Today in AgBioView from www.agbioworld.org : September 13, 2005
* GM Crops Provide Benefits to Organic Growers
* Re: You are What You Eat
* Kenya to Repeat Field Trial for Bt Maize
* Revisiting Biotech Wheat
* India: Bumper Crop for GM Augmented Cotton
* Monsanto's Sales Double in India
* Technology Transfer 'Essential' for African Agriculture
* Open Source and Biotech
* Science Without Conscience is Worse than No Science
* Latest from Greenpeace India
* A Farewell to Bacterial Antibiotic Resistance Markers?
GM Crops Provide Benefits to Organic Growers
- Bob MacGregor
Now that the exclusion of GM crops from organic agriculture is becoming
increasingly enshrined in government definitions of the production
practice around the world, it will be harder to undo this entrenched
position when its disadvantages become too blindingly obvious for even the
most intransigent organic growers to discount.
However, this doesn't mean that organic growers can't benefit
substantially from GM crops in the meantime. We hear a lot about organic
growers risking "contamination" from neighboring GM crops (even though
this doesn't undermine their certification, it could harm the
marketability of their crops), but I haven't seen much about the pest
management advantages gained by organic growers who are neighbors to, say,
a Bt corn or cotton field.
Conventional growers have long grumbled about organic fields being a
source of weed, disease and insect pests; the opposite is true for fields
where these are effectively controlled. From an epidemiological
perspective, widespread use of Bt corn or cotton, as well as the various
RR crops, will make the whole neighborhood more benign to the production
of organic crops as background levels of weed seeds and insect pests
diminish. This observation should put a different slant on the issue of
coexistence, but I haven't seen it discussed to any extent. Is the effect
of pest population control by GM crops too slight to have any significant
impact on neighboring growers or has everyone just been focusing too much
on "Us vs. Them"?
Re: You are What You Eat
- The Slovak Spectator (Letter to the editor), September 9, 2005
Re: You are what you eat, Volume 11, Number 33, August 29 - September 4,
Foods produced through genetic modification (GM) technology are accepted
by the scientific community around the world. They are transparently and
extensively tested prior to any human consumption. As a result, they are
beneficially and safely used by people worldwide.
Unfortunately, the recent Spectator article on this topic appears to have
relied on fact-twisting and scare tactics contrary to the scientific
realities regarding GM foods. The benefits of GM technology have been
consistently recognized by global scientific organizations.
In a June 2005 study, the World Health Organization concluded: "The
development of GMOs offers the potential of increased agricultural
productivity or improved nutritional values that can contribute directly
to enhancing human health and development.
From a health perspective, there may also be indirect benefits such as a
reduction in agricultural chemical usage, enhanced farm income, crop
sustainability and food security, particularly in developing countries. As
the WHO study shows, acceptance of GM products is not just an American
position. The European Food Safety Agency (EFSA) determined recently that
EU member states had NO scientific basis for enacting safeguard measures
against GMOs. In 2000, the Vatican's Pontifical Academy of Sciences
stated, "Enhanced production of qualitatively improved food under
sustainable conditions could greatly alleviate both poverty and
These are goals that will become even more urgent as our numbers increase
by an estimated two billion additional people over the next few decades.
Modern science can help meet this challenge if it is applied in an
appropriately constructive social and economic context. Genetically
modified plants can play an important role in alleviating world food
Contrary to Greenpeaces assertion in the article that the Monsanto
Corporation was hiding studies and documentation about its GM product MON
863, the entire report was already in the possession of many countries,
including those in Europe.
In fact, the EFSA released the following statement after Greenpeace
announced its "discovery": "The GMO Panel has given careful consideration
to the arguments set out in the report.
Following its investigation of the report, and of the retrospective
evaluation of renal tissues and data derived from the 13-week rat feeding
study performed by independent peer reviews, the GMO Panel concludes that
there is no evidence presented in the report that changes the conclusion
already reached by the GMO Panel earlier this year in its Opinions on the
safety of the insect-protected genetically modified maize MON 863 (EFSA
2004a, b). These opinions state that the results of the rodent toxicity
study with MON 863 maize did not indicate concerns about its safety for
human and animal consumption.
