Module 321
Plant Physiology
And Diversity
In conjunction with
PLANT BREEDING ............................................................................................................................................................. 4
HORTICULTURE ................................................................................................................................................................... 4
CLONAL REPRODUCTION AND FORESTRY ............................................................................................................................ 5
SEED DORMANCY AND PRE-HARVEST SPROUTING ............................................................................................................... 5
GENETIC MODIFICATION OF PLANTS........................................................................................................................ 6
OVERVIEW ........................................................................................................................................................................... 6
INCREASED YIELD ............................................................................................................................................................... 6
INSECT RESISTANCE ............................................................................................................................................................ 6
HERBICIDE RESISTANCE ...................................................................................................................................................... 7
VIRUS RESISTANCE .............................................................................................................................................................. 7
Papaya ........................................................................................................................................................................... 7
Squash (Pumpkins) ......................................................................................................................................................... 7
Potato ............................................................................................................................................................................. 7
Tobacco .......................................................................................................................................................................... 8
STRESS TOLERANCE ............................................................................................................................................................ 8
Salinity Tolerance .......................................................................................................................................................... 8
Shade Avoidance Syndrome ........................................................................................................................................... 8
Drought Tolerance ......................................................................................................................................................... 9
OTHER TRAITS ..................................................................................................................................................................... 9
Nutritional Benefits ........................................................................................................................................................ 9
Pre-Harvest Sprouting ................................................................................................................................................... 9
BIOPHARMING ................................................................................................................................................................... 10
BIOLISTIC GENE GUNS ........................................................................................................................................................ 10
CELLULASES IN INDUSTRY .......................................................................................................................................... 11
CARBON TRADING .......................................................................................................................................................... 11
PHYTOREMEDIATION .................................................................................................................................................... 12
HERBICIDES – USES AND MARKETS .......................................................................................................................... 12
NITROGEN AND FERTILISERS – USES AND MARKETS ........................................................................................ 13
Introduction to this resource
This resource is designed with one aim in mind, that being to help the students taking module 321
appreciate the diverse ways in which biological knowledge has been harnessed to create wealth and
resolve problems.
The facts and examples are by no means exhaustive, but they should help illustrate the biological and
economic importance of the topics covered within the module. This is also written for the students
rather than academics, and all of this material, including that for other modules is on the York
BioEnterprise website.
.
http://www.york.ac.uk/depts/biol/bioenterprise/
Plant Breeding
In horticulture as well as agriculture, new breeds of plant with enhanced or novel properties are
continually being sought. In the horticultural world, a novel rose makes the headlines, especially
something like the blue rose developed by Florigene, which was thought to be impossible. There is
also a race to produce the first true black pigmented plant.
http://www.suntory.com/news/2004/8826.html - Developing the blue rose. Press release and details
http://www.florigene.com – Blue roses and other biotech developed flowers, final products.
Natural breeding methods are also used, with novel attractive varieties attracting attention and sales.
Individuals as well as companies strive to create novel appearances, smells, or other traits such as
longevity. Successful breeds can even make the news, such as that developed by David Austen
http://news.bbc.co.uk/2/hi/uk_news/england/shropshire/3632831.stm - New rose variety.
http://news.bbc.co.uk/2/hi/business/3551023.stm - New arid-tolerant strains
Seed companies also pursue breeding programs to develop new higher yield or more resistant hybrids.
In recent years this has branched out into the entirely new field of GM crops, but companies associated
with GM such as Monsanto also pursue more traditional methods of breeding.
http://www.monsanto.com/monsanto/us_ag/layout/seed/seed_science/section2a.asp - DEKALB and
Asgrow strain corn from Monsanto
Horticulture
British horticulture is worth about £2bn each year. Of this the UK fresh cut flower and indoor plant
market is worth over £1.45bn, which represents an average annual spend per person of £26. There
is a host of other impressive statistics available at this link:
http://www.nfu.org.uk/stellentdev/groups/public/documents/farming_facts/factsonbritishhor_ia412
f45c7-2.hcsp - Facts & Figures about the British flower market
http://www.metz.nl/en/index.html - Major European flower wholesaler with market details.
