Wageningen, The Netherlands
March 12, 2008
Genetically modified plants can be
developed that perform significantly better than existing
varieties in dry and saline soils. This is the conclusion of the
doctorate thesis, to be defended by Shital Dixit at Wageningen
University on March 14. Dixit discovered genes that radically
enhance the seed production of rice and Arabidopsis plants in
dry and saline conditions. This is a major breakthrough
considering the rising demands for food and the effects of
climate change.
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).
The Plant Sciences Group of
Wageningen UR is a collaboration of:
- Plant Research International B.V.
- Applied Plant Research (Praktijkonderzoek Plant & Omgeving
B.V.)
- Wageningen University |
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