APPLICATION OF TISSUE CULTURE IN CROP IMPROVEMENT

Presented by,M.Uma Maheshwari

Why genetically engineer plants?

• To improve the agricultural, horticultural or ornamental value of a crop plant

• To serve as a bioreactor for the production of economically important proteins or metabolites

• To provide a powerful means for studying the action of genes (and gene products) during development and other biological processes

TRANSGENIC PLANTS

NUTRITIONALQUALITY

BIOTIC STRESSTOLERANCE

ABIOTIC STRESSTOLERANCE

PHARMACEUTICALS & EDIBLE VACCINE

HYBRID DEVELOPMENTFOR HIGHER YIELD

ENHANCED SHELF LIFE

INDUSTRIAL PRODUCTS

Applications of Tissue Culture• Improved Nutritional Quality• Insect resistance• Disease resistance• Herbicide resistance• Salt tolerance • Delayed Fruit Ripening• Biopharmaceuticals and Vaccines

Golden Rice

• 124 million children worldwide are deficient in vitamin A, which leads to death and blindness

• b-carotene is precursor to vitamin A & consuming milled rice leads to vitamin A deficiency

• Mammals make vitamin A from b-carotene, a common carotenoid pigment normally found in plant photosynthetic membranes

The prototype of golden rice was developed in 2000 and is a light yellow color (b). It contains

1.6 mg/g of carotenoid. In 2005, new transgenic lines were developed

that dramatically increased the amount of carotenoid synthesized, making the rice a deep

golden color (c). This latest form contains 37 mg/g of

carotenoid, of which 84% is b-carotene – trial

Genes involved in golden rice

Rainbow cauliflower

• Produced by traditional breeding –Non Transgenic

• The Orange cauliflower has higher than normal levels of b-carotene that encourages healthy skin

• Purple colour comes from Anthocyanin which may prevent Heart disease by slowing blood clotting

• Tests of the orange cauliflowers in America found that they contained 25 times the concentrations of beta carotene in normal cauliflowers

Insect resistant plants• Bt gene of a bacterium Bacillus

thuringiensis has found to encode endotoxin which pose cidal effect on certain insect pests

• The cry gene found to express the proteinaceous toxin, when specific pest ingest the toxin, they are killed

• The toxin affect specific group of insects and do not harm silkworm, butterflies and other beneficial insects

• Using biotechnological approaches many transgenic plants with cry gene have been developed eg., Bt-brinjal, cauliflower, cabbage, canola, corn, maize, tobacco, rice, soyabean

δ -endotoxin gene (Cry gene) of Bacillus thuriengenesis

GENE FOR Bt TOXIN WAS TRANSFERREDTO OBTAIN BT TRANSGENIC PLANTS

PLANT SYNTHESIZES INACTIVE PROTOXIN

PROTEINASEDIGESTION ININSECT GUT MAKES THEACTIVE TOXIN

Toxin binds a receptor on the gut epithelial cells, forms a channel on the membrane. This causes

electrolyte leakage and insect death

INSECT FEEDS ONTRANSGENIC PLANT

Herbicide resistant plants• Plants that can tolerate

herbicides • The herbicide disturb the

metabolic activity of photosynthesis or synthesis of amino acid

• For the development of herbicide resistant plants two main strategies are being applied– Modification of target molecules

that may be insensitive to herbicides

– Degradation of herbicides

• Attempts have been made to develop resistant against three herbicides– Glyphosate– Sulphonylurea– Imidazolinoles

• A herbicide resistant gene for EPSPS was isolated from plants and transferred to Petunia and transgenic Petunia was developed

• Transgenic tomato was developed by introducing a mutant als gene of tobacco (inhibits sulphonylurea, imidazolinoles)

• A gene resistant to PPT was isolated from Medicago sativa inhibits GS involved in ammonia assimilation

• Incorporated in to tobacco and thus transgenic tobacco is developed with PPT resistant

• A number of micro organisms are also involved in the degradation of herbicides

• Accomplished by genes coding specific enzyme PAT which degrades the herbicide PPT

• Nitrilase encoded by bxn gene of Klebsiella bromoxynil, GST degrades herbiscide Atrazine

• Several crops have developed: transgenic potato, oil seed rape and sugarbeet(with bar gene), transgenic tomato (bxn gene)

Virus resistant plants

• Plant viruses yield several loss in economically important plants• Two main approaches for developing genetically resistant plants