The Slovak Spectator article also presents the inaccurate view that
farmers planting GM insect-resistant crops increase pesticide usage. In
fact, farmers who use GM crops are able to increase their use of non-toxic
phytocides. The use of caustic pesticides has dropped substantially as a
result of GM crops. The increased use of these phytocides allows farmers
to decrease tillage, save money on fuel, reduce tractor emissions, and
save soil that would otherwise have been lost.
Finally, Greenpeace claimed that the recent visit to Slovakia of Madelyn
Spirnak, Senior Advisor on Biotechnology to the United States Department
of State, was nothing more than a lobbying effort on behalf of U.S.
corporations. In fact, Ms Spirnak visited with Slovak government
officials, NGOs, scientists, and lawmakers in order to better understand
how the country is implementing EU and WTO requirements and what role
biotechnology will play in Slovakias economic future.
GMOs have been used in agriculture for over ten years without a single
health problem of any kind. The reality is that they have brought great
benefits in needy areas, for example, substantially raising productivity
among smallholder farmers in South Africa and vastly increasing cotton
production in India.
Eighteen countries around the world, including Spain and Germany in the
EU, the United States and Canada in North America, and Argentina in South
America, are leading the way in implementing this technology.
These countries are not interested in coercing others to employ the
technology, but simply want fair access to markets based on established
scientific principles instead of artificial political barriers and
Lawrence Silverman Deputy Chief of Mission US Embassy, Bratislava, Slovakia
Kenya to Repeat Field Trial for Bt Maize
- CropBiotech Net, http://www.isaaa.org/kc
The Kenya Agricultural Research Institute (KARI) and the International
Maize and Wheat Improvement Center (CIMMYT) are set to repeat the confined
field trial for Bt maize contrary to media reports that the government has
The trial to test the effectiveness of Bt maize that was genetically
modified to resist Kenyan stem borers started in May 2005 at an open
quarantine site at Kiboko, near Nairobi. It is to be repeated following an
inadvertent application of Furadan, a systemic insecticide, by the
technician in-charge to control white grubs.
CIMMYT and KARI project managers said the erroneous use of the insecticide
effectively invalidating the trial results, prompting them to notify the
National Biosafety Committee (NBC) on 18 July 2005 who recommended that
the current crop be immediately harvested and destroyed under the
supervision of the Kenya Plant Health Inspectorate Service (KEPHIS), which
also supervised its planting.
The Insect Resistant Maize for Africa (IRMA) project, a joint undertaking
of KARI and CIMMYT, will apply for the NBC’s permission to repeat the
trial at the same site once the Furadan has disintegrated--eight weeks
from the date it was applied.
For more information, contact Daniel Otunge of the Kenya Biotechnology
Information Center at email@example.com.
Revisiting Biotech Wheat
- Ross Korves, Truth About Trade & Technology, Sept. 8, 2005
Over a year has passed since commercialization of Roundup Ready (RR) hard
red spring wheat in the U.S. and Canada was put on indefinite hold over
concerns about market acceptance in the two countries and in major wheat
importing countries. The continued expansion in production of biotech
crops indicates that biotech wheat may have a brighter future in the years
Biotechnology continues to grow in acceptance as a valuable production
tool to increase output, lower costs, reduce pesticide use and enhance
consumer value. Last year Brazil established a government regulatory
structure for biotech crops. Biotech white corn for human consumption is
increasingly accepted by small growers in South Africa. India has approved
additional varieties of Bt cotton for more areas of the country. China
has completed extensive farmer field trials on Bt rice. Australia has had
broad adoption of Bt cotton and is having a wide ranging debate on
production of other biotech crops. The Philippines has approved additional
varieties of biotech corn. The EU and Japan have approved additional corn
varieties for import for feed and food use. Over one billion acres of
biotech crops have been planted since commercialization began in 1996.
The issue of biotech wheat is much wider than just herbicide tolerance.
Syngenta is working on a biotech fusarium head blight (FHB) resistant
wheat. FHB is considered to be the number one problem in yield and quality
for small grains. The fungus can be controlled with pesticides, but the
spray window is fairly narrow for the best control.
Less talked about is drought tolerant biotech wheat. Drought tolerance is
an issue for the richest soils in the U.S. and Argentina and the poorest
soils in Africa. Wheat has been characterized as a "desert weed" because
of its limited need for water, but it still needs substantial water at
critical seed formation and development stages.
