Genetic Diversity of Isolated Populations of Indonesian Landraces of Rice (Oryza sativa L.) Collected in East Kalimantan on the Island of Borneo

Although the genetic diversity of rice germplasm has been well characterized globally, few studies have taken an in-depth view of a large number of rice landraces on a local scale. To better understand the relationships between rice genetic diversity and associated geographic and cultural factors, we collected and characterized 183 rice landraces from 18 villages along the Bahau and Kayan rivers in the Indonesian province of East Kalimantan on the island of Borneo. A genetic diversity analysis using 30 microsatellite markers detected a clear distinction between the indica and japonica varietal groups (F-st=0.59), with 80% of the landraces identified as tropical japonica and 20% indica, which largely correlated with the field-level ecotypes: upland japonica and lowland indica. Indigenous knowledge from local farmers was gathered about the names, origins, and uses of the landraces, which provides a rich background to compare with the genetic relationships of these traditional varieties.