the gm debate professor a j trewavas frs frse · 2018-06-07 · the gm debate professor a j...

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THE GM DEBATE Professor A J Trewavas FRS FRSE "The old saying that vox populi;vox dei as every philosopher knows cannot be trusted in science" DARWIN 1876. Origin of Species. The science is quite clear concerning the crops on trial in the UK. The debate is really about values, feelings and beliefs. Assessments will always be made on a case-by-case basis. Approval of one GM crop does not provide blanket approval of all. In risk assessment, relative risk is crucial. Comparison is made with what we do now and is accepted as safe from a history of experience. There is no absolute safety for anything in human life but we act as though there is. Who regards their motor car as unsafe? How far should society bow to claims by one group who regard growing GM as a commercial threat because that is the way they define their business or to others who claim it is their commercial right to grow GM? Current plant breeding We have all eaten genetically engineered food all of our lives. Conventional plant breeding: A. Uses natural mutants: that is natural genetic engineering. Why wait for nature to mutate the right genes? If we replicate by GM what nature has already done (e.g. insert dwarfing genes) is there really a difference? B. Induced mutation. Radiation used on 2252 crop samples to speed up mutation rates enormously (IAEA Vienna 1999). Estimates suggest radiation modifies up to 10% genome. 80% worlds wheat has genes derived from radiation induced mutagenesis 1 . C. Genes obtained from weeds for pest resistance 2 . In cereals hardly any species barrier exists. D. In comparison GM is much more targeted, quicker and more accurate.

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Page 1: THE GM DEBATE Professor A J Trewavas FRS FRSE · 2018-06-07 · THE GM DEBATE Professor A J Trewavas FRS FRSE "The old saying that vox populi;vox dei as every philosopher knows cannot

THE GM DEBATEProfessor A J Trewavas FRS FRSE

"The old saying that vox populi;vox dei as every philosopher knows cannot be trustedin science" DARWIN 1876. Origin of Species.

The science is quite clear concerning the crops on trial in the UK.The debate is really about values, feelings and beliefs.

Assessments will always be made on a case-by-case basis. Approval of one GM cropdoes not provide blanket approval of all.

In risk assessment, relative risk is crucial. Comparison is made with what we do nowand is accepted as safe from a history of experience. There is no absolute safety foranything in human life but we act as though there is. Who regards their motor car asunsafe?

How far should society bow to claims by one group who regard growing GM as acommercial threat because that is the way they define their business or to others whoclaim it is their commercial right to grow GM?

Current plant breeding

We have all eaten genetically engineered food all of our lives.

Conventional plant breeding:

A. Uses natural mutants: that is natural genetic engineering. Why wait for natureto mutate the right genes? If we replicate by GM what nature has already done(e.g. insert dwarfing genes) is there really a difference?

B. Induced mutation. Radiation used on 2252 crop samples to speed up mutationrates enormously (IAEA Vienna 1999). Estimates suggest radiation modifies upto 10% genome. 80% worlds wheat has genes derived from radiation inducedmutagenesis 1.

C. Genes obtained from weeds for pest resistance2. In cereals hardly any speciesbarrier exists.

D. In comparison GM is much more targeted, quicker and more accurate.

Page 2: THE GM DEBATE Professor A J Trewavas FRS FRSE · 2018-06-07 · THE GM DEBATE Professor A J Trewavas FRS FRSE "The old saying that vox populi;vox dei as every philosopher knows cannot

Gene flow

To the same crop:

A. Figure now known for oil seed rape from detailed studies by Roush and others inAustralia3. Maximum spread, 0.07%.

B. Distance of spread up to 3 kilometres probably by bees.

C. Varietal purity, seed certification and/or product segregation not a problem whichonly guarantee 99.5% purity4.

D. Organic regulations- EC level for non-GM description is 0.9% GM in sample.

E. Gene stacking of Herbicide Tolerance (HT) in volunteer hybrids have beenreported in Canada arising from two GM rape and one conventional HT rapegrown in close proximity. Any mixture of cultivars of one crop grown in closeproximity will give rise to similar problems. Cross resistance to herbicides is wellknown5. Problems not unique to GM crops and more of a nuisance than aproblem.

