Friday, January 28, 2011

Arabidopsis Thaliana


Arabidopsis is an angiosperm, a dicot from the mustard family (Brassicaceae). It is popularly known as thale cress or mouse-ear cress. While is has no commercial value - in fact is considered a weed - it has proved to be an ideal organism for studying plant development.

Some of its advantages as a model organism:-

1. It has one of the smallest genomes in the plant kingdom: 115,409,949 base pairs of DNA distributed in 5 chromosomes (2n = 10).

2. Very little of this is "junk" DNA so most of the DNA encodes its 25,498 genes.

3. Transgenic plants can be made easily using Agrobacterium tumefaciens as the vector to introduce foreign genes.

4. The plant is small - a flat rosette of leaves from which grows a flower stalk 6-12 inches high.

5. It can be easily grown in the lab in a relatively small space.

6. Development is rapid. It only takes 5-6 weeks from seed germination to the production of a new crop of seeds.

7. It is a prolific producer of seeds (up to 10,000 per plant) making genetics studies easier.

8. Mutations can be easily generated (ex. by irradiating the seeds or treating them with mutagenic chemicals.

9. It is normally self-pollinated so recessive mutations quickly become homozygous and thus expressed.

10.Other members of its family cannot self-pollinate. They have an active system of self-incompatibility. Arabidopsis, however, has inactivating mutations in the genes - SRK and SCR - that prevent self-pollination in other members of the family.

11.However, Arabidopsis can easily be cross-pollinated to

   @ do genetic mapping and
   @ produce strains with multiple mutations.

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