Genetic variation within the endangered quillwort Isoëtes hypsophila (Isoetaceae) in China as evidenced by ISSR analysis

The genetic diversity of 56 individuals of Isoëtes hypsophila Hand.-Mazz. from China was investigated by ISSR. Twelve primers were screened from 65 primers, and a total of 119 DNA fragments were scored, of these, 82% were polymorphic bands, which indicated that high levels of genetic variation existed in the natural populations. Genetic diversity varied greatly among populations with the percentage of polymorphic band (PPB) values ranging from 8 to 35%. An analysis of molecular variance (AMOVA) was used to apportion the variation between regions, among populations within regions, and within populations. Results indicated that most of the variance (85%) occurred between Yunnan and Sichuan. The variances among populations within regions and within populations, however, were only 5 and 10%, respectively. In the among-population analysis, the larger part of genetic variation (77%) resided among populations, and less (23%) presented differences within populations. UPGMA cluster analysis showed that there was no distinct genetic differentiation between populations from Sichuan province. A number of causes including limited gene flow, genetic drift and inbreeding might have led to these observed genetic profiles of I. hypsophila.