Origin and evolution of aus type fragrant rice (Oryza sativa L.) : A review

Abstract

Diversity in wild forms and landraces of a crop in a region is an indicator and the core tenet of determining its centre of origin. Jeypore tract of Odisha with diverse rice forms is considered as the earliest, independent rice domestication region of aus ecotype. The aus group of Asian cultivated rice is a distinct population with unique alleles for biotic and abiotic stress tolerance and high genetic diversity even in its fragrant accessions, detected at the molecular level. Annual wild rice Oryza nivara is considered as the progenitor of aus rice. The aus type fragrant rice is the original crop of Indian sub-continent, domesticated in hill areas by primitive tribes, around 4500 years ago. The Chinese japonica rice which came to India later, inherited chloroplast and nuclear genome from wild aus rice and the resulting hybrids formed the aromatic group. Loss or gain of phenotypic characters is the common feature of evolution. The aus landraces possessing characters such as black hull, red pericarp, poor panicle features, low grain yield, associated with wild rice species have evolved into cultivated forms from the intermediate stages of domestication. Considering the archeological evidences, genetic inferences and correlations of different investigations relating to aus type fragrant rice, Jeypore tract is regarded as the place of origin and evolution of this small but significant group of fragrant rice.