explain me with the points.....?

Question

Application of plant tissue culture
Plant tissue culture used widely to plant science has many commercial application. These include-
(1) as a tissue for transportation followed by either short-term testing of genetic constructs or regeneration of transgenic plants.
(2) large-scale growth of plant cells in liquid culture in bioreactors as a source of secondary products, like biopharmaceuticals.
(3) a plant breeder may use tissue culture to screen cells, rather than plants for advantageous characters e.g. herbicide resistance/tolerance.
out of several points i could not understand these 3 mantioned above can you plz explain them in detail in an well understanding language
thanx

Answer 1

Wow! That is difficult for Even me to decipher, and I know the English language. No wonder kids have problems in these subjects with wordage such as that. They're statements are a bit fuzzy.

I have two links for you to check out, that may help you to better understand what they are saying:

http://aggie-horticulture.tamu.edu/tisscult/pltissue/pltissue.html

And: http://en.wikipedia.org/wiki/Plant_tissue_culture

How soon do you need this information? I have contacted a friend who knows this science better than I. But she won't be able to confer with me until late tonight. Can you get this information by tomorrow? Until then, check out those two sites. I hope those will help to better explain what you're asking. Will get back to you as soon as I know more.


OK.......Here's the best explanation of the statements above that we could muster for you. Hope they will help.

Application of plant tissue culture
Plant tissue culture used widely to plant science has many commercial application.

(1) as a tissue for transformation followed by either short-term testing of genetic constructs or regeneration of transgenic plants.

Transformation is the name given to the process of altering plant cells by adding foreign genes to them, so called because you transform the cell from its original form to a new form. If you added new genetic sequences to a plant cell then after you had done this it would be known as a transformed cell.

What normally happens when a cell is transformed is that the new genetic material is put into the cell in the form of what we call a “construct”. All that this is is a length of genetic code of interest to the plant breeder which is joined to other important sections of code which are important to allow the new section to work properly inside the cell and to allow workers to select cells that have been transformed successfully from those which were not.

When you have cells that have been successfully transformed, they can be used for short experiments to see if the construct they now carry is working properly and producing the effect that plant breeders want. These short-term tests do not involve growing the cells on into plants so can provide the breeder with a quick result which enables him, for example, to choose which transformed lines to do further work on and which can be discarded.

The transformed plant cells can also be used to grow into proper plants using plant tissue culture. These are known as “transgenic” plants as they carry genetic information which is foreign to them and has been artificially introduced.

(2) large-scale growth of plant cells in liquid culture in bioreactors as a source of secondary products, like biopharmaceuticals.

The plant cells are just the same as the ones we talked about in point 1. One of the most common cells used is called a protoplast which is basically a plant cell which has had the outer cell wall removed. If you do a Google image search you will find lots of pictures of protoplasts. As well as protoplasts, you can also culture slightly more complex plant forms in bioreactors. When they are grown in liquid culture, all it means is that the cells are suspended in a special liquid which provides everything they need to grow and work properly.

A bioreactor is the name for the system in which the cells are maintained and grown. Bioreactors are run under very strict control levels for sterility, temperature, gas content and light etc and are set up in the best way for each sort of cell type.

“a source of secondary products” - as the cells grow and multiply, they have to make other cells, so to do this they need to make all the building blocks for those new cells, such as proteins. All these building blocks are coded for by the genes inside the plant cell and are produced by the cells. The building blocks are therefore called “gene products”. However, as we said in point 1, you can add new bits of genetic code to the plant codes and what is often done is to insert a gene code which tells the cell to make a protein which the plant would not normally make. For example, you might put the gene code for making the human hormone insulin into a bean plant cell, and if the transformation works, you might get bean cells which also produce insulin as one of their gene products. If you grew lots of these cells in a bioreactor, you can then harvest the liquid which contains the insulin, and hopefully it would be used in the pharmaceutical industry. This is why products like this are known as biopharmaceuticals to show they are different to chemically produced products.


(3) a plant breeder may use tissue culture to screen cells, rather than plants for advantageous characters e.g. herbicide resistance/tolerance.

We talked about putting genetic codes into cells in points 1 and 2. Another code which some plant breeders like to add to their plants is a genetic code to give the plants resistance to herbicides which are chemicals that would normally kill the plant. The main reason for doing this is so that if a farmer is growing a vegetable crop and wants to control a weed in that crop he can spray the whole crop with herbicide to kill the weeds, but the transgenic crop plants will not be affected and will keep growing, but will not have to compete against the weeds for food and water.

However, it takes a long time to get from a single plant cell such as the protoplast to a proper plant, and to do proper tests on the plants to see if they really ARE resistant to the herbicides, you need many hundreds of plants, all of which will need to be produced from one single parent plant. So it takes many weeks, even months to get a small number of adult plants and maybe years to produce seed from these plants to get enough to use in trials.

One way of getting a faster result and eliminating the failed plants right at the start is to do what is called “screening” . This involves a very small scale selection of cells which are successfully transformed by growing them in selective conditions, so that only the ones which are transformed correctly will survive and go on to be grown on into larger plants. For example, if you have transformed cells to be resistant to herbicide A then you would culture transformed cells/plantlets in media containing herbicide A. Cells with resistance to it will live, others (which have not transformed correctly) will die.