The gene, referred to as SPIKE, was discovered in a japonica rice variety called Daringan by scientists at the Japan International Research Centre for Agricultural Science (JIRCAS) and the Philippine-based International Rice Research Institute (IRRI).
When inserted into indica rice — which accounts for 70 per cent of global rice production — the gene could boost productivity by up to 36 per cent, showed the study published in the Proceedings of the National Academy of Sciences (2 December).
Researchers have long noted japonica rice varieties for such characteristics as large leaves and panicles (the branch structure of the rice plant that bears the grains), a vigorous root system, and thick stems — all characteristics that are related to higher potential yields, an IRRI press statement said.
However, japonica plants are grown in only about ten per cent of farms worldwide because of their longer harvesting period compared with indica varieties reducing the number of cropping times, says Tsutomu Ishimaru, a plant breeder from IRRI and JIRCAS and one of the authors of the paper.
Ishimaru says the yield from variety indica IR64 bred to express the SPIKE gene was 13 to 36 per cent higher compared with the regular crop. In the rice variety indica IRRI146 the output was 18 per cent higher.
The gene is now being tested on several commonly consumed rice varieties of rice in Bangladesh, India, Indonesia, Laos and the Philippines, he says.
But it would likely take another 3 to 4 years before a rice variety with the SPIKE gene will be available for commercial planting, Ishimaru says.
He also emphasises that the technique used in inserting the SPIKE gene into rice plants is not a genetic modification.
“This is not GM rice. We use marker-assisted breeding using DNA markers,” he says.
Marker-assisted breeding is the combination of molecular genetics with conventional breeding where two varieties are crossed in the traditional way and the resulting types are selected using a DNA-marker, in this case the SPIKE gene, Ishimaru says.
Aris Hairmansis, a plant geneticist at the Indonesian Institute for Rice Research in West Java, says this finding is good news for rice breeders but it would be better to combine this SPIKE gene with other genes that can regulate the efficiency of fertiliser absorption.
“I think the next step is how to manage the cultivation of these new varieties in the field. If we want maximal output, we need optimal input such as the [the amount of] fertilisers,” Hairmansis says.
Link to full paper