Biotech wheat also holds promise for consumer traits. Protein quality,
nutrient content, reduced allergens, freshness and shelf-life of products
are all consumer issues at various levels of research. Without acceptance
of biotech production practices, consumer traits would have to carry the
whole weight of gaining regulatory and consumer acceptance of biotech
Wheat has to compete with other crops for the use of farmland. Some
analysts consider RR wheat and FHB resistant wheat as the first major
production technology breakthroughs for wheat since semi-dwarf varieties
in the early 1970s. The competition for farmland can be seen in the shift
in crop acreage over the past 10 years in North Dakota, a major growing
area for hard red spring wheat. Prior to 1996 government farm program
payments were tied to historical planting patterns for crops. The 1996
farm bill allowed farmers to respond more to market prices and production
In 1995 North Dakota farmers planted 11.3 million acres of wheat. By 2005
wheat plantings fell to 8.9 million acres. Soybeans, canola and corn which
benefit from biotechnology have increased acreage in North Dakota from
1995 to 2005. Soybean acres increased from 0.7 million acres to 3.0
million, canola from 0.2 million acres to 1.0 million acres, and corn for
grain from 0.7 million acres to 1.5 million acres.
In a June 2005 report William Wilson and others from North Dakota State
University estimated that hard red spring wheat yields would increase by
11-14 percent with the use of Roundup Ready Wheat (RRW). They noted this
is similar to yield increases with the adoption of biotech corn. Estimates
of cost savings range from $8.30 to $11.57 per acre for adopters of RRW.
Nonadopters are expected to save about $2.28 per acre as other herbicide
treatments are expected to have lower prices to meet the new competition.
For 2000 to 2004 North Dakota spring wheat yields averaged 36 bushels per
acre and market prices averaged $3.22 per bushel. An increase of 11
percent in yield would increase yields by 4 bushels per acre and gross
income by almost $13 per acre. The combined increase in yield and
reduction in cost would be over $20 per acre. Total gross income per acre
averaged $115 for 2000-2004.
U.S. and Canadian wheat growers also face the possibility that China may
jump ahead of them in releasing a biotech wheat. Most of the attention in
China is now focused on a decision to allow commercial biotech rice
production. Once that decision is made, China would likely also allow
production of other biotech food crops, including wheat. If China commits
to commercialization of biotech wheat, researchers in other countries that
are major wheat producers are likely to step up commercialization efforts.
While countries like Japan and the EU are rich enough to have the luxury
of rejecting biotech wheat, other price sensitive buyers are much more
likely to be accepting if some of the lower costs of production are
reflected in lower market prices. The Wilson report cited earlier
suggested that the market price difference for biotech wheat may be
$0.15-0.25 per bushel. Spring wheat is considered a premium wheat because
of its higher protein content. The ability to get a premium product for
less than a premium price could cause some buyers to accept biotech wheat.
U.S. and Canadian wheat producers cannot idly set by as the biotech
revolution continues to march around the world. They will have to address
real market issues and find solutions that work for producers and
India: Bumper Crop for GM Augmented Cotton
Mumbai, 9 Sept. (AKI) - The season's favourable climate, coupled with the
widespread use of genetically modified seeds (GM) have guaranteed India a
bumper cotton harvest with a production of 25 million bales, up seven
percent from 2004. Despite calls from environmental groups for a boycott,
the sale of GM seeds in India has increased by 131 percent since the
beginning of the year.
GM seeds were first introduced in the country in 2002: mostly hybrid seeds
or the so-called BT seeds containing strands of Bacillus Thuringiensis, a
bacteria that strengthens the cotton plant's resistance against
boll-weevil, a parasite commonly found in India.
Besides hybrid varieties, the BT seeds are the only GM seeds whose use is
approved by the Indian authorities. Still, environmental activists argue
that the introduction of such seeds will stifle and eventually replace
local cotton varieties, leading to the loss of bio-diversity, which they
say is essential for maintaining a natural balance.
But Indian cotton growers appear delighted with the results of the GM
seeds. "The GM seeds have made their impact and the harvest is destined to
grow," said R. K. Baldua, deputy president of Gujarat Ambuja Exports, one
of the main cotton exporting companies in Gujarat, the Indian state which
tops national cotton production figures.
According to Baldua, half of all cotton fields in India are now cultivated
with GM seeds, except in Gujarat where this year the proportion has shot
up to 90 percent.
