Seed Health Management for Better Productivity - Govind Ballabh ...

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(Seed Health Management for Better Productivity)and genetic engineering to transfer relevant genes in to our crops. Modern biotechnologicalmethods have enabled to unravel the molecular basis of a trait which has led to identification ofcandidate genes/proteins. Genetic engineering has potential to transfer these important candidategene/protein across the species which is otherwise not possible by conventional plant breedingmethods. As a result of this complementation superior crop varieties are now being generatedwhich are highly productive, nutritive and tolerant to various biotic and abiotic stresses as well costeffective both for consumers and farmers.Biotechnology will be a key factor in development in the coming decades. Geneticengineering/modification techniques hold enormous promise in developing crop varieties with ahigher level of tolerance to biotic, abiotic stress and insect resistance (BT). Some genes usuallyconfer resistance to herbicides, insects, pests and resistance to draught and salinity. This providesstrength to harness useful genes for developing plant types with in-built resistance for biotic andabiotic stresses and improved nutritional quality. A conducive atmosphere for application of frontiersciences in varietals development and for enhanced investments in research and development is apressing requirement. At the same time, concerns relating to possible harm to human health andbio-safety as well as interests of farmers, must be addressed.Genetically modified seedsModern biotechnology has introduced new agricultural products based on the preciserecombinant DNA technology incorporating the desired gene with important agronomical traits inthe recent years. The introduction of genetically modified Bollgard cotton seeds containing aprotein from soil microbe called Bacillus thuringiensis (Bt), which protects the crop from bollwormsand requires less pesticides has been a successful story in India. India's average per-hectareyield has risen by two-thirds to 501 kg since farmers started planting GM seeds in 2002.In 2004, the global area of transgenic crops continued to grow for the eight consecutiveyears at a sustained growth rate and was found to approx 83 million hectares in year 2004compared with 67.7 million hectares in 2003. Of six leading GM crop countries (USA, Argentina,Canada, Brazil, China and South Africa), China and South Africa had the highest year to yearincrease with approx. 40% growth rate. China increased its Bt cotton area for the sixth consecutiveyear. The US$ 2.5 billion GM seed market is dominated by a single corporation that sells GMseeds for four major crop commodities (soybean, maize, cotton, canola) in three countries (USA,Argentina and Canada). The expansion in this direction could include possibilities such as:1. The application of GM technology to a wider range of crop types giving improved yield andquality.2. A range of more valuable agronomic traits, such as resistance to common pests orimprovements in the efficiency with which crops can assimilate nutrients.3. GM foods with consumer benefits, such as longer shelf life, or health benefits, such asimproved nutritional content or reduced allergenicity.- 192 -
(Seed Health Management for Better Productivity)4. A wide range of non-food crops, which could include the production of pharmaceuticals,industrial oils, renewable materials and crops which could be used directly in theproduction of energy and fuel. Production for fuel could become increasingly attractive inthe event of more favorable revenue conditions applying to bio-fuels.The GM seed market represents about 10% of the commercial seed market worldwide.The total GM seed market in India has an estimated value of US$25 million. India increased its BTcotton area by 100%; India placed 8 th partition with 0.1 million hectares production. GEAC hasapproved the commercialized cultivation of BT cotton in April 2002 in six states in the country,which include Maharashtra, Gujarat, M.P., A.P., Tamil Nadu and Karnataka. Other crops such asmustard, soybean corn and potatoes are expected to receive approval in the near future. The GMseeds segment in India is dominated by various companies such as Mahyco, Monrto, ProAgro,Aduantor, Mahyco Monsanto.Biotechnological tool for maintenance of hybridityBarnase-barstar system : Gene barnase encodes an RNAse which kills the cells in which it isexpressed by degrading RNA. The expression of barnase was confined to tapetal cells by fusing itwith the promoter of tobacco tapetum specific gene TA29 ( gene construct : pTA29- barnase; ppromoter ). When the chimaeric gene construct was transferred and expressed in tobacco andoilseed rape, the tapetal cells of anthers were destroyed and there was no pollen development.However there was no effect on female fertility. Since the male sterility due to barnase isdominant, the male sterile lines are always heterozygous (barnase/- ; the – sign indicates absenceof barnase gene in homologous chromosome) and they have to be maintained by crossing to anynormal, non transformed male fertile line (-/-; barnase gene absent). Thus male sterile lines (barnase/-) will have to be crossed to be normal fertile lines (-/-), and only 50% of the progeny fromsuch crosses will be male sterile while rest 50% will be male fertile (-/-). In a hybrid seedproduction programme the male fertile plants present in male sterile line must be identified andeasily eliminated. This has been done by linking the barnase gene with the bar gene fromStreptomyces: bar gene confers resistance to herbicide phosphinothricin. When such male sterile (barnase-bar/-) plants are maintained by crossing with normal male fertile (-/-), all the male sterileprogeny ( barnase-bar/- ) are resistant to the herbicide, while all the male fertile plants (-/-) areherbicide susceptible. The male fertile plants are therefore eliminated by a herbicide spray at anearly stage of plant growth.The male fertility of barnase male steriles is restored by another gene, barstar, of thebacterium B. amyloliquefaciens. The gene barstar encodes a specific inhibitor of barnase encodedRNase. The barstar product forms a highly stable 1:1 non-covalently bound complex with the barnaseRNase; this reaction provides protection to the bacterial cells from their own RNase product.Transgenic plants expressing barstar are male fertile without any phenotypic effect, and are easilymaintained in the homozygous state. When a homozygous barstar male fertile line is crossed with abarnase male sterile all the progeny plants are male fertile since barstar gene product effectively- 193 -
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Page 219 and 220: potential. An improvement in qualit
Page 221 and 222: 9. Session Arrangement CommitteeDr.
Page 223 and 224: 9. Dr. Pradip Kumar BorahSr. Scient
Page 225 and 226: TRAININGONANNEXURE-IIISEED HEALTH M
Page 227 and 228: ANNEXURE-IVCENTRE OF ADVANCED STUDI
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