Koussevitzky, a research associate in the University of Nevada's College of Agriculture, Biotechnology and Natural Resources, as well as Ron Mittler, an associate professor of biochemistry and molecular biology, has made an important step forward in the understanding of how chloroplasts communicate with a cell’s nucleus when stresses such as drought, heat, salinity or light become too great on the organism.

In their study [*abstract], published in Science this week, they determined that multiple distress signals in plants converge on a single pathway, which then channels the information to the nucleus. The study was part of a collaborative effort led by Joanne Chory, professor and director of the Plant Biology Laboratory at the Salk Institute for Biological Studies in La Jolla, Calif., and investigator with the Howard Hughes Medical Institute.

Koussevitzky, looking at the end of the signaling pathway, found the corresponding binding factor known as ABI4, a plant transcription factor the function of which is well understood. It prevents light-induced regulatory factors from activating gene expression. Additional work in the project had determined that the chloroplast-localized, nuclear-encoded protein GUN1 is required for integrating multiple stress-derived signals within the chloroplast. This work was conducted by the first co-author of the article, Ajit Nott, who was a research associate in Dr. Chory’s lab.

Many of the nuclear genes that encode chloroplast proteins are regulated by a “master switch” in response to environmental conditions. This “master switch,” like a binary computer, can activate or de-activate certain sets of genes based on stress signaling processes (image 2, click to enlarge):
:: :: :: :: :: :: :: :: ::

“One of our suggestions in the paper is that ABI4 seems like a prime candidate to be the ‘master switch,’” Koussevitzky said. “ABI4 binds to a newly identified sequence motif, and by doing so prevents light-induced regulatory factors from activating gene expression. It has a role in so many signaling processes in the plant, it might actually be the ‘master switch’ that researchers have been looking for.”

The discoveries are critical to future research efforts in designing new generations of plants, Mittler said.

“A lot of things that occur in the chloroplast are important for production, for growth, for response to the environment,” he said. “So this is a very basic mechanism of communication between the chloroplast and the nucleus. It had been previously suggested that the elements in this process go through multiple pathways. This work shows that the elements actually go through this one particular route.

“Now we are in much better shape in solving the question of generating plants that can use marginal water, or marginal soil, and do so in a way that the plant won’t completely suppress its normal metabolisms and activate all of its stress metabolisms when faced with a lot of stress. If you want to generate a plant that is more tolerant, you need to deal with these two things.”

Added Koussevitzky: “We’re trying to put the signaling pathways in the context of the plant’s stress response. It will take a little more tweaking, but at least knowing that it is going through a certain particular pathway will enable researchers to design what the targets should be downstream from these pathways.”

Work for the project was supported by a grant from the Department of Energy, the Howard Hughes Medical Institute, EMBO long term and Howard Hughes Medical Institute fellowships.

Image 1: the basic structure of a plant cell.

Image 2 (for the experts): Revised model of retrograde signaling pathways from chloroplasts. (A) When plastid development is impaired or when plastids are stressed, inhibition of PGE, accumulation of Mg-ProtoIX and the redox state of the PET generate a common signal depicted by X. X could either be a process facilitated by GUN1 or a product of GUN1 activity. GUN1 may either be required to generate the signal (pathway 1) or perceive it (pathway 2). In response to the GUN1-derived signal ABI4 binds the promoter of Lhcb preventing GBF (a G-box binding factor required for tissue-specific, light-induced expression of Lhcb) from binding. Unknown steps in the pathway are indicated by question marks. (B) In developed, non-stressed plastids no GUN1 derived signal is emitted, ABI4 does not bind the Lhcb promoter and GBF enhanced transcription occurs. The question mark indicates the unknown fate of ABI4. Thus, the data favor a model in which retrograde signals from damaged plastids are transmitted to repressors of nuclear gene expression. From the Supporting Online Materials [*.pdf].

More information:
Shai Koussevitzky, Ajit Nott, et al., "Multiple Signals from Damaged Chloroplasts Converge on a Common Pathway to Regulate Nuclear Gene Expression" [*abstract], Published Online March 29, 2007, Science; DOI: 10.1126/science. 1140516

University of Nevada, College of Agriculture, Biotechnology and Natural Resources

Ron Mittler's research page.

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