GM maize gives virus nowhere to hide

Normal maize is susceptible to maize streak virus Copyright: CGIAR

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Crop scientists in South Africa have developed a maize variety that is resistant to maize streak virus, a move they hope will help alleviate food scarcity and promote the reputation of genetically modified (GM) foods in Africa.

The scientists — from the University of Cape Town and the seed company PANNAR — claim the new variety shows resistance to the virus in successive plant generations and in crosses with other varieties.

The all African team hopes the technology will help to address other viral diseases affecting African food crops such as the wheat dwarf virus, sugarcane streak virus and other viruses that affect barley, oats and millet.

They reported their findings this week (8 July) at the annual meeting of the American Society of Plant Biologists in Chicago, United States.

Maize streak virus (MSV), endemic to sub-Saharan Africa and the Indian Ocean Islands, retards the growth of infected plants and causes them to grow deformed cobs, decreasing the amount of grain that can be harvested.

Instead of crossing varieties with different degrees of resistance to MSV, the scientists mutated a viral gene that encodes a protein the virus needs to replicate itself and inserted it into maize plants.

When the virus infects the GM maize, the presence of the mutated protein prevents the virus from replicating and killing the plant. Field trials of the crop are scheduled to begin soon.

Simon Gichuki, director of the biotechnology department at the Kenya Agricultural Research Institute (KARI) said the new variety will have to be taken through field trials before its resistance is fully proven.

He says KARI has used the approach to develop varieties of crops such as pawpaw and sweet potato but some field trials were unsuccessful. “The environment in the green house is different from out there in the farms,” Gichuki told SciDev.Net. Field trials will also assess the new crops’ impact on the environment, he added.

Gichuki added that getting new plants to farmers takes time, as any new resistant crop has to pass regulations and national trials to determine their distinctiveness, uniformity and stability.

The researchers also looked at 389 Ugandan MSV samples to assess the diversity and genetic characteristics of the virus.

They found that most prevalent strains of MSV are a product of recombination of different viral genotypes, a process that helped highlight how the virus has evolved to cause disease in crops.