AgBioView - http://www.agbioworld.org, http://agbioview.listbot.com
I am going on holiday so the next to last for some weeks no doubt
to your ultimate relief.
3rd reply below
I have recently been in touch with a group called Worldwrite. email email@example.com. They are a
charity and take groups of school teenagers to different countries and took a group to the Punjab to talk to
farmers. They found the majority of attitudes towards the use of GMO's very different to the views
expressed apparently on behalf of Indian farmers in the west. The group say that primitivism and
environmentalism are Western ideologies born of disenchantment with western society. These ideas do
not come from the developing world but are most certainly imposed upon them. They are ideas that can
have devastating consequences, shaping the way forward for the developing world and are a modern form
of domination. That pretty well paraphrases what I said last time about neo-colonialism. The concerns of
the old populations which dominate Europe, Japan and the USA are very different to those in developing
countries where the majority may still be under 15 years old. In all the GM debates I have seen nothing, no
recognition of this problem at all and it is part and parcel of my distrust and dislike of Greenpeace that it
believes it has the right to try to impose its view by direct action on others including the developing world
instead of through democratic processes. Melchett has written to me demanding apologies for what I have
said about Greenpeace but I have told him that I regard his organisation as dangerous and inimical to the
future of mankind. The most cogent example of this behaviour is to be found with DDT. This compound
was removed from use as an insecticide because of fears about certain bird populations. But we imposed
our views on the third world where removal of DDT caused at least in Sri Lanka an increase of malaria cases
from 17 to 2.5 million in a few years. There are similar examples in India. Malaria kills particularly young
children. We had not right whatsoever to impose our western view upon them. I think there is still a form of
western arrogance. We must allow others to make up their minds about what they want and don't want free
of our prejudices.
There are too many people who paint problems as impossible barriers to change. When problems occur we
must not retreat from technology but use it to solve the problems, to rise to the challenge to use what we
have, our ultimate resource is our intelligence. No problem is insoluble although from what I have heard
from anti-GM people (perhaps like yourself I do not know)you would have thought it was the end of the
world. It is perhaps to me a relief that the Chinese will have nothing to do with Greenpeace or western
attitudes about it. The Chinese Professor I had in my lab thought the whole business of labelling a joke.
But it means the torch of progress passes to their hands, our societies are in definite decline. The rise of
Greenpeace mirrors our decline and eventual fall. That will not be a popular view with people on your
network but it has to be faced. No-one wants to see the world a desert but environment is very much in the
eye of the beholder and providing it does not threaten the survival of our own species then environmental
assessments are completely subjective. It seems not to be recognised that there is nothing natural about
the UK environment. It has been worked over several times. But I find it pleasant and attractive. I am glad
that wolves or bears no longer roam the Scottish mountains because it enables me to do so. The Chinese, if
you don't know have 8-10 GM crops in the field, they have 40 waiting for approval and have 25 molecular
biology institutes devoted to GM crop production. That is why Greenpeace will fail ignominiously in the
end because China dominates South East Asia economically. We have populations frightened of notional
risks and that is not good. So this part deals with some of the problems you have raised.
The other points in your letter which if I remember were the Aachen declaration (you didn't think much of
it), population predictions and economics; horizontal gene transfer comes in there somewhere.
Now I sent you the Aachen declaration because I wanted to establish two things with you. Firstly
ecologists are not synonymous with environmentalism. Ecological science is part of biological science and
is not distinct. Biology is constructed as a hierarchical series and ecology or the study of ecosystems
happens to be the top part of the hierarchy. Environmentalism is a pseudo-religious, political activity
based on certain mistaken preconceptions about human behaviour and the world in which we live. The
notion that ecology underpins environmentalism is quite wrong; we are not animals but thinking people
and thus not subject to the same principles that control other species. We are stewards of this world, good
gardeners if you like and we construct and manipulate to see the world as we wish. That is how it should
be that is our biological destiny given our large and imaginative brain. We are the only one that can
formulate that view that is why we are unique. The article by Patrick Moore that I sent you detailed some of
the more frightening and obscure beliefs which have infiltrated environmentalism.