F. All current GM crops and equivalents do not survive in fallow fields6.

Introgression

A. Two parents must be equally compatible.

B. Fecundity must coincide

C. Suitable pollen vector must be present

D. Resulting progeny must be fertile and ecologically fit.

Page 3: THE GM DEBATE Professor A J Trewavas FRS FRSE · 2018-06-07 · THE GM DEBATE Professor A J Trewavas FRS FRSE "The old saying that vox populi;vox dei as every philosopher knows cannot

With current herbicide tolerant (HT) and pest resistant GM crops- introgression at alow rate can occur from oil seed rape into several closely related weeds like wildturnip or sugar beet into sea and fodder beet.

Should we be concerned?

A. Current introgression hybrids do not survive (lack fitness).

B. HT not considered to be of genetic value outside farm environment and thusquickly lost.

C. Weeds are a sea of natural mutant variants; HT already present in weedpopulations as indicated by speed of resistance development (3-20 years)5.(Weeds worldwide have resistance to 15 different herbicides). Pest resistance isalready present in weeds2 and in most plants, as indicated by rapid spread ofexotics transferred from their normal environment when pest pressure is removed.Thus present GM traits are not novel.

D. No evidence that genes inserted by GM transfer more vigorously to weeds.

E. At least 3 crops marketed with resistance to herbicides from conventionalbreeding-rape resistant to atrazine, maize resistant to isobutazolidone, soybeanresistant to sulfonylurea. No known problems have emerged with their use.

F. Traits which could increase weediness potential are those that increase toleranceto drought, cold or dormancy. However crops with these traits are alreadycurrently used and they do not currently lead to increased weed problems. In theUK an estimated 1000 crop cultivars are introduced every year from conventionalbreeding mainly for pest resistance but other unique traits are probably present butuntested.

G. Will there be impacts on biodiversity? Currently the HT trait has been introducedinto many different lines of rape. See advantages to HT crops later.

Avoiding Gene flow.

Two methods at least are available:

A. Use of terminator technology- production of sterile seed.

B. Transformation via the chloroplast genome.

Advantages of chloroplast GM compared to nuclear GM7:

1. Chloroplast traits in most crops are maternally inherited-pollen does not containchloroplasts.

2. Much higher expression achievable-when used with Bt protein 100% kill of targetinsects thus no resistance development.

Page 4: THE GM DEBATE Professor A J Trewavas FRS FRSE · 2018-06-07 · THE GM DEBATE Professor A J Trewavas FRS FRSE "The old saying that vox populi;vox dei as every philosopher knows cannot

3. Single site for incorporation of gene. Incorporation uses homologousrecombination.

4. No gene silencing.

5. Multigene constructs and whole operons expressed in chloroplasts.

6. Systems for ready transformation present. Potato and tomato transformed.

7. Cholera vaccine and biologically active somatotrophin expressed in chloroplasts.

8. Marker gene removal method present using CRE-lox.

9. However seed spread still possible.

Benefits to the use of HT crops

"Had we not originally gone contrary to the laws of nature by plowing the land wewould have avoided the problems as well as the time consuming efforts to solve them.We would have missed all of the erosion, the sour soils, the mounting floods, thelowering water table, the vanishing wildlife, the compact and impervious soil surface"Ed Faulkner, (1943) Plowmans Folly 8.

All of Faulkner's claims have been established by measurement and indicate thesuperiority of no-till agriculture over organic and conventional ploughingtechnologies. Ploughing is the most damaging soil treatment and no-till agriculturemost easily introduced with HT crops to avoid weed problems. Organic has no choicebut to plough to mineralise nitrate and bury difficult weeds.

