In YESTERDAY’S post, “FARMING SERIES: CLEAN GENE (Part 1)” , I briefly explained the clean gene technology that has been developed to rid transgenic plants of unwanted genes that have been integrated for the identification purpose and making sure only the gene(s) of interest are retained in the progeny of the parent transgenic. These are generally propagated through tissue culture and micropropagation techniques. NOW before going into details about this new technology that aims to produce ‘safe’ transgenics; I would like to explain the basics from scratch for our readers from non-science backgrounds.
What is a gene?
It’s simply a segment of DNA that carries hereditary ‘information’.
The DNA (our genetic material) is a biological molecule in the form of a double stranded helix. It simply contains a sugar and phosphate backbone and nitrogenous bases (4 different types) that help the two strands remain attached via complementary base pairing with the help of hydrogen bonds.
These bases A,T,G,C are present in a particular order and are read by certain enzymes that transcribe this info into an RNA (contains ribose-sugar in place of deoxyribose sugar and Nitrogenous base Uracil (U) in place of Thymine (T)).
For a clearer picture, you can check out this link “The Central Dogma” and other 3D animation videos in that site. Or if you want to get to the basics, You can check out this comprehensive website that offers a lot of animation on the basic concepts of classical genetics.
So the mRNA is like a messenger carrying a message that is important for your survival. The mRNA now gets read and proteins are formed. Proteins are a part of the cell membrane, present in the cytosol, in the cytoskeleton (as tubulins, keratins etc), as enzymes (biological catalysts) etc.
Now that we know what a gene is and what it does, we can also infer that some forms of a particular gene are more desirable than others. For example tallness and dwarfism in some plants get conferred from the different forms (alleles) of the same gene. Mendel’s classical laws demonstrate how these alleles are distributed to the progeny and traditional breeding techniques make use of it. But technological advancements have enabled us to transfer genes (desirable genes) between species, between kingdoms whose populations would not interbreed under natural conditions. This is what you need and how it’s done:
So for the creation of transgenic plants, we have used some selectable marker genes that are usually antibiotic resistance genes or herbicide resistance genes. The PROBLEM is these genes also get incorporated into the transgenic plants. Antibiotic resistant genes might get transferred to humans or animals via consumption or herbicide resistant genes can be transferred to their wild plant relatives. So to eliminate these risks, the clean gene technology was created.
By using a BINARY VECTOR strategy like the one described above, the selectable marker can be integrated on a separate vector and gets incorporated into a different region of the genome and can be segregated from the gene of interest through the natural process of recombination and crossing over.
Recombination and crossing over is what happens in the germ cells of the sexually reproducing organisms so that when the zygote is formed after fertilization, no two individuals are alike. Even identical twins (genetically similar) have some amount of dissimilarities due to factors that may be epigenetic (mainly influenced by their environment and are non heritable).
You may also like:
©The Idea Bucket, 2013.