Recovery of genetic diversity in threatened plants through use of germinated seeds from herbarium specimens

Abstract

The reintroduction of ex situ conserved individuals is an important approach for conserving threatened plants and reducing extinction risk. In this study, we elucidated the effects on the genetic diversity of wild populations of Vincetoxicum pycnostelma Kitag. [=Cynanchum paniculatum (Bunge) Kitag.] by modelling the genetic consequences of reintroducing plants using the germinated seeds of herbarium specimens. This semi-natural grassland herb is threatened in Japan. First, we tested the germinability of seeds from herbarium specimens collected from nine sites in Kinki and Tokai districts, Japan (one specimen per site, total 206 seeds). Next, we analysed the genetic diversity and structure of germinated seedlings and the current wild individuals using nine polymorphic microsatellite markers. Germination was observed for 38 seeds (18.4 %) from four specimens collected 3–18 years prior to the study. Although the genetic diversity of the specimens’ seeds was lower than that of the wild population because of the small sample size, the seedlings from specimens taken from three sites had unique alleles that did not exist in the wild populations. Consequently, viable herbarium specimens’ seeds with unique alleles could be useful resources for recovering the genetic diversity in threatened wild plant populations.