Endosperm is a funny word, but some scientists are serious in their attempt to make us healthier by engineering rice endosperm enriched with purple, antioxidant-rich anthocyanins.
Anthocyanins are antioxidant-boosting pigments that aid in decreasing the risk of certain cancers, cardiovascular disease, diabetes, and other chronic disorders. They are found naturally abundant in some black and red varieties of rice. But polished, white rice completely lacks these nutrients as the grains are stripped of their husk, bran and germ - leaving only the endosperm.
Engineering a more nutritious endosperm has been on the menu for some time. Previous approaches have developed rice enriched in beta-carotene and folate, but not anthocyanins. Attempts to engineer anthocyanin production in rice have failed because the underlying pathways of biosynthesis, which the plant uses to produce organic chemical compounds, are highly complex, and it has been difficult to transfer multiple genes into the plants.
But a team of researchers has recently developed a system to express eight anthocyanin pathway genes into the plants, resulting in the successful biosynthesis of anthocyanins in the endosperm of rice varieties that don’t naturally produce the antioxidant-rich pigment. And they published their results last month in the science journal 'Molecular Plant.'
"We have developed a highly efficient, easy-to-use transgene stacking system called TransGene Stacking II that enables the assembly of a large number of genes in single vectors for plant transformation," said senior study author Yao-Guang Liu of the South China Agricultural University. "We envisage that this vector system will have many potential applications in this era of synthetic biology and metabolic engineering."
What’s the future of purple grains? The transgene stacking vector system could be used to produce many other important nutrients and medicinal ingredients. But for now, the researchers plan to evaluate the safety of purple rice as a biofortified food, and also try to produce more purple endosperm cereal grains.
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