Gene Orange (Or) plays an important role in the accumulation of carotenoid and participates in the non-pigmented plastidation of chromosomes. It does not interfere with the carotenoid synthesis, but regulates the process of reservoirs for the isolation and storage of carotenoids. Or gene expression increased carotenoid accumulation in the scar tissue of rice and sweet potato. Applying gene technology to express the carotenoid accumulation gene is an important way to improve carotenoid content, increase the nutritional value of maize, contribute to human health and effective in breeding.

The research team of Vietnam Academy of Science and Technology has isolated the Or gene from the Hoang Long sweet potato variety (IbOr) (code KX792094.1) and the Or gene from cauliflower (code KX396544.1). The team also designed two expression structures carrying the IbOr gene to enhance carotenoid accumulation: pCambia2300/Ubi/IbOr/Nos and pCambia2300/Glo1/IbOr/Nos.

The pCambia2300/Glo1/IbOr/Nos construct was successfully transferred into several maize lines and developed 18 transgenic lines with a total carotenoid content increase from 1.756 to 12.515 times, respectively, and β-carotene increased from 2,022 to 19,002 times. Of these, six lines had β-carotene levels more than 10 times.

For more information, read the article from the Institute of Agricultural Science for Southern Viet Nam.