As well as being about simply growing flowers which also
involves the pesticide, herbicide and biocontrol industries,
horticulture also relies on the production of new breeds. Various
companies around the world continually breed varieties of plants in
attempts to get progeny with new traits, such as the blue rose from
Florigene and Suntory. Blue roses were considered something of a
holy grail until recently, when biotech was used to transfer genes
coding for the blue pigment making enzyme, flavonoid 3’5’hydroxylase to rose plants.
http://www.hortresearch.co.nz/ - Breeding and modification programs.
http://www.suntory.com/news/2004/8826.html - Developing the blue rose. Press release and
details
http://www.florigene.com – Blue roses and other biotech developed flowers. Final products.
Natural breeding methods are also used, with novel, attractive varieties attracting attention and
sales. Individuals as well as companies strive to create novel appearances, smells, or other traits
such as longevity. Successful breeds can even make the news, such as that developed by David
Austen
http://news.bbc.co.uk/2/hi/uk_news/england/shropshire/3632831.stm - New rose variety.
http://news.bbc.co.uk/2/hi/business/3551023.stm - New arid-tolerant strains
Clonal Reproduction and Forestry
The ability of plants to reproduce clonally is of great benefit in several industries. The primary of
which is the forestry industry, where straightness of limb and height of tree are valued. There is
also the promise of uniformity in size and shape of forests, with a consequent cost saving in
management and processing, as well as perhaps greater growth rates and reduced harvesting
cycles. By selecting the “elite” trees that fit these criteria, and producing cuttings, or harvesting
their seed whole forests are being created with the desired properties but only 1 or 2 genotypes.
The global trade in primary forest products such as logs, sawn wood, panels, pulp, and paper was
nearly US$273 billion in 1997.
http://www.forests.qld.gov.au/educat/btl/clonal.htm - Australian research and clonal forestry.
http://www.forestry.gov.uk/forestry/kirn-5lebqz - UK clonal forestry.
http://www.forestry.gov.uk/forestry/GGAE-5HNLVP - Various presentations and resources.
http://www.worldforestry.org/wfi/trade-1.htm - World forestry market data.
Seed Dormancy and pre-harvest sprouting
Seed dormancy is nature's way of setting a time clock that allows seeds to initiate germination
when conditions are favorable for survival of the seedlings. For example, dogwoods produce
mature seeds in the autumn, but seeds that germinated would face a harsh winter and poor chances
of survival. Thus, dogwoods have developed a mechanism that keeps the seeds dormant until
spring when conditions are favorable for germination, as well as seedling growth and survival.
Various mechanisms are used to control dormancy, summarised in various books and websites.
Dormancy is a big issue for farmers. Pre-harvest sprouting (PHS) of wheat grain is a particular
problem, as it causes downgrading of grain quality, severely limits end-use applications and results
in substantial financial losses to farmers and food processors. Tolerance to PHS is therefore a
highly desirable but complex trait sought by plant breeders.
Germination can be artificially induced via various methods from scarification of the seeds to
storage in a cold, moist environment or even using growth promoters like gibberellins.
The agricultural seed industry is worth approximately $24.4 billion and 30% of this is controlled
by just 10 companies. DuPont, Monsanto, Syngenta, Groupe Limagrain and Advanta
(AstraZeneca) are the 5 largest companies in this sector. It is likely that most farmers throughout
the UK buy their seeds from one of these companies.
http://www.ces.ncsu.edu/hil/hil-8704.html - Seed dormancy in trees and shrubs.
http://www.sproutnet.com/seed_dormancy.htm - Seed supplier with details on dormancy.
http://seeds.thompson-morgan.com/uk/en - World renowned seed company
http://www.etcgroup.org/documents/com_globilization.pdf - Report on the trend of centralisation
and acquisition in the seed and agrichemical industry.
Genetic Modification of Plants
Overview
Demand for crop commodities is increasing dramatically, as world population has tripled over the past
70 years to more than 6 billion and is expected to reach 8 billion by 2025. World agricultural
production is already falling short of what is required, and is going to have to increase in line with the
extra demand. GM, fertilisers and better farming practices are going to play crucial roles.
In 2003, about 167 million acres (67.7 million hectares, about 25% of all land under cultivation) in 18
countries, was planted with GM crops, the principal ones being herbicide and insecticide-resistant
soybeans, corn, cotton, and canola. Of the 67.7 million hectares the USA had the biggest share with
63%. Others included Argentina (21%), Canada (6%), Brazil (4%), China (4%), and South Africa
(1%).
