The mapping population consisted of 353 (BC₂F₁) plants derived from a cross between Jefferson and O. rufipogon (IRGC 105491). The O. sativa cultivar Jefferson, a long-grain tropical japonica cultivar, has been used as the recurrent parent. It is a high-yielding variety, with a semi-dwarf plant type, a high level of disease resistance, early maturity, and good grain quality. The donor parent, O. rufipogon (IRGC 105491), is an accession of the presumed wild relative of rice and has been previously chosen to be a common donor parent for multiple wild QTL studies. The linkage map consisted of 153 microsatellite and RFLP markers distributed along 12 chromosomes. The average intermarker distance was 10.3 cM and the total distance was 1457 cM.