Saturday, June 2, 2012

The genes of Arabidopsis

Arabidopsis thaliana plants being grown in the Manna
Center for Plant Biosciences at Tel Aviv University
Arabidopsis isn't the most impressive plant in the world to look at. Chances are that you may even have walked on this little mustard plant and not given it a second thought. But arabidopsis has a few qualities that have made it the most influential plant in the world.

Arabidopsis has a very short life cycle, less than two months, is small, and each plant yields hundreds of not thousands of seeds. These three characteristics, coupled with the evolutionary quirk that arabidopsis has relatively a small amount of DNA, has made it the most studied plant in the world.

While Arabidopsis has almost the same number of genes (~25,000, but this is open to debate) as found in most plants and animals, it contains very little of a type of DNA that’s called "non-coding DNA" which made determining its sequence relatively easy to do. To put things in perspective, while Arabidopsis contains about 25,000 genes in 120 million nucleotides (the building blocks of DNA), wheat has the same number of genes in 16 billion nucleotides, and human beings have about 22,000 genes, less than the petite Arabidopsis, and in 2.9 billion nucleotides.  These numbers should be taken with a grain of salt as the precise definition of “gene” is evolving and with it the numbers. But the general trends and scales are correct.  Almost all of the genes found in Arabidopsis are also present in plants that are important agriculturally and economically, such as cotton and potato and poplar trees.


  1. It is good to see that it is accepted that there is no precise definition of a gene as of today. Is the definition of a gene going farther and farther away the more and more we know about the genetic material and its orgnisation?

    1. I try not to get too much into definitions. But, the more we know about genes, the less we actually have. So a a gene with 20 splice variants is now considered one gene, rather than 20.