Pigmented rice is known to be much more nutritious than white rice and could be an important resource for improving human health and combating malnutrition. However, better yields and agronomic characteristics are needed if these varieties, which include black, brown and red, are to be widely accepted by farmers.
An international team led by Magdy Mahfouz and Khalid Sedeek of KAUST has demonstrated that the desirable agronomic traits of shorter stalk length and early maturity can be introduced into black rice.
Sedeek, a postdoc in Mahfouz’s lab, says the first step toward these improvements was to gather comprehensive genomic information.
“Although the genomes of different Japanese AND indicate rice varieties have been assembled, full genome sequences are only available for some pigmented varieties,” he says.
The researchers selected three black rice varieties and two red rice varieties for whole genome sequencing. To detect further genetic variations, they sequenced 46 other varieties.
“The next step was to analyze the composition of these varieties to identify those with superior nutrition as candidates for improvement,” says Sedeek. To do this, the researchers looked at 63 varieties of black, red, and brown rice, with black rice showing the best nutrient content across a wide range of compounds, including carbohydrates, amino acids, secondary metabolites, lipids, peptides, and vitamins. .
Pigmented rice (especially black rice) is also rich in essential trace elements, including iron, zinc, copper, manganese and selenium. Especially the Indonesian black rice Cempo Ireng (the rice genotype richest in iron and the black rice genotype richest in zinc) could provide the daily requirement of these essential elements.
The researchers used these nutrient and metal ion profiles to identify several nutrient-rich strains with higher levels of antioxidants and other beneficial compounds and elements, which could likely be strains for improvement.
One of them was Cempo Ireng. However, despite its resistance to pests and diseases, farmers are reluctant to grow crops Cempo Ireng thanks to its long stem and five-month life cycle. Sedeek has set up a system of remanufacturing and processing in Cempo Ireng and then used CRISPR/Cas 9 to eliminate three repressors of flowering time, resulting in a shorter early maturing variety.
Improved agronomic traits in pigmented rice varieties have the potential to make them more suitable for cultivation and incorporation into the food chain. However, Mahfouz notes, more work is needed to determine whether these engineered traits can coexist with other important traits, such as yield, in pigmented rice.
“However,” he says, “this research provides important resources for bioengineers and crop farmers to continue improving pigmented rice and exploiting its potential benefits for human health.”
Mahfouz and his team now plan to improve a local red rice variety known as Hassawi rice. This particular variety of rice, native to Saudi Arabia, has immense cultural and economic significance in the region. Using CRISPR technology, the group aims to improve the productivity and other key traits of Hassawi rice to meet the unique needs of the local Saudi market.
Multi-omic resources for targeted agronomic improvement of pigmented rice
Article publication date
May 11, 2023
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