Such figures signify a striking trend analysts say, pointing to how the
move to GM cotton has also involved first-time cotton farmers who have
abandoned their traditional crops such as tobacco and rice. The result is
that the total cotton hectarage in India this year has risen to 9.5
million hectares compared to nine million in 2004.
This despite the fact that a packet of GM seeds costs more than four times
the sum needed to buy a packet of non-GM seeds, which on average cost some
450 rupees, or nine euros.
According to officials of the US-based Monsanto agriculture and food
technology multinational, many cotton farmers have been attracted by the
greater variety of seeds on offer - up to 20, including semi-hybrids and
BT. Monsanto, a major producer of GM seeds is seeking approval from the
Indian authorities for the introduction of up to 100 varieties in the
Indian market. The US group has already awarded contracts to 19 Indian
companies for the production of such seeds in India.
Monsanto's Sales Double in India
- BBC News, Sept 7, 2005 http://news.bbc.co.uk/2/hi/south_asia/4223284.stm
Global biotech giant Monsanto says its sales of genetically modified
cotton seeds in India so far this year are more than double the figure for
2004. A Monsanto spokeswoman said the 131% jump vindicated Indian farmers'
faith in genetically altered cotton seeds.
Environmental activists have opposed Monsanto's attempts to market its
products in India over the years.
Critics say GM crops have not been studied adequately and could harm the
environment, a charge the firm denies. India's cotton industry plants all
types of cotton seeds on more than 7.9 million hectares a year.
Fight against pests Monsanto said it had sold more than three million
packets of genetically modified cotton seeds in India so far this year,
compared to last year's figure of 1.3 million packets.
A company spokeswoman, Ranjana Smetacek, told the BBC the rise in sales
was due to new varieties of seeds and to take up of the seeds by new
states in 2005. "This year, we have sold 20 different hybrids of BT cotton
seeds, as compared to four varieties last year, and we made a major
breakthrough in three northern Indian states - Punjab, Haryana and
Rajasthan," she said.
Technology Transfer 'Essential' for African Agriculture
- David Dickson, SciDev.Net, Sept 9, 2005
The winner of last year's World Food Prize says major reforms are needed
in the way Africa's agricultural research is organised if the continent is
to substantially increase food production.
Monty Jones, executive secretary of the Forum for Agricultural Research in
Africa, urges closer links between scientists and farmers to ensure that
research results are not only put into practice, but also disseminated
effectively between countries and regions. Jones won the 2004 prize for
his work on 'New Rice for Africa' (NERICA), which combines African and
Asian strains of rice into a new variety uniquely adapted to conditions in
West Africa .
Speaking yesterday (8 September) at the annual meeting of the British
Association for the Advancement of Science in Dublin, Ireland, he said
that one of the major challenges facing African agriculture was the
limited distribution of agricultural technologies.
"Too often [African] research programmes have been developed in isolation."
A technology developed in one African country might not get used elsewhere
because the infrastructure to transfer it is non-existent, he said. Jones
noted that there had been key successes in agricultural research in
Africa. Cassava yields, for example, have gone up by 40 per cent in the
past decade or so, thanks to the efforts of organisations such as
Nigeria's National Root Crops Research Institute. This has reduced the
need to import rice.
But overall, Jones painted a gloomy picture, in which agricultural
productivity had been declining in Africa for the past four to five
decades. Aware of the economic and social importance of agriculture, in
2002 the continent's political leaders called for African agriculture to
grow at an annual rate of six per cent by 2020.
Achieving this "daunting task" means, however, that Africa must become a
strategic player in agricultural research and development, said Jones.
He emphasised that science and technology had an important role to play.
But for this to happen, it would be important to build up both
institutions and human resources, as well as reform research practices, he
"For example, national institutions tend to stretch themselves too thinly,
and operate on meagre resources. They need to diversify their sources of
funding, and also involve the users of research -- including farmers and
the private sector who will be responsible for taking technology to the
market -- from the outset."
He said research institutes needed to become more involved in agribusiness
and with production. "We need to develop agricultural markets in Africa,
as well as find ways of developing appropriate technologies," said Jones,
adding that it was important "to follow an 'innovation system' approach to
agricultural research for development".
One problem, he explained, was that international research centres, such
as those operating through the Consultative Group of International
Agricultural Research (CGIAR), tend to be isolated from realities on the
ground. "They should integrate their work into regional priorities and
national programmes," he said. "We need to come up with a new mindset
within which everyone works as a team, and realises that they have a role
to play in driving the region's development."
