|Keywords:||Genetic engineering; Biosafety/Foodsafety; Apomixis; Cell-/Tissue culture.|
|Correct citation:||Visser, B. (1998), "Effects of Biotechnology on Agro-biodiversity." Biotechnology and Development Monitor, No. 35, p. 2-7.|
Since the Convention on Biological Diversity (CBD) was signed
in 1992, the value of biological diversity in general, and agro-biodiversity
in particular, has gained recognition world-wide. Agro-biodiversity can
be defined as the total of components, structure and functions in agro-ecosystems
relevant for agricultural production. Agro-biodiversity is first of all
of vital importance for the food security of future generations. This diversity
can be exploited to overcome new pests and diseases, to cope with climate
changes and a growing world population, to react to changing consumer demands
and to make production more sustainable. Furthermore, agro-biodiversity
is related to cultural values and traditions. Finally, many believe that
diversity has an intrinsic value and that mankind is responsible for the
survival of ecosystems and all that constitutes these systems.
Technology in general has had an impact for ages on the development of agro-biodiversity. Utensils in agriculture, food processing technology and seed storage systems, for example, have always been developed in close interaction with the diversity present in agriculture. This includes the genetic diversity of landraces and varieties within crop and animal species, the diversity of different crops and animals at the farm and the diversity within the entire agro-ecosystem. Some technologies, like fermentation technology, have influenced the properties that farmers consciously selected for their crops and animals. Others, like seed storage and fodder production, have resulted in conscious as well as unintended selection in landraces and animal breeds. The adaptation of crops and animals to the available technologies has determined their role in the farming system. And finally, the development of the farming systems has greatly influenced the agro-ecosystems in which they function, as is evident from the current discussions on the sustainability of high-external-input systems.
Biotechnology, like all preceding technologies, has influenced and will further influence agro-biodiversity. In this article an inventory will be made of the likely or potential effects of modern biotechnology on agro-biodiversity.
Common effects of agriculture and biotechnology on biodiversity
Both agriculture and biotechnology make use of biodiversity and thus show us the value of biodiversity. Likewise, both agricultural practices and biotechnology impose a threat to the existing biodiversity on which they depend. Modern agricultural practices, stemming from the rise of a modern breeding industry and from the Green Revolution, have caused massive genetic erosion, the disappearance of many diverse populations of crops maintained by farmers and adapted to local circumstances. The application of modern biotechnology may result in a wider use of genetic diversity, whether present in wild or domesticated species, for the benefit of future food security. However, it may also potentially result in the further narrowing of the genetic base of our food crops, because of the high costs of biotechnology and, consequently the tendency to focus on few varieties or breeds only. It may even result in the introduction of novel organisms which form a risk to the (agricultural) environment.
Genetic erosion, now commonly regarded as a negative development, was caused by the rise of the modern breeding industry and marketing decisions of that industry, and did not form a natural necessity. The socio-economic context in which biotechnology is developed and applied includes competition, research structures, seed markets and intellectual property rights. It will also determine which applications and, consequently, which effects of biotechnology on the conservation and utilization of biodiversity will dominate. For a number of biotechnologies the picture of positive and negative potentials, depending on the socio-economic context, begins to appear.
In vitro technology and reproduction technology
* Tissue culture of crops offers the possibility of rapid propagation of large numbers of genetically identical plants. The technology can be used for the propagation of desirable genotypes of vegetatively propagated plants. It is applicable in particular in the case of highly heterozygous clones, of which the genotypes are lost in sexual reproduction, and for plants with decreased fertility or long generation cycles. Tissue culture is therefore popular in horticulture and forestry. The technology can also be used to lower the virus pressure in starting materials. These applications may increase the availability of genetically diverse starting materials. Moreover, tissue culture can be used for conservation of genetic diversity. However, if the technology is mainly used to supply large areas with genotypically identical materials, the net effect of the technology on genetic diversity will be negative. At present, the net effects are still difficult to measure. However, for some crops which have already been reproduced by conventional clonal propagation techniques for many years, the trend is clearly negative. In the case of banana, only a few varieties are dominant world-wide.
* Inbreeding of properties from distant relatives using in vitro methods can result in novel combinations of genetic diversity. In practice this option is not very popular in breeding because of the long generation times and high costs related to the introduction of genes from distant relatives. It has mainly led to rarities like a hybrid between potato and tomato and the ‘shoat’, a hybrid of sheep and goat.
* Cryopreservation, the preservation at temperatures as low as -196 °C, can be used for conservation of plant meristems, but until now by far the most important application has been the conservation of sperm of animal species. Effects on genetic diversity of this application in artificial insemination have been mainly negative: the very successful bull Sunny Boy has produced the sperm for nearly 1 million inseminations in the Netherlands, which is over 75 per cent of the total, and left a massive genetic impact on Dutch livestock.
