Wealth creation in Genetic Resources
“Genetic Resources means genetic material of actual and potential value. They constitute plants, animals, microorganisms; and food or other natural products isolated from them” (CBD, 1993). From selection of specific desired traits and qualities possessed by crops and animals to the present use in biotechnology and genetic engineering, agriculture has evolved over the years. However, in terms of sustainability, the current state of affairs and the proposed future of crop and livestock breeding leaves much to be desired. This article covers the following: “Genetic change in nature and development of genetic diversity”; “Directed selection and domestication”; and “Preservation of agrobiodiversity”. Wealth creation in genetic resources is the result of preservation of agrobiodiversity.
Genetic change in nature and development of genetic diversity: Through evolution, new species emerge and others go extinct. Evolution is influenced by natural selection resulting in genetic diversity. Natural selection is the “raw material that humans have worked with in domesticating plants and animals and creating agroecosystems” ( Gliessman, 2007). The concepts of adaptation and natural variation are very important in understanding natural selection. Adaptation refers to both “a process and to a characteristic resulting from that process”. Natural variation exists at the genotypic and phenotypic levels. Species genetic variation is caused by mutations in DNA replication and meiosis in sexual reproduction. Failure in meiotic divisions may result in polyploidy and this is another source of variation. Natural selection is a constant occurring phenomenon because of constantly changing environmental conditions. Man’s interference with natural habitat is accelerating extinction rate, eliminating ecotypes and thus eroding natural genetic diversity and the potential for its renewal ( Wilson, 1992).
Directed selection and domestication: The practice of directed selection by humans has caused genetic change that is different from that which is occurring in natural populations. Man has selected specific favourable traits resulting in loss of others (such as traits that ensure “environmental resistance”) over the period ( Gliessman, 2007). Methods that have resulted in changes in the genetic makeup of crop species include mass selection; pure line selection; hybridization; induced polyploidy; and transgenic modification. However, traditional methods of mass selection “tend to preserve much of an organism’s genetically rich structure”. In contract, the controversial transgenic modification of crops has a number of potential drawbacks (Bottrell, 1996; Lu and Snow, 2005; Saito and Miyata, 2005) although “plants perform exceedingly well in specific, highly altered modern agricultural environments”. Loss of genetic diversity has the following consequences. Firstly, crops and livestock become genetically vulnerable to pests and diseases attack and extreme weather. For example, China has lost 90% of rice varieties since 1950 (Global Crop Diversity Trust ). Secondly, crops and animals cannot survive and produce optimum yields without external inputs from humans and some of these external inputs are detrimental to the environment and human health. Thirdly, other genetic resources such wild relatives of crops and habitats are lost.
Preservation of agrobiodiversity : To preserve agrobiodiversity, there is the need to shift back to genetic diversity which involves: breeding for durable resistance in crop plants; on-site selection and conservation of plant genetic resources and; preservation of minor crops and non-crop resources.
“Selection for durable resistance requires the accumulation of many resistance characters using population-level breeding methods, and relies on an understanding of the simultaneous nature of the interaction between a crop, pests, the environment and the human managers” ( Gliessman, 2007). This durable resistance is also called horizontal resistance (Robinson, 1996) and relies on open pollination and “locally adapted landraces”. A case study for horizontal resistance exists for bean crops in Mexico. This is a departure from vertical resistance which has two weaknesses: firstly, resistance is only possible as long as the limiting factor (pests, diseases, weeds etc.) remains constant; secondly, “genes providing partial resistance to the wider spectrum of pathogens are lost”.
On-site selection and conservation of plant genetic resources involves ex situ and in situ methods of conservation. Some limitations of ex situ conservation include limited funding resulting in limited number of plant species collection in genebanks therefore inability to fully restore “genetic erosion” and “severing of the adaptive tie between genome and environment (Hamilton, 1994; Nevo, 1998). Brush (2004) stated the need for in situ conservation to ensure sustainability. It eliminates static preservation associated with ex situ conservation as “it allows genetic screening to occur, maintaining and strengthening local landraces”. A case study in India involves the establishment of Gene-Seed-Grain banks which appears to forestall the static nature of genebanks.
Genetic resources encompass both the few crop species providing almost all the food needs of humans and “locally important, minor, or underutilized crops” including non-crop and wild species that have the potential to become new crops. These should also be the focus of genetic conservation especially in their traditional agroecosystems (Altieri and Nicholls, 2004) because they “form part of the whole-system, horizontal resistance process that is essential for maintaining a genetic basis for sustainable agricultural systems”. Livestock genetic diversity is also important and needs to be conserved since it is has a relatively greater risk of extinction. “Animal’s genome cannot easily be stored in a genebank” ( Gliessman, 2007).
In conclusion, “we need to reduce vulnerability and dependence on human interference through a strategy of diversifying the agricultural landscape, the crop species in agroecosystems, the varietal composition within species, and the resistance mechanisms within varieties” ( Gliessman, 2007). Let us all help in wealth creation in genetic resources.
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References:
Altieri, M. A. and Nicholls, C. I. 2004. Biodiversity and Pest Management in Agroecosystems. 2nd ed. Howarth press: Binghamton, NY.
Bottrel, D. G. 1996. The research challenge for integrated pest management in developing countries: A perspective for rice in southeast Asia. Journal of Agricultural Entomology 13(3): 185-193.
Brush, S. B. 2004. Farmer’s Bounty: Locating Diversity in the Contemporary World. Yale University Press: New Haven, CT.
Convention on Biological Diversity (CBD), 1993.
Gliessman S. 2007. Agroecology: The Ecology of Sustainable Food Systems. Taylor and Francis Group, LLC.
Hamilton, M.B. 1994. Ex-situ conservation of wild plant species: time to reassess the genetic assumptions and implications of seed banks. Conservation Biology 8(1): 39-49.
Lu, B. R. and Snow A. A. 2005. Gene flow from genetically modified rice and its environmental consequences. Bioscience 55(8): 669-678.
Nevo, E. 1998. Genetic diversity in wild cereals: regional and local studies and their bearing on conservation ex situ and in situ. Genetic Resources and Crop Evolution 45(4): 355-370.
Qualset, C. and Shands, H. 2005. Safeguarding the Future of U.S Agriculture: The Need to Conserve Threatened Collections of Crop Diversity Worldwide. University of California, Division of Agriculture and Natural Resources, Genetic Resources Conservation Program. Davis, CA, USA.
Robinson, R.A. 1996. Return to Resistance: Breeding Crops to Reduce Pesticide Dependence. AgAccess:Davis, CA.
Saito, T. and Miyata T. 2005. Situation and problems on transgenic technology for insect pest control. Japanese Journal of Applied Entomology and Zoology 49(4): 171-185.
Wilson, E. O. 1992. The Diversity of Life. W.W. Norton and Co.: New York and London.
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