Transgenic plants

plant genetic transformation, Applications and differnt types of GM crops are discussed.

1. ASSIGNMENT APPLICATIONS OF TRANSGENIC PLANTS Submitted By, Bhanupriya R Class no. 7661

2. INTRODUCTION Transgenic plant technology is defined as an in vitro gene transfer technique for transferring desirable genes. Technique also called plant genetic transformation. It involves recombinant DNA techniques, allowing artificial insertion of genes to plants, its subsequent stable integration into the plant genome and expression of foreign gene.

3. Transgenes are introduced into plant genome vector mediated transformation or direct gene transfer mechanism . Aim of plant transgenic technology is to create diversity of plant serving human needs and benefit producers, processors and consumers

4. APPLICATIONS OF TRANSGENIC PLANTS Herbicide resistance Insect resistance Virus resistance Altered oil content Delayed fruit ripening Drought,cold,salinityresistance Pollen control Enhanced shelflife Pharmaceutical&edible vaccines Biotic&Abiotic stress tolerance Nutritional quality

5. INSECT RESISTANT PLANTS The Bt toxin isolated from Bacillus thuringiensis has been used in plants. The gene has been placed in corn, cotton, and potato, and has been marketed. • Alkaline protein degrades gut wallof lepidopteranl arvae Corn borer catepillars Cotton bollworm catepillars Tobacco hornworm catepillars Gypsy moth larvae Eg : Bt cotton, PRSV- pappaya

6. Bacillus thuringiensis (or Bt) is a facultative anaerobic, gram-positive , soil-dwelling bacterium, commonly used as a biological alternative to a pesticide; alternatively, the Cry toxin may be extracted and used as a pesticide. During sporulation many Bt strains produce crystal proteins ( proteinaceous inclusions), called δ endotoxins (Cry proteins), which are encoded by cry genes, and have insecticidal action. This has led to their use as insecticides, and more recently to genetically modified crops using Bt genes. • In most strains of B. thuringiensis the cry genes are located on the plasmid

7. MODE OF ACTION The sporulated Bt with ICP or spore-ICP complexes must be ingested by a susceptible insect larva followed by solubilisation, and processing from a protoxin to an activated toxin core in the insect digestive fluid. • The toxin core travels across the peritrophic matrix and the C-terminal region binds to specific receptors called cadherins on the brush border membrane of the gut cells, resulting in pore formation by the N-terminal domain. • Accumulation of toxin oligomers results in toxin insertion in the membrane, pore formation, osmotic cell shock, septicaemia and ultimately insect death

8. HERBICIDE TOLERANT PLANT Three approaches:

9. In 1994 the first genetically modified soybean was introduced to the U.S. market, by Monsanto In 2014, 90.7 million hectares of GM soy were planted worldwide, 82% of the total soy cultivation area Roundup Ready Soybeans are a series of genetically engineered varieties of glyphosate -resistant soybeans produced by Monsanto Roundup Ready Soyabean

10. Glyphosate (A Herbicide) Also known as Roundup Glyphosate kills plants by interfering with the synthesis of the essential amino acids phenylalanine, tyrosine and tryptophan These amino acids are called "essential" because animals cannot make them; only plants and micro-organisms can make them and animals obtain them by eating plants Plants and microorganisms make these amino acids with an enzyme called 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) At the molecular level, Glyphosate inhibits this enzymes activity

11. Glyphosphate resistance in crop plants 1.Over expression of EPSPS gene :- An over expression gene of EPSPS was detected in petunia . Gene from petunia was isolated & introduced in to other plants . The transgenic plants can tolerate glyphosphate 2 -4 times higher than that required to kill wild type weed plants

12. Use of mutant EPSPS Detoxification of glyphosphate :- The soil microorganisms posses enzymes glyphosphate oxidase that converts to glyphosate to glyoxylate . the gene was isolated from ochrobactrum anthropy & was introduced in to crop plants e.g : oil seed rape glyphosate glyphosate oxidase glyoxylate + amp

13. Examples of herbicide resistant plants

14. Fungal or bacterial resistant plants Pathogenesis-Related(PR) Proteins and the Generation of Disease Resistant Transgenic Plants: All the anti-pathogenic proteins formed in re­sponse to pathogen attack can be termed as pathogenesis related (PR) proteins. They are low molecular weight compounds. When intro­duced into the genome of the plant by the pro­cess of transgenesis , they have been proved to be very helpful in the control of many bacte­rial and viral diseases.

15. Some of the most important PRs (a) Chitinase : This is the enzyme which is involved in hydrolysing the cell wall of chitin present in the cell wall of fungi. The chitinase , isolated from the soil bacteria, Serratiamarcescens , has been successfully cloned in tobacco plants. These transgenic plants producechitanase naturally and can prevent the attack of fungal pathogens such as Rhizoctoniasolani . (b) Glucanase : This is another enzyme that dissolves the cell wall of fungi. Glucanase gene isolated from barley has been success­fully introduced in the genome of tobacco plant which confers resistant against the attack of Rhizoctoniasolani .

