Oryza sativa, commonly known as Asian rice or indica rice, is the plant species most commonly referred to in English as rice. It is the type of farmed rice whose cultivars are most common globally, and was first domesticated in the Yangtze River basin in China 13,500 to 8,200 years ago. Oryza sativa belongs to the genus Oryza of the grass family Poaceae. With a genome consisting of 430Mbp across 12 chromosomes, it is renowned for being easy to genetically modify and is a model organism for the botany of cereals. Classification Oryza sativa contains two major subspecies: the sticky, short-grained japonica or sinica variety, and the nonsticky, long-grained rice variety. Japonica was domesticated in the Yangtze Valley 9–6,000 years ago, and its varieties can be cultivated in dry fields (it is cultivated mainly submerged in Japan), in temperate East Asia, upland areas of Southeast Asia, and high elevations in South Asia, while indica was domesticated around the Ganges 8,500-4,500 years ago, and its varieties are mainly lowland rices, grown mostly submerged, throughout tropical Asia. Rice occurs in a variety of colors, including white, brown, black, purple, and red rices. Black rice (also known as purple rice) is a range of rice types, some of which are glutinous rice. Varieties include Indonesian black rice and Thai jasmine black rice. A third subspecies, which is broad-grained and thrives under tropical conditions, was identified based on morphology and initially called javanica, but is now known as tropical japonica. Examples of this variety include the medium-grain 'Tinawon' and 'Unoy' cultivars, which are grown in the high-elevation rice terraces of the Cordillera 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. Nomenclature and taxonomy Rice has been cultivated since ancient times and oryza is a classical Latin word for rice while sativa means "cultivated". Genetics / is a gene that regulates the overall architecture/growth habit of the plant. Some of its epialleles increase rice yield. An accurate and usable Simple Sequence Repeat marker set was developed and used to generate a high-density map in McCouch et al., 2002. A multiplex high-throughput marker assisted selection system has been