Oryza glaberrima plant multiple different varieties, to suite varying microhabitats and to stagger the harvest. A 2006 survey showed that a village typically cultivated 25 varieties of rice; an individual household would on average have 14 varieties and grow four per year; this, however, is down from the seven to nine varieties per woman that was average in previous decades. Women, who are traditionally responsible for the seeds, trade them often over long-distance networks. Varieties, each with subtypes, include: The cultivars the Africa Rice Center calls TOG 12303 and TOG 9300 have low shattering, and thus yields comparable with low-shattering Asian rice
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