No till benefits compared to till9:

1. Farm fossil fuel use 1/3rd.

2. Erosion reduced to 5% ploughed field. Soil nutrition, structure and drainage vastlybetter.

3. Pest predators and large earthworms up 6 fold.

4. Birds and nest increase anywhere from 3-100 fold. Time requirements for youngbird feeding reduced five fold.

5. Preventing sediment losses improves aquatic habitat. Run off greatly diminished.Herbicides no longer detectable in soil drainage. Nitrate 1/20th.

6. Soil moisture better balanced during drought.

7. Soil carbon accumulates- released on ploughing when introduction of oxygenbreaks down organic material.

8. Mimicks seasonal change in meadow and prairie.

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References.

1. Poehlman JM (1979). Genetics and plant breeding: mutation. In "Breeding fieldcrops" 2nd edition Westport. AVI publishing.

Institute of Radiation Breeding http://irb.affrc.go.jp/

2. Baum, M et al., (1992) Wide crosses in cereals. Annual Review Plant Physiologyand Plant Molecular Biology 43, 117-143.

Goodman R.M et al., (1987) Gene transfer in crop improvement. Science 236, 48-54.

3. Rieger MA, Lamond M., Preston C et al., (2002) Pollen-Mediated Movement ofHerbicide Resistance Between Commercial Canola Fields. Science 296: 2386-2388.

4. MacLeod J. (2002) Pollination and Gene Flow. In GM crops Understanding theIssues. Pages 49-59. UK Agricultural Biotechnology Industry.

5. Cousins R and Mortimer M, (1995). Dynamics of weed populations. CUPCambridge.

6. Crawley MJ, Brown SL, Hails RS, Kohn DD, Rees M. (2001) Transgenic crops innatural habitats. Nature 409, 682-683.

Crawley MJ, Hails RS, Rees M, Kohn, D. and Buxton, J. (1993). Ecology oftransgenic oil seed rape in natural habitats. Nature 363, 620-622.

7. Daniell H and Dhingra A. (2002). Multigene engineering: dawn of an excitingnew era in biotechnology. Current Opinion in Biotechnology 13, 136-141.

Maliga P (2002) Engineering the plastid genome of higher plants. Current opinionin Plant Biology 5, 164-172.

Gewolb J (2002). Plant Scientists see big potential in tiny plastids. Science 295,258-259.

8. Faulkner E. (1943), Plowmans Folly. Grosset and Dunlap, New York

9. Basore NS, Best LB, Wooley JB. (1986). Bird nesting in Iowa no tillage and tilledcropland. J Wildlife management 50, 19-28.

Warburton DB and Klimstrea WD. (1984). Wildlife use of no-till andconventionally tilled fields. Journal of Soil and Water Conservation. 39, 327-330.

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House GJ and Parmalee RW. (1985) Comparison of soil arthropods andearthworms from conventional and no-tillage agroecosystems Soil and Tillageresearch 5, 351-360.

Hall, JK Mumma RO and Watts DW. (1991) Leaching and runoff losses ofherbicides in a tilled and untilled field. Agriculture, Ecosystems andEnvironment. 37, 303-314.

Glenn S and Angle JS. (1987) Atrazine and simazine in runoff from conventionaland no till corn watersheds. Agriculture Ecosystems and Environment 18, 273-280.

Fawcett RS, Christensen BR and Tierney DP. (1994) The impact of conservationtillage on pesticide runoff into surface water. Journal of Soil and WaterConservation 49, 126-135.

Highinbotham S, Leake AR, Jordan VWL and Ogilvy SE. (2000) Environmentaland ecological aspects of Integrated, organic and conventional farming systems.Aspects of Applied Biology 62, 15-20.

Jordan, VWL, Leake AR, Ogilvy S. (2000) Agronomic and environmentalimplications of soil management practices in Integrated Farming Systems.Aspects of Applied Biology 62, 61-66.

Leake AR (2000) Climate change, farming systems and soils. Aspects of AppliedBiology 62, 253-259.

Paul EA and Harowod RR. (2000) Greenhouse gases in intensive agriculture:contribution of individual gases to the radiative forcing of the atmosphere.Science 289, 1922-1925.