Jones's institution, the Forum for Agricultural Research in Africa is
pursuing this objective, by for example stimulating the creation of
regional and subregional research organisations, and linking these
organisations to political bodies such as the New Partnership for Africa's
Development (NEPAD). "Today, Africa is the only region in the world in
which agricultural productivity is declining," he said. "We believe we can
reverse this trend."
Open Source and Biotech
- William Bains (Rufus Scientific, UK) Nature Biotechnology v.23, p.1046;
September, 2005; www.nature.com/nbt . Reproduced in AgBioView with the
permission of the editor
To the editor: Your editorial in the June issue (Nat. Biotechnol. 23,
633, 2005) on the biotech open source movement skirted round one critical
difference between biotech and the software industry whose 'open source'
movement Richard Jefferson seeks to emulate. Writing software is cheap and
can be done in your bedroom. Doing biotech is expensive and is done in
laboratories. Economics dictate that paying for this means that someone
has to get a return, either in money (which applies to industry) or kudos
(which drove the genome project).
The same was true of software when computers were vast and expensive and
needed air-conditioned rooms to work in. Software then was far simpler
than today. But it was expensive to produce and use, with the result: no
open source. The only way that biotech can be open source is if it becomes
technically as well as legally accessible.
There is no logical barrier to doing gene splicing or parallel chemistry
or surgery in a garage. But, for a variety of reasons, some historical and
some very practical, it is not done. What Jefferson should be doing is
thinking through the biotech equivalent of the microcomputer, the biotech
technology that any teenager can use at home (without killing themselves
and everyone around them). Then 'open source biology' would become a
But that is not the main reason for looking for the microcomputer of
biology. When computers were vast and expensive and made of individual
transistors, the benefits they bought were limited, restricted to the
bottom line of large corporations and governments, and widely distrusted.
Once the microcomputer got into the hands of inventive teenagers, the
'computer revolution' exploded on us, and commercial interests followed
with technological marvels. Open source biology would do more than provide
a cheaper route to new malaria therapy. It would start the real biotech
revolution, the one that some of us have been waiting for since 1973.
(But...please don't try it out in my garage!)
Science Without Conscience is Worse than No Science
- Gargi Parsai, The Hindu (India), September 12, 2005
Jacques Diouf, Director-General of the Food and Agriculture Organisation,
has strong views on the issue of genetically modified organisms. In an
interview, he says we need to put in place an internationally agreed
How is India moving towards the World Food Summit goal of reducing hunger
by half by 2015?
- India has made progress from having 25% of its population undernourished
in the base period used by the World Food Summit in 1992 to 21% in the
period of 1999-2001, which is a progress. But if you are projecting it in
cutting by half the number of hungry people, that is not sufficient.
Because the population is growing at 1.6% you need to cut even more the
number of undernourished people to achieve the goal.
What is your sense of the direction in which the Indian Government is
moving in food and agriculture?
- We appreciate the new focus and priorities of the Indian Government to
the rural sector, particularly that it has agreed to invest more in
agricultural, water and rural infrastructure. We have also discussed the
importance of contract farming - to allow farmers to produce under legally
agreed conditions - and the whole question of productivity, which has been
on the rise with the green revolution, but has stagnated. On the
environment side is the whole question of reforestation but also of
community forestt development.
What is the FAO's role in legislation and the regulatory framework to
protect farmers' rights?
- After seven years of long difficult negotiations, FAO member countries
arrived at a unanimous decision on the International Treaty on Plant
Genetic Resources that recognises the rights of breeders, farmers and
research institutions who have improved seeds to a level where someone
adds a gene [and develops a variety]. We have to address the issue of how
these will concretely benefit farmers and that the benefits would be
effectively shared between the farmers and those who will invest in
additional work on timproving these genetic resources.
What about the Intellectual Property Rights on varieties developed from
resources taken from the common gene pool?
- We are working on the need to address the issue of the common
interpretation of the provisions of the International Treaty on Plant
Genetic Resources, the Convention on Bio-diversity, and the provision of
the Trade Related Intellectual Property Rights (TRIPS) in the WTO.
There is a lot of focus on diversification. In view of your projections
this year of a drop in cereal production, is that a sustainable goal?