In the coming years other crops will be grown commercially or field-tested. Current research is
looking at products such as sweet potatoes resistant to a virus that decimates the African harvest, rice
with increased iron and vitamins that may alleviate chronic malnutrition in Asian countries, and a
variety of plants able to survive weather extremes. Also on the horizon are bananas that produce
human vaccines against infectious diseases such as hepatitis B; fish that mature more quickly; fruit and
nut trees that yield years earlier, and plants that produce new plastics with unique properties.
http://www.ey.com/global/download.nsf/International/Beyond_Borders_2003_Executive_Summary/$f
ile/2003%20Beyond%20Borders%20exec%20sum.pdf - Ernst and Young Overview of GM crop
industry used by professionals and very well referenced. Worth a look.
http://news.bbc.co.uk/2/hi/americas/4076525.stm - GM Cocaine anyone?
Increased Yield
Syngenta spent about $30m (£21m) decoding the rice genome in order to
develop new high-yield strains of the crop that feeds almost half of humanity.
What they didn’t expect though was that approximately 98% of the known
corn, wheat, and barley genes are present in rice. This similarity has allowed
Syngenta to map more than 2000 cereal traits on the rice genome. They expect
to be able to improve both in yield and quality of new strains of cereals. As
well as simply increasing the amount of grain per head of wheat or the size of
the potato tuber, yield can be increased by reducing attack by or competition with pest species. This
type of research usually falls into the categories of insect, herbicide and disease resistance and novel
traits.
http://rise.genomics.org.cn/index.jsp - Oryza sativa L. ssp. japonica (Syngenta) – The genome
http://news.bbc.co.uk/2/hi/science/nature/1910889.stm - News Report
Insect Resistance
"Bt" is short for Bacillus thuringiensis, a soil bacterium whose spores contain a crystalline (Cry)
protein. In the insect gut, the protein breaks down to release a delta-endotoxin which binds to and
creates pores in the intestinal lining, resulting in ion imbalance, paralysis of the digestive system, and
after a few days, insect death. The use of Bt to control insect pests is not new various insecticides
containing Bt and its toxins (e.g., Dipel, Thuricide, Vectobac) have been sold for many years. These
products have been considered safe for mammals and birds, and safer for non-target insects than many
conventional insecticides. What is new in Bt crops though is that a modified version of the bacterial
Cry gene has been incorporated into the plant's own DNA, so that the plant's cellular machinery
produces the toxin. This gene has been successfully inserted into cotton, potatoes, canola and maize,
and more products are planned. In 2004 Monsanto sold over 1.3 million packets of transgenic cotton
seeds in India alone. GM is a highly contentious area of bioscience, but supporters of bt transgenic
crops highlight increased yields, lower use of chemical pesticides and supposedly better returns for the
farmers. The 2003 turnover of the big 4 GM seed producers Aventis, Monsanto, Syngenta and DuPont
were $17.8, $4.9, $5.5 and $26.9 billion respectively.
http://www.agbios.com/dbase.php - Easy searchable database and some very good examples.
Herbicide Resistance
One of the main focuses of GM research, Over 30 products on the market from Glyphosphate
(Roundup) tolerant soybean, cotton and canola to ulfonyl urea herbicide tolerant Carnations.
http://www.agbios.com/dbase.php - Easy searchable database and some very good examples.
Virus Resistance
Plant viruses cost the agricultural and horticultural sectors millions each year. Biotech companies have
been researching natural resistance as well as trying to develop new strains of GM crops with
engineered traits for resistance. Three commercial products are currently marketed; Papaya, Squash
and Potatoes.
http://www.apsnet.org/online/feature/BioTechnology/Engineering.html - Overview of plant virus
research.
http://www.whybiotech.com/index.asp?id=1262 - Potential benefits for another crop - strawberries
Papaya
Papaya (Carica papaya L.) is grown commercially in over 48 countries with a
combined harvest of 7 million metric tonnes. It is valued as a nutritional tropical
fruit, grown throughout the Caribbean and south America. Strains were developed
to resist the papaya ringspot virus (PRSV). The plants express viral coat proteins,
and although the exact mechanism is not know, it is thought that this interferes
with one of the first steps in viral replication, that of uncoating (removal of CP
from the incoming virus). The license is held by the Papaya Administration
Committee of Hawaii, and the seeds are marketed as Rainbow and SunUp. The
Hawaiian market is estimated at around $100 million annually.
