TRENDS IN BIOSCIENCES 6-1, 2013 EDITION

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2 Trends in Biosciences 6 (1), <strong>2013</strong> Aromatic Plants from Brazil Approximately 2/3 of the biological diversity of the world is estimated to be in tropical zones, mainly in developing countries. With nearly 55,000 native species, Brazil is considered the country with the greatest biodiversity on the planet. These species are distributed over six major distinct biomes: Amazon (30,000); Cerrado (7,000); Caatinga (4,000); Atlantic rainforest (16,000), Pantanal (10,000) and the subtropical forest (3,000) India is a major center of origin and diversity of crop and medicinal plants. India poses out 20,000 species of higher plants, one third of it being endemic and 500 species are categorized to have medicinal value (Krishnan, et al., 2011). (B) Species Diversity This diversity includes the variation of species within the particular region. Each of these biological communities’ represents and adaptation of plants to particular regimes of climate, soil and other aspects of the environment. Global biodiversity is frequently expressed as the total number of species currently living on Earth, i.e., its species richness. Between about 1.5 to 1.75 million species have been discovered and scientifically described (LeCointre and Guyader, 2001; Cracraft, 2002). Species richness and species evenness are probably the most frequently used measures of the total biodiversity of a region. Species diversity is also described in terms of the phylogenetic diversity, or evolutionary relatedness, of the species present in an area. (C) Ecosystem Diversity An ecosystem is a community plus the physical environment that it occupies at a given time. An ecosystem can exist at any scale, for example, from the size of a small tide pool up to the size of the entire biosphere. However, lakes, marshes, and forest stands represent more typical examples of the areas that are compared in discussions of ecosystem diversity. Ecosystem diversity refers to the diversity of a place at the level of ecosystems. The term differs from biodiversity, which refers to variation in species rather than ecosystems. Table 1. Gene banks of various crops in India Crop species Location of gene bank centre Wheat DWR, Karnal (Haryana) Rice CRRI, Cuttack (Orissa) Potato CPRI, Shimla (Himachal Pradesh) Cotton CICR, Nagpur (Maharashtra) Sugarcane SBI, Coimbatore (Tamil Nadu) Tobacco CTRI, Rajahmundry (Andhra Pradesh) Pulses IIPR, Kanpur, (Uttar Pradesh) Forage Crops IGFRI, Jhansi Plantation Crops CPCRI,Kasargod, (Kerala) Tuber Crops (except Potato) CTCRI, Trivandrum (Kerala) Oilseed Crops DOR, Hyderabad (Andhra Pradesh) Horticultural Crops IIHR, Bangalore (Karnataka) Sorghum NRC Sorghum, Hyderabad (Andhra Pradesh) Groundnut NRC Groundnut, Junagadh (Gujarat) Soybean NRC Soybean, Indore (Madhya Pradesh) Maize IARI, New Delhi Ecosystem diversity can also refer to the variety of ecosystems present in a biosphere, the variety of species and ecological processes that occur in different physical settings. Environmental disturbance on a variety of temporal and spatial scales can affect the species richness and, consequently, the diversity of an ecosystem. Ecosystems may be classified according to the dominant type of environment, or dominant type of species present; for example, a salt marsh ecosystem, a rocky shore intertidal ecosystem, a mangrove swamp ecosystem. Because temperature is an important aspect in shaping ecosystem diversity, it is also used in ecosystem classification (e.g., cold winter deserts, versus warm deserts) (Udvardy, 1975). Genetic modification and the sourcing of genes In vitro technology formed a prerequisite for the development of genetic modification of plants. Genetic modification of plants combines techniques for plant tissue culture, techniques for cloning, in vitro amplification (PCR), and transfer of DNA, either by the use of the soil bacterium Agrobacterium tumefaciens as a vector, through electroporation or by the use of a particle gun. It is based on the ability to change the genetic constitution of a single cell and regenerate a new plant from that single cell. The technology can be used to transfer a gene from a wild relative simply to speed up breeding, but it can also be used for the transfer of genes into the plant gene pool that could not be introduced into plant genomes by other means. Molecular marker technology has been used to identify genotypes and to confirm intergeneric hybrids between papaya and related Vasconcellea species. Molecular maps have been developed for some species. Genetic diversity within populations and between related wild species has been determined for some fruits. Specific DAF markers have been identified for sex determination in papaya; a SCAR marker has been developed to identify dwarfism in bananas; and, a CAPS marker to identify a PRSV-P resistant gene in highland papaya. The major application in genomics has been the rapid progress in sequencing the papaya genome in Hawaii (Drew, 2008). In 1999 more than 70 transgenic crop varieties were registered for commercial cultivation. The crops involved include corn, soybean, rapeseed, tomato, tobacco, potato, chicory, papaya, pumpkin and clover. In 2005, biotech soybean continued to be the principal biotech crop, occupying 54.4 million hectares (60% of global biotech area), followed by maize (21.2 million hectares at 24%), cotton (9.8 million hectares at 11%) and canola (4.6 million hectares at 5% of global biotech crop area). During the first decade, 1996 to 2005, herbicide tolerance has consistently been the dominant trait followed by insect resistance and stacked genes for the two traits (James, 2005). In the future diversification may be expected not only from the private sector, but also from the (international) public sector. The CGIAR Challenge programme Generation focuses on drought tolerance in cereals, legumes and clonal crops.
