Oryza sativa Mountains of northern Luzon, Philippines. Glaszmann (1987) used isozymes to sort "O. sativa" into six groups: "japonica", "aromatic", "indica", "aus", "rayada", and "ashina". Garris "et al." (2004) used simple sequence repeats to sort "O. sativa" into five groups: "temperate japonica", "tropical japonica" and "aromatic" comprise the "japonica" varieties, while "indica" and "aus" comprise the "indica" varieties. Rice has been cultivated since ancient times and "oryza" is a classical Latin word for rice. "Sativa" means "cultivated". Debates on the origins of the domesticated rice are numerous. In 2011, genetic evidence showed that all forms of Asian rice, both "indica" and "japonica",
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