[To contribute to this conference, send your message to biotech-room3@mailserv.fao.org. For further information on the Electronic Forum on Biotechnology in Food and Agriculture see Forum website.
NB - participants are assumed to be speaking on their own behalf, unless they state otherwise.]

-----Original Message-----
From: Biotech-Mod3
Sent: 17 June 2002 08:28
To: 'biotech-room3@mailserv.fao.org'
Subject: 49: GM Insects

My name is Kim Brooks, and I work for the Pew Initiative on Food and Biotechnology in Washington DC, United States. The Pew Initiative on Food and Biotechnology is a nonprofit, nonpartisan research project whose goal is to inform the public and policymakers on issues about genetically modified food and agricultural biotechnology, including its importance, as well as concerns about it and its regulation. It is funded by a grant from The Pew Charitable Trusts to the University of Richmond.

My employer is doing some research regarding genetically modified insects and mites, and therefore, we are looking for information on gene flow as it relates to insects and other arthropods. Is there anyone who could be of help to us on this subject? Any resources or other information regarding this topic would be greatly appreciated.

Kimberly Brooks
Assistant Director of Science Policy
Pew Initiative on Food and Biotechnology,
United States
Email: kbrooks (at) pewagbiotech.org

[Anyone who has resources or information about this subject, can contact Kimberly directly. In addition, anyone who wishes to share their views and/or experiences on gene flow aspects of GM insects and mites in food and agriculture, can post them to the conference.....Moderator]

-----Original Message-----
From: Biotech-Mod3
Sent: 17 June 2002 08:49
To: 'biotech-room3@mailserv.fao.org'
Subject: 50: Mexican maize issue

My name is Niels Louwaars, working in Wageningen, The Netherlands.

Now that we are midway the discussion, I think it is good to list a number of issues related to gene flow, that are quite often not clearly separated in the discussion so far.

First there is the issue of biological possibility of gene flow, mainly through cross fertilisation, which can be dealt with by the botanical files concept I mentioned earlier (message 19, June 6).

The second issue is the types of effect that such gene flow can lead to. In our discussion on the mexican maize issue (available for interested people at the address below) referred to by Glenn Ashton (in message 47, June 14) we identify the following:

* aspects of biodiversity (within the crop species and its relatives): which are not essentially different from introgression of genes from scientifically bred varieties into landraces and wild/weedy populations

* Philosophical/ethical considerations: genes from foreign species may be regarded by local communities as a threat to the natural integrity of the local crops

* Food safety aspects: when the introgressed genes have not been tested for food safety, e.g. when Starlink maize genes would introgress into local crops.

* Trade aspects: where farmers intend to sell their product at premium prices in certified non-GMO markets, unintended introgression of transgenes may pose a threat to the commercial position of these farmers.

* Rights aspects: introgression of patented genes may sooner or later lead to claims by the holder of the patent, even where the genes were introduced unintentionally.

I think that it would be helpful if contributors to the discussion identify the aspects that they want to contribute their views on. With several of the contributions, the comments are not very clear about the risks that are referred to.

Niels P. Louwaars
Plant Research International
POBox 16
6700 AA Wageningen,
The Netherlands
n.p.louwaars (at) plant.wag-ur.nl

-----Original Message-----
From: Biotech-Mod3
Sent: 17 June 2002 09:08
To: 'biotech-room3@mailserv.fao.org'
Subject: 51: Re: Impacts of GM plants/animals on genetic diversity

This is from Dr Wayne Knibb. I am a population geneticist working on aquacultured species, in Australia.

My note is a response to Bill Muir (message 34, June 10). Two of his comments caught my attention:
- "but I do not think that risk [of GM plants or animals to genetic variability within species...Moderator] is any greater than with domestic breeding"
- "A transgene should be thought of as a mega-mutation, and nothing more" [These 2 quotations are from the last and fifth paragraphs respectively of Bill Muir's message...Moderator]

Do these comments suggest that natural processes can generate risk? If so, it would be instructive to calculate the relative "risks" from natural and engineered mutations. For common and fecund species (e.g. scallops and many aquacultured species), we can calculate that some populations have spontaneous mutations in every loci every generation, and multiple mutations per quantitative trait. Can we then infer that the extra "risk" generated by a single engineered change is negligible/infinitesimal? (see Knibb 1997 and elsewhere). Moreover, if we view genetic engineering as a little risky, should we view natural evolution and spontaneous mutation as positively dangerous?

Dr Wayne Knibb
Principal Research Scientist
Bribie Island Aquaculture Research Centre
144 North Street, Woorim
PO Box 2066
Bribie Island Queensland 4507
Australia
Ph (07) 34002000 / 2052
Fax 34083535
Mobile: 0418732126
e-mail: wayne.knibb (at) dpi.qld.gov.au

Knibb, W. R. 1997. Risk from genetically engineered and modified marine fish. Transgenic Research. 6:59-67.

