Uses of Transgenic plants

Transgenic plants for Molecular Farming

Many plant products useful for humans such as sugars, fatty acids, starches, celluloses, rubber, and wax are obtained by using the traditional methods. The efforts are going on to use genetic engineering to increase their production. In this regard, the transgenic plants can play an important role as ‘factories’ for manufacturing specialty chemicals and pharmaceuticals. Some of the examples are: increase in the level of mannitol in transgenic tobacco plants following the transfer of the gene for mannitol dehydrgenase from E.Coli to tobacco. Similarly Chimeric genes having CaMV promoter and encoding human serum albumin (HSA) were transferred and transgenic potato and tobacco plants were obtained. The secretion of protein was achieved by using either the human preprosequence or the signal sequence from extra cellular PR-S protein from tobacco. HSA was secreted in transgenic leaf tissue.

Transgenic plants to study regulated gene expression

Transgenic plants have been used to study the expression of genes in different environmental conditions or at different stages of development which can lead to induction or suppression of gene expression. Using transgenic plants it was possible to recognize the regulatory sequences involved in differential expression of gene activity. The regulatory sequences of a number of structural genes was studied using this method. E.g. In order to study heat shock genes which start transcription under thermal stress and reduces the expression of many other vital genes, a gene construct, carrying NPT II reporter gene was fused with upstream region of heat shock gene hsp70 from Drosophila. This was then introduced into Tobacco. The expression of NPT II due to heat shock was comparable to that of endogenous plant heat shock genes. Similarly when hsp 70 gene of maize, with 1.1 kilobases of upstream sequence was introduced in petunia, it exhibited heat inducibility. Similar studies were carried out using different systems such as the gene for small subunit of ribulose bisphosphate carboxylase (rbcS) was transferred from pea plant to petunia and tobacco plants and the soybean rbcS gene was transferred to petunia. The gene expressed itself in transgenic plants. The gene for chlorophyll a/b binding protein (Cab gene) was transferred from pea plant and wheat to tobacco.

Transgenic plants suitable for food processing

Transgenic plants suitable for food processing have also been developed. Tomatoes showing ‘delayed ripening’ were developed either by using antisense RNA against enzymes involved in ethylene production (e.g. ACC synthase) or by using gene for ACC deaminase, which degrades 1 aminocyclopropane-1 carboxylic acid (ACC) which is an immediate precursor to ethylene. This not only increases the shelf life of tomato but also the tomatoes can stay longer on the plant which gives more time for accumulation of sugars and acids for improving flavour. Therefore they are described as ‘Flavr Savr. Another example is the development of bruise resistant tomatoes which express antisense RNA against polygalacturonase (PG), which attacks pectin in the cell walls of ripening fruit and softens the skin.
Tomatoes with elevated sucrose and reduced starch could also be produced using sucrose phosphate synthase gene.

Some pathogens for which resistance has been transferred in some crop plants

Pathogens Disease Resistance gene Source of gene  Transgenic Crop
Wild fire Acetyl transferase gene - Tobacco
Brownspot Chitinase gene Serratia
Marcescens (soil bacterium)
- Chitinase gene Bean Tobacco
Late blight Osmotin gene Potato Potato

-According to the 2010 data, the Current World hectarage of Biotech crops is: 148.6 million hectares

-In 2009, World hectarage of Biotech crops was: 135 million hectares

Key findings of 2010:

    • Growth remains strong, with biotech hectarage increasing 14 million hectares -- or 10 percent -- between 2009 and 2010.
    • Farmers in Pakistan and Myanmar planted insect-resistant Bt cotton for the first time.
    • Sweden (the first Scandinavian country to commercialize biotech crops) planted a new biotech high-quality starch potato approved for industrial and feed use.
    • Germany also planted the same biotech potatoes as Sweden in 2010, resuming its place among the eight EU nations now growing either biotech maize or potatoes.
    • The most popular crop is soya, while the most common modification is tolerance to herbicides.
    • International Service for the Acquisition of Agri-biotech Applications (ISAAA) expects an additional 12 countries to adopt biotech crops by 2017.
    • GM crops are the fastest adopted crop technology, with 80-fold increase from 1996 to 2010, year-to-year growth of 9 million hectares or 7%.
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