The second point made in the Aachen declaration is the statement that Greenpeace try to imply that
something like pollen movement is unique to GM plants. Of course it isn't. The spread of pollen and genes
is not unique to GM but has been happening ever since pollen evolved. And as species evolve and
change there will be exchange of genes at different rates between these separating groups. The
phenomenon is not new! Of course fertility is limited to closely related plants and domestication being a
form of artificial selection, accelerated evolution, has left weedy relatives in their countries of origin. So
genes do spread from crops to some weeds in some countries but so what. The supposition seems to be
that some basic character about a weed will be altered. I disagree strongly. Such views do not recognise
that weeds (true weeds) are a sea of natural mutant variants in which you will find genes amongst the
population for virtually anything weedy that can ever be conceived. If they didn't they would not survive
as well as they do.
Wheat has been grown in the Middle East for ten thousand years in the presence of the very weeds from
which it was domesticated. We have produced an awfully large number of wheat's and in many cases gone
back to the originals to get other genes for particular purposes. Nothing has happened; the weeds have not
become more invasive more difficult to deal with their gene pool may have shifted slightly but no-one
knows because no-one even thought about it then. We should not get frantic about things that happen all
the time. Present day wheat does not survive in fallow fields, it disappears within two years submerged
and out-competed by weeds and this was shown by Lawes around the turn of the century. We have
removed from wheat the capability to act like a weed; the genes we have introduced or amplified are fatal to
its weedy qualities. We have done the same with dogs; none of our domesticated dogs would survive long
in the company of wolves. Domestication of wheat resulted from the deliberate change in about half the 12
characters required for a plant to be a weed. How many genes that involved I do not know but certainly
more than 6.
Rape lasts about seven years in fallow fields but these are data which I have only seen quoted and not
published. Rape domestication is more recent and these measurements do not include rape in which erucic
acid has been removed from the seed oil (i.e. canola). Erucic acid is essential to prevent predation of seeds
by slugs and other seed eating animals. Again the same conclusion holds. When some green organisation
or other destroyed poplar trees with lowered lignin their justification was that this would contaminate the
poplar gene pool for ever. I am unable to visualise how a wild poplar with very low lignin content could
ever survive in the wild. Conditions are hard and natural selection ruthless in wilderness. And the same is
true for all sorts of characters that we put into crop plants. To reiterate, a weed population is a sea of
natural mutant variants and the single genes that we can put in at present are never going to improve its
weediness. So even if there is GM crop in the field and there is a low rate of exchange of genes with a
weedy relative, removal of the GM crop from the field will result in loss of any exchanged gene from the
weed because it will be no advantage in the struggle to survive. It seems to be forgotten that in most cases
there is replacement of one weed individual by another. There is a superabundance of pollen and a
superabundance of seeds but only one of those comes through to reproduce.
There has been discussion about Bt and whether this might increase weediness because it will give
improved insect resistance. Any self-respecting weed already has the capabilities in its population to deal
with any predatory insect otherwise it will not be a weed for long. I am unable to think of any gene we
could put in that would enable a weed to survive better. If we take herbicide resistance genes in GM rape
(B.napus) then the acquisition has been carefully measured (in B. rapa the nearest relative in which
introgression will occur) as about 1 in ten thousand (Nature paper). But the hybrids of Bnapus/rapa will
only survive if the wilderness is sprayed with herbicide.
But then if you spray weed populations with herbicide you will end up with resistant weeds. World wide
there are over 100 weeds with resistance to some 16 different herbicides. In fact four crops are available
with natural herbicide resistance and in an addition one of these (sulfonylurea) has the resistance gene
introduced after isolation, back into the crop from which it was derived (Mazur 1989). This method will
increasingly be used once micro-arrays become freely available. Resistant individuals will be located and
their different genes isolated and inserted back.
