There are about 100 genes in Arabidopsis that are closely related to human disease genes

Prof Mike Bevan, John Innes Centre

It is estimated that there are about 250,000 flowering plants and they can be found in every ecosystem on our planet. They convert sunlight and carbon dioxide into food and useful chemicals.

It is thought that flowering plants also produce at least 100,000 other substances not found in animals, many of which provide the basis for medicines.

Understanding how flowering plants do this could help scientists make new drugs with which to fight disease.

All living things

The split between plants and animals occurred about 1.6 billion years ago.

Flowering plants evolved about 200 million years ago and mankind started to domesticate plants only 8,000 years ago. The timescale is important.

It means that the 26,000 genes in the Arabidopsis genome are found almost everywhere.

The emergence of flowering plants is recent in evolutionary terms, so Arabidopsis must have most of its genes in common with all other plants.

The study of this convenient plant will therefore aid our understanding of all plants and indeed of the way evolution works on a molecular and genetic level.

Be clear about it: all other living things on Earth, including humans, are relatives of Arabidopsis. Most of its genes have counterparts in animals.

Hardy plants

How those genes work in plants will provide a unique insight into how they work in animals.

"There are about 100 genes in Arabidopsis that are closely related to human disease genes - diseases such as hereditary deafness, blindness and cancers," Professor Mike Bevan, the European co-ordinator for the Arabidopsis Genome Initiative, said.

"This shows that many basic processes such as the ability of an organism to repair damage to its DNA, which occurs due to environmental insult, are deeply conserved between plants and animals."

These mechanisms which are associated with maintaining genome stability allow Arabidopsis to grow in varying climatic conditions.

Learning just how they work will assist plant scientists in making economic crops more hardy.

How like us

Analysis of the gene sequence suggests that so-called signalling pathways that respond to bacteria and parasites may be more abundant in plants than in other animals.

Professor Richard Wilson, of the Washington University School of Medicine, said: "Just as animals have immune systems, plants have ways of protecting themselves too.

Just as animals have immune systems, plants have ways of protecting themselves too

Professor Richard Wilson

"As scientists begin to understand the genes that code for protective proteins, they may be able to make plants more resistant not only to diseases but to insects, wind and drought."

Many of the Arabidopsis genes are responsible for the upkeep of the strong cell wall, something that animals lack. Their particular functions are crucial to the fundamental difference between animals and plants.

Overall the Arabidopsis genome underscores just how inter-related are all living things on Earth.

"Even though both plants and animals have dealt with the issues of multi-cellular existence for over 1.5 billion years, they've dealt with that in parallel tracks," Dr Richard Gallagher, chief biological sciences editor at the journal Nature, said.

"This means that comparisons between plants and animals are going to tell us a huge amount about the constraints on biology and a huge amount about evolution. This is what I find particularly exciting about Arabidopsis thaliana."