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Sent: 08 June 2002 11:57
Subject: 27: Re: gene flow risk assessment - plants
I am Peter Jenkins, a policy analyst with the International Center for Technology Assessment in Washington, DC.
Below is a quote from Dr. Nickson (message 24, June 7):
"As a personal observation, the current biotech products have shown no measureable risks compared to the risks already present from their traditionally grown counterparts."
This observation cannot be reconciled with the GM herbicide resistant canola experience. Below is a quote from The Royal Society of Canada, "Elements of Precaution: Recommendation for the Regulation of Food Biotechnology in Canada," (January 2001) at 122-23 (citations omitted; these points were also stated by Professor Joe Cummins, in Message 12, June 5) [The report can be found at http://www.rsc.ca/foodbiotechnology/GMreportEN.pdf ...Moderator]:
"Traditionally, volunteer crop plants occur at relatively low densities and are eliminated from crops by selective herbicides. However, this management tool is complicated if volunteers are herbicide resistant. Unfortunately, herbicide-resistant volunteer canola plants are beginning to develop into a major weed problem in some parts of the Prairie Provinces of Canada. Indeed, some weed scientists predict that volunteer canola could become one of Canada's most serious weed problems because of the large areas of the Prairie Provinces that are devoted to this crop. Of particular concern is the occurrence of gene exchange via pollen among canola cultivars resistant to different herbicides. This can occur through crosses between volunteer plants and the crop, or between different volunteer plants. Three classes of herbicide-resistant canola (resistant to glyphosate, glufosinate and imidazolinone) are currently grown in western Canada. Recent evidence indicates that crosses among these cultivars have resulted in the unintentional origin of plants with multiple resistance to two, and in some cases three, classes of herbicide. Such "gene stacking" represents a serious development because, to control multiple herbicide-resistant volunteer canola plants, farmers are forced to use older herbicides, some of which are less environmentally benign than newer products. This example involving the origin of multiple herbicide-resistant canola serves to illustrate the dynamic nature of weed evolution within managed agroecosystems. It also demonstrates that crops plants are not immune from becoming weeds of agriculture under the appropriate selection regimes.
Because of the large areas devoted to herbicide-resistant canola in the Prairie Provinces, it is not surprising that opportunities for the genetic mixing of different varieties occur. Despite the best efforts of growers, seeds may often be transported accidentally between fields containing different herbicide-tolerant canola varieties by farm machinery, or simply be blown from trucks transporting seeds to and from fields. Indeed, it has been argued that seed spillage, a form of gene dispersal, may be a much more common mechanism resulting in hybridization between varieties than is likely by long-distance pollen flow by animal pollinators. Regardless of the mechanisms giving rise to multiple herbicide-tolerant canola varieties, this example illustrates the problems in trying to predict the likelihood of gene flow from small-scale test plots involving relatively small numbers of plants. In addition, it emphasizes the inherent difficulties in areas of the landscape. Industry argues that as long as "good farming practices" are followed, these problems should not occur. This perspective may be unduly na´ve. Environmental assessments associated with the release of GM crops should take account of the fact that in the real world human error and expediency may often compromise guidelines for the growing of such crops." [end quote]
Dr. Nickson also stated: "This lack of knowledge has resulted in broad characterizations of the hazards associated with gene flow from GM crops such as: impacts on biodiversity, impacts on population dynamics, genetic swamping, and alterations of gene pools; all of which are inoperative in terms of science based hypothesis testing."
It seems overbroad to suggest that those potential hazards are "inoperative", i.e., not amenable to scientific testing. I cannot believe other scientists would concur.
I submit that Dr. Nickson is simply acknowledging the difficulty of testing for those potential gene-flow and weediness related hazards because of the difficulty of scaling up small-scale field tests to the broad world of supervariable habitats, misfeasance and malfeasance by product users, etc. For example, Monsanto proposes to release an herbicide resistant creeping bentgrass despite the fact that creeping bentgrass is a recognized weed in a wide variety of natural and semi-natural habitats. Aimed primarily at golf courses (this one's not about "feeding the poor") and homeowners in all sorts of imaginable landscapes, this is the most ubiquitous and potentially significant GM product Monsanto has ever proposed. Once glyphosate tolerant GM creeping bentgrass seeds are in the wholesale and retail marketplaces and planted out, they would be impossible to recall and whatever impacts they do have in managed or wild settings would probably be in essence irreversible, whether Dr. Nickson believes they are operative or not.
I will especially appreciate comments related to any gene flow or related risks/hazards specific to herbicide resistant creeping bentgrass.
Peter T. Jenkins, Policy Analyst
International Center for Technology Assessment
660 Pennsylvania Ave. SE, Suite 302
Washington, DC 20003 USA
Tel: 202.547.9359 ext. 13
Email: peterjenkins (at) icta.org
Sent: 08 June 2002 12:16
Subject: 28: Is double fertilization a complication in fruits and grain
Prof. Joe Cummins, Prof. Emeritus of Genetics, University of Western Ontario, Canada.
I was stimulated to think about Dr. A.A. Badr's comment (message 21, June 7) on horticulture and biotechnology and the problem of pollination in fruit trees. I recently had a question about genetically modified papaya in Hawaii, a recent approval by the United States Department of Agriculture (USDA) for commercial application. The question was "will the papaya fruit on existing trees be effected in any other than the fruit seeds, following pollination by insect or wind". That, to me, was a truly astute question. as there is a problem, double fertilization in higher plants.
Double fertilization is when the pollen tube enters the ovule through the micropyle and ruptures. One sperm nucleus fuses with the egg forming the diploid zygote. The other sperm nucleus fuses with the polar nuclei forming the endosperm nucleus. Most angiosperms have two polar nuclei so the endosperm is triploid (3n). The tube nucleus disintegrates. The food in the cotyledons is derived from the endosperm which, in turn, received it from the parent sporophyte. In many angiosperms (e.g., beans), when the seeds are mature, the endosperm has been totally consumed and its food transferred to the cotyledons. In others (some dicotyledons and all monocotyledons), the endosperm persists in the mature seed.
In corn, fertilization with pollen from a transgenic corn plant of a non-transgenic flower results in a cob with grains which are mainly triploid endosperm with a small proportion of diploid endosperm. In contrast the dicotyledon fruit may be rich in endosperm milk or papaya in which the endosperm may mainly have been "consumed" as the fruit matures. However, the term "consumed" is deceptive as there seems to be few or no published studies on the fate of transgenic DNA as the endosperm matures. "Consumed" transgenic DNA may or may not persist in the mature fruit.
The approval of papaya ("USDA-APHIS Response to Cornell University and the University of Hawaii Petition 96-051-01p for a Determination of Nonregulated Status for 'Sunset' Papaya Lines 55-1 and 63-1" [available at http://www.aphis.usda.gov/biotech/dec_docs/9605101p_det.HTM ...Moderator] did not include any data on the fate of endosperm DNA in the maturing fruit. Nevertheless, growers of non-transgenic papaya would be shocked to find that their fruit was richly transgenic. Similar considerations are true of a number of fruits and grains being considered for commercial release.
Professor Joe Cummins,
University of Western Ontario.
jcummins (at) uwo.ca
[From the FAO Biotechnology Glossary (http://www.fao.org/DOCREP/004/Y2775E/Y2775E00.HTM), double fertilization is defined as "a process, unique to flowering plants, in which two male nuclei, which have travelled down the pollen tube, separately fuse with different female nuclei in the embryo sac. The first male nucleus fuses with the egg cell to form the zygote; the second male nucleus fuses with the two polar nuclei to form a triploid nucleus that develops into the endosperm."...Moderator]