Three varieties of the Asian cultivated rice ( Oryza sativa L.) were used to develop the genetic map: Balilla, Dular and Nanjing 11. Balilla is a japonica variety from Italy, Dular is an indica variety from India and Nanjing 11 is an indica variety in China. A cross was made between Balilla and Dular, and the resulting F₁ plants were crossed to Nanjing 11.
A map, including 159 RFLP loci and one morphological marker locus, was constructed on the basis of 235 of the 281 true hybrid plants using MAPMAKER. The total length of the map was 1674 cM, with an average distance of 10.9 cM between adjacent loci. The chromosome 1 map has been updated based on recent publication from the same lab.