Dr Rikus Kloppers of Pannar told Lloyd Phillips about the ins and outs of man-modified cultivars, and how biotechnologies from GM to conventional breeding offer farmers a brighter future.
The term “biotechnology” refers to more than just genetic engineering, or moving bits of DNA between species. According to Dr Rikus Kloppers, manager of technical services for Pannar Seed, it more often refers to techniques using molecular breeding (also known as marker-assisted breeding, which uses genetic “fingerprinting” to help breeders match DNA profiles to physical characteristics) or genetic engineering, biotechnology can also refer to conventional breeding.
“With conventional breeding, the intended trait of the donor isn’t the only one carried to the progeny,” says Dr Kloppers. “The only way to eventually obtain progeny carrying the trait of interest, plus the preferred background of the well-adapted parent, would be through back-crossing over a long period. Molecular breeding, which shouldn’t be confused with genetic engineering, became a very important tool for conventional breeders, allowing them to identify and track important characteristics in their breeding material, speeding up the process and getting improved varieties in a shorter turnaround time.
” In genetic engineering, on the other hand, traits can be moved between totally different or unrelated species. This can even extend to taking genes from a plant and putting them into an animal, or vice versa. “Just four bases or nucleotides – thymine, guanine, cytosine and adenine – provide the entire genetic code of all living organisms, plant or animal,” explains Dr Kloppers. “The only thing that differentiates all these species at a genetic level is the sequence of these four bases in the DNA strings making up the chromosomes. These bases are able to produce 20 different amino acids and their different combinations form proteins that enable all living organisms to function in their unique ways.”
Gene transfer
According to Dr Kloppers, gene transfer from one species to another could either be conducted by what is know as the particle acceleration “gene gun” (PAGG) method or by the agrobacterium method. With the PAGG Method, DNA is passed through gold or tungsten pellets and then inserted into the nucleus of a plant or animal cell. With this method, the cell’s contents are transformed in one shot before the cell is isolated and grown in a laboratory. In the agrobacterium method DNA is inserted in particular single-celled bacteria, which transfer it into a plant cell. Genetic engineering’s effectiveness in breeding desirable characteristics into crops, is evidenced by the wide variety of genetically modified (GM) crops that are now grown commercially around the world. The latest survey indicates that worldwide, 114.3 million hectares have been planted under GM crops during the past 2007 season.
Commercially important crops, such as maize and soybeans, have been genetically modified to carry traits that are said to ease farmers’ management and input costs while still yielding good volumes of grain. RoundUpReady crops are resistant to the herbicide, RoundUp, while insect resistant or Bt crops targets and control the African stalkborer – a major pest in maize.
“Genetic engineering is possible through the miracle of the genetic code found in all species of living organisms, plant or animal”, says Dr Kloppers. “Just four bases or nucleotides, namely thymine, guanine, cytosine and adenine, provide the entire genetic code of all living organisms. The only aspect that differentiates all these species at genetic level is the sequence of these four bases in the DNA strings making up the chromosomes. These bases are able to produce twenty different amino acids and their different combinations form proteins that are the building blocks of life and cause all living organisms to function in their unique ways. The understanding of these factors combined with modern technological innovations, are what make genetic engineering possible.”
According to Dr Kloppers, gene transfer from one species to another could either be done by what is know as the Particle Acceleration “Gene Gun” (PAGG) Method or by the Agrobacterium Method. With the PAGG Method, DNA is passed through gold or tungsten pellets and then inserted into the nucleus of a plant or animal cell. With this method, transforming the contents of a cell is only required once before the transformed cell is isolated and then grown in a laboratory. The Agrobacterium Method uses certain varieties of single celled bacteria to transfer DNA already inserted in a bacterium, into a plant cell. The bacterium is small enough to enter the plant cell.
“South Africa, and many other countries, have a very strict approval process for the introduction of GM products. This is why the development of GM products to a commercial level is generally very slow. Since 1997, there have been only ten GM products approved for use in South Africa, of which four are currently marketed by Pannar Seed. Despite this, the market for GM crops seeds has grown hugely both here and internationally, with South Africa currently rated number 8 in the world for the acceptance of GM crops,” Dr Kloppers points out.
The United States Department of Agriculture’s Foreign Report for July 2007 revealed that in SA, 44% of all maize, 59% of all soybeans, and 92% of all cotton, grown is GM. Of the 1,2 million hectares of GM maize grown in this country, 77% is Bt and 23% is RoundUpReady. Dr Kloppers explains that Bt was the first GM maize variety introduced into SA. The Bt gene is said to prevent African stalkborer from feeding on the maize and then spoiling the crop. Insect damaged maize cobs can also result in the secondary growth of fungi which produces mycotoxins that can be highly toxic to humans or other animal species.
However, the commercial use of certain GM crop varieties is also governed by strict rules and legislation. In the case of Bt maize, farmers have to plant a “refuge area” of non-GM maize next to a Bt maize field. African stalkborer in the Bt maize field that might develop resistance to the gene will hopefully breed with non-Bt relatives from the “refuge area”, thus diluting the potential resistance of the former insects. In effect, this process is the farmers’ version of uncontrolled conventional breeding where the non-Bt resistant insects pass on their weaknesses to the potentially BT-resistant insects.
Dr Kloppers continues, “Companies that develop GM crop varieties spend many millions getting these products commercialised, partially explaining the cost of this technology. Therefore, these companies are also exceptionally protective of their intellectual property as it relates to the development of the products and these developments are all protected by patents and patent laws. This is why farmers who buy and use GM seeds are not allowed to produce and sell their own seeds from a GM crop originally developed by a seed company. There is already a second generation of USA developed RoundUpReady soybeans which is linked to yield increase genes and gives an approximate yield increase of 7%. Unfortunately, the developer of this product is concerned about introducing it into South Africa because of the reputation that this country’s farmers have internationally for producing and illegally selling seed that they originally sourced from the seed companies. This whole situation is pitiful because South African farmers could really benefit from this new product.”
Pannar says that the development of GM products comes with great responsibility for seed breeders. Companies must carry out numerous risk assessments and various safety tests on their products before they can be approved for commercial use. Additionally, various quality tests have also to be done before a product can be sold commercially to the farmer. According to Dr Kloppers, these tests include qualitative, quantitative DNA testing, enzyme linked immunosorbant assays (ELISA) and bioassays. Before a RoundUpReady cultivar/hybrid can be sold for example, companies have to test every seed lot and verify that a minimum of 98% of the seeds in a bag sold carry the trait and adhere to the legislative requirements in terms of quality and safety. In addition, controls must be in place to ensure that these GM seeds are sold or used only where it is legal to do so.
Maize streak virus (MSV) is a notorious problem disease in many of the maize production regions of SA and the rest of Africa. Pannar has been working with the University of Cape Town for the last 15 years to develop GM maize seed which is resistant against the virus – a first for of its kind in the world and developed in Africa for a uniquely African maize disease affecting small scale and commercial farmers. This product’s development still has a long way to go through a strict approval process, and the earliest that this seed will be available commercially is approximately by 2014.
“Imagine how Africa’s food security could benefit if a genetically modified product was developed that had both maize streak virus and drought tolerance respectively. This product could be especially important for subsistence and small-scale maize growers on the continent,” says Dr Kloppers.
