Genome Sizes Are Changing

Research by  scientists from the Max Planck Institute for Developmental Biology in Tübingen, have shown reduction in genome size in close relative plants in the genus Arabidopsis.  They used the Thale cress plant, the most widely studied flowering plant in genetics, and its relative the lyre-leaved rock cress. Both plants shared a common ancestor around ten million years ago and their lineages have sinced divereged. The genome of the thale cress has been decoded to have 125 million base pairs and includes 27,025 genes distributed on five chromosomes.  The lyre-leaved rock cress produced a base pair sequence with  207 million base pairs or letters which is over 50 percent bigger than that of the thale cress.  Scientists are thinking that the difference between the two species, in term of their number of genes, is not that significant because the lyre-leaved rock cress has around 32,670 genes distributed on eight chromosomes. They also say considerable parts of the thale genome have been lost. Although many differences are accounted for through small deletions in the transposons, sequences of DNA that can move, other elements are still being lost from the thale genome.  They also consider the fact that the lyre-leaved rock cress has eight chromosomes and conclude the thale cress genome is a "more streamlined genome as the form derived through evolution." Through their analysis, the scientists have laid the foundations for further insights into how evolution in plants can take effect on the level of genes and molecules.