Concerns about the bioengineered plants continue in spite of the multitude of advantages presented. Many of these concerns are legitimate and are being taken seriously. We are just beginning to recognize how plants fight off predators through internal biochemicals and morphological features ( see previous class on secondary defenses). Very often our reductionist views may cause more problems than solutions.....
Social concerns include the cost and distribution of engineered seeds. There is no doubt of the expense involved in developing such plants; companies should be able to recoup their costs. However in the past many of the advances in this field were supported by the government ( US and others) and the rights to use these crops were given to all without high additional costs. The uptake of ag-engineering by private firms who will charge for these advanced seeds means that countries with the largest growing populations and the lowest net incomes will least afford these crops. Already these companies are engineering crops with a second gene complex that will not allow the organism to pass on the gene to the seed produced by the crop. In one way this is good.. it should prevent the spread of the inserted gene(s) into weeds, etc. but it also means that the farmer must buy these seeds annually from the company. For small farmers and for those in 3d world nations this expense cannot be borne, and will make them less able to compete on the world market.
Genetic pollution and superweeds
A major concern is that genes that have been copied from one species and inserted into another might 'escape' and spread to other organisms, thus causing 'genetic pollution'. For example, herbicide-resistant crops might cross-breed with related weeds and produce herbicide-resistant 'superweeds'.
Unlike animals there is a greater probability of this occurring as:
Antibiotic resistance
Genes that code for antibiotic resistance are sometimes inserted into plant cells together with the 'useful' gene; these 'marker' genes enable scientists to select cells that have been successfully modified. Such antibiotic-resistance markers in crops might spread to animals or humans, rendering medical or veterinary use of the antibiotic ineffective. There is a move to use antibiotics not used by the general public but this difficult as the number of functional antibiotics available has decreased due to limited development by companies and the 'loss' of functionality due to resistance developed by organisms with overexposure in the environment.
Unstability of genome produced may lead to surprises...
Some genes that are inserted into genetically modified plants might be unstable (there is a high probability that they will be lost from the plant cells; see problem with gene gun) ), or might show unexpected effects because it is difficult to predict where in the plant genome the genes will insert. The plant produced in the lab may not be identical to that in the field over time....
Pest resistance
Genetically modified crops that are designed to be resistant to a particular pest might have unintentional (and unpredictable) effects on harmless or beneficial organisms (e.g. ladybirds and bees). We know from past experiences with chemical pesticide use that upsetting the trophic chain can have unexpected and unhappy consequences.
Very often an apparent pest may be actually controlling the explosion of a second or third competitor on that plant. If we eliminate one another may become still a greater pest. Many other possibilities similar exist.
Persistence and weediness
Genetically modified plants might, intentionally or unintentionally, be more vigorous than their non-modified relatives. They can therefore effectively become 'weeds'. If plants are more 'persistent' (e.g. survive over winter better), they could rapidly dominate ecosystems at the expense of other plants. If they show 'weediness' characteristics, they could also spread to new habitats.
1. Concerns over Engineered Crops and Superweeds: The Transgenic Squash
The Freedom2 Squash and its cousins look like any other plump yellow squash, but actually they represent significant improvements. These squash varieties have been genetically engineered by the Asgrow Seed Co. of Kalamazoo, Michigan, to resist two common plant viruses. In large-scale field trials in Texas over the last two years, Freedom2 has significantly out-produced lesser squash. Yet despite Freedom2's virtues, a debate has begun swirling about this and other transgenic crops. The public's original fears about genetically engineered crops have subsided, but now some biologists are raising a new concern: that advantageous genes, such as those that make Freedom2 resist viruses, may escape from transgenic crops to their weedy relatives and thus create a hardy new race of weeds.
New ecological crop data appears to show that genes can move from transgenic crops to wild relatives more often than once thought. As more and more transgenic varieties are planted, some plant geneticists worry that it is only a matter of time before the transfer of an engineered gene creates a new weed or invigorates an old one. This year alone, eight new transgenic crops have been approved for wide-scale field tests, including a cousin of Freedom2 that resists even more viruses. Even rare genetic transfers to wild plants could have the potential for devastating effects. Agricultural officials say that they already assume that gene flow may occur to wild populations, and that they approve field trials only when they are convinced that there is no hazard. And they note that the dangers of creating a "superweed" are at the moment hypothetical. After all, the Freedom2 Squash, which was approved 2 years ago, and its weedy relative, the Texas gourd, haven't taken over Texas yet. Agriculture experts also say that any risk has to be weighed against the benefits of transgenic crops--especially in developing countries, where nonprofit agencies are trying to introduce the new varieties to nations that need them most.
First-generation hybrids between crops and wild plants are often sterile, so researchers once thought that gene flow from transgenic crops to weeds would be minimal. However, a new report has documented unusually high rates of such gene flow by studying 12 marker genes in cultivated and wild sunflowers. For example, near fields where sunflowers had been growing for 10 years, the frequencies of the marker genes in wild sunflowers averaged about 28%; in a 35-year-old system, the figure was 38%. Another report showed that, in a population of wild strawberries growing within 50 meters of a strawberry field, more than 50% of the wild plants contained marker genes from the cultivated strawberries. Lastly, a third report from Denmark, showed, not surprisingly, that the same thing can happen with genes from transgenic crops. In a study of hybrids of transgenic oilseed rape, which carried a gene for herbicide resistance, and a weedy relative in the canola family, Brassica campestris, or field mustard, the results showed that first-generation crosses resisted herbicides, and so apparently had retained the transgene, and had highly fertile pollen.
