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Newly bred varieties of a climate-hardy crop that contains four times as much Vitamin A could provide a solution to millions in Africa suffering from malnutrition related to vitamin A deficiency, a study published in the latest issue of Crop Science reports.
Cassava, Africa’s second most important staple crop, is often eaten where poverty and malnutrition are widespread. Although high in carbohydrates and able to withstand disease, drought and pests, and to grow in degraded soil, cassava contains very few nutrients.
So a team of researchers at the International Center for Tropical Agriculture (CIAT), led by plant breeder Hernan Ceballos, set out to fast-track boosting the vitamin A content of cassava to reach millions in Africa suffering from vitamin A deficiency.
An estimated 250 million preschool children globally are vitamin A deficient, most of them in Africa and Asia, according to the World Health Organisation. Up to 500,000 will go blind every year – and half of them will die within 12 months of losing their sight, the organisation warns.
CIAT researchers have produced cassava with a fourfold boost in beta-carotene, the orange pigment used by the body to make vitamin A. The work is all the more remarkable because it has been done in less than half the normal time needed.
Usually, the selection process needed to demonstrate crucial genetic changes takes about 8 years. But to meet an ambitious goal set by the Bill & Melinda Gates Foundation, which funded the research, researchers devised a “rapid-cycling” breeding method for cassava.
Unlike other genetic traits of cassava, beta-carotene is “trustworthy”. That is, you can demonstrate increased or decreased levels in a short time, without extensive tests to verify results.
This is typical of what scientists call “high-heritability” genetic traits. In humans, blue or brown eyes are an example of such traits – easy to judge relatively soon after birth. IQ, by contrast, is a low-heritability trait – one that takes years to become evident.
Because beta-carotene is a high-heritability trait, researchers were able to “rapid-cycle” the process of crossing one cassava variety with other roots of high beta-carotene content. This reduced the time needed to create the new variety to three years.
“We suspected that beta-carotene had high heritability at the beginning, but now we know it for sure,” said Ceballos, who called the work “a breakthrough” in demonstrating the responsiveness of cassava to breeding changes.
“It’s hugely exciting,” he said.
JUST THE FIRST?
The results have implications beyond boosting beta-carotene content in cassava. By unraveling a bit more of the mystery surrounding the genetic makeup of the crop, scientists now know that rapid breeding for other high-heritability traits is possible.
Resistance to diseases, for example, could be tested more rapidly. “For the first time, we can use this knowledge to inform our decisions when developing new varieties,” said Ceballos.
There remains the hard work of getting the improved varieties into the field where farmers can use them – and ensuring that they are accepted by farmers. This baton has been picked up by CIAT’s partner, the International Institute of Tropical Agriculture (IITA).
“We have made fantastic progress in boosting the nutritional content of cassava, and now we’ll concentrate on production of commercial varieties, for use in Africa and Latin America,” Ceballos said.
Boosted vitamin A is expected to benefit about 70 million people in developing countries who consume at least 500 calories from cassava roots every day.