Genetic diversity and relationship of endangered plant Magnolia officinalis (Magnoliaceae) assessed with ISSR polymorphisms

Twenty-eight populations of the rare medicinal plant Magnolia officinalis (Magnoliaceae) were sampled across its natural range, and inter-simple sequence repeats (ISSRs) markers were used to assess the genetic variation within and among populations. Twelve primer combinations produced a total of 137 unambiguous bands of which 114 (83.2%) were polymorphic. M. officinalis exhibited a relatively low genetic diversity at population level (the percentage of polymorphic loci PPB = 49.8%, Nei’s genetic diversity H = 0.194, Shannon’s information index I = 0.286). However, the genetic diversity at species level was relatively high (PPB = 83.2%; H = 0.342; I = 0.496). The coefficient of gene differentiation (GST, 42.8%) and the results of analysis of molecular variance (AMVOA) indicated that genetic differentiation occurred mainly within populations. The estimated gene flow (Nm) from GST was 0.669. It indicated that the fragmentation and isolation of populations might result from specific evolutionary history and anthropogenic activity. Genetic drift played a more important role than gene flow in the current population genetic structure of M. officinalis. Conservation strategies for this rare species are proposed based on the genetic data.

► This study reports on genetic diversity in the endangered species, M. officinalis.
► ISSR markers used to identify genetic variation and population differentiation.
► M. officinalis had low population-level genetic diversity.
► 666 individuals from 28 populations in China over a large geographical range was analyzed.
► This study is a very thorough investigation of the population genetics of M. officinalis.