- There will be a drop in cereal production to demand and as a consequence
an obligation to draw on the stocks that exist. World population is
expected to move from six billion to nine billion ... by which year, is
controversial. That would need about 60% of the present world production
against constraints on land, soil, water, productivity and so on. To
achieve that is no miracle. You have to invest in rural infrastructure,
technology, conservation, and marketing.
The FAO seems to have changed its stance last year towards genetically
modified organisms (GMOs). You've talked of wearing two hats on this?
- There has been no change. We have always been wearing two hats. One is
of being an organisation which, with the World Health Organisation, sets
standards through the Codex Alimentarius [food code ] for the quality [and
safety] of food. On the other hand, we help developing countries build
their institutions and train their people to be up to the level of
scientists, policy makers, and research institutions in the developed
Our second hat is that we are saying that biotechnology has a great
potential and progress made on molecular biology which is allowing us to
do gene mapping, the possibility of transferring genes, of introducing
genes directly resistant to drought, disease and so on, is positive. Human
progress is based on the progress of science. But science without
conscience is something worse than no science. Therefore we have to be
careful on how and on what we use the science and we have to look in
advance at the postsible problems on the environment and on human health.
We, therefore, are saying that we need to get an internationally agreed
framework - not a framework pushed by specific interests, financial
interests - where we will discuss the principles to be applied to GMOs,
such as the problem of experimentation, labelling, the principle of
precaution and many other aspects where the fight is going on. Therefore
we tell countries that each of them has a responsibility to apply the
principle of precaution. And how tto apply that principle scientifically
needs to be addressed internationally. Up till the time this is done, it
is up to the national governments to adopt national legislation to protect
the environment and the health of people and to ensure that they do not
take undue risk. But at the same time we do not also say that we do not
want any science when other people are developing it and may end up being
more powerful and we will have to go and buy the seed from them.
What about the influence of industry on nations on these issues? You have
the example of the study on rats fed on GM maize...
- Industry is defending its interest and there is nothing wrong in that.
At the same time other people have to defend the interests of their
populations and environment and put in place the right regulations and
But industry getting into research in corn, canola, cotton, and soya is
not going to solve the problem of food security.
- Yes, but why aren't governments investing in products that are more
important for their populations? They have to decide their national
budgets and priority. National governments are responsible to their people
and accountable to them.
How actively are you involved in the WTO negotiations? Are you consulted?
- We are not involved in consultations because the legal framework of the
WTO is for negotiations among member states. But we are recognised by the
WTO in capacity building. Also all the standards that are applied in the
sanitary and phytosanitary (SPS) system are the standards of the FAO and
the WHO on the Codex and the standards of FAO and of the International
Plant Protection Commission. The WTO does not create those standards. It
applies them to deal with any disputes arising within nations that are
tradting in agriculture commodities.
So has the shift in focus resulted in budget cuts for the FAO?
- Naturally the cut-off of resources of the FAO makes it more difficult to
perform its job. We have a budget of regular programme to the tune of $
750 million per biennial but we received this year per biennial $ 150
million additionally in voluntary contributions, an indication of
countries [willingness] to provide us additional resources. But we prefer
to have the resources in the regular programme so that they are not
subject to priority setting.
A recent National Survey in India showed that 40% farmers would quit
farming given the choice and that only a minuscule knew about the WTO...
- The negotiations within the WTO are negotiations of governments. What
each government does to educate its population is a national problem. We
can only ensure that those who go to negotiate are adequately trained and
empowered to be able to defend the interests of their farming community.
We bring all the data and information at their disposal. For example, we
are saying it is not fair to provide up to $ 300 billion of support to
farmers in the developed countries against the poor farmers of developing
coutntries. But each country would have to negotiate the interests of its
farmers on its own.
How do you view your partnership with India?
I view it with a lot of prospects and hope. We are happy that India is
willing to work with FAO to assist other developing countries in Asia and
Africa in particular through the South-South cooperation. We also want to
build on the experience of Indian institutions in research, particularly
in the seed sector so as to not have to re-invent the wheel in other
Latest from Greenpeace India
Have you seen this presentation by Greenpeace India on why geneticists
have got it all wrong? Will make you weep.
Perhaps one of your esteemed contributors could write a witty critique for
- Best wishes, Robert
Robert Blood Associates, Freiburg, Germany
A Farewell to Bacterial ARMs?
