How Yellow Corn Reduces Blindness, Child Death, By Researchers

DECREASING or increasing the function of a
newly discovered gene in corn may
increase Vitamin A content and have
significant implications for reducing
childhood blindness and mortality rates,
according to a Purdue University-led study.
Torbert Rocheford, the Patterson Endowed
Chair of Translational Genomics and
professor of Agronomy at Purdue, led the
study that made findings in yellow and
particularly orange corn, a type he said
likely originated in the Caribbean and is
popular in some African, Asian and South
American countries as well as in northern
Italy.
The orange colour comes from relatively
higher levels of carotenoids, one of which is
beta-carotene. Humans convert beta-
carotene, which also is abundant in carrots,
into Vitamin A during digestion.
Rocheford is using simple visual selection
for darker orange colour combined with
more advanced molecular natural diversity
screening techniques to create better lines
of the orange corn.
“We’re sort of turbocharging corn with
desirable natural variation to make it darker
and more nutritious, ” Rocheford said.
Between 250,000 and 500,000 children —
mostly in Africa and Southeast Asia -go
blind each year because of Vitamin A
deficiency, according to the World Health
Organisation. Half of those children will die
within a year of going blind. Rocheford said
that increasing beta-carotene levels in cereal
grains, such as corn, was an economical
approach to addressing these deficiencies
in developing countries.
He added that the gene beta-carotene
hydroxylase 1 (crtR-B1) altered beta-
carotene in corn in a way that reduced pro-
Vitamin A activity. Through a process
known as hydroxylation, beta-carotene is
converted into other carotenoids that can
cut the amount of pro-Vitamin A that is
created through digestion in half, or
eliminate it altogether. Reducing the
function of the crtR-B1 gene would reduce
hydroxylation considerably.
“Because of this, selecting a form of the
gene that does not have much activity
causes beta-carotene to build up, ” said
Rocheford, whose findings were published
in the journal Nature Genetics.
“ We’re have started to move the favourable
‘weak’ allele into breeding materials.”
Conversely, “strong alleles” increasing crtR-
B1 function boost the hydroxylation
process, which creates more zeaxanthin.
Zeaxanthin is a micronutrient that could
protect against macular degeneration, the
leading cause of blindness in people over
55 in Western industrialised nations,
according to the American Macular
Degeneration Foundation.
Zeaxanthin makes up 75 per cent of the
central macula in human eyes, according to
the AMDF, and data show that macular
pigment increases through dietary
supplements.
Rocheford said that the findings were
encouraging for addressing problems in
both developed and developing nations.
“It is like a designer gene. We can select one
version for the U.S. population to increase
zeaxanthin and a different version to
increase beta-carotene for the needs of the
developing world, ” he said.
Rocheford’s research will continue to look
for ways to improve the nutrient profile of
orange corn through simple visual selection
and more advanced DNA and compound
analyses. He said further that efforts would
focus on other genes that also held promise
to increase pro-Vitamin A in corn.
Another challenge, he admitted, would be
introducing a new variety of corn to
consumers.
“ The U.S. only grows yellow and white corn
and Africa largely grows white corn,”
Rocheford said. “But parts of the world -
some parts of Asia and South America -
actually prefer orange corn. ”