Assessment of genetic diversity among androdioecious ancient Osmanthus fragrans trees by SSR markers

• In this paper, the genetic diversity of Osmanthus fragrans, one of the nine androdioecious species in seed plants, was detected.
• The present study is the first report on microsatellite-based characterization of androdioecious ancient O. fragrans trees.
• The observed and expected heterozygosities of hermaphrodites were higher than males in ancient O. fragrans trees.

The well known ornamental plant, Osmanthus fragrans, is one of the rare androdioecious species in nature. Determining the genetic diversity of this species may assist in its conservation and genetic improvement. Data of 10 ancient tree populations of O. fragrans were used to assess its genetic diversity and population structure with microsatellite markers. A high level of genetic diversity was observed with POPGENE. As anticipated the heterozygosity of ancient hermaphrodite trees was higher than male ones, although the number of hermaphrodites was far fewer than males. Abundant gene exchange between males and hermaphrodites was detected, and trees from the same population often clustered together. Androdioecy is an important factor that determines the genetic structure of O. fragrans and there is an urgent need to conserve ancient O. fragrans germplasms especially the hermaphrodites.