The first intraspecific genetic linkage maps of wintersweet [Chimonanthus praecox (L.) Link] based on AFLP and ISSR markers

Wintersweet [Chimonanthus praecox (L.) Link] (n = 11), a dichogamous species, is a famous traditional fragrant flower plant in China. We used AFLPs and ISSR to construct a genetic linkage map on a pseudo-F2 population of wintersweet derived from a cross between the individuals H4 and H29. A total of 370 polymorphism markers was generated from 12 AFLP primer combinations and 9 ISSR primers. Two separate female and male maps were constructed using 84 female-specific and 51 male-specific testcross markers, respectively. The maternal H4 map included 80 markers ordered in 12 linkage groups; while the paternal H29 map had 47 markers in 8 linkage groups. At a minimum logarithm of the odds (LOD) score of 3.0 and maximum map distance of 50 cM, the female map covered 2417.8 cM, with an average distance of 25.61 cM and maximum map distance of 48.2 cM between two loci. In contrast, the male map covered 1184.2 cM, with an average distance of 25.7 cM and maximum map distance of 49.0 cM between two loci. These genetic maps will serve as a framework for mapping QTLs and provide basic information for future molecular breeding studies.