The simple anwser is that plants researchers use Arabidopsis as a model
plant that has relevance to agriculturally important plants - The parallel
is that we do vast amounts of research on yeast, not because we are
interested in improving bread and beer, but because it's a model
eukaryote. Arabidopsis is a good plant model because :
1. it is very small and has a fast life cycle, thus several generations a
year can be grown by the tens of thousands in greenhouses or incubators.
That's not possible with crop species.
2. Beacuse you can grow many plants, you can find mutants easily.
3. The small genome (not small number of chromosomes, but small number of
kilobases) means that less effort would be required to sequence the
genome. Crop species have much larger gemones.
4. A coordinated effort by researchers around the world has resulted in
an ordered array of molecular markers on the genome. The mutants you find
in "2" can be mapped relative to these markers and the gene that is
mutated can be found and cloned by inching down the genome. This is much
easier (athough still lots of work) with a plant with a small genome. For
a plant with a large gemone and several sets of chromsomes as in most crop
plants, this would be almost impossible, even with unlimited numbers of
This ability to clone genes is part of what makes the research on
arabidopsis so important to crop plants. The economically important plants
have the same genes. Although they are not identical in sequence, they are
close enough that clones from arabidopsis can be used to isolate them.
In addition, the work on arabidopsis has greatly accelerated the
understanding of the molecular biology of plants. Because of the ability
to easily isolate mutants and find their genes, we now have genes for all
the fatty acid desaturases that determine oil quality. The genome of crop
species (such as canola) are being altered by biotech companies (like
Calgene) in order to make differnet kinds of oil - ones that are more
nutritional, for instance, or ones that have increased industrial value.
These different kinds of crops perhaps will benefit farmers by increasing
the market for agricultural production.
carries at nrel.gov