Science - September 8, 2005

High-yielding dry rice is not an illusion

A high-yielding rice variety that requires less water; it isn’t just a dream according to Kurniawan Rudi Trijatmiko. The PhD candidate devoted his research to examining the role that drought resistance genes play in rice and Arabidopsis, a plant often used as a model in genetic research.

Demand for rice is likely to grow so much that it will not be possible to rely only on irrigated rice in the future. The very productive wet form of rice cultivation, which has been carried out in Asia for thousands of years, accounts for about three-quarters of the present world rice production. The combination of a growing world population and climate change, however, is likely even in the short term to lead to a shortage of fresh water for irrigation.

There is still a large difference in productivity between irrigated and non-irrigated rice. ‘Selecting rice for drought resistance is a complex matter, as there are many genes that influence this characteristic. Fortunately, recent developments in plant genomics have made it possible to try and select for this characteristic,’ says Dr Andy Pereira, a rice researcher at Plant Research International and one of Trijatmiko’s supervisors.

One thing researchers have notied is that the most important genes for drought resistance are still present in the high-yield rice varieties. It looks as though they are associated with the dwarf gene that was so important in the development of high-yield varieties during the Green Revolution. This also explains why the SHINE gene, responsible for drought resistance in Arabidopsis, also works in rice when it is introduced through genetic transformation.

‘Arabidopsis and rice are not closely related in the plant kingdom, but resistance to drought is a typically conservative trait that must have been present in plants at a very early stage in their evolution. Most of the genes are present, but we just need to help them a little,’ suggests Pereira.

The interesting thing about the SHINE gene is that it is responsible for a thicker waxy layer in Arabidopsis, leading to shiny leaves. Trijatmiko looked at whether the presence of the SHINE gene in rice also leads to extra wax on the leaves, but this turned out not to be the case. It is responsible however for fewer stomata in the leaves. This results in less water loss through evaporation, thus making the plant better able to survive drought.

In addition to the SHINE gene, a number of other genes that are involved in drought tolerance have also been identified. ‘We are now discussing the next step with our Indonesian partners: introducing these genes in cultivars that can be used there. We want to test these in the field,’ says Pereira.

The research is part of the Biotechnology Research Indonesia-Netherlands (BIORIN) project that is financed by the Netherlands Academy for Arts and Sciences (KNAW). This in turn is part of the Generation Challenge Program of which Pereira is coordinator for the International Rice Research Institute (IRRI). / GvM

Kurniawan Rudi Trijatmiko received his PhD on Wednesday 7 September, under Professor Evert Jacobsen, chair of plant breeding.