http://www.whybiotech.com/index.asp?id=1646 - What where who and why of transgenic Papaya
http://www.agbios.com/dbase.php?action=Submit&evidx=37 - Patent history and background
Squash (Pumpkins)
Another important crop in the US, Squash and Pumpkins suffer from infection by cucumber
mosaic virus (CMV), watermelon mosaic virus (WMV) 2, and zucchini yellow mosaic virus
(ZYMV). Yellow crookneck squash (Cucurbita pepo L.), together with pumpkins, gourds, and
other squash, are grown in over 83 countries with a combined harvest of 15 million metric tonnes
in 2000. Other than removal of virus-infected plants, there are no other effective control measures
for these crops once infected. The CZW-3 squash line was developed using recombinant DNA
techniques to resist infection by CMV, ZYMV, and WMV2 by inserting virus-derived sequences
that encode the coat proteins (CPs) from each of these viruses. The mode of action is thought to be
the same as for virus resistant Papaya.
http://www.agbios.com/dbase.php?action=ShowProd&data=CZW-3 - Virus resistant squash info.
Potato
Potato (Solanum tuberosum L.) is grown commercially in over 150 countries with a combined
harvest of 311 million metric tons and is the fourth most important food crop in the world,
providing more edible food than the combined world output of fish and meat. Potato crops suffer
from viral and insect attack.
The Colorado potato beetle is the most destructive insect pest of potatoes in North America and
can completely defoliate potato plants. Traditional control is with insecticides. Viral attack from
Potato virus Y (PVY) is known to infect over 342 plant species in 69 genera and 27 families,
causing loss of yield and crop quality. Both problems were solved in one step by Monsanto who
used existing successful commercial potato strains and added virus and beetle resistance genes.
The transgenic NewLeaf® potato contain two novel genes, the cry3A gene from Bacillus
thuringiensis, which encodes an insecticidal endotoxin protein and the coat protein gene from
PVY-O. The exact mechanism of resistance to the virus is not fully understood.
Monsanto marketed the NewLeaf brands successfully during 2000-2002 but decided to halt
production after McDonalds cancelled orders for the potatoes and introduced a “no-GM” policy.
http://www.monsanto.co.uk/achievements/newleaf_potatoes.html - Monsanto NewLeaf plus page
http://www.agbios.com/dbase.php?action=ShowProd&data=RBMT15-101%2C+SEMT1502%2C+SEMT15-15 - Virus resistant potato info.
Tobacco
Tobacco Mosaic Virus is heavily studied and well characterised. Genes for the virus coat protein
have been inserted into several strains of the plant, conferring resistance to the virus. At the
moment no GM strains resistant to TMV are available commercially.
Stress Tolerance
Plant stresses are generally due to light, water, mineral nutrients and CO2 and can usually take the
form of either a lack, or a surfeit of the critical factor.
http://www.plantstress.com – excellent resource detailing the various issues along with updates on the
progress of research from the literature.
Salinity Tolerance
According to the United States Salinity Laboratory (USSL), UN Food and Agriculture
Organization (FAO), and others monitoring salinity, approximately one billion of the 13 billion
hectares worldwide are now salt-affected: roughly 30% of all irrigated lands globally, and more
than 50% of all land in some countries. Various teams around the world are working to increase
crop plant tolerance to saline soils by trying to transfer salt-tolerance genes from halophiles into
crop species. As yet no commercial varieties of crop plants have been produced, but research is
continuing. Exelixis and their subsidiary Agrinomics LLC have made some progress in this field
though their press releases have been somewhat few and far between recently. Grain BioTech, a
company spun-out from Murdoch University in Australia, does however have several varieties in
field trials, due to be approved in 2005. The test crops are modified with three genes that enable
them to take up water despite the harsh environmental conditions, and the plants currently have 30
per cent more stalks and seed heads than traditional wheat varieties in these conditions.
http://www.biotechnologydirectory.com.au/companies/grainbio.htm - Grain BioTech
http://www.the-scientist.com/yr2002/mar/research1_020304.html - Report on salinity tolerance.
http://www.exelixis.com – Company working to solve the problem.
http://www.biosalinity.org/ - Everything to do with halophytes and their adoption into agriculture.