-----Original Message-----
From: Biotech-Mod3
Sent: 17 June 2002 10:59
To: 'biotech-room3@mailserv.fao.org'
Subject: 52: Chloroplast transgenes and gene flow

Some apparent fallacies in transgene containment by chloroplast genetic engineering:

Recently a number of projects have been launched based on the presumption that genetic modification of chloroplasts will prevent spread of transgenes, based on the assumption that chloroplast genes are strictly maternally inherited. [The topic of transplastomic plants, i.e. with the transgene(s) inserted into plastids (e.g. chloroplasts) instead of the nuclear genome, has previously been mentioned in message 40, June 11...Moderator]. In the majority of proposals and publications showing that some plants do inherit chloroplasts maternally and that pollen has a limited role in such transmission, little or no consideration has been given to pollination of chloroplast transgenic crops by weedy relatives to form hybrid plants that are weeds that transmit transgenes maternally (or possibly through both egg and pollen).

Pollination of a chloroplast transgenic crop by a variety lacking transgenes or by a variety containing nuclear transgenes may alter the nuclear-cytoplasmic balance, leading to altered chloroplast transmission. Plastids may be inherited strictly maternally, exclusively paternally, or biparentally. Gymnosperms have mainly paternal (pollen) transmission of plastid genes while most flowering plants seem to have maternal plastid inheritance. About one third of the flowering plants investigated have displayed biparental plastid inheritance to some degree (1). Among the flowering plants, rye shows paternal plastid inheritance (1). Predominantly paternal inheritance has been observed in chaparral (2). Alfalfa has predominantly paternal inheritance accompanied by both biparental and maternal variants(3,4). The medicinal herb damiana has clearly paternal inheritance (5) as does kiwi (6). Experiments with calla lilies showed that nuclear-cytoplasmic interactions determined the paternal, biparental or maternal transmission of plastids. Interspecific hybrids showed maternal chloroplast transmission in the F1 generation, but from either maternal or paternal parents in the backcross (7).

These studies show that individual crop plants and weeds need full analysis of the mode of chloroplast transmission before it could be concluded that the transgenic chloroplast modifications eliminate transgene transmission through pollen. Even plants that appear to have clear maternal plastid transmission may show leakage of pollen transmission (8), a frequency of one transgenic plastid containing pollen granule in 100 or 1000 could lead to significant transgenic pollution of nearby crops or weeds.

The results described above indicate that the claim that chloroplasts are maternally inherited and transgenic chloroplasts contain the release of polluting transgenic pollen is not always valid. The numerous crops or wild plants that show biparental or paternal inheritance of plastids means that each crop must be carefully studied. When a transgenic chloroplast crop plant is fertilized by weed pollen (for example Canola also has weedy relatives in Canada with which it could form hybrids - birdsrape mustard in eastern Canada, feral B. rapa canola in western Canada, and wild radish (Raphanus raphanistrum L.)), the crop forms a weed hybrid with maternal plastid inheritance but the nuclear cytoplasmic relationship has been altered which may result in weeds that show either paternal of biparental inheritance of plasmids. A few crop-weed hybrids can quickly establish transgenic weeds.

In conclusion, much has been written promoting chloroplast transgenes as a way of preventing spread of transgenes to crops or weed. I have not seen any discussion of the genetic consequences of weeds or crops pollinating chloroplast transgenic crops. Certainly, weed intrusion could easily establish transgenic weeds. Chloroplast transgenes offer the real advantage of producing multiple gene copies that are not much affected by gene silencing (neither pre-transcriptional nor post-transcriptional silencing) and a potential to transform the plastid genome using homologous recombination, which is not possible with nuclear transgenes. The use of plastid transgenes to prevent gene spread is still on rather shaky grounds until the plastid containment is fully proven by direct experiment.

References
1. Mogensen,HL and Rusche,M "Occurrence of plastids in rye sperm cells" 2000 Am J. Bot. 87,1189-92
2.Yang,T,Yang,Y, and Xiong,Z "Paternal inheritance of chloroplast DNA in interspecific hybrids in the Genus Larrea" 2000 Am.J. Bot. 87,1458-2000
3. Schumann,C and Hamcock,J. "Paternal inheritance of plastids in Medicago sativa" 1991 Theor and Appl Genet 78, 863-66
4. Rusche,M,Mogensen,H.,Zhu,T. and Smith,T. "The zygote and prembryo of alfalfa" 1995 Protoplasma 189,88-100
5. Cipriani,G,Testolin,R and Morgante,M. "Paternal inheritance of plastids in interspecific hybrids of the genus Actinidia revealed by PCR-amplification of chloroplast DNA fragments" 1005 Mol and Gen Genet 247,693-97
6. Tustolin,R and Cipriani,G "Paternal inheritance of chloroplast DNA and maternal inheritance and maternal inheritance of mitochondrial DNA in the genus Actinidia" 1997 Theor and Appl Genet 94,897-903
7. Yao, J. and Cohen,D. "Multiple gene control of pastime-genome incompatibility and plastid DNA inheritance in interspecific hybrids of Zantedeschia" 2000 Theor. Appl Genet. 101,400-6
8. Avri,A and Edelman,M. "Direct selection for paternal inheritance of paternal inheritance of chloroplasts in sexual crosses of Nicotiana 1991 Mol Gen Genet 225,273-7

Professor Joe Cummins,
University of Western Ontario.
Canada
jcummins (at) uwo.ca