Genetic linkage groups based on population Y13Zh (Yueyou 13 × Zhenzhuhei). RIL (recombinant inbred line) population Y13Zh consisted of 142 lines, derived from a cross made from the female parent Yueyou13, a Spanish type with high yield, and male parent Zhenzhuhei, a Virginia type with dark purple testa and high protein (32.4%) content. Linkage analysis was performed with JoinMap using a minimum LOD score of 3.0 and linkage maps were drawn using MapChart for Windows. Underlined markers were EST-SSRs. Markers that showed significant distortions from 1:1 segregation are indicated by *. Markers that amplified two loci are designated by an Arabic number (-1 or -2) appended to the locus name to distinguish the two loci 1 and 2 after the marker name.