( qualify the value of the model genomes ...)One species, many genomes

Still, it is surprising that Arabidopsis has such a plastic genome. In contrast to the genome of humans or many crop plants such as corn, that of Arabidopsis is very much streamlined, and its size is less than a twentieth of that of humans or corn—even though it has about the same number of genes. In contrast to these other genomes, there are few repeats or seemingly irrelevant filler sequences. "That even in a minimal genome every tenth gene is dispensable, has been a great surprise," admits Weigel.

Detailed analyses showed that genes for basic cellular functions such as protein production or gene regulation rarely suffer knockout hits. Genes that are important for the interaction with other organisms, on the other hand, such as those responsible for defense against pathogens or infections, are much more variable than the average gene. "The genetic variability appears to reflect adaptation of local circumstances," says Weigel. It is likely that such variable genes allow plants to withstand dry or wet, hot or cold conditions, or make use of short and long growing seasons.

Such genome analyses of unprecedented details will allow a much better understanding of local adaptation, and this was indeed one of the main reasons for conduction the study. "By extending these types of studies to other species we hope to help breeders to produce varieties that are optimally adapted to rapidly changing environmental conditions," explains Weigel. He is already collaborating with the International Rice Research Institute (IRRI) in the Philippines to apply the methods and experience gathered with Arabidopsis to twenty different rice varieties. '"/>

Source:Max-Planck-Gesellschaft