The genetically modified (GM) maize is resistant to maize streak viruses (MSV), that can destroy most of a maize crop. The viruses are endemic to sub-Saharan Africa and adjacent Indian Ocean islands. Scientists at the University of Cape Town, South Africa, along with colleagues at the South African seed company, Pannar Pty, told attendees at the American Society of Plant Biologists annual meeting that they hope will help alleviate food shortages as well as promote the reputation of GM foods in Africa. Whether the maize will affect global supplies is unknown at the current time, with indications being that the maize will initially supply only African markets. If the trials prove successful, this could see yet another increase in the number of hectares cultivated with GM crops. A recent publication of new figures from The International Service for the Acquisition of Agri-biotech Applications (ISAAA) showed that in 2006 the number of hectares globally cultivated with GM crops increased by 12 million hectares. Most of this growth came from countries such as China and India. Resistance to MSV is not straightforward, said the researchers since this requires multiple genes located on different chromosomes. The South African researchers took an alternative approach to solving the problem, by taking a mutated viral gene that encodes a protein that the virus needs to replicate itself and inserted it into maize plants. They surveyed almost 400 Ugandan MSV isolates, and found that the most prevalent strain of this virus is a product of recombination of different viral genotypes. By identifying the specific mutation, the researchers were able to provide protection against MSV. When the virus infects one of these transgenic maize plants, the mutated protein, which is expressed at a high level, prevents the virus from replicating and killing the plant. The transgenic maize variety has proven consistently resistant to MSV and the trait can be reliably passed on to the next generation and in crosses to other varieties. The impending field trials will ensure that the GE maize variety has no unintended effects on beneficial organisms that may feed on it, as well verifying that the viral protein is digestible and non-allergenic. The researchers also plan to extend their research to disease caused by similar viruses, which can affect other crops, including barley, wheat, oats, sugarcane, and millet.
