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Scientists have moved a step closer to learning the genetic secrets of
maize, one of the world's most important food crops, and using this
knowledge to boost crop yields, October 2004 by Mike Shanahan .

The researchers, led by Joachim Messing, director of the Waksman Institute
of Microbiology at Rutgers University in New Jersey, United States, have
published a series of papers providing the most comprehensive picture yet of
the crop?s evolution and genetic structure.

"This research will help enable scientists and farmers to make major
improvements in one of the world's most significant crops," says Messing.

The researchers conservatively estimate that the maize genome ? its entire
genetic makeup ? includes about 59,000 genes, short sequences that code for
individual proteins. That is more than any other species whose genome has
been sequenced so far. The most recent assessment of the human genome,
published last week (21 October) in Nature, puts the total number of human
genes at between 20,000 and 25,000.

Messing told SciDev.Net that the research has importance implications for
developing countries.

"More nutritious maize is critical for Africa," he says, adding that it
should be possible to boost the crop's nutritional value because "it already
has all the genes necessary".

According to Messing, the richness of the maize genome means that increasing
its nutritive value would not require adding genes from other species, but
only changing the way existing genes function.

"One example is amino acids, which are stored as proteins in the seeds that
we eat," says Messing. Some maize varieties have more nutritious proteins,
but the genes controlling their production can be 'silenced' when the
variety is crossed with other strains. Messing anticipates being able to
prevent this silencing by moving a short sequence of genetic material called
a 'regulator' from a gene that is not silenced to the one that is.

The research also revealed that the maize genome is highly complex because
many of its genes have moved to different locations on chromosomes during
its evolution. This phenomenon ? unknown in any other species ? has
implications for genetic engineering.

According to Messing, it means that fears that genetic modification could
lead to instability in a species? genetic material are unfounded.

Sequencing the entire maize genome is a priority driven by the world?s
economic and nutritional needs, says Messing. About US$12 million has been
spent so far on research laying the groundwork for full genome sequencing,
and the US National Science Foundation recently announced a US$30 million
programme to fund that research.

Messing's team's findings are presented in three papers in the journal
Genome Research and one in the Proceedings of the National Academy of
Sciences.

[www.genome.org]

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