Now then if I sow a crop of naturally resistant rape the spread of resistance genes to weeds is identical to
the GM rape isn't it? So why the distinction between GM resistant crops and naturally resistant crops? In
fact the ecological effects of spraying a field of naturally resistant rape and GM inserted resistant rape are
the same as well. And of course if there is any DNA in the samples consumed by us then at some stage we
all eating the resistance gene from natural resistance present in the population!
There has been a lot of discussion about whether the use of herbicide resistant GM crops is
environmentally friendly or not. There has been an argument over whether the amounts of herbicide are
reduced, the kinds of herbicide used and whether zero tillage is a good idea. From all the literature which I
have here and averaging it out there might be a marginal reduction in overall herbicide application on a per
hectare basis but it depends on the climatic zone and clearly depends on the perceived or genuine weed
problem of the particular farm. Glyphosate is innocuous; glufosinate less so. However as I understand the
situation, the actual area in total put down to GM resistant beans or maize varies from year to year. So if
you assess on an area basis you can take what figures you want to support any point of view. We are not
talking about big variations here. None of the figures I have here and I have a very fat folder on it are
varying by more than 10-15% either way. On a ha basis there is some slight reduction with a change in
what is used as a herbicide because of course you use glyphosate instead of other things.
The technique does involve zero tillage. Zero tillage is definitely advantageous in areas where soil
erosion is common and does enable farmers to use sloping land which otherwise is difficult because
ploughing encourages soil erosion on slopes. So for certain areas the use of GM rape or maize will enable
the use of farmland which is currently difficult to manage and suffers erosion. Also zero tillage has been
reported to result in much less damage to invertebrates, molluscs and birds. Zero tillage is a desirable
objective but it seems that ploughing once every ten years is also required. Eventually of course if this
method is used continuously then resistant weed populations will develop. Crop rotation will solve that
issue. But you can actually allow the weeds to grow for several months with this technology before killing
them with advantages for bird and insect populations accordingly.
So what we have here is a complex problem in which it seems to me no one view is scientifically right or
wrong. My own view is that this is a commercial situation, farmers are not stupid in the main and know if
they are being conned. The product is commercial and lives or dies on the market place. I have certainly
seen farmers who find the use of GM herbicide resistance marginal and it seems to be convenience that
attracts as much as anything. However I cannot see the arguments about superweeds or anything like that.
Introduced plants usually by gardeners are the superweed if you want one. They are a nuisance not a
serious problem. Simply removing the GM crop from the field will lead to the loss of any herbicide resistant
gene from weeds in five or six generations or the population geneticists have been lying to us over the
Again I see no problem with Bt maize. There are no weedy relatives and corn is used as animal fodder in
the UK. There have been various measurements of pollen distribution after the Monarch fiasco and it is
not widely spread although claims for miles fail to recognise the totally slim probability of successful
pollination at such distances, well below the capability of seed merchants to determine purity. So I regard
Bt maize and the furore around it as largely irrelevant. You have brought up the secretion of Bt in roots. Do
try to remember that many of these things can only now be investigated because of modern technology.
Protein secretion by roots is well established and there is a patent on plants secreting antibodies. But of
course the process has been going on ever since roots burrowed into the ground; it is not something
which has just started with GM. We have bred many insecticidal plants, and the reasons for resistance are
normally unknown. Some of these will be proteins interfering in the digestive systems of insects I do not
doubt and there are many naturally-resistant plants as I know from my own gardening experience. The only
difference now is that we know what has been put in by genetic engineering so there is actually something
The secretion of mucilage and the sloughing off of root cells has been studied for many years and of
course the mucilage has proteins in it. If you spray Bt spores as per organic farming then Bt will last a long
time in the soil likely last a lot longer because Bt itself is a soil organism. There are about 130 different
kinds of Bt bacteria and they do synthesise a broad spectrum of insecticidal proteins but these are limited
to killing lepidopteran larvae (caterpillars) and some predatory beetles.