– PDR (Pathogen Derived Resistance)– non PDR (non- pathogen derived resistance)

• Roger Beachy and co-workers first introduced Coat protein (CP) of TMV in to tobacco

• In many crops, virus resistance have been achieved through introducing CP

• CPMR is the most favoured strategy to make virus resistant plants

Host Transgene Increase in yieldover non-transgenic plants

Tomato TMV, CP geneCMV, Satellite gene

4014

Potato PVX, PVY CP 38Squash CMV+ZYMV+WMV2

+CPZYMV+WMV2 CP

9790

Papaya PRSV CP 90

Disease resistance plants• Genes that provide resistance

against plant viruses have been successfully introduced into crop plants such as tobacco, tomato, rice, potato ,etc

• Transgenic tobacco plant • Expressing tobacco mosaic virus

coat protein gene were first developed

–Viral capsids inhibit viral replication of TMV when infected• Virus coat protein mediated

protection is successful for viruses with ss RNA

SALT TOLERANCE

• A large fraction of world’s irrigated land cannot be used to grow most important crops due to increased salinity in soil

• Researcher's have created transgenic tomatoes that grew well in saline soils

• The transgene introduced was sodium/proton antiport pump that sequestered excess sodium in vacuole of leaf cells

Delayed ripening

• Antisense technology is used produce the Flavr-Savr tomato in 1994.

• Enzyme polygalacturonase breaks down structural polysaccharide pectin in wall of a plant.

• This is part of the natural decay process in a plant

• Monsanto identified the gene than encodes the enzyme and made another gene that blocked the production of the enzyme.

Pharmaceutical production in plants• Genetically modified plants have been

used as “bioreactors” to produce therapeutic proteins A recent contribution is the generation of edible vaccines.

• Edible vaccines are vaccines produced in plants that can be administered directly through the ingestion of plant materials containing the vaccine. Eating the plant would then confer immunity against diseases.

• Edible vaccines produced by transgenic plants are attractive for many reasons.

• The first human clinical trial took place in 1997. Vaccine against the toxin from the bacteria E.coli was produced in potato

Edible vaccines • Vaccines consisting of transgenic plant-derived

antigens offer a new strategy for development of safe, inexpensive vaccines.

• The vaccine antigens can be eaten with the edible part of the plant or purified from plant material

Rabies- Tomato plants expressing rabies antigens could induce antibodies in mice

Cholera-Transgenic potato with CT-B gene of Vibrio cholerae was shown to be efficacious in mice .

Norwalk virus- transgenic potato expressing norwalk virus antigen showed seroconversion

Hepatitis B- First human trials of a potato-based vaccine against hepatitis B have reported encouraging results

If vaccines are intimately presented together with food, the guts immune system faces a conundrum

• Plant seeds may be a potential source for plastics that could be produced and easily extracted.

• A type of PHA (polyhydroxylalkanoate) polymer called “poly-beta-hydroxybutyrate”, or PHB, is produced in Arabidopsis, or mustard plant.

• PHB can be made in canola seeds by the transfer of three genes from the bacterium Alcaligenes eutrophus, which codes for enzymes in the PHB synthesis pathway.

• A polymer called PHBV produced through Alicaligenes fermentation, which is sold under the name Biopol

Molecular Farming (Biopolymers and Plants)

What are some of the advantages of GM foods?

GM crops are more productive and have a larger yield. Offer more nutritional value and better flavor. A possibility that they could eliminate allergy-causing properties in some foods. Inbuilt resistance to pests, weeds and disease. More capable of thriving in regions with poor soil or adverse climates. More environment friendly as they require less herbicides and pesticides. Foods are more resistant and stay ripe for longer so they can be shipped long distances or kept on shop shelves for longer periods. As more GM crops can be grown on relatively small parcels of land, GM crops are an answer to feeding growing world populations.

What are some of the advantages of GM foods?

• Disease resistance There are many viruses, fungi and bacteria that cause plant diseases.

• Plant biologists are working to create plants with genetically-engineered resistance to these diseases.

• Cold tolerance Unexpected frost can destroy sensitive seedlings. An antifreeze gene from cold water fish has been introduced into plants such as tobacco and potato.

• With this antifreeze gene, these plants are able to tolerate cold temperatures that normally grow

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. 

• At the present time, genetically modified foods are dangerous for the world that we live in, not just for its people, but the delicate balance between organisms that inhabit it.

Thank

you