Multiple ovulation, in vitro fertilization and embryo transfer in combination with cryopreservation may allow the rapid propagation of selected animal breeding material. This results in the rapid replacement of heterogeneous, locally adapted populations by homogeneous stocks, as has happened in the case of chicken.
Apomixis and terminator technology
Apomixis, the seed formation from unreduced egg cells without fertilization (see also Monitor No. 19), occurs in nature in some plant species like cereals. The resulting offspring is genetically identical to the parent. For commercial breeding this development is of little interest since it may create a way to surpass the biological property protection offered by hybrid varieties. It offers farmers the possibility to produce seeds for the next growing season with the same properties as the parent plant, which until now cannot be realized using hybrids.
However, modern plant-breeding industry may move into crops largely ignored so far, using a new technology, called terminator technology. The American cotton seed company Delta and Pine Land and the United States Department of Agriculture (USDA) announced they had received a patent on a technique that genetically disables a plant to set seeds that germinate when planted again (see also the article on seed sterility patent in this issue). This technology can potentially be used in all cultivated crops. Varieties of crops like rice, wheat, sorghum and soybean, which could not effectively be marketed using hybrids may now be commercially protected by using this new technology. This would open some of the world’s largest food crops to profitable breeding and further increase the risk of genetic erosion, which has already progressed extensively in these crops. The net effect of this technology is likely to be negative.
Biological test kits and DNA marker technology
Using biotechnology, ready-to-use and simply applicable test kits have been developed for identification of viruses, fungi and other pathogens in the field. These kits can be implemented as precision instruments for a rational selection of control strategies and moments in integrated pest management. As compared with traditional pesticide use, integrated pest management has a positive effect on the total biodiversity in agro-ecosystems. Similar kits applied in diagnosis of animal diseases may remove barriers between nations in the exchange of breeding material for livestock and this could also increase the availability of a wider array of breeding material. The likely net effect of biological test kits on agro-biodiversity is therefore positive.
Many agronomically important traits are governed by a large number of genes which interact at different regulatory levels. These traits are called quantitative traits. Traditionally, manipulation of the genes involved forms the domain of breeding.
Molecular markers enable localization of the genome sites involved in such properties and this knowledge may render breeding faster and more precise. Marker technology can be applied for the exploitation of genebank ex situ collections as well as for the improved use of elite breeding materials. It can be used for quantitative traits such as yield, mineral use, food quality, taste, storage capacity, resistance and adaptation to physical stresses. Considering that most commercial crop varieties currently exhibit a narrow genetic basis, marker technology offers the opportunity for rapid corrective measures in case of outbreaks of new pests and diseases. Furthermore, the technology can be used preventively to determine the relationship between genetic materials and genetic properties and enables rational choices aiming at an increase of genetic diversity.
In animal breeding determination of genetic relationships in animal populations is a major application. This allows a rational selection of reproduction schemes which best maintain the genetic diversity present in the population.
Finally, the technology can be used for fundamental research on the relationship between the level of genetic diversity in a crop and its versatility in reaction to changing conditions.
The applications described above are largely possibilities. Marker technology will surely be used by industry to improve current breeding practices, but it is uncertain to what extent applications will be realized that benefit maintaining or increasing biodiversity and versatility in agriculture.
Genetic modification has been applied in both plant and animal breeding, although commercial applications have only been realized in the former domain, e.g. insect resistance and herbicide resistance in maize, cotton and soya bean, and prolonged shelf life of tomato. In view of the high costs of genetic modification, the technology will only be applied in a few economically important crop varieties of major crops grown in the industrialized world, and possibly in animal breeds. If the resulting genetically modified organisms form an agricultural success this may lead to replacement of several conventional varieties and thus to a decrease in genetic diversity in that crop or animal. Furthermore, patent protection will limit the use of such varieties in further breeding by others and thus prevent the spread of the newly introduced traits. Although patent protection is not a necessary consequence of biotechnology, its result is that the net effect of genetic modification on biodiversity is likely to be negative. This is contrary to popular statements about the addition of novel genes to available crop genotypes.
Genetic modification of micro-organisms with an agricultural value such as genetically modified Bacillus thuringiensis may improve bio-insecticidal sprays or enlarge their host range. Modification in relation with nitrogen fixation, which can reduce the use of artificial nitrogen fertilizers, offers only very limited opportunities in the short run because of the intricate biochemical pathways involved. Positive effects on biodiversity stemming from the reduction of the use of artificial fertilizers is therefore unlikely.
