My Innovative Lesson Plan through MonoAct - Topic- Chemical Pesticides - [BEd- Natural Science [2014-2015]

Calotropis gigantea

GENETICALLY MODIFIED CROPS AND ITS FUTURE PROSPECTS

Genetically modified crops are plants with modified genome by the introduction of new gene or any DNA sequence of interest – a method called genetic engineering. Such crops are differently named as GMC or GM
crops or biotech crops etc. In January 1983, Monsanto Company in St. Louis, Missouri,
first developed transgenic plant. The first commercially grown genetically modified 
food crop was a tomato created by California
Company in the early 1990s called the Flavr Savr, then came GM potatoes, modified with an insecticide gene taken from the snowdrop, were toxic to rats.

PROCESS OF DEVELOPING GM CROPS

The main steps involved in the development of GM crops are:

1. Insertion of the gene(s) into a transfer vector.  
2. Plant transformation. 
3. Selection of the modified plant cells. 
4. Regeneration into whole plants.  
5. Verification of transformation and characterization of the inserted DNA fragment. 
6. Testing of plant performance. 
7. Safety assessment.

METHODS OF GENE TRANSFER IN PLANTS

1. Vector-mediated or indirect gene transfer – Ti plasmid of Agrobacterium tumefaciens  is used as a vector.   

B. Vectorless or direct gene transfer – no vector use.

i) Chemical mediated gene transfer – PEG, dextran sulphate, Calcium phosphate  etc.

ii) Microinjection -  using fine tipped (0.5 - 1.0 µm diameter)glass needle or micropipette.

iii) Electroporation - a pulse of high voltage is applied.

iv)  Particle gun/Particle bombardment  - by a gun

v)  Liposome mediated gene transfer /Lipofection - 

 

 

APPLICATIONS OF Transgenic plants

A.  Stress tolerance

i)    Abiotic stress tolerance :

ii)   Herbicide tolerance : Glyphosate resistance

iii) Other abiotic stresses :

B.  Insect resistance

i)   Bt genes  transfer :

ii)  Cowpea trypsin inhibitor gene (CpTi)  transfer :

C.  Virus resistance 

D.  Resistance against Fungal and bacterial infections

E.  Delayed fruit ripening 

F.  Male Sterility  

G.  Production of biofuels 

H.  Improved shelf life 

I.   Production of useful by-products

i)  Drugs :

ii) Materials : 

J.  Bioremediation 

 

 

ADVANTAGES OF GMO CROPS

•          Less pesticide is needed to be used due to insect pest resistant.

•          They are more ecofriendly

•          Decrease in costs of growing and farming,

•          Higher crop yields.

•          Decrease in food prices due to lower costs and higher yield.

•          Scientific development of agriculture, health and related sciences.

•          Creation of “super foods” or New foods.

•          New products.

NEGATIVE IMPACTS OF GM CROPS

—  i) Test : The taste of GMOs are not as good or "natural".

—  ii) Environment : Unintended environmental impacts include harming non target and/or beneficial species in the case of crops with engineered insecticidal properties, as well as the development of new strains of resistant pests.

—  iii) Health : At present, there is no evidence to suggest that GM foods are unsafe. Some GMO crops causes allergy. Residual toxins resulting from introduced genes of the bacteria Bacillus thuringiensis in so called Bt crops are unlikely to harm humans.

—  iv) Markets : Due to controversy, GMO crops have less demand in the commercial market.

 

FUTURE PROSPECT OF GM PRODUCTS

Future envisaged applications of GMOs are diverse and include drugs in food, bananas that produce human vaccines against infectious diseases such as Hepatitis B, metabolically engineered fish that mature more quickly, fruit and nut trees that yield years earlier, and plants that produce new plastics with unique properties. While their practicality or efficacy in commercial production has yet to be fully tested, the next decade may see exponential increases in GM product development as researchers gain increasing access to genomic resources that are applicable to organisms beyond the scope of individual projects. Safety testing of these products will also at the same time be necessary to ensure that the perceived benefits will indeed outweigh the perceived and hidden costs of development.

CONCLUSION

Transgenic plants possess a gene or genes that have been transferred from a different species. Although DNA of another species can be integrated in a plant genome by natural processes, the term transgenic plants refers to plants created in a laboratory using recombinant DNA technology. The aim is to design plants with specific characteristics by artificial insertion of genes from other species or sometimes entirely different kingdoms. GM crops grown today, or under experimental development, have been modified with traits intended to provide benefit to farmers, consumers, or industry.

