Scientist cracks rice gene

Thai discovers how to manipulate the aroma

PIYAPORN WONGRUANG

A rice researcher has made a major scientific breakthrough with the aroma of jasmine rice _ keeping the fragrance and, even better, adding the aroma to any rice variety.

The study started from one puzzle: why the aroma of rice diminishes? That remained an unanswered question until 2004 when a group of scientists led by Assoc Prof Apichart Vanavichit, the director of the Rice Gene Discovery and Rice Science Centre, managed to crack the genetic code of jasmine rice. The study kicked off at the centre's laboratory in Kasetsart University in the early 2000s.

''There is something very interesting about rice,'' said Mr Apichart. ''The species has plenty of varieties, but it mutates in a certain way that allows us to study some traits, including the aroma.''

It was widely suspected among rice scientists that the genes responsible for the aroma might be located in chromosome 8 of aromatic rice, but no one managed to isolate them.

In order to distinguish the genes from other genes, the research team developed an identical twin to first study its function in regard to aroma and then used it to confirm the gene on chromosome 8. Eventually they managed to identify the gene responsible for aroma in jasmine rice.

''We wanted to know why the degree of aroma in rice grains was different, and whether this was also because it came from different sources. We have learned that some wild rice varieties also carry these genes, and that made us more curious to examine more,'' said Mr Apichart.

They also learned that the gene they found was not superior but inferior.

Mr Apichart explained that aroma was caused when the gene that commands it lost certain genetic codes. Through time, the rice with such a gene will try to fix this false genetic composition and, as a result, the rice's aroma will be eliminated.

The discovery by the team of scientists carries critical implications for the country's rice breeding programmes.

For many years rice breeders improved varieties with little attention to aroma because they lacked a specific technique to help them look into the molecular composition of rice.

Without regular examinations and maintenance, the aroma in rice can diminish or even disappear as a result of the mutation process of the rice, he said.

In order to help rice breeders better monitor rice aroma, Mr Apichart's team developed a precise testing method based on the known mutation sequence of the gene which helps examine the transmission of the gene from generation to generation. They have also been inventing ways to put more aroma into any rice varieties.

In their laboratory, the scientists conducted the genetic modification to prove that rice aroma could be manipulated. They inserted the genes commanding rice aroma into non-aromatic Japanese Nipponbare.

The result of the experiment was rice with an emerging aroma.

Mr Apichart has been granted a patent in the US to protect the developed technology. He said there is a trade aspect involved with the new knowledge and the use of the technology.

He noted the genes commanding rice aroma are located in the region where genes are easily exchanged, and through the technology rice developers can improve the quality of rice and put it in a better position in the market.

With the patent, Mr Apichart hopes that Thai farmers will be protected by the same technology.

However, he said there is no plan to introduce the technology in rice, in the wake of concerns over genetic engineering technology which may affect the marketing of Hom Mali rice.

Instead, he said, conventional breeding with the help of molecular marking that helps guide genetic exchanges for desirable results is still the main choice for rice breeding here. However, there is a lot of work still to be done as it needs a lot of improvements.

''We have the potential to lead in the field of rice development, but we still lack a lot of necessary resources,'' he said.

''Our rice breeders, for instance, do not know enough about molecular interrelationships of the aromatic gene to the rest of the genome and the environment. For example, why aromatic rice is more susceptible to insect and pest damage should be subject to more understanding. We have a lot of things to do and learn here to push our rice development forwards.''

Wanlop Pichpongsa, the assistant managing director of Capital Rice, one of the leading exporters of jasmine rice, said rice's aroma plays a significant role in attracting customers in the market. He said there were times when rice traders were questioned about lack of fragrance in their exported rice.

Thanks to the scientists' work, a stable aromatic quality of rice could be ensured, and the value of rice in the market could therefore be maintained, he said.

Somsong Chotechuen, an agricultural scientist of the Pathum Thani Rice Research Centre of the Rice Department, said the work of Mr Apichart's team is significantly beneficial to rice development in the country as it advances it with the new molecular knowledge.