16. DEVELOPMENT OF VIRUS RESISTANT PLANTS Chemicals are used to control the insect vectors of viruses, but controlling the disease itself is difficult because the disease spreads quickly. • Plants may be engineered with genes for resistance to viruses, bacteria, and fungi. • Virus-resistant plants have a viral protein coat gene that is overproduced, preventing the virus from reproducing in the host cell, because the plant shuts off the virus protein coat gene in response to the overproduction. • Coat protein genes are involved in resistance to diseases such as cucumber mosaic virus, tobacco rattle virus, and potato virus x

17. ALTERED OIL CONTENT • Oil content in plants are altered by modifying an enzyme in the fatty acid synthesis pathway. • Varieties of canola and soybean plants have been genetically engineered to produce oils with better cooking and nutritional properties. • Genetically engineered plants may also be able to produce oils that are used in detergents, soaps, cosmetics, lubricants, and paints.

18. DELAYED FRUIT RIPENING • Allow for crops, such as tomatoes, to have a higher shelf life. • Tomatoes generally ripen and become soft during shipment to a store. • Tomatoes are usually picked and sprayed with the plant hormone ethylene to induce ripening, although this does not improve taste • Tomatoes have been engineered to produce less ethylene so they can develop more taste before ripening, and shipment to markets.

19. Fruit ripening is a natural aging or senescence process that involves two independent pathways, flavor development and fruit softening . Typically, tomatoes are picked when they are not very ripe (i.e., hard and green) to allow for safe shipping of the fruit. Polygalacturonase is a plant enzyme that degrades pectins in plant cell walls and contribute to fruit softening. In order to allow tomatoes to ripen on the vine and still be hard enough for safe shipping of the fruit, polygalacturonase gene expression was inhibited by introduction of an antisense polygalacturonase gene and created the first commercial genetically engineered plant called the FLAVR SAVR tomato .

20. POLLEN CONTROL Hybrid crops are created by crossing two distantly related varieties of the same crop plant. The method may generate plants with favorable traits, such as tall soybean plants that make more seeds and are resistant to environmental pressures. For success, plant pollination must be controlled. This is usually done by removing the male flower parts by hand before pollen is released. Also, sterilized plants have been genetically engineered with a gene from the bacteria Bacillus amyloliqueifaciens ( barnase gene ). This gene is dominant gene for male sterility

21. DEVELOPMENT OF STRESS- AND SENESCENCE-TOLERANT PLANTS: GENETIC ENGINEERING OF SALT-RESISTANT PLANTS Overexpression of the gene encoding a Na+/H+ antiport protein which transports Na+ into the plant cell vacuole This has been done in Arabidopsis and tomato plants allowing them to survive on 200 mM salt ( NaCl )

22. EDIBLE VACCINES FROM PLANTS In the edible vaccine, Transgenic plants are used as vaccine production systems. The genes encoding antigens of bacterial and viral pathogens can be expressed in plants in a form in which they retain native immunogenic properties. Initially thought to be useful only for preventing infectious diseases, it has also found application in prevention of autoimmune diseases, birth control , cancer therapy, etc. Edible vaccines are currently being developed for a number of human and animal diseases.

23. Why edible vaccine?

24. HISTORY OF EDIBLE VACCINES

25. GOLDEN RICE Golden rice is a genetically modified rice with enhanced levels of vitamins . This is a transgenic rice capable of producing beta carotene, a precusor of vitamine A in the edible part of rice, endosperm,by using recombinant DNA technology(Ingo potrykus &Peter beyer 2000 ). This rice was created by transforming rice by the addition of 3 beta carotene biosynthesis genes &one bacterial gene. The presence of beta carotene in rice endosperm gives a characteristic yellow color to the rice and hence the name golden rice.

26. CONCLUSION Genetically-modified foods have the potential to solve many of the world's hunger and malnutrition problems, and to help protect and preserve the environment by increasing yield and reducing reliance upon chemical pesticides and herbicides. Yet there are many challenges ahead for governments, especially in the areas of safety testing, regulation, international policy and food labeling . Many people feel that genetic engineering is the inevitable wave of the future and that we cannot afford to ignore a technology that has such enormous potential benefits. However , we must proceed with caution to avoid causing unintended harm to human health and the environment as a result of our enthusiasm for this powerful technology.

27. REFERENCES Vaeck , M., Reynaerts , A., Höfte , H., Jansens , S., De Beuckeleer , M., Dean, C., Zabeau , M., Van Montagu, M. and Leemans , J., 1987. Transgenic plants protected from insect attack.  Nature ,  328 (6125), p.33 . Rastogi , smitha.,Pathak , Neelam.,2011. GENETIC ENGINEERING.Oxford unversity press, New Delhi.p.629. http :// en.wikipedia.org/wiki/Genetically_modified_crops Schuler , T.H., Poppy, G.M., Kerry, B.R. and Denholm , I., 1998. Insect-resistant transgenic plants.  Trends in Biotechnology ,  16 (4), pp.168-175.

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