Wageningen scientist discovers genes that increase yield on marginal soils

The constantly rising world population and the changing climate will make it essential in the future to cultivate crops in soils where current varieties are unproductive. These so-called marginal soils are often too dry or contain too much salt for cultivation. There are many such areas around the world that are currently not being used for food production, and climate change will lead to huge increases in marginal soils.

Varieties that are less susceptible to drought and/or salt might make it possible to grow crops in marginal soils. Within plant biology, there are mechanisms known which allow plants to protect themselves against the a biotic stress caused by a lack of water or excessive salt. Using the genes which set these mechanisms into action and genetic modification, varieties can be developed which make the most of these mechanisms and are therefore resistant to drought and salt.

Shital Dixit studied the so-called 'HARDY' gene, found in a collection of Arabidopsis mutants in which certain jumping genes increase the activity of genes. Via genetic modification, Dixit developed Arabidopsis plants in which the HARDY gene was more active. She discovered that these genetically modified plants grew better under drought stress than ordinary Arabidopsis plants. The 'HARDY plants' used water more efficiently than normal plants. During desiccation of the soil, the plants were found to vaporise considerably less water while maintaining their growth. When the soil was dry, the HARDY plants lived on and recovered after being given water. They also proved to be resistant against high saline concentrations in the soil.

By means of genetic modification, Dixit managed to transfer the HARDY gene to rice. The HARDY rice plants also turned out to be tolerant to both drought and salt. To Dixit’s surprise, these improved rice plants also performed at least as well in optimal cultivation conditions as ordinary rice plants. The general rule in plant biology is that plants with increased stress tolerance perform worse in optimal conditions than plants without tolerance. This makes the HARDY system even more promising in practical applications.

The HARDY gene encodes for a so-called transcription factor, meaning that a whole chain of genes is regulated. A plant can therefore turn an entire drought or salt tolerance mechanism on or off with a single switch. Dixit also discovered that the SHINE gene, which also encodes for a transcription factor, is capable of making rice tolerant to salt as well.

In her research, Dixit showed how a large group of plants with mutations that cause genes to be more active can be valuable for tracking genes that increase stress tolerance. Dixit selected two mutants from one of these plant groups, which after more detailed research proved to use water more efficiently and to have a tolerance for higher saline concentrations.

Dixit performed her research at Plant Research International (Wageningen UR). It was financed by the WOTRO programme of The Netherlands Organisation for Scientific Research (NWO).