- Philip A Rea, Nature Biotechnology v.23, p.1085 - 1087; September, 2005;
www.nature.com/nbt . Excerpts reproduced in AgBioView with the permission
of the editor
'A plant gene that confers antibiotic resistance provides a 'cleaner' selectable marker for plant transgenesis.'
In a stroke of serendipity, researchers investigating plant responses to
the explosive TNT have stumbled upon a transporter gene that may obviate
the need for bacterial selectable markers in the generation of transgenic
plants. As described in this issue, Mentewab and Stewart1 were studying
the effects of 2,4,6-trinitrotoluene in Arabidopsis thaliana when they
identified an endogenous gene that confers resistance to the antibiotic
kanamycin. This finding promises to alleviate concerns about the use of
selectable markers from non-plant sources for the identification and
selection of genetically modified plants.
Large-scale TNT manufacture has been operational for over a century, and
many production facilities and military bases are heavily contaminated
with this potent xenobiotic. Of the hazards presented by TNT (apart from
the obvious), the most persistent and insidious is its facility, when
ingested, to yield highly reactive derivatives that cause anemia,
hepatitis and male sterility, and are thought to be involved in some
cancers. Given the magnitude of the problem and the prohibitively high
costs of conventional soil decontamination technologies, there is much
interest in phytoremediation -- the use of native plant species or
genetically engineered plants to remove or detoxify xenobiotics in soil
and ground water -- as a minimally intrusive, cost-effective means of
tackling TNT contamination.
It was in the quest for plant detoxification genes that Stewart and
colleagues2 identified by cDNA microarray analyses some 52 genes that are
upregulated in A. thaliana seedlings grown on media containing micromolar
concentrations of TNT. One of these genes, At3g55130, also known as
AtWBC19 (for A. thaliana white-brown complex subfamily member 19) was
scrutinized further because its putative product is a member of the
ATP-binding cassette (ABC) protein superfamily, which is rich in pumps
that extrude and sequester endogenous and exogenous toxins3, 4. The next
step was what any investigator in the same position would do: T-DNA
insertion mutants for this gene were acquired from the Arabidopsis
Biological Resource Center, Ohio State University
(http://www.arabidopsis.org/abrc/tdna_lines.jsp). It was at this stage,
while characterizing these mutants in preparation for investigations of
the sensitivity of homozygotes to TNT, that the experiments took an
unexpected turn. Mentewab and Stewart noted that the growth of roots of
AtWBC19 T-DNA insertion mutants on plates containing kanamycin, the
antibiotic resistance marker (ARM) used to select stable transformants
containing the T-DNA insertion, was retarded compared with T-DNA mutants
with insertions in other genes. They speculated that AtWBC19 is capable of
contributing to antibiotic resistance and went on to show that this is
indeed the case. AtWBC19 mutants are hypersensitive to kanamycin in the
growth medium and, when expressed in tobacco (Nicotiana tabacum), the
wild-type AtWBC19 gene confers levels of kanamcyin resistance comparable
to those conferred by conventional bacterial ARMs.
Although the case should not be overstated, this discovery has the makings
of a 'clean (green) gene' technology. It may offer a new tool for
generating genetically modified crops that allays many of the anxieties,
justified or otherwise, associated with the use of bacterial genes. By
deploying as a selectable marker a gene that was in the plant gene pool
long before genetically modified crops came on the scene, concerns over
horizontal gene transfer from transgenic plants to microbes and the
creation or exacerbation of microbial antibiotic resistance become moot.
Moreover, this new marker would not necessitate new selective agents or
substantial revision of current screening protocols.
It is because concerns, real or perceived, have been voiced about the
potential of genetically modified crops to inadvertently introduce or
amplify endogenous or exogenous toxins and/or allergens, change the levels
of essential nutrients or compromise antibiotic therapies that the US Food
and Drug Administration requires a full evaluation of a genetically
engineered crop when uncharacterized DNA sequences are used. By contrast,
most of these concerns would probably be immaterial if AtWBC19 were a
plasma membrane - localized extrusion pump. It is therefore with
enthusiasm that the results of the next phase of characterization of this
selectable marker--mechanistic investigations of how it confers kanamycin
resistance--are anxiously awaited by all factions of the plant
biotechnology community, but especially those with special interests in
genetically modified crops, phytoremediation or plant ABC transporters.
Philip A. Rea is in the Plant Science Institute, Department of Biology,
University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.