Are there advantages to Bt corn? It depends on what your pests are and how serious they are. In parts of
the US no pesticide at all has been used on Bt maize, in others you still need additional pesticides because
you get other insects like aphids which are not killed by Bt. So at the best Bt crops like Bt cotton work well
where the corn borer or boll-worm populations are high and in other areas where it isn't then marginal
benefit is achieved. An insect can trash a crop very quickly. Bt potato against the colorado beetle is a case
in point where real and substantial benefit occurs. There are problems with resistance recurring but refuges
may sort that one out. I am well aware that integrated pest management schemes work well in some cases
but in others they don't. So I think arguments about whether it is good or bad should leave it really to the
farmer to decide. There are definite reductions in pesticide application and these have been quantified and
There has been discussion about whether this new protein put into plants how can we predict its effects
and so on. 10,000 years of plant breeding have been doing this without regard and without concern. We
have put thousands of new genes into crop plants from associated weeds (remember a sea of natural
mutant variants) and from, in a number of cases, different species. Every year 1000 new cultivars of
common crops are incorporated into UK agriculture which you eat. None of these are ever tested. Triticale
has a chunk of rye chromosome inside it. And unless you can point to some likely new thing then I think
objections are simply not valid; they simply represent unjustifed fear. We are not talking about deadly
nightshade genes into maize but a fairly innocuous protein. Sure no one can predict the effect but an awful
lot of testing goes into these crops before they can be released and despite the millions of crop types and
lines that we have produced, I know of only three that have ever been withdrawn. Another important point
in this country not commonly known is that unless new crops can be demonstrated to be advantageous
then they are not placed on the licensed list of crops allowed to be grown.
The area where Bt maize is grown will determine its usefulness so you will always be able to stump up with
cases where it doesn't work well or doesn't do what companies claim for it. Farming covers a multitude of
soils and conditions no hard and fast rule can be given. To me it is a commercial product and should be
allowed to live or die on the market place. Many normal crop cultivars are the same. Where you grow it
makes a big difference to yield and other problems like insect damage.
I should add here that there have been discussion about whether GM maize should be grown in Mexico
where the only known weedy relative teosinte exists. Again I do not see a problem. Teosinte will have
resistance in its population to any insect already that eats it otherwise it would have keeled over and
disappeared. Furthermore we know that corn has been grown in Mexico for at least five thousand years and
there has been an exchange of genes throughout that time. What those exchanges were no-one knows we
but we have not managed to change anything about the weediness of the products.
To interpolate in this very long letter. I know that there are concerns about insertion sites for GM material.
However about 20% of the plant genome (so far as we know from sequencing) consists of transposons.
These move around the genome each time reproduction occurs and the direct estimate in Antirrhinnum is
that one transposon moves at random for each gamete formed. Transposons are a major element in
biological variation. From this you can appreciate that within one breeding cycle in a field of plants virtually
every gene is interrupted or promoters interrupted and so on. Insertion of GM constructs mimic a natural
process that has been going on all the time. So statements that we are going to generate some new
metabolic pathway or chemical or some new fusion protein or soemthing fail to recognise that this has
already been done. The millions of cultivars of crops that we have, are already a list of random insertions
into teh crop genome.
Now to come to horizontal or vertical gene exchange (HGE or VGE) between different organisms particularly
plants and bacteria. First of all we must discount any lab studies because artificial methods can be used
and are not relevant to anything we want to examine. Thus it is meaningless to me to quote electroporation
with bacteria and foreign DNA and as we shall see this is more difficult than the literature often implies and
it is where experience of the technology carried out frequently with different constructs becomes valuable.
There seem to me to be four possibilities.
GE happens all the time.
GE happens frequently but with constraints
GE happens rarely
GE never happens.
The concerns expressed here have been about plant bacterial exchange usually and I have seen a lot of
things which do not convince me from my own extensive lab experience. It can be difficult to transform
bacteria in the lab with the techniques we have on offer even with perfect constructs to do it. Getting it to
work with any old bit of DNA is frankly impossible without careful selection of strains for recombination
and with appropriate nucleotide sequences on the end bits of the DNA. Transformation requires a plasmid
and the GE that occurs between bacteria naturally, requires plasmid exchange. Now I bring this up because
I seem to recall that Eva said there would be DNA in the soil that could transform bacteria. Well if there is
DNA there, it will be DNA from every organism on the planet and it has been there for an awful long time.