MISHRA & DWIVEDI, Biodiversity and its responsibility in biotechnology: A review 3 Genetic modification efforts of the M.S. Swaminathan Foundation regard combating drought and salinity in locally adapted rice and wheat varieties, whereas the Indian Initiative on Crop Biofortification focuses on bio-availability and bioefficacy with respect to iron, zinc and phosphor in rice, wheat and maize. Native biodiversity and biotechnology Biodiversity in the wild has been massively reduced in the industrialised countries over many centuries and about half the tropical rain forests have already been destroyed. Yields of cereals in LDCs have gone up very considerably in the last forty years primarily as the result of the Green Revolution. However, the annual growth increases in cereal yields in LDCs have slowed down from about 3% during 1967- 82 to about 1% per year from 1993 onwards. This lowering of the rate at which yields have increased means that productivity will probably not keep up with the demands of increased populations. The consequences for biodiversity are devastating as more land will be required for farming which will primarily come from areas with high native biodiversity, and in particular tropical rain forests. The single most promising way to avoid habitat destruction is to increase farm yields in a process that has been called the “Second Green Revolution”. Several components will be required including training and education of farmers (in particular of women who do most of the farm work in LDCs), more favourable economic and political climates, availability of farm credit schemes, etc. In addition, technical contributions will be necessary and, in particular, improved seed produced either by traditional crop breeding or by modern biotechnology. Reliance will have to be more on the latter since traditional breeding appears to have reached a plateau in yield and is slower, less precise and only feasible when interbreeding is possible. So agricultural biotechnology, which is viewed frequently in the public debate as harmful to biodiversity, is, paradoxically, likely to contribute to conserving it. A more limited concern that largely affects Northern Europe is the conservation of native plants and animals, in particular birds, in farmed areas. Their habitats are fields, hedges, roadsides and fallow land where they depend for food on insects and seeds produced by weeds in or near crops. Computer models suggest that more intense weed control measures may lead to smaller amounts of seeds being available to birds. This depends far more on weed management regimes rather than on transgenic plants. Herbicide tolerant beets allow farmers to control weeds later by treating after the seedlings have emerged. The more efficient methods may allow setting aside of more land. Setting aside more farmland requires financial incentives. Impact of agricultural biotechnology on biodiversity With the introduction of GM crops, concern has been raised that overall genetic diversity within crop species will decrease because breeding programs will concentrate on a smaller number of high value cultivars. However, several studies have specifically focused on this subject and they have concluded that the introduction of transgenic cultivars in agriculture has not significantly affected levels of genetic diversity within crop species. For example Sneller, 2003 looked at the genetic structure of the elite soybean population in North America, using coefficient of parentage (CP) analysis. The introduction of herbicide-tolerant cultivars with the Roundup Readyw [Monsanto http://www.monsanto.com/ monsanto/layout/ products/productivity/ roundup/ default.asp) trait was shown to have had little effect on soybean genetic diversity because of the widespread use of the trait in many breeding programs. Only 1% of the variation in CP among lines was related to differences between conventional and herbicide-tolerant lines, whereas 19% of the variation among northern lines and 14% of the variation among southern lines was related to differences among the lines from different companies and breeding programs. Similarly, when Bowman, et al., 2003 examined genetic uniformity among cotton varieties in the USA, they found that genetic uniformity had not changed significantly with the introduction of transgenic cotton cultivars. Genetic uniformity actually decreased by 28% over the period of introduction of transgenic cultivars. In conclusion, biotechnology represents a tool for enhancing genetic diversity in crop species through the introduction of novel genes. This does not aim at the single transgene inserted, but is based on the fact that beneficial characters can now be inserted in a variety of crops that have been neglected because of the limitations of traditional breeding methods, which failed to enhance the traits. There is great potential to achieve drought tolerance in vegetables (Slabbert, 2004) and to avoid postharvest losses in African grain staple crops. Impact of biotechnology on agro biodiversity Biotechnology has provided tools to more effectively maintain and utilize genetic resources ex situ as well as onfarm, and has thus contributed positively to the conservation of genetic resources. A limited contribution of biotechnology to the development of novel genetic resources in agroecosystems may also emerge in the near future, as a result of introgression of novel traits by means of genetic modification. However, the increasing role of biotechnology also forms a potential threat to the survival of agrobiodiversity in the environment, whether this is in the farmer’s field (on-farm), or in natural ecosystems (in situ). The impact of biotechnology on agrobiodiversity retains several components, which are very different in nature but do closely interrelate. While new technological developments take place at a rapid pace, their environmental and social implications are not well understood, let alone under control. Biological, socio-economic and cultural effects can be distinguished, and the various biotechnological applications differ strongly in the degree
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