[Population genetic structure and interspecific introgressive hybridization between Camellia meiocarpa and C....

A total of 11 pairs of SSR primers were applied to study the genetic diversity of five sympatric populations of Camellia meiocarpa and C. oleifera, the populations' genetic structure, and the interspecific introgressive hybridization. The alleles shared by the two species were 57, accounting for 96.6% of the total. There were two specific alleles in C. oleifera, but no specific alleles in C. meiocarpa. Certain difference was observed in the phenotypic frequency between the two species, and the intraspecific genetic diversity of the two species was high. At species level and population level, the polymorphism information content of the two species was between 0.25 and 0.50, suggesting that the genetic polymorphism was moderate. The mean value of genetic differentiation among the sympatric species was 0. 057, being obviously lower than that of the foreign species (C. meiocarpa 0.332; C. oleifera 0.201) and of xyloid angiosperms (0.102). The mean value of gene flow among the sympatric species was 10. 072, which was significantly higher than that among the foreign species (C. meiocarpa 1.006, C. oleifera 1.990). The UPGMA cluster results showed that the genetic relationship of the two species was very close to, meaning that there existed an obvious interspecific introgressive hybridization. C. meiocarpa was possibly a variety of C. oleifera as a result of the introgressive hybridization.