A severe form of maize streak virus in Africa and Asia may have formed from two mostly harmless viruses in grass. Scientists hope knowing this will help point to a cure. Transcript of radio broadcast.
the VOA Special English Agriculture Report.
maize streak virus causes one of the most destructive crop diseases in Africa.
Not only is it economically damaging, it can also threaten food security. Maize
crop failures lead to hunger in some areas. Maize streak disease also strikes
parts of Asia.
insects known as leafhoppers carry the virus from field to field. Not much food
can come from a field badly infected with the virus. The maize plants cannot
produce a healthy cob. The disease gets its name from the streaks of yellow and
white that discolor the leaves.
are many less harmful kinds of maize streak virus. These cause minor infections
in crops like sugarcane and wheat. But only one kind causes the most severe
form of maize streak disease.
have been working to understand how this form of the virus got started and
spread. They studied eighty versions of maize streak virus. They found that the
severe kind may have formed from a recombination of less harmful grass viruses.
In the process of recombination, the parent viruses exchanged a gene.
study compared the genome of the maize streak virus with those of ten related
but less harmful viruses. A genome contains all the information about an
organism, including information carried from its parent organisms.
The most severe virus may have formed
more than a century ago, when two mostly harmless viruses that infect wild
Darren Martin of the University of Cape
Town in South Africa led the research. He says the researchers found that every
maize streak virus that severely affects maize came from an ancestral virus.
That ancestral virus was the recombinant result of the two comparatively
But the virus they formed was stronger.
It could infect more plants than its parents. It could live through winters in
wild grasses better than its relations. The researchers believe that this
quality also made the severe form of maize streak virus spread faster.
from several parts of the world took part in the study, which appeared in the
Journal of General Virology. The research continues. The goal is to find more
biological information that could help lead to a cure.
that's the VOA Special English Agriculture Report, written by Jerilyn Watson.
For more reports -- with transcripts, MP3s and podcasts -- go to
voaspecialenglish.com. I'm Steve Ember.