Shade Avoidance Syndrome
When plants grow at high density, they perceive a decrease in the relative amounts of incoming red
light to light of other wavelengths. This change serves as a warning of competition, prodding the
plants to flower and create seeds. The byproduct of this process is that plant stems grow longer and
leaf volume declines, leading to decreases in biomass and yield, obviously an issue in crop plants!
Various labs around the world are trying to understand the genes and pathways responsible for this
trait, and to breed or engineer varieties that ignore these signals of competition.
http://www.hhmi.org/news/chory5.html - Details about the discovery and problem.
Drought Tolerance
Research into drought tolerance in crop plants is progressing, but it will be a few years yet before
farmers see the results. The end result could be of great benefit though, as freshwater scarcity has
been ranked by the UN as the second greatest environmental problem (behind climate change)
facing the new century. Researchers from Cornell University announced as far back as 2002 that
they had engineered rice with genes that synthesize trehalose, which is a sugar vital for extreme
drought tolerance. It seems that trehalose helps maintain individual cell structure and function
during severe environmental stresses that would kill most plants. Once the stress is removed, the
sugar also seems to help plant cells regain function and efficiency.
http://www.whybiotech.com/index.asp?id=2967 – Overview of state of research into drought (and
salinity) tolerance.
Other Traits
A wide variety of other aspects of plant growth and function have been looked at, all designed to offer
benefits to producers and ultimately consumers.
Nutritional Benefits
There is one major example of a GMO designed to confer nutritional advantages and that is socalled “Golden” rice, which contains high levels of Beta-Carotene, the precursor for vitamin A.
Between 100 and 140 million children and adults in 118 countries are vitamin A deficient, which
in severe cases can lead to blindness and death. Traditional rice varieties have a very low amount
of Beta-Carotene, and traditional breeding methods had failed to improve on this. However,
biotech came to the rescue and Golden Rice was developed by the Institute of Plant Sciences in
Zurich, who used genes from the daffodil to give the rice nutritionally significant levels of BetaCarotene. The rice was tested and made available cheaply to farmers and governments. However,
as with all GMO’s the rice suffered negative publicity and campaigning, which has meant it has
had difficulty getting government approval for use.
http://www.biotech-info.net/GR_tale.html - Complete story of the development of golden rice
written by the chief scientist involved in its development.
Pre-Harvest Sprouting
Pre-harvest sprouting (PHS) of wheat grain is a particular problem, as it causes downgrading of
grain quality, severely limits end-use applications and results in substantial financial losses to
farmers and food processors. Tolerance to PHS is therefore a highly desirable but complex trait
sought by plant breeders.
The agricultural seed industry is worth approximately $24.4 billion and 30% of this is controlled
by just 10 companies. DuPont, Monsanto, Syngenta, Groupe Limagrain and Advanta
(AstraZeneca) are the 5 largest companies in this sector. It is likely that most farmers throughout
the UK buy their seeds from one of these companies.
http://www.ces.ncsu.edu/hil/hil-8704.html - Seed dormancy in trees and shrubs.
http://www.sproutnet.com/seed_dormancy.htm - Seed supplier with details on dormancy.
http://seeds.thompson-morgan.com/uk/en - World renowned seed company
http://www.etcgroup.org/documents/com_globilization.pdf - Report on the trend of centralisation
and acquisition in the seed and agrichemical industry.
Biopharming
The concept of medicines from plants is not new. Many common medicines, such as codeine, the
laxative Metamucil and the anti-cancer drug Taxol are purified from plants, to say nothing of scores of
herbal nostrums. But biopharming's great promise lies in recombinant techniques giving plants radical
new capabilities, and producing cheap drugs for the worlds markets. Various companies have
products, such as lactoferrin and lysozyme from rice which is being developed by Ventria Bioscience
and recombinant trypsin and recombinant aprotinin from maize, produced by Prodigene. The vast
majority of biopharming products are still at the research or clinical trial stages though, and have yet to
surmount the negative publicity common to all GM products.
http://www.prodigene.com - TrypZean™ and AproliZean™ from maize.
http://www.ventriabio.com/products - Lactoferrin and Lysozyme in rice.
http://www.lsbc.com – Large Scale Biology Corp was the first company to have its biopharmed
products clinically tested on lymphomas in humans. The company produces various proteins and
therapeutics using its GENEWARE® technology to transform tobacco plants.
