The extent of clonality and genetic diversity in Sagittaria lichuanensis (Alismataceae), an endemic marsh herb in China

摘要

Genetic variation and clonal diversity of seven natural populations of the rare, highly clonal marsh herb Sagittaria lichuanensis were investigated using inter-simple sequence repeat (ISSR) markers. Of the sixty-five ISSR primers screened, seven produced highly reproducible bands. Using these primers, a total of 76 DNA fragments were generated with 22 (29.0%) being polymorphic, indicating lower genetic variation at the species level compared to others in the same genus. With the use of 22 polymorphic markers, we were able to identify 9 genets among the 231 samples analyzed. The proportion of distinguishable genets (PD: mean 0.039), Simpson's diversity index (D: mean 0.309), and evenness (E: mean 0.292) exhibited low levels of clonal diversity compared to other clonal plants. The result implies that sexual reproduction might not have played an important role in these populations. The founder effect or the bottleneck effect could be responsible for the current pattern of the genetic variation revealed in S. lichuanensis populations.