Botany of this species is encoded by about 135 million base pairs of DNA, forming one of the smallest genomes among flowering plants. "Arabidopsis" was the first plant to have its genome sequenced, in 2000. The sequencing of some other relatively small genomes, of rice ("Oryza sativa") and "Brachypodium distachyon", has made them important model species for understanding the genetics, cellular and molecular biology of cereals, grasses and monocots generally. Model plants such as "Arabidopsis thaliana" are used for studying the molecular biology of plant cells and the chloroplast. Ideally, these organisms have small genomes that are well known or completely
Helitron (biology) Helitron (biology) Helitrons are one of the three groups of eukaryotic class 2 transposable elements (TEs) so far described. They are the eukaryotic rolling-circle transposable elements which are hypothesized to transpose by a rolling circle replication mechanism via a single-stranded DNA intermediate. They were first discovered in plants ("Arabidopsis thaliana" and "Oryza sativa") and in the nematode "Caenorhabditis elegans", and now they have been identified in a diverse range of species, from protists to mammals. Helitrons make up a substantial fraction of many genomes where non-autonomous elements frequently outnumber the putative autonomous partner. Helitrons seem to have a major role