Genetically modified veterinary vaccines offer an opportunity to increase the health of all sorts of livestock, be it indigenous or exogenous, common or rare and net effects are hard to predict. However, increased use of more effective vaccines might fit the tendency to control the environment rather than to exploit genetic diversity in the search for better production.
A positive role of biotechnology in maintaining and enlarging agro-biodiversity
Is the picture of the effects of biotechnology on agro-biodiversity indeed so gloomy? Much will depend on the ways biotechnology is exploited, and positive applications are certainly feasible. To summarize, what is the potential of biotechnologies to stop and reverse the decrease in diversity in agriculture?
* Maintenance of genetic diversity. Marker technology can be used to study relationships between genetic material, in starting materials for breeding and in small animal populations, and to monitor the genetic developments in in situ and on-farm conservation projects. Cryopreservation increases the options for conserving starting material, in particular for animals and for those crops which cannot be maintained using normal practices.
* Utilization of genetic diversity. Markers can also be used to increase the efficiency of breeding strategies and to focus on desirable traits. Since markers allow precise identification of the genetic make-up of varieties, they allow relaxation of legislation on uniformity of crop varieties and may support reintroduction of genetically more heterogeneous and versatile varieties. Finally, markers can be used to trace properties which are important in ecological farming or other forms of sustainable production which are currently under-utilized. Cryopreservation in combination with artificial insemination may help to support the maintenance of rare breeds or rare properties.
* Reduction of pesticide use. Integrated pest management using test kits and resistance breeding using marker technology or (in cases of durable resistance) genetic modification may reduce the need for pesticides with an overall positive effect on biodiversity.
The overriding socio-economic context
In many countries, government policies and efforts of private breeding companies have stimulated the shift from food production for subsistence or for the local community in complex farming systems to production of fewer crops and breeds for the national or global market. Often this has implied a shift from many local, well adapted landraces to few modern high-external-input varieties. These policies and market efforts have resulted in a concomitant loss of diversity. These effects occurred in most developed countries but have now also become highly significant in most developing countries. Opening markets and globalizing economies, and the efforts of the international and national breeding institutes on major food crops are responsible for these effects. Higher food production based on high-external-input varieties and loss of traditional genetic diversity which we may need in future are two sides of the same coin.
Modern biotechnologies will strengthen these effects. Tissue culture techniques and artificial insemination require relatively low investment costs and limited expertise and are now well within the reach of most developing countries. Marker technology and genetic modification clearly require higher inputs, better facilities and more expertise, but are applied by several developing countries. And certainly, institutes which focus on agriculture in developing countries, e.g. the Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT), the International Rice Research Institute (IRRI), the Centro Internacional de la Papa (CIP), the Centro Internacional de Agricultura Tropical (CIAT) and the International Livestock Research Institute (ILRI), have acquired these latter techniques and are involved in applications which will render novel breeding products for agricultural production. Only the International Plant Genetic Resources Institute (IPGRI) and the Centres’ System Wide Initiative on Plant Genetic Resources of the Consultative Group on International Agricultural Research (CGIAR) are unambiguously dedicated to the rescue of agro-biodiversity that has remained. Future breeding strategies within the CGIAR Centres will probably have a major impact on conservation and utilization of genetic diversity in farmers’ fields in developing countries.
In the CBD, loss of biodiversity in general and agro-biodiversity in particular has been recognized as undesirable. Improvement of production under low-external-input conditions, long-term sustainability, and future versatility of agricultural production are all dependent on a wide and rational utilization of agro-biodiversity. In modern agriculture, agro-biodiversity has received too little attention. Genetic diversity was regarded as being functional in breeding programmes, but not in the field where conditions are controlled and where uniformity is required for high yields. Development and application of technology in agriculture took place from this perspective, and largely ignored negative effects on agro-biodiversity. Conservation of biodiversity for the food security of future generations and for a more sustainable agricultural production requires a change in this attitude. It also requires a change in socio-economic conditions in agriculture which have caused the neglect for maintenance of biodiversity. This change should be based on the acknowledgement of the value of in situ conservation of genetic diversity and the need to consciously develop and use technology in this direction. This change should form a challenge for both governments and industry when opening new markets. Only then will the net effect of biotechnology on biodiversity be positive.
Centre for Genetic Resources the Netherlands (CPRO-DLO), P.O. Box 16, 6700 AA Wageningen, the Netherlands. Phone (+31) 317 477184; Fax (31) 317 481094; E-mail L.Visser@cpro.dlo.nl
This article was based on the report ‘Agro-biodiversity and the effects of new technologies’ by Bert Visser, Joost Jongerden and Jaap Hardon, that will be published in 1998 by the Rathenau Institute, Den Haag, the Netherlands.
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