Question

What do new biotechnology techniques allow scientists to do that traditional breeding could not? Explain

Answer 1

The goal of both new biotechnology techniques and conventional plant breeding is to produce crops with improved characteristics by changing their genetic makeup.

Conventional breeding achieves it by crossing together plants with relevant characteristics, and selecting the offspring with the desired combination of characteristics, as a result of particular combinations of genes inherited from the two parents. BT achieves this by adding a new gene or genes to the genome of a crop plant.

Biotechnology has opened an exciting frontier in agriculture. The new techniques provided by biotechnology are relatively fast, highly specific, and resource efficient. It is a great advantage that a common set of techniques—gene identification and cloning, for example—are broadly applicable. Scientists have learned to genetically alter certain crops to increase their tolerance to certain herbicides.

The major differences between traditional breeding and molecular biological methods of gene transfer lie neither in goals nor processes, but rather in speed, precision, reliability, and scope. When traditional breeders cross two sexually reproducing plants or animals, tens of thousands of genes are mixed. Each parent, through the fusion of sperm and egg, contributes half of its genome (an organism's entire repertoire of genes) to the offspring, but the composition of that half varies in each parental sex cell and hence in each cross. Many crosses are necessary before the ''right'' chance recombination of genes results in offspring with the desired combination of traits.

Molecular biological methods alleviate some of these problems by allowing the process to be manipulated one gene at a time. Instead of depending on the recombination of large numbers of genes, scientists can insert individual genes for specific traits directly into an established genome. They can also control the way these genes express themselves in the new variety of plant or animal. In short, by focusing specifically on a desired trait, molecular gene transfer can shorten the time required to develop new varieties and give greater precision. It also can be used to exchange genes between organisms that cannot be crossed sexually.

The traditional goal of crop production remains unchanged: to produce more and better crops at lower cost. However, the tools of biotechnology can speed up the process by helping researchers screen generations of plants for a specific trait or work more quickly and precisely to transfer a trait. These tools give breeders and genetic engineers access to a wider universe of traits from which to select.

Although powerful, the process is not simple. Typically, researchers must be able to isolate the gene of interest, insert it into a plant cell, induce the transformed cell to grow into an entire plant, and then make sure the gene is appropriately expressed. If scientists were introducing a gene coding for a plant storage protein containing a better balance of essential amino acids for human or animal nutrition, for example, it would need to be expressed in the seeds of corn or soybeans, in the tubers of potatoes, and in the leaves and stems of alfalfa. In other words, the expression of such a gene would need to be directed to different organs in different crops.

Scientists have taken another important step in using genetic engineering to improve crop production: They have for the first time engineered plants to be resistant to powerful herbicides. One example is glyphosate, a common, effective, and environmentally safe herbicide. However, glyphosate indiscriminantly kills crops as well as weeds. Thus, it must usually be used before crop plants germinate. Yet by engineering crops to be resistant to glyphosate, scientists hope to expand the range of the herbicide's applications. Scientists have isolated a glyphosate-resistance gene and successfully transferred it into cotton, poplar trees, soybeans, tobacco, and tomatoes. The gene was derived from the bacterium Salmonella typhimurium .