Biolistic gene guns
The first gene guns were developed from research at Cornell University, and
later at the Particle Technology Laboratory at the University of Minnesota.
These universities have since licensed their patents to various companies. Some
examples of commercially available gene guns are below.
http://www.it.umn.edu/news/inventing/2000_Fall/nano_genegun.html - History
of the gene gun.
http://www.bio-rad.com/ - Search for “Helios” to see their hand held gene gun product.
Cellulases in Industry
Cellulose is an integral part of plant cell walls, but it poses several problems when plant material is
used commercially. In the paper industry for example, wood chips have to be "cooked" along with
sodium hydroxide and sodium sulphide at high temperature in order to remove lignin and disrupt the
cellulose fibres. Cellulases get most use in the production of recycled paper, as recycled pulp has a
high proportion of small fibres, which makes drainage of water from the pulp slow. Cellulases are
used to digest these fine fibers, increasing the drainage rate and speeding the manufacturing process.
http://www.borealforest.org/paper/mill.htm - Paper manufacturing process.
http://www2.biotech.wisc.edu/jeffries/wolnak/wolnak.html - Cellulases in paper manufacturing.
http://www.dyadic-group.com/wt/dyad/bio_refining - FibreZyme L Cellulase from Dyadic.
Carbon trading
The EU Emissions Trading Scheme, covering 25 countries in the European Union is set to start in
2005. It aims to help reduce emissions from the European Union to 8% below 1990 levels by the end
of 2012. Member States have accepted caps on their emissions of greenhouse gases, starting with
carbon dioxide. Overall about 12-16 thousand installations (which together produce over 40% of
European emissions) are covered by the scheme. Examples include Mineral Oil refineries Installations
for the production of pig iron or steel, glass, ceramics, industrial plants for the production of pulp from
timber. Governments are set to allocate their available emission credits to companies. But if the
companies exceed these limits they either have to pay fines, or buy credits from other companies. This
is where the global carbon traders come into the picture, buying credits from one company and selling
them on to those that need them. During the first phase of the scheme, an excess emissions penalty of
€40 per ton of CO2 emitted will be levied on all installations that fail to meet their target for CO2
emissions; this will rise to €100 per ton during the latter phases of the scheme.
The World Bank's Carbon Market Intelligence Study was recently published and
it projected that the value of the carbon market is set to increase to $10bn by
2007.
Only a few deals have currently been completed, for example a
“major European company” has recently bought carbon credits
from collaboration between three Sugarcane waste-fired
electricity generation facilities in Brazil. A seven-figure
volume of CERs (Certified Emission Reductions) from these
facilities was bundled together and purchased. The CERs will
be generated from renewable energy, using sugarcane waste residue as a fuel for electricity
cogeneration. This is the first public transaction of CERs by a company in the European Union.
http://www.co2e.com/images/cm/CO2ePressRelease.doc - 1st EU trade from CO2e
http://www.pointcarbon.com/ - Global Carbon Trading with live bidding prices
http://unfccc.int/ -United Nations Framework Convention on Climate Change homepage (Kyoto)
http://www.prototypecarbonfund.org - World Bank Prototype Carbon Fund
http://www.biocarbonfund.org - BioCarbon Fund
http://www.communitycarbonfund.org - Community Carbon Fund
http://www.ecosecurities.com - Ecosecurities
http://www.unep.net/climate/ - UNEP Environment Network Climate site
http://www.inencogroup.com/emissions_trading.html - UK firm
http://www.carbonriskmanagement.com/index_engl.htm - Entrepreneur’s own site
http://www.forest.nsw.gov.au/publication/forest_facts/growing_trees/default.asp - Growing trees for
carbon credits – Australian government guide.
Phytoremediation
Phytoremediation is defined as “Biological remediation of environmental problems using plants.”
Plants can be used to remove toxic metals from soils, stabilise slopes or degrade chemicals.