There is nothing special about GM DNA that is going to make this a particular concern and even more so
because DNA is degraded as organisms die. Once a construct has been incorporated into DNA it simply
can't get out again because it has lost a number of the other bits including chaperone proteins and OR
necessary to get it into plant DNA in the first place.
Number 1 certainly happens in bacteria. But remember they do exchange plasmids not genomic material
otherwise we would never have bacterial species.
Number 4 can be eliminated because we know that Agrobacterium is able to infect a limited a number of
plants in the solanaceae and part of its infective routine is to inject its own DNA into plant cell DNA and
transform it. However I have never seen evidence that the inserted DNA actually gets into reproductive
DNA in the flower. In fact pollen usually excludes viral DNA so it will undoubtedly exclude bacteria.
However no agrobacterial sequences have been found in plant DNA so far sequenced like in tobacco. I
think we would have picked it up by now if it was in anyway common.
There are also retroviruses which can carry pieces of DNA around but they carry only small portions if at
all. But again if retroviruses have been doing this they have been doing it for hundreds of millions of
years. Sequencing data does not suggest that GE is at all high. If it was common as in bacteria we would
have difficulties with the separation of species and it would be obvious from comparative genome
sequencing work. So I don't find the process to be going on at a rate that anyone should be concerned
about. in other words number 3 is about right and that seems to match experience.
Can we actually produce a rate at which number 3 happens. Syvanen reviewed this area in Nature in 1999
and had to conclude that no evidence had yet turned up to support it but not much has been done on GE
between different organisms. Remember that recent reports that attempted to demonstrate the transfer of
antibiotic resistance genes from plants to bacteria have failed. There is a recent report that some plant DNA
may get into endo-symbionts in the gut of bees but I don't know what the data is because it hasn't been
published. There are have been reports of finding chloroplast DNA fragments in milk but again this has
been going on since cows munched grass; they haven't turned green. There are also reports of DNA
fragments in blood cells and a few other things but it should be borne in mind that if this process occurrs it
has always occurred. If this process is rare and has been going on from time immemorial why should I be
concerned? My life is full of risky things. I have a 1 in 200 chance of being killed on the roads by another
driver; I have a 1 in 5000 chance of dying from anaphylactic shock due to over consumption of food to
which I am allergic. I have a 1 in a 100,000 lifetime chance of dying in a train crash. I have to place the risk
to myself of the rarity of gene transfer as being considerably lower than those. And if GE is common then
genome sequencing will expose it. I have seen one claim that a plant gene looks like a bacterial gene ( I
think it was glutamate dehydrogenase or some such) but how can one tell? I cannot get frantic or
concerned about remote possibilities particularly as the surety of people dying from starvation if we don't
come up with the goods is so much higher. The whole business I find over-hyped and not believable
based on what is known at present. The phenomenon is rare.
The consequences of not developing GM seem never to be on the agenda. I have several concerns here.
Global warming is definitely happening; we do no know what man's contribution to this warming actually is
but we do know that the predictions are for greater variation in the extremes of climate. One reasonable
prediction posits cessation of the gulf stream from excess rain and provides a perfectly reasonable
mechanism as to how this can happen. Our average temperatures would be reduced by five degrees
centigrade and we would completely need to restructure agriculture. Very recent ice core analyses indicate
that climate changes can occur in the fraction of a decade. We need to be prepared for this situation and
the primary feature of GM for plants is the speed at which it can happen. We should be experimenting in
depth and trying things out. My version of the precautionary principle is not look before you leap but be
This letter is far too long but I hope explains in detail what I know and think.
PS remains of answer to your letter to follow soon.
Anthony Trewavas FRS
Institute of Cell and Molecular Biology
University of Edinburgh
Edinburgh EH9 3JH
Phone 44 (0)1316505328
Fax 44 (0)1316505392
web site http://www.ed.ac.uk/~gidi/main.html
To view the web site simply click on the address