Here is an essay on the ‘Applications of Biotechnology in Agriculture’ for class 9, 10, 11 and 12. Find paragraphs, long and short essays on ‘Applications of Biotechnology in Agriculture’ especially written for school and college students.
Applications of Biotechnology in Agriculture
- Essay on Improving Nutritional Quality
- Essay on Salt and Drought Tolerance
- Essay on the Production of Diseased Resistant Plants
Essay # 1. Improving Nutritional Quality:
Seed proteins which provide about 70% of the proteins are deficient in some of essential amino acids. Eight species of cereals contribute over 50% of the total world food calorie requirements. Cereal seeds have a low lysine, tryptophan and threonine contents, whereas legume seeds are deficient in methionine and cysteine.
Some seeds crops like rice have low protein contents but better amino acid balance. Crop improvement is mainly aimed to increase the yield, protein contents and improvement of characters like baking quality of wheat and malting quality of barley.
The four major types of seed proteins are albumin (soluble in water), globulin (soluble in salt solutions), protamines (soluble in alcohol) and glutelins (soluble in dilute acid or alkali). Prolamin is the major storage protein of cereals and it is deficient in lysine, rich in proline, glutamine and asparagine.
The main storage proteins of rice is glutelin. In oats globulin forms the principal nitrogen storing protein. An increase in free threonine levels has been achieved in barley and maize seeds. Alternation in the relative proportions of different proteins in the seed may be more effective way of maintaining amino acid balance.
The genes coding for a number of storage proteins have been cloned. Nutritional improvement can be achieved by site directed mutagenesis with the objective of introducing more lysine or methionine codons into gene sequences.
Essay # 2. Salt and Drought Tolerance:
Salinity is a problem in large area of India. Osmoregulation with organic and inorganic solutes, cellular compartmentation, patch clamp studies, acidic proteins and genetic engineering of plants are some of the areas which represent an interface of basic and applied knowledge. Salt rich soils have less productivity rate. The production of selections with increased salt and drought tolerance has relied on obtaining variants arising during cell cultures.
Essay # 3. Production of Diseased Resistant Plants:
Plant viruses cause serious losses of yield and quality in most crops. The losses may range from 5-90%. Substantial crop losses occur due to attacks by insect pests and microbial pathogens. Presently little know how is available about genetic mechanism of disease resistance in plants. Genetic engineering promises to have an enormous impact on the improvement of crop species.
It has been suggested to develop new genes for disease resistance and to expand the utilization of existing disease resistant genes using genetic manipulation techniques. Genetic transformation can boost plant breeding efforts for developing disease resistant varieties. Cloning of plant genes responsible for pest and disease resistance will help in elucidating some of the biological mechanisms of resistance.
Now the disease resistant genes can be isolated and transferred to high yielding susceptible plants to produce pathogen free plants. To locate the pathogen gene is a difficult task. Difficulties may be further enhanced if the disease resistant character is polygenic trait. But inspite of all these drawbacks, still it is possible to identify, isolate and transfer the gene/genes to the host.
Several disease resistant somaclones have been identified for resistance to early blight of potato caused by Alternaria solani. Similarly in sugarcane resistance to diseases like fiji and downy mildew have been recovered. Scientists have tried to use to Agrobacterium gene transfer system to produce tobacco plants with increased resistance to TMV.
Cross protection phenomenon means that plants injected with one strain of virus resist infection by second related strain. Cross protection has been found to be effective in number of viral diseases. Although the mechanism of cross protection is not fully understood, if has been suggested that protection from viral disease could be achieved with the help of gene transfer. Genetically engineered cross protection provides an useful tool of developing disease resistant plants.
Some bactericidal proteins like lysozyme, cecropins and attacins have been located in pupae of giant silk moth Hylophora cecropia. These proteins have exhibited antifugal activity against pathogen like Phytophthora infestans.
From among more than 800 plants about 2% of somaclones displayed enhanced resistance to late blight of potato disease. In maize, somaclonal variation has induced resistance to race T of soluthern com blight caused by Drechslera maydis. Transgenic tobacco plants that express barley ribosome inactivating protein (RIP) exhibited protection against fungus Rhizoctonia solani.
Insect resistant plants can also be developed. Progress in engineering insect resistance in transgenic plants has been made through the expression of insect toxin gene of Bacillus thuringiensis in plants. Most strains of this toxin gene are toxic to lepidopetran larvae.
The toxicity is due to toxin gene named as Bt-2. Bt toxin gene has been cloned from the bacteria and expressed in plants to provide resistance from insects without the requirement of insecticides. It has created a type of biopesticide e.g. Bt cotton, Bt corn, rice, tomato, potato and soyabean etc.
Sal bacterium Bacillus thuringiensis (Bt) forms a cry (crystal) protein. This cry protein is toxic to larvae of certain insects as lepidopterans (tobacco bud worm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). There are several different types of cry proteins. Each cry protein is toxic to different groups of insects. B. thuringiensis produces some types of protein crystals in a specific stage of their growth and development.
The gene encoding cry protein i.e., ay gene has been isolated and transferred into several crops. Proteins encoded by the genes cry IA and cry II Ab control the cotton bollworms and that of cry IAb controls the com borer. The protein formed by gene cry III Ab controls the Colorado potato beetle and cry III Bb controls corn root worm. This is a case where transgene product directly produces the phenotype of interest.
Why Bt toxin does not kill the Bacillus bacterium?
Bt toxin is present in the form of inactive protoxin. However when this inactive form is ingested by a insect, it is converted into active toxic form. This happens due to alkaline pH of gut which solubilizes the crystals. Such toxic activated forms binds to surface of midgut epithelial cells. This forms pores and leads to formation of cell swelling and lysis. Due to all this, finally insect is killed.
A nematode Meloidogyne incognita attacks roots of tobacco plants. As a result, crop yield is decreased. Through Agrobacterium vectors, normal copy of genes specific to the nematodes were introduced into host plant. Introduced gene (complementary DNA) generated from in RNA by using enzyme reverse transcriptase. The genes of nematodes were introduced into host plants in a way that both sense and antisense RNA were formed.
Antisense RNA is complementary to sense or coding RNA. A dsRNA (double stranded RNA) was formed from these two complementary RNAs. The ds RNA by a process called RNA interference neutralized (silence) specific in RNA of nematode. Due to all this, in transgenic host, parasite could not survive by expressing specific interfering RNA. Thus tobacco transgenic plant could be saved from the attack of nematode.