BANANA BUNCHY TOP

Banana bunchy top is a viral disease caused by a single-stranded DNA virus called the Banana Bunchy Top Virus (BBTV). It was first identified in Fiji in 1889, and has spread around the world since then. Like many viruses, BBTV was named after the symptoms seen, where the infected plants are stunted and have "bunchy" leaves at the top. The disease is transmitted from plant-to-plant in tropical regions of the world by banana aphids, which can also feed on Heliconia and flowering ginger (from the Zingiberaceae family), which is an important factor in control of the disease. There are no resistant varieties, so controlling the spread by vectors and plant materials are the only management methods. Symptoms include spotting any deformed plant appearance.   

With fewer banana plantations in the Bunchy Top infection regions, we can really step up the effort to find every last infected plant as soon as possible before aphids can spread the disease.

Importantly, we know Bunchy Top exists in home gardens so we need your help in our quest to completely eradicate this disease.

What does BBTV look like?

In its early stages the symptoms are difficult to see to the untrained eye. The first symptom is short dark dot-dash lines appearing along the veins of the youngest leaf starting from the mid-rib.

Symptoms include dark striping on leaf mid-ribs

You can see these dot-dash lines best when you look upwards towards the sky through the bottom side of the youngest leaf.Dark green stripes running along the mid-rib of the infected leaf may also be present. When the disease is more advanced, each new leaf becomes shorter, narrower and stands more upright, giving a ‘bunched’ leaf appearance – that’s why it is called ‘Bunchy Top’.

Plant growth is stunted and the leaves roll slightly upwards and tend to become yellow or light green (see picutre of an infected plant, above right).

Bunchy Top is difficult to identify in its early stages in any banana variety, including Cavendish and Lady Fingers, so trained professional inspectors should be called to find infected plants early before the disease spreads any further.

How is it spread?

Bunchy Top can only be spread in two ways:

Aphids on an infected plant

1. Banana aphids

The aphid is a small black insect which looks similar to other aphids you see in your garden.

The difference is that the banana aphid spreads Bunchy Top after it has fed for many hours on an infected plant. Aphids can by carried many kilometres on the wind so they can progressively infect many banana plantations and backyard plants.

2. By infected planting material

The biggest problem is that well meaning people give away young plants or suckers to neighbours and friends.

How does it affect plants?

New leaves look “bunched”

Banana plants infected with Bunchy Top will produce only small bunches, or no bunches at all.

The plants cannot recover from the disease and new suckers will also be infected.

Bunchy Top gets its name because the disease causes new leaves to become shorter, narrower and to stand more upright giving a “bunched” leaf appearance. This makes it difficult for the plant to produce a bunch.

Management

There are no resistant varieties of banana against BBTV, so the most common method of control is chemical control of the aphid vectors. Another way to help control the virus is to remove and destroy any infected plants before the virus can spread, which is a practice known as rogueing. Quarantines are also implemented to prevent the import of any potentially infected plant materials, including one in Hawaii that prevents the movement of fruits from the island of Oahu to any other island, since BBTV is widespread in Oahu. Fruit is not often produced on infected plants, but if it is, the fruit will be deformed, which easily identifies if there is any virus present in the fruits to comply with quarantine regulations. Since bananas are not the only host, the alternate hosts for both the virus and the aphid must also be monitored for disease, and sprayed with pesticides to control the aphids more. When planting at the beginning of the season, the seed material or suckers should be obtained from BBTV free areas of the world or from cultures that are grown and developed to be free of the virus.Currently, there is ongoing research into biopriming, or inducing systemic resistance by using bacteria that live inside the host but do not infect.

Control of banana bunchy top is achieved by killing the banana aphids then destroying all infected material. First, the aphids should be killed on the infected banana material, and then all the plant material should be destroyed to prevent the spread of the virus. Infected banana plants can be sprayed with an insecticide like Sevin to reduce or get rid of the aphid population, since control of viruses starts with control of the vectors.The agriculture department, however, recently obtained an EPA waiver for the pesticideProvado is a means of controlling the aphids that spread the disease.

Flowers Viewed in Ultra-Violet Light

                                 Many flowers appear differently under UV light, often showing patterns of rings or lines not visible to our naked eye. The photos above show Rudbeckia flowers as our eyes would see them (left) and using a special UV camera filter (right). The UV markings are designed to be seen by insects, which are able to see in the ultraviolet spectrum. They seem to be most often found in yellow flowers, and are thought to serve as "landing pads". Called nectar guides, they serve as directional signals that point the pollinators to the nectar or other reward, such as pollen. These areas of UV reflectance are often sturdier than the non-reflectant part of the petal, which wear down faster, so sometimes as the flowers start to fade at the end of the summer it's possible for our human eyes to see where the nectar guides are.