Virus scare

Published: Monday 15 September 2008

Lethal viruses are taking over the world of food

IN agricultural research, new breakthroughs have helped elaborate the workings of two strains of potentially lethal viruses destroying important food crops like wheat and maize.

Research into the Maize Streak Virus (msv) destroying Africa's most important food crop has thrown light on the strain's emergence and its rapid spread across the continent. According to University of Cape Town researchers, msv has descended from relatively harmless wild grass affecting strains by a process called recombination. In this process, genes are selectively exchanged between the strains making the offspring more powerful. Two grass adapted msvs recombined over the years to produce the present-day "wide-host range" strain that can infect maize severely and survive harsh weather conditions more effectively than its parents.

Transmitted by leafhoppers (Cicadulina mbila), major symptoms include severely dwarfed cobs and yellowing. More tests are required to develop resistance strategies, said the study.

In Texas, the Triticum mosaic virus poses threat to wheat crops while being difficult to detect and contain, say Texas Agrilife Research scientists. It is transmitted by the wheat curl mite (Eriophyes tulipae). This also carries the wheat streak mosaic virus. Both the viruses cause yellowing and stunting.

Previous research had shown that the wheat streak virus reduces water uptake in plants. The researchers are now studying the water uptake and yield reduction of the plants affected by the Triticum mosaic virus. If detected earlier, it can help prevent waste of irrigation.

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