Genetic erosion of plants 


Saiful Islam Shyam


Soil, water, and genetic resources constitute the foundation upon which agriculture and world food security are based. Of these, the least understood and most undervalued are plant genetic resources. They are also the resource most dependent upon our care and safeguarding. And they are perhaps the most threatened. Plant genetic resources for food and agriculture consist of the diversity of genetic material contained in traditional and modern varieties grown by farmers as well as crop, wild relatives and other wild plant species that can be used for food, feed for domestic animals, fibre, clothing, shelter, wood, timber, energy, etc.In the past decades, the globalisation process has spread environmentally unfriendly agriculture and its technology to many parts of the South. In recent years, the harmful effects of this model have been recognised. But, in the past most agricultural aid has been for promoting the Green Revolution model, which uses seeds with a high response to big doses of inorganic fertiliser and chemical pesticides. These few seed varieties have displace a wide range of traditional seeds, thus eroding crop biodiversity. There is also a mounting evidence of growing concern with other ecological problems, such as increasing soil infertility, chemical pollution of land and water resources, pesticide poisoning, and pest infestation due to growing pest immunity to pesticides. These are symptoms of a technological system in decline and the system's main claimed benefit, high productivity, is itself now in question.A report by an independent group of experts provides details of recent findings of potential serious threats. These include the possibility of certain genetically engineered bacteria killing soil organisms, thus reducing nutrient supply to plants and threatening their survival; the rapid transfer of transgenes from oilseed rape (engineered to be herbicide tolerant) to its weedy natural relative; and the survival and spread of genetically-engineered organisms.With disillusionment setting in about the Green Revolution, commercial resources are now turning to the new bio-technologies. There is need for great caution in this regard, for the claimed benefits of genetic engineering are far from being proven, whilst there is increasing evidence of real and potential risk. Given the concerns about bio-safety, aid resources should not be channelled to developing the new bio-technologies as a new technological panacea. To do so would mean that the lessons from the Green Revolution experience have not been learnt, and developing countries could then face a new set of ecological and safety threats. The conservation and sustainable utilisation of plant genetic resources is key to improving agricultural productivity and sustainability thereby contributing to national development, food security, and poverty alleviation. Today the world is not food-secure in terms of access to food. Many plant genetic resources which may be vital to future agricultural development and food security are threatened today. Recent losses of diversity have been large, and the process of erosion' continues. Of major concern is the irreversible loss of genes, the basic functional unit of inheritance and the primary source of the variation in the appearance, characteristics, and behaviour among plants. Gene complexes, and species can also be lost, and in effect become extinct. And plant varieties can also disappear. The chief contemporary cause of the loss of genetic diversity has been the spread of modern, commercial agriculture. The largely unintended consequence of the introduction of new varieties of crops has been the replacement - and loss - of traditional, highly variable farmer varieties. This process was the cause of genetic erosion most frequently cited by countries. For example, of the 7,098 apple varieties documented as having been in use between 1804 and 1904, approximately 86 per cent have been lost. Similarly 95 per cent of the cabbage, 91 per cent of the field maize, 94 per cent of the pea, and 81 per cent of the tomato varieties apparently no longer exist. The processes of modernisation and varietal replacement, well documented in the US, have now occurred in many other countries and have surely led to substantial losses of unique genetic materials.In Africa, the degradation and destruction of forests and bush lands is cited as a main cause of genetic erosion. Most countries in Latin America report major genetic erosion of forest species of economic importance. The Executive Chairman of Bangladesh Agricultural Research Council says, "some 8,500 cultivars of rice were there in the early 1960s in the area that constitutes Bangladesh. Current estimates put the figure at only a few dozens of rice cultivars that can be found in farmers' fields. The erosion of genetic resources imperils future development of plants that are used for food, fibre, fuel, and industrial uses due to the loss of sources of useful genes." The loss of genetic diversity in agriculture reduces the genetic material available for use by present and future generations. Developmental and evolutionary options for various species may, therefore, be shut off in the process. The concomitant increase in uniformity may also lead to greater risks and uncertainty.

Source: The Daily Independent, Dhaka, December 2, 1999

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