Genetic diversity of an amphicarpic species, Amphicarpaea edgeworthii Benth. (Leguminosae) based on RAPD markers

Amphicarpaea edgeworthii Benth. is an amphicarpic legume widespread in China. Amphicarpy describes the phenomenon that a plant produces aerial as well as subterranean fruits. A. edgeworthii can reproduce via three kinds of flowers: aerial chasmogamous flowers, aerial cleistogamous flowers, and subterranean cleistogamous flowers. Although there are some studies on the population genetic structure of species with both chasmogamous and cleistogamous flowers, none has been done for that of an amphicarpic species so far. The present study uses random amplified polymorphic DNA (RAPD) to assess level and pattern of genetic variation in 15 natural populations of A. edgeworthii. A total of 131 stable and clearly scored RAPD bands were achieved from 13 primers. The average genetic diversity within populations estimated by Shannon's information index was 0.218 at the population level, but ranged from 0.119 to 0.302, which was significantly different (P < 0.01). Different statistical analyses revealed a high level of genetic differentiation among populations (GST = 0.473-0.527). Thus, the pattern of genetic structure of A. edgeworthii is consistent with that of an inbreeding species.