Striking gold with black, brown and red rice

Newswise — Basic research provides chances for novel forms of colored rice and a means to tackle malnutrition.

Colored rice, comprising black, brown, and red varieties, is acknowledged for its superior nutritional value compared to white rice and holds significant potential as a valuable asset in enhancing human health and combating malnutrition. Nevertheless, the widespread adoption of these varieties by farmers necessitates the development of enhanced yield and agronomic characteristics.

A research team, spearheaded by Magdy Mahfouz and Khalid Sedeek from KAUST, has successfully demonstrated the incorporation of favorable agronomic attributes, such as reduced stem length and early maturation, into black rice[1].

Sedeek, a postdoc in Mahfouz's lab, claims the initial phase in achieving these enhancements is the collection of extensive genomic data.

"Although the genomes of multiple japonica and indica rice types have been compiled, complete genome sequences are limited to a handful of pigmented varieties," he remarks.

The scientists opted for three black and two red rice cultivars to undergo whole-genome sequencing. To identify additional genetic variations, they sequenced an additional 46 varieties.

"The subsequent stage involved examining the composition of these cultivars to pinpoint those exhibiting superior nutritional qualities, thus qualifying as potential candidates for enhancement," Sedeek explains. For this purpose, the team assessed 63 varieties of black, red, and brown rice, with black rice emerging as the most nutrient-rich among them, showcasing a diverse array of compounds such as carbohydrates, amino acids, secondary metabolites, lipids, peptides, and vitamins.

Colored rice, particularly black rice, is abundant in vital microelements such as iron, zinc, copper, manganese, and selenium. Notably, the black Indonesian rice variety known as Cempo Ireng stands out as the rice with the highest iron content and the most zinc-rich genotype among black rice varieties. It has the potential to meet the daily requirements for these essential elements.

Based on the nutrient and metal-ion profiles, the researchers identified several rice varieties that exhibited high levels of antioxidants and other beneficial compounds and elements. These nutrient-rich varieties are strong contenders for further improvement and development.

Among these varieties, Cempo Ireng stood out as a potential candidate. However, despite its remarkable resistance to pests and diseases, farmers hesitated to cultivate it due to its long stem and lengthy five-month life cycle. To address this issue, Sedeek implemented a regeneration and transformation system in Cempo Ireng. Subsequently, CRISPR/Cas9 technology was employed to disrupt three flowering time repressor genes, leading to the development of a shorter and earlier maturing variant of Cempo Ireng.

The enhanced agronomic characteristics found in pigmented rice varieties hold the potential to render them more suitable for cultivation and integration into the food supply chain. Nevertheless, Mahfouz emphasizes that further research is required to ascertain whether these engineered traits can coexist harmoniously with other crucial traits, such as yield, in pigmented rice.

"However," he affirms, "this research furnishes vital resources for crop bioengineers and breeders, enabling them to persist in enhancing pigmented rice and harnessing its potential advantages for human health."

With their focus turned towards the local Saudi Arabian variety called Hassawi rice, Mahfouz and his team have set their sights on its improvement. Hassawi rice carries great cultural and economic significance in the region, making it an important target for enhancement. By leveraging CRISPR technology, the group aims to boost the productivity and enhance other essential traits of Hassawi rice, aligning them with the distinctive demands of the local Saudi market.