Aug 19 : The white rice that feeds more than half of today’s world’s population, evolved some 10,000 years ago from wild red rice in the Himalayan plains, according to a recent study published online in PLoS Genetics.

Susan McCouch, professor of plant breeding and genetics at Cornell University, and her team has determined that 97.9 percent of all white rice is derived from a mutation (a deletion of DNA) of a single gene originating in the Japonica subspecies of rice.

Prof. McCouch and her team found that this predominant mutation is found in the Indica subspecies of white rice.

The team also found a second independent mutation (a single DNA substitution) in the same gene in several Aus varieties of rice in Bangladesh, accounting for the remaining 2.1 percent of white rice varieties.

Surprisingly, neither of these two mutations is found in any wild red rice species.

The team found that both mutations produced shortened versions of the same protein in which the missing part is responsible for activating the molecular pathway leading to grain colour in rice.

“We think that other domains of this protein are critical for other functions in the plant, because we never see the protein entirely deleted, just the part of the molecule that affects the pathway for grain colour,” said Prof. McCouch.

The researchers believe ancient farmers actively bred and spread white rice varieties first throughout the Himalayan region and then the rest of the world because these varieties cooked faster compared to red rice.

Also disease and insects were easier to see amid the white grains, they said.

The farmers may also have favoured one mutation over the other because it may have produced favourable grains more consistently, the researchers wrote in their study. (ANI)