Plant breeding is the science and art of improving crop plants through the study and application of genetics, agronomy, statistics, plant pathology, entomology, and related sciences (Kuckuck et al; 1991). Increased crop yield is the primary aim of most plant-breeding programs; advantages of the hybrids and new varieties developed include adaptation to new agricultural areas, greater resistance to disease and insects, greater yield of useful parts, better nutritional content of edible parts, and greater physiological efficiency.
Humans have been improving crops for yield and other characteristics since the advent of agriculture. Plant biotechnology involves processes such as genetic engineering which involves the direct addition of foreign gene/genes to the genome of an organism. It is a type of genetic modification. Traditional plant breeding also modifies the genetic composition of plants. It involves techniques such as crossing and selection of new superior genotype combinations. Firstly traditional methods tend to breed plants that can sexually mate with each other. This limits the new traits that can be added to those that already exist in that species. Secondly when plants are crossed, many traits are transformed along with the trait of interest. Whereas genetic engineering, on the other hand, is not bound by these limitations. It involves the removal of a specific fragment of DNA from one plant or organism and transferring the genes for one of a few traits into another. No crossing is required hence the sexual barrier between species is overcome. It is more specific in that a single trait can be added to a plant (Bajaj .Y; 2001).
According to Rost .T.I et al (2006), another difference between traditional plant breeding and plant biotechnology is the number of genes transferred to the offspring in each case. Plants contain approximately 80 000 genes which recombine during sexual hybridization. The offspring may therefore inherit around 1000 new genes as a result of this recombination. This is equivalent to a 0.0125 % change in the genome. By contrast when a specific gene is transferred into a plant, there is a 0.0025% change in the genetic information of the plant, it is argued that plant biotechnology provides a more precise approach to crop improvements than sexual hybridization.
Plant biotechnology through genetic engineering can cause harmful toxins to be produced by transformed plants, though it is still unclear whether it is due to the technique itself on the nature of the foreign gene. The introduction of a gene that it is known to encode a toxin in one organism will induce a similar effect when introduced into a different organism (Raven P.H et al; 1992). There has been a case where a transgenic soybean containing a gene from Brazil nuts elicited an allergic reaction in some people. The gene from Brazil nuts had been well characterized and its product known to cause an allergy, hence extensive laboratory tests. This illustrates why rigorous characterization of a gene is required before permitting its introduction into a novel species. However there is also the potential...