Enhanced Rhizosphere Biodegradation takes place in the soil immediately surrounding plant
roots. Natural substances released by plant roots supply nutrients to microorganisms, which
enhances their biological activities. Plant roots also loosen the soil and then die, leaving paths for
transport of water and aeration. This process tends to pull water to the surface zone and dry the
lower saturated zones. Phyto-accumulation is the uptake of contaminants by plant roots and the
translocation/accumulation (phytoextraction) of contaminants into plant shoots and leaves. Phytodegradation is the metabolism of contaminants within plant tissues. Plants produce enzymes, such
as dehalogenase and oxygenase, that help catalyze degradation. Investigations are proceeding to
determine if both aromatic and chlorinated aliphatic compounds are amenable to phytodegradation. Phyto-stabilization is the phenomenon of production of chemical compounds by
plant to immobilize contaminants at the interface of roots and soil
There are several limitations with phytoremediation. Firstly it is a new technology,
still very much in its infancy and so there is as yet little regulation and guidelines
about how best to use it. Also, only the top layers of soil actually penetrated by the
plant roots would benefit from the process, and there is a limit on the amount of
toxicity plants can survive so phytoremediation is usually not an option for the very
worst contaminated sites. Without proper control there is also scope for the
mobilisation of hazardous chemicals into the groundwater, or of bioaccumulation into
animals and humans.
http://www.ars.usda.gov/is/AR/archive/jun00/soil0600.htm - Great resource on phytoremediation.
http://www.envirotools.org/ - Overview of remediation technologies and applications
Herbicides – Uses and Markets
Since the Second World War, agriculture has become bigger, more intensive and more specialised. It
is one of the world’s largest industries, employing 1.3 billion people and producing $1.3 trillion-worth
of goods a year. World output of food per head has gone up by some 25% over the past 40 years, even
though land use has grown by only 10% and world population has increased by 90%. Food prices in
real terms have fallen by two-fifths, so that rich consumers in America, for example, now spend only
14% of their household income on food.
http://www.economist.com/surveys/PrinterFriendly.cfm?Story_ID=295632 – Global agricultural
industry.
Herbicides account for over half the value of the $29 billion global pesticide market,
and post-emergent products are the fastest growing area, partly led by their use in
combination with GE crops, and in no-till agriculture. However an important concern
is herbicide resistance, which as for pesticides is becoming a major problem.
Glyphosate is the most successful herbicide in history, and with sales of over $3 billion a year it
accounts for over 10% of the total value of the world pesticide market. Its sales are greater than the
total of the next 10 largest agrochemical active ingredients. Although it was first characterised in 1964,
its herbicidal properties were not recognized until Monsanto independently synthesised and patented it
in 1970. It is estimated that Monsanto directly or indirectly control 80% of the global glyphosate
market, especially via their control of the Roundup Ready crop market.
http://www.pan-uk.org/pestnews/pn60/pn60p23.htm - Report on global herbicide use
http://www.monsanto.com/monsanto/layout/products/productivity/roundup/default.asp - Roundup(R)
http://www.panna.org/resources/panups/panup_20030414.dv.html - 6 largest agrichemical companies
Nitrogen and Fertilisers – Uses and Markets
Demand for crop commodities is increasing dramatically, as world population
has tripled over the past 70 years to more than 6 billion and is expected to reach
8 billion by 2025. It is estimated that if no fertilisers were available then even
now up to 2 billion people would starve. PotashCorp, the world’s largest
producer of Phosphorous and Nitrogen fertilisers posted 2003 sales of over
$2.3bn. Other large fertiliser producers include IMC, Belaruskali, Cargill and
Agrium.
Over 120 million tons of nitrogen fertiliser are used each year globally. Yet only
~20 million tons are retained in the food we eat, some are retained in the terrestrial ecosystem but the
majority is washed into the water systems, eventually ending up in the sea. This pollution causes
several environmental problems, the best documented of which are algal blooms which use up the
available oxygen and suffocate fish.
http://www.potashcorp.com/ - The world’s largest fertiliser company. Excellent market resource
section detailing almost everything you could want to know about the production and uses of
fertilisers.
http://news.bbc.co.uk/2/hi/science/nature/3577711.stm - Dead Zones and algal blooms
http://www.esa.int/export/esaCP/SEM340NKPZD_Protecting_0.html - Nitrogen pollution map.
http://www.esa.org/sbi/sbi_issues/issues_text/issue1.htm - Report on nitrogen pollution.
http://news.bbc.co.uk/2/hi/science/nature/4038205.stm - Can mankind feed itself? The BBC
investigates