Newly Developed Purple Rice Could Help Fight Cancer

Purple endosperm rice. Photo credit: Qinlong Zhu of the South China Agricultural University.

(CN) – A newly developed genetic engineering approach is capable of generating antioxidant-rich purple rice that could help decrease the risk of certain cancers, diabetes and other chronic disorders.

Chinese researchers used the new technique to produce the genes needed to increase the production of antioxidant-boosting pigments called anthocyanins in rice endosperm – seed tissue that provides nutrients to developing plant embryo. The team published their findings Tuesday in the 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 lead author Yao-Guang Liu, a researcher at the South China Agricultural University in Guangzhou, China.

Genetic engineering approaches have been used to develop rice enriched in folate and beta-carotene, but have yet to stimulate anthocyanin production. While anthocyanins are naturally present in some varieties of black and red rice, they are absent from polished rice grains because the bran, husk and germ have been removed.

Previous attempts to engineer the production of anthocyanins in rice were thwarted by the complex biosynthesis path of the health-promoting compounds, in addition to challenges stemming from efficiently transferring many genes into plants.

In order to determine the relevant genes, the team analyzed sequences of anthocyanin pathway genes in different rice varieties and identified the defective genes in japonica and indica subspecies that do not produce anthocyanins.

The team then developed a transgene stacking strategy for expressing eight anthocyanin pathway genes in the endosperm of the japonica and indica subspecies. The resulting purple rice had elevated anthocyanin levels and antioxidant activity in the endosperm.

“This is the first demonstration of engineering such a complex metabolic pathway in plants,” Liu said.

The transgene stacking vector system could also be used to increase the production of many other key medical ingredients and important nutrients, according to the study.

“Our research provides a high-efficiency vector system for stacking multiple genes for synthetic biology and makes it potentially feasible for engineering complex biosynthesis pathways in the endosperm of rice and other crop plants such as maize, wheat, and barley,” Liu said.

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