Even so, ecologists say, there is no need to worry about most transgenic crops. Many transgenes, such as those that make tomatoes ripen more slowly, wouldn't give wild plants an advantage. And many crops don't have native relatives that could hybridize with transgenic strains. Freedom2 was the first U. S. transgenic crop with a weedy relative to be approved, and USDA officials say they took special care in the case. After looking at data from Asgrow and outside reviewers for over two years, APHIS decided to deregulate because the virus doesn't infect the Texas gourd in the wild, so the transgene wouldn't confer any special advantage.
But some plant taxonomists are not convinced and feel that more evidence is needed to establish that the viruses don't affect the wild Texas gourd, noting that the crucial data came only from Asgrow and were not an exhaustive survey of wild populations. These scientists say they don't want to stop transgenic crops cold, but they fear that the Freedom2 has established a precedent and that ecological concerns will be swept aside as more and more crops are approved. Federal officials counter that there should be limits to regulation, and that in many cases, it's the company's responsibility to protect their investments by making sure that transgenic crops don't lend their genetic strengths to weeds. Herbicide-resistant crops are usually developed by the herbicide marketers themselves, so if the transgene escapes into a wild population and eventually renders the herbicide obsolete, the company will lose a portion of its herbicide market.
As ecologists and regulators debate these issues, the stakes surrounding transgenic crops are rising. Developing nations, where crops may have more native relatives, are beginning to test and adopt the new varieties. For example, a potato genetically engineered for virus resistance has been in field trials in Mexico since 1992. If this year's large-scale trials go well, the potato could come up for deregulation in mid-1997. The introduction of transgenic crops to regions where many crops originated raises another concern. One of the centers of diversity for the potato is central Mexico, for example, and many wild potatoes still grow there. Traditional breeders and transgenic crop critics worry that transgenic varieties could introduce a potentially dominant genotype into the wild. Such a takeover would reduce the genetic pool available to breeders who currently tap these diverse populations to develop new crop strains.
It is hoped that existing rules for selling seed crops would prevent such a takeover by guarding against hybridization. Most widely grown crops go through a rigorous certification process in which fields are monitored for signs of hybridization. Many feel it is important for developing nations to get the benefits of new technologies, and say that careful seed certification in these countries can prevent the shadowy dangers of gene flow. Most developing nations posses limited arable land and burgeoning populations, and are going to need some infusion of technology in order to meet their food needs.
Whether or not transgenic crops spawn superweeds, they are likely to generate continued debate, as the opinions of officials sometimes clash with those of research ecologists. The official U.S. position is that transgenic crops should be deregulated on a case by case basis that adequately reviews the issues of gene flow to weedy relatives. How well this position protects the centers of diversity of important crops remains to be seen.
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2. World population is expected to double to more than 10 billion people by the year 2050. Few other new technologies will be able to approach biotechnology's potential to help avoid starvation in the next century.
Tuesday, January 26, 1999
Genetically engineered barley carries a gene that may help the plants resist attack by barley yellow dwarf virus.The United Nations Food and Agriculture Organization set the tone for an agriculture conference this week when it said that biotechnology is a powerful tool to feed an increasing world population. However, the organization urged caution when evaluating the positive and negative aspects of biotechnology.
"All concerns must be clearly balanced, respecting ethical aspects but reflecting the actual and potential possibilities of increasing food supplies and alleviating hunger," the organization said in a report prepared for the Committee on Agriculture.
Committee delegates from 100 countries will meet this week in Rome to discuss issues such as organic farming, urban agriculture and the monitoring of land and fresh water resources.
World population is forecast to reach 7.5 billion people by 2020, with 6.3 billion living in developing countries. Even though the population growth rate is decreasing, the increase in the absolute number of people to feed combined with current technology may cause us to reach the carrying capacity of agricultural lands.
Biotechnology, which includes the application of tissue culture, immunological techniques, molecular genetics and recombinant DNA techniques in all facets of agricultural production and agro-industry, together with other technologies, could provide solutions for some of the old problems hindering sustainable rural development and achievement of food security, the Food and Agriculture Organization said.
According to the organization, biotechnology-derived solutions built into the genotype of plants could reduce the use of agrochemicals and promote sustainable yields. The application of pesticides and fungicides could be reduced through plants with genetic pest resistance. Plants with a high tolerance for conditions of salinity or high iron toxicity could help to improve agricultural production in marginal areas.
Some biotechnological techniques, like in-vitro culture, are very helpful for maintenance of germplasm collections of species with low fertility and of species that are hard to keep as seeds or in field gene banks, according to the report.
"Biotechnology may reduce genetic diversity indirectly by displacing landraces and their inherent diversity as farmers adopt genetically uniform varieties of plants and other organisms. At the same time, it increases the potential to preserve and sustainably use diversity. In the case of endangered animal breeds, cryopreservation and somatic cloning can strengthen traditional conservation strategies," the report said.
The report calls for biotechnology research and policy efforts focused on the needs of the poor who depend on agriculture, especially in marginal areas where it will be difficult to achieve productivity increases.
"Adequate biosafety regulations, risk assessment of biotechnology products, mechanisms and instruments for monitoring use and compliance to ensure that there will be no harmful effects on the environment or for people" are also required, according to the report.
Some of the potential environmental risks concern plant pests. Gene escape from genetically modified organisms may result in increased weediness in wild species, according to the Food and Agriculture Organization.
The inclusion of novel genes for herbicide resistance in plants may increase the occurrence of weeds with resistance to certain agrochemicals, the report warned.
"The inclusion of pest resistance in plants should be carefully evaluated for potential development of resistance in pests and possible side-effects on beneficial organisms."
The report encourages the Food and Agriculture Organization help members to optimize their capacity to develop, adapt and utilize biotechnology and its products to suit their needs and environment, and thus enhance global food security and improve living standards for all.
