Genetic variation in the endangered and endemic species Changium smyrnioides (Apiaceae)

Changium smyrnioides H. Wolff (Apiaceae) is an endangered plant endemic to Eastern China. Levels of genetic variation and patterns of population structure in C smyrnioides were investigated using inter-simple sequence repeat (ISSR) markers. Of the 100 primers screened, 18 produced highly reproducible ISSR bands. Using these primers, 196 discernible DNA fragments were generated with 166 (84.7%) being polymorphic, indicating considerable genetic variation at the species level. In contrast, there were relatively low levels of polymorphism at the population level with the percentage of polymorphic bands (PPB) ranging from 29.6% to 36.2%. Genetic diversity within populations ranged from 0.10 to 0.13, averaging 0.24 at the species level. A high level of genetic differentiation among populations was detected based on Nei's genetic diversity analysis (52.9%), Shannon's index analysis (54.3%) and AMOVA analysis (52.3%). No significant statistical differences (analysis of molecular variance [AMOVA], P = 0.6) in ISSR variation was found between regions. However, among populations (52.3% of the variance) and within populations (47.7% of the variance), there were significant differences (P < 0.001). Restricted gene flow (Nm = 0.446) among populations may result from several factors, such as low seed dispersal, isolation of populations and/or self-pollination. Limited gene flow among populations is a plausible reason for the high genetic differentiation observed for this species. (C) 2003 Elsevier Ltd. All rights reserved.