History of plant breeding and a cultivated crop species that has evolved from wild populations due to selective pressures from traditional farmers is called a landrace. Landraces, which can be the result of natural forces or domestication, are plants or animals that are ideally suited to a particular region or environment. An example are the landraces of rice, "Oryza sativa" subspecies "indica", which was developed in South Asia, and "Oryza sativa" subspecies "japonica", which was developed in China. For more on the mechanisms of domestication, see Hybrid (biology). Humans have traded useful plants from distant lands for centuries, and plant hunters have been sent
Plant genome assembly products were used to clone remaining gaps, and YACs allowed the characterization of telomere sequences. The resulting sequenced regions were 115.4 Mb of the 125 Mb predicted size of the genome and a total of 25,498 of protein-coding genes. To sequence and assemble the genome of Oryza Sativa (japonica), the same strategy was used. For Oryza Sativa a total of 3,401 mapped clones in a minimum tiling path were selected from the physical map and assembled. One of the most important crops in the world, maize (Zea mays), is the last plant genome project primarily based on Sanger BAC-by-BAC strategy.