Selecting optimal F1 segregation population for genetic linkage mapping in tree peony

We established three large F1 segregation populations of tree peony (Paeonia Sect. Moutan) through controlled hybridization, using three seeding individuals of P. ostti ‘Fengdan’ as female parents, labeled as M24, M49 and M68, and using P.×suffruticosa Zhongyuan Group ‘Hongqiao’, P.×suffruticosa Japan Group ‘Huawang’ and ‘Hei Longjin’ as male parents, correspondingly. The number of progeny of the three populations is 366, 233 and 197, respectively. We detected the levels of polymorphism between parents of the three segregation populations by employing 19 pairs of simple sequence repeat (SSR) primers. The results showed that, 19 pairs of SSR primers could produce the most informative polymorphism loci of 27 between the ‘Fengdan’ M24 and ‘Hongqiao’ among the parents of three segregation populations. The genetic distance between ‘Fengdan’ M24 and ‘Hongqiao’ was 0.707 0, the farthest among the parents of three segregation populations. Therefore, the segregation population of ‘Fengdan’ M24 × ‘Hongqiao’ was selected for the construction of genetic linkage map in tree peony. On this basis, segregations of genotype in randomly selected 195 progeny from mapping population were investigated using SSR marker. Of 19 pairs of SSR primers, 15 pairs showed the polymorphisms in mapping population, and 13 pairs (86.7%) of them segregated in an expected Mendelian ratio (P0.01). Furthermore, hereditary variations in plant height, ground diameter, current year branch length, compound leaf length, compound leaf width, and petiole length of those 195 progeny were measured and analyzed. The results indicated that the differences of the 6 phenotypic traits of mapping population were significant, and their variation coefficients were all greater than 15%. All above lead to the conclusion that segregation population of ‘Fengdan’ M24 × ‘Hongqiao’ was optimal for the construction of genetic linkage map in tree peony.