Chromosome and genome evolution in rice

Abstract

Genomic and species divergences in rice offer a major advantage in genetic and evolutional studies, as well as for practical breeding purposes. The genus Oryza is classified into nine genomes comprising 23 species (two cultivated and 21 wild). Classification of the genome has been made based on the ability of a known tester genome to form paired bivalent chromosomes during meiosis in an F1 hybrid with an accession of unknown genome. Varied levels of partial sterility have been observed in the crosses between a variety of accessions, both across species as well as within a species, suggesting continuous evolution of the genome. The pattern of genome and chromosomal evolution of the genus Oryza and of the family Poaceae has been resolved progressively over the last decades. The observed results, possible relationships and impact on genome and chromosome evolution are reviewed in this chapter.